Pluto 1
Author's First Image WITH Pluto!!!
Pluto entering...
SEDS (Students for the Exploration and
Development of Space) Homepage
Lots of Pluto Web
Sites
Pluto Express
Pluto has several homepages
Gemini infrared
views of Pluto and Charon
NASA-funded researchers have discovered the most distant object orbiting Earth's sun. The object is a mysterious planet-like body three times farther from Earth than Pluto.
"The sun appears so small from that distance that you could completely block it out with the head of a pin," said Dr. Mike Brown, California Institute of Technology (Caltech), Pasadena, Calif., associate professor of planetary astronomy and leader of the research team. The object, called Sedna for the Inuit goddess of the ocean, is 13 billion kilometers (8 billion miles) away, in the farthest reaches of the solar system.
This is likely the first detection of the long-hypothesized "Oort cloud," a faraway repository of small icy bodies that supplies the comets that streak by Earth. Other notable features of Sedna include its size and reddish color. After Mars, it is the second reddest object in the solar system. It is estimated Sedna is approximately three- fourths the size of Pluto. Sedna is likely the largest object found in the solar system since Pluto was discovered in 1930.
Brown, along with Drs. Chad Trujillo of the Gemini Observatory, Hawaii and David Rabinowitz of Yale University, New Haven, Conn., found the planet-like object, or planetoid, on Nov. 14, 2003. The researchers used the 48-inch Samuel Oschin Telescope at Caltech's Palomar Observatory near San Diego. Within days, telescopes in Chile, Spain, Arizona and Hawaii observed the object. NASA's new Spitzer Space Telescope also looked for it.
Sedna is extremely far from the sun, in the coldest know region of our solar system, where temperatures never rise above minus 240 degrees Celsius (minus 400 degrees Fahrenheit). The planetoid is usually even colder, because it approaches the sun only briefly during its 10,500- year solar orbit. At its most distant, Sedna is 130 billion kilometers (84 billion miles) from the sun, which is 900 times Earth's solar distance.
Scientists used the fact that even the Spitzer telescope was unable to detect the heat of the extremely distant, cold object to determine it must be less than 1,700 kilometers (about 1,000 miles) in diameter, which is smaller than Pluto. By combining available data, Brown estimated Sedna's size at about halfway between Pluto and Quaoar, the planetoid discovered by the same team in 2002.
The elliptical orbit of Sedna is unlike anything previously seen by astronomers. However, it resembles that of objects predicted to lie in the hypothetical Oort cloud. The cloud is thought to explain the existence of certain comets. It is believed to surround the sun and extend outward halfway to the star closest to the sun. But Sedna is 10 times closer than the predicted distance of the Oort cloud. Brown said this "inner Oort cloud" may have been formed by gravity from a rogue star near the sun in the solar system's early days.
"The star would have been close enough to be brighter than the full moon, and it would have been visible in the daytime sky for 20,000 years," Brown explained. Worse, it would have dislodged comets farther out in the Oort cloud, leading to an intense comet shower that could have wiped out some or all forms of life that existed on Earth at the time.
Rabinowitz said there is indirect evidence that Sedna may have a moon. The researchers hope to check this possibility with NASA's Hubble Space Telescope. Trujillo has begun to examine the object's surface with one of the world's largest optical/infrared telescopes, the 8-meter (26- foot) Frederick C. Gillett Gemini Telescope on Mauna Kea, Hawaii. "We still don't understand what is on the surface of this body. It is nothing like what we would have predicted or what we can explain," he said.
Sedna will become closer and brighter over the next 72 years, before it begins its 10,500-year trip to the far reaches of the solar system. "The last time Sedna was this close to the sun, Earth was just coming out of the last ice age. The next time it comes back, the world might again be a completely different place," Brown said.
NASA's Jet Propulsion Laboratory, Pasadena, Calif, manages the Spitzer Space Telescope. For more information about the research and images on the Internet, visit:The planetoid, currently known only as 2004 DW, could be even larger than Quaoar--the current record holder in the area known as the Kuiper Belt--and is some 4.4 billion miles from Earth.
According to the discoverers, Caltech associate professor of planetary astronomy Mike Brown and his colleagues Chad Trujillo (now at the Gemini North observatory in Hawaii), and David Rabinowitz of Yale University, the planetoid was found as part of the same search program that discovered Quaoar in late 2002. The astronomers use the 48-inch Samuel Oschin Telescope at Palomar Observatory and the recently installed QUEST CCD camera built by a consortium including Yale and the University of Indiana, to systematically study different regions of the sky each night.
Unlike Quaoar, the new planetoid hasn't yet been pinpointed on old photographic plates or other images. Because its orbit is therefore not well understood yet, it cannot be given an official name.
"So far we only have a one-day orbit," said Brown, explaining that the data covers only a tiny fraction of the orbit the object follows in its more than 300-year trip around the sun. "From that we know only how far away it is and how its orbit is tilted relative to the planets."
The tilt that Brown has measured is an astonishingly large 20 degrees, larger even than that of Pluto, which has an orbital inclination of 17 degrees and is an anomaly among the otherwise planar planets.
The size of 2004 DW is not yet certain; Brown estimates a size of about 1,400 kilometers, based on a comparison of the planetoid's luminosity with that of Quaoar. Because the distance of the object can already be calculated, its luminosity should be a good indicator of its size relative to Quaoar, provided the two objects have the same albedo, or reflectivity.
Quaoar is known to have an albedo of about 10 percent, which is slightly higher than the reflectivity of our own moon. Thus, if the new object is similar, the 1,400-kilometer estimate should hold. If its albedo is lower, then it could actually be somewhat larger; or if higher, smaller.
According to Brown, scientists know little about the albedos of objects this large this far away, so the true size is quite uncertain. Researchers could best make size measurements with the Hubble Space Telescope or the newer Spitzer Space Telescope.
The continued discovery of massive planetoids on the outer fringe of the solar system is further evidence that objects even farther and even larger are lurking out there. "It's now only a matter of time before something is going to be discovered out there that will change our entire view of the outer solar system," Brown says.
The team is working hard to uncover new information about the planetoid, which they will release as it becomes available, Brown adds. Other telescopes will also be used to better characterize the planetoid's features.Comet-chasing mission Rosetta will now set its sights on Comet Churyumov-Gerasimenko. During its meeting on 13-14th May 2003, ESA's Science Programme Committee decided Rosetta's new mission baseline. The spacecraft will be launched in February 2004 from Kourou, French Guiana, using an Ariane-5 G+ launcher. The rendezvous with the new target comet is expected in November 2014.
http://sci.esa.int/content/news/index.cfm?aid=13&cid=36&oid=32381
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JPL press releases, November 2, 2002, and November 4, 2002
NASA's Stardust spacecraft successfully completed a close flyby of asteroid Annefrank early today, Nov 2, as an opportunity for a full dress rehearsal of procedures the spacecraft will use during its Jan. 2, 2004, encounter with it primary science target, comet Wild 2.
Annefrank is about 4 kilometers (2.5 miles) across. Stardust passed within about 3,300 kilometers (2,050 miles) of the asteroid at 04:50 today, Universal Time (8:50 p.m. Nov. 1, Pacific Standard Time). Radio signals confirming the basic health of the spacecraft after the flyby were received about 30 minutes later via an antenna at the Canberra, Australia, complex of NASA's Deep Space Network, said Thomas Duxbury, project manager for Stardust at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
Stardust visually tracked the asteroid for 30 minutes as it flew by at a relative speed of about 7 kilometers (4 miles) per second, a major goal of this test opportunity. Although no dust was anticipated near the asteroid, the spacecraft's dust instruments were in use as they will be at Wild 2: the dust collector was open and the dust counter from the University of Chicago and dust mass spectrometer from Germany were turned on.
Images and information from the flyby period are being transmitted from the spacecraft today and through the coming week. Stardust's scientists and engineers are analyzing the data to maximize the probability of success during the 2004 encounter with comet Wild 2.
November 4, 2002
Late Friday evening Pacific time on November 2, 2002 at the Jet Propulsion Laboratory (JPL) in Pasadena, California, and at Lockheed Martin Space Systems - Astronautics (LMA) near Denver, Colorado, the NASA STARDUST flight team pulled off a tremendously successful close flyby of the main belt asteroid Annefrank. This flyby was used as an engineering test of the ground and spacecraft operations that will be implemented at the primary scientific target, Comet Wild 2 (pronounced "Vilt" 2) just over one year from now.
STARDUST is a low-cost Discovery Mission that continues to perform as expected after more than three and a half years into a planned seven-year mission to rendezvous with Comet Wild 2 in January 2004. STARDUST will collect cometary dust samples, flowing from the nucleus just hours before spacecraft flyby, and return the samples to Earth in a Sample Return Capsule in January 2006. The close flyby of Annefrank offered a unique opportunity to thoroughly test all planned operations on the spacecraft and ground support operations which will be used during the rendezvous with Comet Wild 2.
"We performed a full dress rehearsal with the cometary dust collector deployed as we flew STARDUST within 3,300 kilometers of Annefrank," said Professor Donald Brownlee, the project's Principal Investigator from the University of Washington. "The spacecraft was poised in its flyby attitude with all the science instruments on. The flyby has exceeded all of our expectations and provided us with unexpected data about the asteroid," said Brownlee.
The approach geometry to Annefrank was much more difficult than will be the case for Comet Wild 2. The spacecraft was pointed over 60 degrees off of the normal Sun and Earth pointing attitude and was running on its battery in order to attempt to detect and capture images of Annefrank.
"The spacecraft performed every command perfectly and did everything asked of it," said Allan Cheuvront, Spacecraft Engineer at Lockheed Martin Space Systems near Denver. "We are thrilled with how well the entire operation went. We couldn't have asked for better performance from STARDUST and the images it captured of the asteroid exceeded everyone's expectations. The spacecraft's pointing, attitude and flight operations were excellent. This really adds to our level of confidence about how well the spacecraft will perform when we reach Wild 2," added Cheuvront. Cheuvront and a team of engineers at Lockheed Martin's spacecraft control center, known as the Mission Support Area, control the spacecraft in conjunction with JPL and the Deep Space Network.
The Navigation Camera was straining to see Annefrank during approach. "This camera was operating at its limit of performance and seeing very dim stars down to about 11th visual magnitude", said Ray Newburn, the Lead Scientist for the camera at JPL.
However, the brightness predicted by Drs. Stephen Synnott and Donald Yeomans of JPL was dimmer than 11th visual magnitude. "We tried everything we could think of including taking multiple long exposures and adding these on the ground", said Dr. T. S. Mike Wang, Optical Navigation Specialist at JPL, "but Annefrank was not cooperating. It was just too dim."
Because of the high probability of not seeing Annefrank during the approach, the flyby was designed to be successful without having to see it up to 20 minutes from encounter. "A flyby distance of 3,000 km (1,864 miles) was chosen so that there was no risk of the spacecraft flying near any possible dust environment or small satellites of Annefrank", said Ed Hirst, JPL Mission Design Manager. "We also wanted to ensure that Annefrank would be in the camera view at the start of the encounter sequence," added Hirst.
Since Annefrank was not seen in the approach images, the flight team felt that the asteroid was at least as dim as predicted and possibly even dimmer. The team decided to send up a new encounter configuration file and set the initial flyby exposures longer. "We had a planned uplink six hours before encounter for this very purpose," said Robert Ryan, Mission Manager at JPL. "We had some communications problems the day before that gave us some difficulty, but NASA's Deep Space Network gave us highest priority, and excellent communications on Friday, allowing us to play back earlier images we missed as well as sending our final encounter commands," added Ryan.
At 8:00 pm (PST) Friday evening, communications were established with the spacecraft to watch its pre-loaded sequence command turn the spacecraft away from the Sun and Earth into its flyby attitude. "We have built up over three years of flight experience and a tremendous amount of confidence and respect for our spacecraft to perform such operations routinely," said Joe Vellinga, STARDUST Program Manager at Lockheed Martin who led the development and manufacture of the spacecraft. "The spacecraft did not miss a beat during its flyby and it maintained all critical thermal, power, attitude, memory and reserves at or above design levels," added Vellinga.
The main function to be tested during flyby was a sophisticated flight computer program that would take over control of the spacecraft to keep the camera view locked on Annefrank during a 25-minute period around its closest encounter. "This software was a derivative of the nucleus tracking software successfully flown on the Deep Space 1 (DS1) flyby of Borrelly," said Dr. Shyam Bhaskaran, developer of the algorithms at JPL. "Based upon my previous experience on DS1, it performed up to my expectations with this encounter at Annefrank with over 60 successful images having Annefrank right in the middle of each image," added Bhaskaran. David Gingerich, Flight Software specialist at LMA who implemented and tested the nucleus tracking software said, "its performance was executed just like the coach drew it on the blackboard."
Over 70 encounter images were obtained that show a typical small solar system body, highly irregularly shaped and cratered. Annefrank is about twice as large as predicted, at least 6 kilometers in diameter, but darker than expected and therefore more difficult to detect in the early images. Not only did the camera perform well but the University of Chicago Dust Flux Measurement Instrument (DFMI) and the German Cometary and Interstellar Dust Analyzer (CIDA) performed as expected.
Professor Tom Economou, DFMI scientist from University of Chicago, stated "we ran for 28 minutes as we will at Wild 2 with DFMI performing all expected functions". Dr. Jochen Kissel, Lead Scientist for CIDA from Max Planck Institute in Garching, Germany, said "I will be able to put CIDA into an even better configuration at Wild 2 based upon the Annefrank experience." Both dust instrument teams are combing through their data to see if by chance they may have seen a dust particle.
"Performing such flight testing before the primary encounter is a critical part of reducing risks and significantly increasing the probability of success when we reach Wild 2", said JPL Project Manager, Thomas Duxbury. "We have performed exhaustive testing and training with LMA at their spacecraft test laboratory and through flight simulations, but these cannot totally replace actual flight operations testing. We learned a lot that will improve our operations at Wild 2 based upon the lessons learned at Annefrank. The bottom line is that if Annefrank had been Wild 2, we would have succeeded in every respect," added Duxbury.
"I applaud the entire flight team," said Don Brownlee. "We could not have asked for more, except possibly for Annefrank to be a little brighter. However, for everything that we could control with the spacecraft, we were nearly perfect.
Even though this was an engineering test, the flyby with Annefrank provided new information previously unknown about the asteroid about its size, shape, spin state and brightness as a function of viewing angle.
"It was an exciting Friday evening for those of us involved in this mission," Brownlee said. "We captured images of a primitive asteroid with a highly significant name and one whose size turned out to be similar to the asteroid that likely killed the dinosaurs 65 million years ago. We have now validated STARDUST's systems and operations and we are eagerly awaiting our encounter with Comet Wild 2, just over one year from now".
Asteroid Annefrank images are available here:
http://stardust.jpl.nasa.gov/photo/annefrank.html
Triennnial Report for the International Astronomical Union, November 4, 2002
The past three years have seen a tremendous growth in the study of
NEOs. This period includes the one-year orbital study of 433 Eros by
the NASA spacecraft NEAR-Shoemaker, followed by a landing on the
asteroid surface http://near.jhuapl.edu. This mission has
effectively resolved in the affirmative the long-standing issue of
the association between S-type asteroids and the primitive ordinary
chondrite meteorites. New radar studies have provided images of NEAs
and include the discovery of several binary objects, which permit the
calculation of densities http://echo.jpl.nasa.gov. Automated
orbital calculation and risk estimates are now continuously available
on-line through the NEO Dynamics system at Pisa
http://newton.dm.unipi.it/cgi-bin/neodys/neoibo and the Sentry
system at JPL http://neo.jpl.nasa.gov/risk/. The Spaceguard Survey
discovery programs, led by the LINEAR MIT system
http://www.ll.mit.edu/LINEAR/, have found more than 600 of the
estimated 1100 +/- 100 NEAs brighter than absolute magnitude H=18
(diameter approximately 1 km). The primary Spaceguard search programs
are supported by the United States government (NASA and the U.S. Air
Force), with an international team for astrometric follow-up. The
goal of the Spaceguard Survey is to find 90% of the NEAs larger than
1 km diameter by the end of 2008. Communication with the international scientific community and with
the interested public represents an important part of the WG efforts.
One tool for public communication is the Torino Impact Scale, which
has been adopted by the WG and other NEO scientists for this purpose.
The Torino Scale is a "Richter Scale" for categorizing the Earth
impact hazard associated with newly discovered asteroids and comets.
The scale is described at http://impact.arc.nasa.gov. Other
websites, although not formally endorsed by the IAU, also provide a
valuable communication functions. These include the NASA NEO Program
Office http://neo.jpl.nasa.gov, the NASA impact hazard website
http://impact.arc.nasa.gov, the UK NEO Information Centre
http://www.nearearthobjects.co.uk, and the Spaceguard Foundation
and its on-line magazine Tumbling Stone
http://spaceguard.ias.rm.cnr.it/SGF/. David Morrison, November 4, 2002
University of Illinois at Urbana-Champaign press release, October 25, 2002
Champaign, Illinois. -- Two of the three largest impact craters on Earth have nearly the same size and structure, researchers say, but one was caused by a comet while the other was caused by an asteroid. These surprising results could have implications for where scientists might look for evidence of primitive life on Mars.
Susan Kieffer of the University of Illinois at Urbana-Champaign,
Kevin Pope of Geo Eco Arc Research and Doreen Ames of Natural
Resources Canada analyzed the structure and stratigraphy of the 65
million-year-old Chicxulub crater in Mexico and the 1.8
billion-year-old Sudbury crater in Canada. Chicxulub is well preserved, but buried, and can be studied only by
geophysical means, remote sensing and at a few distant sites on land
where some ejecta is preserved. In contrast, Sudbury has experienced
up to 4-6 kilometers of erosion, and is well exposed and highly
studied by mining exploration companies because of its rich mineral
resources. By working back and forth with data from the two craters, the
researchers were able to re-create the structures and then estimate
the amount of melt in each structure. The amount of melt is critical
for determining if long-lived hot-water circulation systems that
might host life formscould have been formed after the impacts. In their field studies, the researchers found that both craters were
about 200 kilometers in diameter. In addition, they identified five
ring-shaped structures with similar character and dimensions. A sixth
ring -- the peak ring in the central basin -- was present at
Chicxulub, but had been eroded away at Sudbury. "While the size and structure of the two craters were similar, they
differed greatly in the amount of impact melt that was produced,"
said Kieffer, who presented the team's findings at the annual meeting
of the Geological Society of America, held Oct. 27-30 in Denver. "Through field studies, we determined that Chicxulub has about 18,000
cubic kilometers of impact melt, approximately four times the volume
of water in Lake Michigan," Pope said. "Sudbury has about 31,000
cubic kilometers of impact melt, approximately six times the
volume of lakes Huron and Ontario combined, and nearly 70 percent
more than the melt at Chicxulub. These differences in volume have
significant implications about the amount of heat available to drive
hot-water circulation systems." The researchers then used an analytical cratering model to examine
possible causes for the huge difference in melt. According to the
simulation results, the difference in melt volume could be readily
explained if Chicxulub -- the impact crater that doomed the dinosaurs
- -- was formed by an asteroid and Sudbury was formed by a comet. "Our calculation of 18,000 cubic kilometers of impact melt at
Chicxulub agreed well with model estimates for an asteroid striking
at a 45 degree angle," said Kieffer, the Walgreen Professor of
Geology at Illinois. "None of the comet impact examples came close to
agreeing." In contrast, the Sudbury impact melt volume of 31,000 cubic
kilometers fell between model estimates for a comet striking at an
angle of 30-45 degrees, Kieffer said. "Similarly, none of the
asteroid impact examples came close to agreeing with the Sudbury melt
volume." Another clue to the craters' origins lies in the impact melts
themselves. The majority of the excess melt at Sudbury is in the form
of a melt-rich breccia -- called suevite -- inside the crater. This
material tends to form in impacts where the crustal target rock
contains a lot of water. Sudbury has much more suevite in the
preserved crater than Chicxulub. "The mystery was that there probably wasn't a lot of water in the
original rocks at Sudbury to account for the excess suevite," Kieffer
said. "But in a comet impact of this size, somewhere around
1,400-2,000 cubic kilometers of water from the comet gets mixed into
the impact melt, and that could play a major role in disrupting the
melt and creating the excess suevite." There is other independent evidence for an asteroid impact at
Chicxulub, the team said, including the purported find of an asteroid
fragment in an oceanic drill core, the amount of iridium spread
around the world at the time of impact, and a telltale chromium 53
isotopic signature. By studying the origin and structure of large impact craters on
Earth, scientists might narrow the search for life on Mars. At
Sudbury, for example, "there is evidence of a huge hydrothermal
system that was driven by the heat of the impact melt," Ames said.
"As a result, there was widespread hot spring activity on the crater
floor possibly capable of supporting life." The researchers are interested in "extrapolating these conclusions
about comet and asteroid impacts to Martian conditions and asking
where we might go to look for similar hydrothermal systems that could
have hosted primitive life forms on Mars," Kieffer said. "Our next
step is to model these hot-water circulation systems that were set up
by the impact melts with fluid flow controlled by structures
(fractures) inside the crater, and then extrapolate the results to
Martian conditions." The National Aeronautics and Space Administration and the Natural
History Museum of Los Angeles County funded this work. A geological map and RADARSAT-1 image of the Sudbury impact crater is
available at
http://www.ccrs.nrcan.gc.ca/ccrs/rd/apps/geo/sudbury/sudbury_e.html
STScI Press Release N.: STScI-PR02-17, October 9, 2002
Michael Brown and Chadwick Trujillo of Caltech are reported
the findings at the 34th annual meeting of the Division
for Planetary Sciences of the American Astronomical Society
in Birmingham, Ala.
Earlier this year, Trujillo and Brown used the Palomar Oschin
Schmidt telescope to discover Quaoar as an 18.5-magnitude
object creeping across the summer constellation Ophiuchus
(it's less than 1/10,000th the brightness of the faintest
star seen by the human eye). Brown had to do follow-up
observations using Hubble's new Advanced Camera for Surveys
on July 5 and August 1, 2002, to measure the object's true
angular size of 40 milliarcseconds, corresponding to a
diameter of about 800 miles (1300 kilometers). Only Hubble
has the sharpness needed to actually resolve the disk
of the distant world, leading to the first-ever direct
measurement of the true size of a Kuiper belt object (KBO).
See
http://oposite.stsci.edu/pubinfo/pr/2002/17
MIT and Williams College Press Release, October 9, 2002
CAMBRIDGE, Mass., and WILLIAMSTOWN, Mass.--Pluto is
undergoing global warming, as evidenced by a three-fold increase in
the planet's atmospheric pressure during the past 14 years--a team of
astronomers from Massachusetts Institute of Technology (MIT), Williams
College, the University of Hawaii, Lowell Observatory, and Cornell
University announced in a press conference at today's meeting of the
Division of Planetary Sciences of the American Astronomical Society in
Birmingham, AL.
The team, led by James Elliot, professor of planetary astronomy and
director of MIT's Wallace Observatory, made this finding by watching
the dimming of a star when Pluto passed in front of it last August
20. The team carried out observations using eight telescopes at Mauna
Kea Observatory and Haleakala in Hawaii, Lick Observatory and Palomar
Observatory in California, and Lowell Observatory in Arizona. Data
were successfully recorded at all sites. An earlier attempt to
observe an occultation of Pluto on July 20 in Chile with observations
only from two sites with small telescopes, as the giant telescopes
involved lost out to bad weather or from being in the wrong location.
The Williams College team included Jay Pasachoff, Bryce Babcock,
Steven Souza, and undergraduate David Ticehurst. For the August
event, they used a Williams College electronic camera mounted to a
University of Hawaii telescope on Mauna Kea to make studies of the
occultation in visible light. They found a dimming lasting 7 minutes,
about one-third of their 2400 data frames, with fine detail that
remains under study and reanalysis. Their visible-light data are
being compared with infrared data obtained by the team at other
telescopes.
Elliot said the new results have surprised the observers, who as
recently as July thought that Pluto's atmosphere may be cooling.
"From the July data we know that Pluto's atmosphere had changed since
1988, but the August data allowed us to probe much more deeply into
Pluto's atmosphere and have given us a more accurate picture of the
changes that have occurred," he said.
Pasachoff, an astronomy professor at Williams College, said that
Pluto's global warming was "likely not connected with that of the
Earth. The major way they could be connected is if the warming
was caused
by a large increase in sunlight. But the solar constant--the amount
received of sunlight each second--is carefully monitored by
spacecraft, and we know the Sun's output is much too steady to be
changing the temperature of Pluto."
Pluto's elliptical orbit is much more out of round than that of the
other planets, and its rotational pole is tipped by a large angle
relative to its orbit. Both factors could contribute to drastic
seasonal changes. .Pluto's atmospheric temperature varies between
around minus 235 and minus 170 degrees Centigrade, depending on the
altitude above the surface. The main gas in Pluto's atmosphere is
nitrogen, and Pluto has nitrogen ice on its surface that can evaporate
into the atmosphere when it gets warmer, causing an increase in
surface pressure. If the observed increase in the atmosphere also
applies to the surface pressure--which is likely the case--this means
that the average surface temperature of the nitrogen ice on Pluto has
increased slightly less than 2 degrees Centigrade over the past 14
years.
Marc Buie, an astronomer at Lowell Observatory, has been measuring the
amount of sunlight reflected by Pluto and says that "the pressure
increase can be explained if the average amount of sunlight reflected
by the surface has decreased, which means that more heat is absorbed
from the sun. This could be the reason that the pressure has been
pumped up."
David Tholen, an astronomer at the University of Hawaii who measured
the size of Pluto in the late 1980s using a series of occultations and
eclipses involving Pluto's satellite, noted that even though Pluto was
closest to the Sun in 1989, a warming trend 13 years later shouldn't
be unexpected. "It takes time for materials to warm up and cool off,
which is why the hottest part of the day on Earth is usually around 2
or 3 p.m. rather than local noon, when sunlight is the most intense,"
Tholen said. Because Pluto's year is equal to about 250 Earth years,
13 years after Pluto's closest approach to the Sun is like 1:15
p.m. on Earth. "This warming trend on Pluto could easily last for
another 13 years," Tholen estimated.
Researchers study faraway objects through occultationsQeclipse-like
events in which a body passes in front of a star (Pluto in this case),
blocking the star's light from view. By recording the dimming of the
starlight over time, astronomers can calculate the density, pressure
and temperature of Pluto's atmosphere. Observing two or more
occultations at different times provides researchers with information
about changes in the planet's atmosphere. The structure and
temperature of Pluto's atmosphere was first determined during an
occultation in 1988.
Pluto's brief pass in front of a different star on July 19 led
researchers to believe that a drastic atmospheric change was under
way, but it was unclear whether the atmosphere was warming up or
cooling down.
In August 2002, a team from Williams College, the University of
Hawaii, and MIT, in an expedition arranged by Elliot, Tholen, and
Pasachoff to the University of Hawaii's telescope in Mauna Kea,
successfully observed the occultation of a faint star by Pluto.
The data resulting from this occultation, when Pluto passed in front
of a star known as "P131.1," led to the current results. "This is the
first time that an occultation has allowed us to probe so deeply into
the atmosphere with a large telescope, which gives a high spatial
resolution of a few kilometers," Elliot said.
A 1997 occultation of a star by Triton (Neptune's largest moon)
revealed that its surface had warmed since the Voyager spacecraft
first explored it in 1989. Pasachoff and Babcock, along with then
Williams student Tim McConnochie, participated in those observations.
On Triton, "Voyager saw dark material rising up as much as 12 km above
the surface, indicating some kind of eruptive activity," Elliot said.
"There could be more massive activity on Pluto, since the changes
observed in Pluto's atmosphere are much more severe. The change
observed on Triton was subtle. Pluto's changes are not subtle."
Pluto and Triton are presently about the same distance from the sun,
and each has a predominantly nitrogen atmosphere (with a surface
pressure 100,000 times less than that on Earth), so one might expect
similar processes to be occurring on these two bodies.
NASA is still deciding whether to send a spacecraft to Pluto, the only
planet not yet observed at close range. The Pluto-Kuiper Belt mission
in the New Horizons Program, if approved, would be launched in 2006
and would reach Pluto 10 years later, seeks to answer questions about
the surfaces, atmospheres, interiors and space environments of the
solar system's outermost objects, including Pluto and its moon,
Charon.
Researchers are looking forward to observing additional Pluto
occultations in the years before the Pluto-Kuiper mission flies by
Pluto. Of particular interest is the prospect of using SOFIA, a
2.5-meter airborne telescope being built by NASA in collaboration with
German astronomers, for Pluto-occultation events when it begins
operating in 2004. Edward Dunham, who leads the occultation effort at
Lowell Observatory, is also leading a team that is building HIPO, a
SOFIA instrument designed specifically to observe occultations. The
combination of HIPO and SOFIA will provide very high quality data on a
much more frequent basis than is possible using ground-based
telescopes alone.
"This is a very complex process, and we just don't know what is
causing these effects" on Pluto's surface, Elliot said. "That's why
you need to send a mission."
This work is funded by Research Corporation, the National Science
Foundation, and NASA's Planetary Astronomy Program.
A press release from Lowell Observatory last summer (based on results
of the July occultation) is at the website:
http://www.lowell.edu/Press/20020815.html
TEAM PARTICIPANTS IN THE PLANNING, PREDICTION, AND OBSERVATION, AND
STUDY OF THE 2002 AUGUST PLUTO OCCULTATION
AEOS Telescope, Haleakala: Lewis Roberts, John Africano, Doyle Hall,
Paul Kerwin, Mark Skinner
Cornell University: Stephen Eikenberry, Dae-Sik Moon, Philip Nicholson
Joint Astronomy Centre: Sandy K. Leggett
Lowell Observatory: Edward Dunham, Amanda Bosh (also Boston
University), Marc Buie, Catherine Olkin, Brian Taylor
MIT: James Elliot, Katie Carbonari, Kelly Clancy, Erica McEvoy, Alison
Klesman, Susan Kern, David Osip, Michael Person, Shen Qu
University of Hawaii: David Tholen and John Rayner
US Naval Observatory (Flagstaff): Stephen Levine and Ronald Stone
Williams College: Jay M. Pasachoff, Steven P. Souza, Bruce A. Babcock,
David R. Ticehurst
Jay M. Pasachoff 7/30/2002
Pluto, 6 billion kilometers away, is so small that it occults (hides)
a star very rarely. In fact, the only previous time it had been known
to do so was 1988, when a team led by MIT professor James Elliot had
detected its atmosphere. Note that if Pluto or another body had no
atmosphere, the star would wink out abruptly (aside, technically, from
optical effects), but that an atmosphere can bend and distort the
starlight so that it fades gradually. In that way, the 1988
occultation gave a lot of information about Pluto's atmosphere. The
light curve (the graph of brightness versus time) showed an abrupt
change at a certain height above Pluto's surface, and two competing
models have been invoked to explain it: a temperature inversion or the
presence of dust.
Elliot and his colleagues have worked since then to find another Pluto
occultation to observe. Pluto is only 0.1 arcsec across, about 1/10
the smallest size normally seen by the best telescopes and 1/5 the
smallest size resolvable by Hubble. Stars are so far away that
their light is parallel, and they project Pluto's shadow full size on
the Earth. Thus the shadow of Pluto on the Earth from a star is about
2300 km across. Even the best astrometry (position measuring) gives an
uncertainty of 1000 km or so a few days in advance of the occultation,
though the Elliot group monitors the positions of Pluto and the star
as time progresses, continually improving their predictions.
They predicted that on July 19/20, a Pluto occultation would be
observable from Chile. They assembled a team of scientists to observe
it and got observing time on some of the world's largest and newest
telescopes, including 8-m Gemini South and the two 6.5-m Magellan
telescopes in Chile. Three teams with portable 35-cm telescopes but
with fast-readout CCD's, capable of observing twice a second to give
time resolution unlike ordinary CCD's, were also participating: one
team from MIT, one team from Lowell Observatory, and my own team from
Williams College. We were to be deployed to the sides of the large
telescopes, perhaps 200 km north or south, to increase the chance that
somebody would see the event. A similar consortium, headed by Bruno
Sicardy of the Observatory of Paris at Meudon, had the 8-m Very Large
Telescope and other fixed and mobile telescopes.
As the time approached, the prediction shifted considerably north,
making it look that sites from mid-Peru north through Central America
would see the occultation, and some of our teams prepared to shift
north. My own team was going to Aruba, given some connections with a
customs agent there from the 1998 solar eclipse expedition and the
weather that was predicted to be better than that in Central
America. Customs and shipping problems prevented us finally from
getting there, though we tried. But by that time, we were in contact
with scientists at four large telescopes at the major observatories in
the Canary Islands, which were in the same part of the track as Aruba,
and helped arrange the use of two of them, including Pablo Perez at
the 4.2 m William Herschel telescope on La Palma and a Belgian group
of astronomers (Katrien Uytterhoeven, Roeland Van Malderen, Geert
Davignon) at the 1.2 m telescope on La Palma. Mark Kidger was already
using the 1.5 and 0.8 m telescopes on Tenerife for both optical and
infrared observations.
In the event, the track shifted back south. The Canary Island
telescopes got good data, but showed a steady light curve, with no
occultation. One member of the French team saw the occultation from
near Arica at Chile's northern boundary, though he used the drift
technique across the CCD to give time resolution, making it relatively
difficult to get accurate photometry. The Elliot-related team of Marc
Buie of the Lowell Observatory and Oscar Saa of the Cerro Tololo
Inter-American Observatory had complete success in observing the
occultation from a site near Iquique, Chile, a couple of hundred kilometers
south of the Peruvian border. They saw an occultation lasting about
104 s, with a dimming of about a factor of 2 at maximum. It will take
some time for the results to be studied and to percolate into new
models of Pluto's atmosphere.
Pluto is moving into a part of the sky with more stars, and a couple
of occultations may be visible each year. The next one is scheduled
for August 20, 2002, and as of this writing is to go over the major
telescopes at Mauna Kea, Hawaii, several of which are to be devoted to
the occultation. My own team from Williams College is taking our CCD
to the 2.2-m telescope of the University of Hawaii there.
Johns Hopkins University Applied Physics Laboratory press release
February 22, 2002
New Horizons mission planners have developed a new strategy that could trim
nearly a year off their original schedule to send a spacecraft to the solar
system's outermost planet.
Now in preliminary development for NASA, New Horizons would be the first
mission to explore Pluto and its moon, Charon, as well as the ancient Kuiper
Belt of rocky, icy objects beyond the planets. If approved and funded later
this year, New Horizons would launch in January 2006, swing around Jupiter
for scientific studies and a gravity boost in 2007, and reach Pluto as early
as 2015.
"As we continued to study the mission, and optimized our launch window, we
realized that we could get the spacecraft to Pluto sooner," says New
Horizons Mission Director Robert W. Farquhar, of The Johns Hopkins
University Applied Physics Laboratory in Laurel, Md., which manages the
mission and will build and operate the spacecraft. "In our best estimates we
can cover the 3 billion miles from Earth to Pluto faster than we once
thought, while keeping all the mission's goals intact."
New Horizons project leaders say a faster trip benefits the mission in many
ways.
"This a great opportunity to improve our scientific return while reducing
mission risks and costs," says New Horizons Principal Investigator S. Alan
Stern, of the Southwest Research Institute in Boulder, Colo. "We'll get a
better look at Pluto itself, since more of the surface will be sunlit and
the atmosphere will be another year away from freezing onto the planet's
surface. We'll have more fuel for the journey into the Kuiper Belt after
exploring Pluto-Charon, and the shorter cruise time reduces some of the
costs associated with flight operations."
New Horizons will characterize the global geology and geomorphology of Pluto
and Charon, map their surface compositions and temperatures, and study
Pluto's complex atmosphere in detail. The spacecraft will then visit up to
three Kuiper Belt objects beyond Pluto.
The Administration released its proposed FY2003 budget for NASA today.
This is the first budget developed by the Bush Administration and the
new NASA Administrator, Mr. Sean O'Keefe. The Division for Planetary
Sciences (DPS) of the American Astronomical Society commends the support
this budget provides for planetary exploration, which includes a new
initiative for nuclear power and propulsion, and a second new
initiative for a New Frontier line of competitively procured planetary
space flight missions. Funding has been increased in real dollars for
Research and Analysis programs, which provide a fundamental knowledge
base allowing for the design of focused, efficient missions.
The Administration gave high ratings to the Discovery program of
low-cost planetary missions and as a result has introduced a new line
of moderately priced missions modeled on the Discovery program. The
New Frontier missions would be about twice the cost of Discovery
missions. The budget proposal would provide for about one Frontier
mission every three years, bringing a new level of flight opportunity
to the science community with competitively procured missions of higher
capability.
The DPS is concerned about the cancellation of the outer planets
program, which included the New Horizons mission to Pluto and the
Europa Orbiter. The cost-capped New Horizons mission was recently
selected after an open competition in which scientists and their
industry partners spent millions of dollars and months of time in good
faith response to a NASA call for proposals. This precedent discourages
community participation in NASA's efforts to produce cost-effective
missions through competition. It should not be repeated. Whether New
Horizons may be resurrected in the New Frontier program will depend on
its ultimate prioritization in the Planetary Decadal Survey.
The surprise in this budget is the proposal to revive development of
nuclear technology for in-space propulsion and power. Development of
this technology was terminated in the 1970s and planetary exploration
has been limited ever since to long, complex flight missions using
conventional propulsion and to spacecraft barely capable of powering a
single light bulb. Nuclear propulsion will increase accessibility of
Solar System objects and decrease the flight time for some missions.
On-board nuclear power will provide a power-rich environment for
science investigations at the planets and increase the lifetime of
these systems to years instead of a few weeks or months.
The planetary Research and Analysis program was given a 3% increase
above inflation, and a new program was funded at $10M to develop
planetary instruments for biological investigations on other planets.
Mars exploration will continue as planned through this decade, but the
large rover planned for 2007 is delayed until 2009 in order to
substitute nuclear for solar power and increase its lifetime from
months to years. A fully competed Discovery-class Mars Scout mission
will be flown in 2007.
The DPS calls upon Congress to support the President's proposed FY03
NASA budget. It builds on the strengths and successes of our planetary
program. New nuclear technology for both power and propulsion will
extend our reach and capabilities to the outermost regions of our Solar
System while increasing our capabilities in the inner Solar System.
The New Frontier program offers exciting opportunities, including
restoration of missions to the outer solar system.
The DPS is the world's largest professional organization dedicated to
the exploration of the Solar System.
PASADENA, Calif., Jan. 24, 2002 (AScribe Newswire) -- NASA's
comet-bound spacecraft, Stardust, successfully completed a
critical deep space maneuver, positioning itself on a course
to encounter comet Wild 2 in January 2004 and collect dust
from the comet.
At 21:56 Universal Time (1:56 p.m. Pacific Time), January
18, 2002, Stardust fired its thrusters for nearly 111 seconds,
increasing the speed of the spacecraft by 2.65 meters per
second (about 6 miles per hour).
"This is the maneuver that sets us up for the bigger
maneuver. It's a combination of increasing the speed of the
spacecraft and at the same time putting it on the path to
reach Wild 2," said Robert Ryan, Stardust's mission manager
at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's
like the setup pass in a basketball game. Now we're ready
to shoot the basket."
The spacecraft responded exactly as planned, said Ryan,
although communication was tricky. Stardust is currently the
farthest solar-powered object from the Sun, over 395 million
kilometers (245 million miles) away. The spacecraft's
signal confirming it had completed the maneuver took almost
30 minutes to reach Earth.
In January 2004, Stardust will fly through the halo of
dust that surrounds the nucleus of comet Wild 2. The
spacecraft will return to Earth in January 2006 to make a
soft landing at the U.S. Air Force Utah Test and Training
Range. Its sample return capsule, holding microscopic
particles of comet and interstellar dust, will be taken to
the planetary material curatorial facility at NASA's Johnson
Space Center, Houston, Texas, where the samples will be
carefully stored and examined.
Stardust's cometary and interstellar dust samples will
help provide answers to fundamental questions about the
origins of the solar system. More information on the
Stardust mission is available at
http://stardust.jpl.nasa.gov.
Stardust, a part of NASA's Discovery Program of low-cost,
highly focused science missions, was built by Lockheed
Martin Astronautics and Operations, Denver, Colo., and is
managed by the Jet Propulsion Laboratory, Pasadena, Calif.,
for NASA's Office of Space Science, Washington, D.C. JPL is
a division of the California Institute of Technology in
Pasadena. The principal investigator is astronomy professor
Donald E. Brownlee of the University of Washington in
Seattle.
San Antonio -- November 30, 2001 -- After a two-month evaluation, NASA has
selected the "New Horizons" proposal, led by Southwest Research Institute
(SwRI), to proceed with preliminary design studies for a mission to the
Pluto-Kuiper Belt (PKB) system. The mission, including science payload,
spacecraft, and launch vehicle, will examine the last unexplored planet in
the solar system and move beyond Pluto to explore multiple objects in the
Kuiper Belt. The mission will also make the next planned exploration of
Jupiter and its moons.
Led by Principal Investigator Dr. S. Alan Stern, director of the SwRI
Department of Space Studies, the winning proposal involves constructing and
flying a complete mission, including development of the spacecraft,
trajectory, science instruments, and an education and public outreach plan.
"We'll be exploring frontier worlds near the edge of the planetary system,"
says Stern, who is based in the SwRI Boulder, Colo., office. "This mission
is likely to rewrite textbooks regarding the origin of the planets, the
nature of the outer solar system, and even the origin of primitive materials
that may have played a role in the development of life."
SwRI leads the New Horizons team, which also includes major partners at the
Johns Hopkins University Applied Physics Laboratory of Laurel, Md.; Stanford
University of Palo Alto, Calif.; Ball Aerospace Corp. of Boulder, Colo.; the
NASA Goddard Space Flight Center of Greenbelt, Md.; and the Jet Propulsion
Laboratory of Pasadena, Calif.
During the New Horizons feasibility study that occurred this summer, the
team designed a spacecraft equipped with sensitive, miniaturized cameras, a
radio science instrument, ultraviolet and infrared spectrometers, and space
plasma experiments. The team believes this combination of science
instruments is ideal to characterize the global geology and geomorphology of
Pluto and its moon Charon, to map their surface compositions, and to
characterize Pluto's atmosphere and its atmospheric escape rate. The
feasibility study also showed the mission could save money using
technologies for deep space exploration that are essentially off the shelf.
Congress has approved $30 million of fiscal year 2002 funds to conduct final
design work of the spacecraft and science instruments and to contract the
launch vehicle. For the mission to continue beyond 2002, the program must
meet two conditions set by NASA. First, the team must pass a NASA-led
"confirmation review" of its work. Second, Congress must approve additional
funding.
"We couldn't be more pleased to be leading this pioneering space mission,"
says Dr. James L. Burch, vice president of the SwRI Space Science and
Engineering Division. "We are happy to have such quality institutions
participating on this mission and are confident of its success."
Pluto is the most distant planet known and the largest member of the Kuiper
Belt. Kuiper Belt Objects -- a class of objects composed of material
believed to have been left over after the formation of the other planets --
have never been exposed to the higher temperatures and solar radiation
levels of the inner solar system. Pluto has large quantities of ices of
nitrogen and simple molecules containing combinations of carbon, hydrogen,
and oxygen that are the necessary precursors of life. The gases comprising
these ices would be largely lost to space if Pluto had come close to the
sun. Instead they remain on Pluto as a sample of the primordial material
that set the stage for the evolution of the solar system as it exists today
- -- including life.
With additional funding, the launch of New Horizons is expected to occur in
January 2006, with the spacecraft arriving at Pluto between 2014 and 2018,
depending on the selection of the launch vehicle. Along the way to Pluto,
New Horizons will capitalize on a gravitational boost from Jupiter.
NASA has selected a team led by The Johns Hopkins University Applied Physics
Laboratory (APL) in Laurel, MD, and Southwest Research Institute (SwRI) in
San Antonio, TX, to develop the first mission to explore Pluto and the
Kuiper Belt region beyond the distant planet.
Headed by Principal Investigator Dr. S. Alan Stern of SwRI, the New
Horizons: Shedding Light on Frontier Worlds mission team also includes Ball
Aerospace, Boulder, CO; Stanford University, Palo Alto, CA; NASA Goddard
Space Flight Center, Greenbelt, MD; and a variety of other universities and
research institutions. Thomas Coughlin is the project manager at APL, which
will manage the mission for NASA and design, build and operate the New
Horizons spacecraft. SwRI will lead the science team and guide development
of the spacecraft's scientific instruments. Ball Aerospace and NASA Goddard
will help develop the payload.
Aiming for a 2006 launch and arrival at Pluto before 2020, NASA officials
say the mission must pass a confirmation review that will address
significant risks such as schedule and technical milestones and regulatory
approval for launch of the mission's nuclear power source. Funding must also
be available; Congress provided $30 million in fiscal 2002 for the mission
to procure a launch vehicle and start developing the spacecraft and science
instruments, but no funding for subsequent years is included in the
administration's budget plan.
Pluto is the most remote planet in the solar system; its elliptical orbit
has an average distance of 3.66 billion miles (5.91 billion kilometers) from
the sun - nearly 40 times the distance between Earth and the sun. The Kuiper
Belt is a source of comets and believed to be the source of much of Earth's
water and the simple chemical precursors of life.
"We'll explore frontier worlds near the edge of the planetary system," says
Stern, who is also the director of SwRI's Department of Space Studies,
Boulder. "This mission is likely to rewrite textbooks regarding the origins
of the planets, the nature of the outer solar system, and even the origin of
primitive materials that may have played a role in the development of life.
We are very excited to be a part of this wonderful NASA mission."
NASA will work with Stern to further define mission costs and to finalize
the design of the spacecraft and its accommodation of the instrument sets.
New Horizons is planned for launch in January 2006 and, depending on the
launch vehicle selected, would reach Pluto and its moon, Charon, in July of
2016 or 2018. On the way, the small, lightweight craft would pass Jupiter,
using the giant planet's gravity as a slingshot toward Pluto and exploring
the Jovian system.
The spacecraft team plans to use several proven subsystems already designed
for other APL planetary missions, saving money while reducing risk and
shortening the project's development schedule. New Horizons' remote-sensing
instruments will characterize the global geology and geomorphology of Pluto
and Charon, map their surface compositions and temperatures, and examine
Pluto's atmosphere in detail. Encounters with Kuiper Belt Objects will occur
after the Pluto-Charon flyby.
"The Kuiper Belt is an archeological dig into the early history of our solar
system," says Dr. Andrew Cheng, New Horizons project scientist at APL. "It's
full of small, icy, dirty and rocky objects that started to build into
planets but, for some mysterious reason, stopped in mid-stride. It's a
fascinating region."
Following the successful management model of NASA's Discovery Program, New
Horizons is a principal investigator-led team representing academia,
industry, NASA centers and other communities. In addition to Stern, Coughlin
and Cheng, the management team includes Mission Director Dr. Robert Farquhar
of APL and Science Payload Manager William Gibson of SwRI. NASA's Jet
Propulsion Laboratory, Pasadena, CA, will provide navigation support, and
tracking and communication services through NASA's Deep Space Network.
"Leading the first mission to Pluto is an exciting opportunity for the
Applied Physics Laboratory," says APL Director Dr. Richard Roca. "We promise
a rewarding mission for NASA and for avid space science supporters, such as
Sen. Barbara Mikulski and the Maryland delegation, who have done so much to
advance science and technology in the state."
New Horizons is the latest of several NASA projects on APL's roster. The Lab
manages the Comet Nucleus Tour (CONTOUR), which launches in July 2002 to
study at least two diverse comets, and Mercury Surface, Space ENvironment,
GEochemistry and Ranging (MESSENGER), set to become the first spacecraft to
orbit Mercury after launching in March 2004. APL also managed the Near Earth
Asteroid Rendezvous (NEAR) mission - which included the first spacecraft to
orbit and land on an asteroid - and recently secured a 12-year, $600 million
contract for missions in NASA's Sun-Earth Connection program.
In November 2001, Congress inserted $30,000,000 into NASA's budget for a
mission to Pluto in 2006. However, the funding at the moment is only
for one year. Also, NASA's two existing radioisotope electrical
generators are spoken for (for the Europa mission), and a Pluto
mission needs one. So the battle isn't over.
http://photojournal.jpl.nasa.gov/catalog/PIA02885
http://photojournal.jpl.nasa.gov/catalog/PIA02886
Working Group On Near Earth Objects
Causes of Chicxulub and Sudbury Craters
A Kuiper-Belt Object Half the Size of Pluto
Pluto is Undergoing Global Warming,
Researchers Find
A map of Pluto's shadow crossing the Earth for the August occultation:
http://occult.mit.edu/research/occultations/Candidates/Predictions/P131.1.html
Images and further discussion of the observations for the August
occultation are on the Williams College site:
http://www.williams.edu/Astronomy/mkpluto.html
Pluto Reveals Its Atmosphere by Occulting a Star
New Horizons Team Plots a Faster Path to Pluto
Pluto Mission Cancelled Again; NASA Space Budget Released
Division of Planetary Sciences of the American Astronomical Society
Membership Release, February 8, 2002
Stardust En Route to Comet Wild 2 in 2004
JPL Press Release, January 25
Pluto in 2014-18
SwRI Press Release, December 2
Plans for the Pluto mission
Pluto Express Is On (Sort-of)
November 26
Pluto/Kuiper-Belt Mission in 2004?
SwRI Press Release, September 27, 2001
Boulder, Colorado- September 27, 2001 -- A team led by the Southwest Research Institute (SwRI) and the Johns Hopkins University Applied Physics Laboratory (JHU APL) has just completed a NASA-funded, "Phase A" design study for a Pluto-Kuiper Belt mission. This team, called "New Horizons," was one of two selected by NASA's Office of Space Science early this summer and funded at a level of $450,000 to conduct Pluto-Kuiper Belt mission studies. The principal investigator of the New Horizons Pluto-Kuiper belt mission study is Dr. Alan Stern of SwRI. The New Horizons study team consists of over 20 scientific experts in Pluto and Kuiper Belt studies, along with almost 100 engineers and other personnel at SwRI, JHU APL, Stanford University, Ball Aerospace, and NASA's Goddard Space Flight Center.
Pluto is the most distant planet known and the largest member of the Kuiper Belt. Kuiper Belt Objects -- a class of objects composed of material left over after the formation of the other planets -- have never been exposed to the higher temperatures and solar radiation levels of the inner solar system. Pluto has large quantities of ices of nitrogen and simple molecules containing combinations of carbon, hydrogen, and oxygen that are the necessary precursors of life. These ices would be largely lost to space if Pluto had come close to the sun. Instead they remain on Pluto as a sample of the primordial material that set the stage for the evolution of the solar system as it exists today, including life.
"NASA asked us to perform a detailed feasibility study for flying a mission to explore Pluto and its giant satellite Charon, and to then go on to the Kuiper Belt." Says Principal Investigator Stern, "We found the mission to be feasible with technologies that are essentially off the shelf for deep space exploration. We also found that a launch as soon as December 2004 can be accomplished."
The New Horizons team studied flying a spacecraft equipped with sensitive, miniaturized cameras, a radio science instrument, ultraviolet and infrared spectrometers, and space plasma experiments. The study team found that this combination of instruments is essentially ideal to characterize the global geology and geomorphology of Pluto and its moon Charon, to map their surface compositions, and to characterize Pluto's atmosphere and its atmospheric escape rate. "These are the very objectives NASA set forth as goals for the Pluto-Kuiper Belt mission," says New Horizons Payload Manager Mr. William Gibson, also of SwRI. "We also found that all of this can be accomplished with a significantly smaller, lighter, and far less power hungry spacecraft than the famous Voyager outer planet reconnaissance missions. It's a real step forward for outer planet exploration."
The New Horizons team designed a complete mission, including spacecraft, trajectory, instruments, and even education/public outreach plans for NASA during the Phase A study. Its mission flies to Pluto using a gravitational boost from Jupiter. "This reduces the necessary flight time and saves money," notes Stern. "The savings comes from the fact that by using Jupiter's powerful gravity as a slingshot, NASA can afford to launch the mission on a smaller launch vehicle. Our plan also saves money by using many subsystems already designed for other recent JHU APL planetary missions; this way, NASA gets the maximum leverage on past investments. Beyond saving dollars, this re-use of existing subsystem designs also reduces risk and speeds the project development schedule."
Should NASA select a Pluto-Kuiper Belt mission for development, it would follow the management philosophy of NASA's highly successful Discovery Program, with a principal investigator-led team representing academia, industry, NASA centers, and other communities. Launch would occur in either December 2004 or January 2006, with the spacecraft arriving at Pluto sometime between 2014 and 2018, depending on the type of launch vehicle and the year of launch. Along the way to Pluto, New Horizons will fly through the Jupiter system. Kuiper Belt object flybys would occur in the years following the Pluto-Charon flyby.
On March 1, NASA's Deep Space Network antennas pulled down their last Near Earth Asteroid Rendezvous (NEAR) mission data, bringing to a close the first mission to extensively study an asteroid. NEAR, which was the first mission in NASA's Discovery Program of low-cost, scientifically focused space missions, and the first to land on an asteroid, has delighted astronomy neophytes and scientists alike.
"NEAR has raised the bar," says Dr. Stamatios Krimigis, Space Department head at The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., which built the spacecraft and managed the NEAR mission. "The Laboratory is very proud to have managed such a successful mission and other universities. The team had no weak links and the result was an historic mission that surpassed everyone's expectations."
"This mission has been successful far beyond what was in the original mission plan," says NEAR Mission Director Dr. Robert Farquhar of APL. "We got the first images of a C-class asteroid when we added a flyby of asteroid Mathilde in 1997; we added two low altitude series of passes over the ends of Eros this past October and January that gave us spectacular images from 2.7 kilometers above the surface; and we achieved the first landing of a spacecraft on an asteroid on Feb. 12. All this at no extra cost. When you talk about ' faster, cheaper, better,' this is what 'better' means."
On Feb. 12 at 3:01:52 p.m. (EST), NEAR Shoemaker made a gentle, picture-perfect 3-point landing on the tips of two solar panels and the bottom edge of the spacecraft body. But the mission wasn't finished yet. Much to the amazement of the mission team and millions of observers around the world who were following the descent, the touchdown was so elegant that the craft was still operating and sending a signal back to Earth even after landing.
Jumping at the chance to get "bonus science" from the spacecraft, which had already collected 10 times more data than originally planned, the mission team asked for and got a 10-day extension and then four more days of DSN antenna time, enabling NEAR Shoemaker to send back data through Feb. 28. The extension was granted to allow the gamma-ray spectrometer to collect data from an ideal vantage point about four inches from the surface. The spectrometer team quickly redesigned software and uploaded it to the spacecraft so they could begin collecting elemental composition readings.
The results were spectacular. "This is the first gamma-ray experiment that has ever been done on the surface of a body other than Earth," says Dr. Jacob Trombka, of NASA's Goddard Space Flight Center, in Greenbelt, Md., who heads the gamma-ray spectrometer team. "In fact, we can say it's the first feasibility study of how to design an instrument to be used on a rover that could select samples from the surface, look for the presence of water, or map the surface for the purpose of future mining."
The gamma-ray spectrometer team was able to retrieve data for a period of seven days after the spacecraft landed. "Right now we know we have good data with strong signatures," Trombka says. "But it will take months to scrutinize what we've collected. What we're looking for is information that will help us more precisely classify Eros and determine the relationship between the asteroid and meteorites that have fallen to Earth."
NEAR Shoemaker now rests silently just to the south of the saddle-shaped feature Himeros as the asteroid twists more and more away from the sun with each rotation, moving the southern hemisphere into its winter season and temperatures as low as minus 238 degrees Fahrenheit (minus 150 centigrade).
Project Scientist Dr. Andrew Cheng of APL, says the glamorous part of the mission is over but now scientists can get down to studying the data, including the more than 160,000 detailed images taken by the spacecraft. "We solved mysteries, we unveiled more mysteries. Now we're sharing the amazing amount of data that we collected with scientists all over the world, to sort through and debate and hopefully to help us discover facts about Eros and our solar system that no one knows today."
"This was a bonus," says NEAR (Near Earth Asteroid Rendezvous) Mission Director Dr. Robert Farquhar of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., which built the NEAR Shoemaker spacecraft and manages the mission for NASA.
"The NEAR mission and the spacecraft were not designed to touch down on the asteroid, and such a maneuver has never been attempted before," Farquhar says. "But the risk was worth taking. During our yearlong study of Eros we collected 10 times more data than originally planned. And now, at the end of the mission, we had a chance to gather close-up images of Eros' surface - capturing features as small as 4 inches (10 centimeters) across - by executing a controlled descent to the surface of Eros. So we took it."
A successful engine burn at 10:31 a.m. (EST), nudged NEAR Shoemaker toward Eros from about 16 miles (26 kilometers) away. Then four breaking maneuvers brought the spacecraft to rest on asteroid's surface in an area just outside a saddle-shaped depression, Himeros, at approximately 3:05 p.m. (EST).
Our solar system may have an outer "edge" just outside the orbit of Pluto, astronomers announced. Their results suggest that early in the history of the solar system, some event stripped away most of the planet-building material beyond 50 times Earth's distance from the sun.
Lynne Allen and Gary Bernstein, of the University of Michigan, and Renu Malhotra of the University of Arizona Lunar and Planetary Laboratory presented the evidence at a meeting of the Division of Planetary Sciences of the American Astronomical Society, October 2000.
It has long been thought that some comets must originate from a collection of small icy bodies orbiting beyond Neptune. These so-called "Kuiper Belt Objects" would be left over from the formation of the large planets 5 billion years ago. The Kuiper Belt Objects were purely hypothetical until 1992, when David Jewitt and Jane Luu of the University of Hawaii discovered the first one. Since that time, over 300 Kuiper Belt Objects have been discovered - but none of them are more than about 55 times as far from the sun as Earth, or 55 AU.
Does the solar system really end beyond Pluto's orbit? Or are the more distant objects just too faint to have been found so far? To address this question, Allen, Bernstein, and Malhotra searched 6 patches of sky, each about the size of the full moon, using a state-of-the-art electronic camera at the Cerro Tololo Inter-American Observatory in the Chilean Andes.
Astronomers have discovered more than 300 Kuiper Belt Objects, but none of them are more than 55 times as far from the sun as Earth. Does the solar system really end beyond Pluto's orbit?
These observations, in 1998 and 1999, were sensitive enough to see a 160-kilometer (100-mile) Kuiper Belt Object to at least 65 AU. They discovered 24 new Kuiper Belt Objects, 9 of which are 160 kilometers or bigger, but again the most distant is near the outer limit of Pluto's orbit. This is the strongest evidence yet that more distant objects are missing.
Some of the known Kuiper Belt Objects as well as many comets are on trajectories that will carry them well beyond the orbit of Pluto. But these are all believed to have formed inside Pluto's orbit and then been pushed outward by an encounter with Neptune or another planet. There are still no known objects which appear to have been created outside Pluto's orbit.
So astronomers are left to wonder what explains this apparent edge: was the primordial solar system originally "small"? Or were there once more distant objects that were pulled away by the gravity of a passing star? Astronomers at telescopes around the world are currently conducting further surveys in an effort to learn more about the history of our solar system.
This Kuiper Belt survey was funded by grants from NASA and the National Science Foundation.
Images and text available at http://www.astro.lsa.umich/users/garyb/WWWKBO.
Astronomers have expressed their major concerns over the NASA-directed work stoppage for the Pluto-Kuiper Express Mission (PKE). The American Astronomical Society's Division for Planetary Sciences (DPS) committee has urged that NASA and the US Congress to find a way to fund this important mission, but not at the expense of other equally important planetary missions or its basic research and analysis programs.
A stop-work order was issued in mid-September, 2000, by NASA Associate Administrator for Space Science Dr. Edward Weiler. The stated reason was ballooning costs for the entire Outer Planets set of missions at JPL (which also includes the Europa Orbiter and Solar Probe), due largely to increased costs for the launch vehicle and radioactive thermal generators (RGTs).
The DPS committee noted that if work on PKE is not resumed before the end of calendar year 2000, it is likely that the 2004 launch opportunity will be lost, and the earliest arrival date would slip by at least 7 years (from 2012 to 2019 or beyond). Pluto is the only planet not yet explored by spacecraft and is therefore of great interest and importance to the planetary science community. It is also moving rapidly outward from the Sun from its perihelion passage in the early 1990s, and if this mission is delayed beyond the 2004 launch, the opportunity to study the tenuous Pluto atmosphere may be lost for centuries.
M.P.E.C. 1999-C03
Issued 1999 Feb. 4, 16:04 UT
The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Commission 20 of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
BMARSDEN@CFA.HARVARD.EDU or GWILLIAMS@CFA.HARVARD.EDU URL http://cfa-www.harvard.edu/iau/mpc.html
EDITORIAL NOTICE
On 1801 Jan. 1 Guiseppe Piazzi discovered the object between Mars and Jupiter that he called Ceres Ferdinandea, "the eighth planet". Following the discovery a year later of a similar object, and in subsequent years further objects in what might be termed the "Cisjovian Belt", Piazzi's discovery eventually became known under either the name Ceres or the symbol (1), where the numeral, originally placed inside a complete circle, indicated that this was the first object found in that region of the solar system. By 1849 the sequence of discoveries in the region had reached (10), and 1868 saw the discovery of (100). By 1923, when (1000) was announced, the set of objects, while still mainly members of that Cisjovian Belt (also known simply as the "Asteroid Belt", or "Main Belt" of "minor planets"), also included objects that approached within 0.1 AU of the earth or extended out to the orbit of Saturn.
Next month, we shall pass (10000) in what is a collection of small objects that are not obviously cometary (although three members do also have well-documented dual status in the Catalogue of Cometary Orbits) and travel around the sun in independent orbits (i.e., satellites are excluded) that are well determined (i.e., with one exception that will surely be eventually remedied, the positions of the objects are very precisely predictable). Again, although the vast majority of the objects are in the Cisjovian Belt, there are members that are at perihelion significantly closer to the sun than Mercury or are at aphelion beyond the orbit of Neptune. It has been traditional to have a special celebration with each thousandth numbering. For example, (1000) was named in honor of the discoverer of Ceres, (2000) in honor of the discoverer of Uranus, (5000) in honor of the International Astronomical Union and (6000) in honor of the United Nations. Obviously, it would be appropriate to have some very special celebration to acknowledge (10000).
Most readers of these Circulars will be aware of recent discussions in the press concerning a proposal that the number (10000) should be given to Pluto. The principal reasoning for this is the recognition during the past few years that Pluto was the first discovered and largest known member of the "Transneptunian Belt" (sometimes called the "Kuiper Belt" or "Edgeworth-Kuiper Belt") of small objects beyond Neptune that possess some similarity, at least dynamically, to bodies in the Cisjovian Belt. Although as many as 95 members (or possible members) of the Transneptunian Belt are now listed, most of the orbital solutions are very weak, and none of the bodies has so far been included in the collection of those with "guaranteed" orbit determinations. A few of the discoveries from 1992-1994 are now approaching this state, which will also allow them to receive permanent names.
Although it is not unlikely that further Transneptunian Objects as large as Pluto will be discovered in the future, Pluto obviously holds a very special place in our appreciation of this new population, and by assigning to it the number (10000), we should guarantee that Pluto will be at the head of the Transneptunian list. It is also very important to affirm that there is absolutely no implied "demotion" or "reclassification" of Pluto from its position in the list of the "planets" (or "major planets" or "principal planets"). Unfortunately, many of the articles that have appeared in the press have accidentally (or deliberately) misinterpreted this issue. As with (2060) = 95P/Chiron, (4015) = 107P/Wilson-Harrington and (7968) = 133P/Elst-Pizarro, where the choice of "minor planet" or "comet" designation depends on the context, we are proposing that Pluto would have dual status as a "major" and a "minor" body. Readers of these Circulars, in particular, will appreciate that Pluto is sufficiently fainter than the other major planets that it can be confused with many other minor planets. We have in fact identified observations of Pluto several times during the past couple of years in data reported by the survey programs for Near-Earth Objects, and some astrometric observers specifically report to us observations of Pluto. There is currently no outlet for publishing these observations. It should be emphasized that the number (10000) would be used only in the context of publishing such observations or in matters directly related to Pluto's place in the Transneptunian Belt.
Much has been made in the press that the IAU is "voting" on Pluto's status, and at least one astronomical organization issued a press release on the subject. Members of the public seem completely baffled by this kind of attention. The question of relevance to the readers of these Circulars concerns the numbering and naming of (10000). Indeed, the IAU Small Bodies Names Committee has already been working on this particular matter for the past month or so. Progress is slow and uncertain, however, and there are some who think that democracy would be better served by seeking opinions from a larger, but informed community. The astronomers, amateur and professional, who contribute material to these Circulars--astrometric observations, identifications, orbit determinations--are such an informed community.
Accordingly, any reader with an opinion on the subject is invited to e-mail it to us at the Minor Planet Center, preferably using the address mpc@cfa.harvard.edu. Such a message could consist of a brief statement such as "I approve (10000) Pluto" or "I do not approve (10000) Pluto", although the value of the latter choice would be augmented if an appropriate alternative suggestion were made for (10000). Brief comments on the subject (preferably constructive) would also be welcome, and writers are encouraged to identify themselves. Modern bureaucracy rarely pays much attention to comments from even an informed public, but since this issue is of concern principally to our readers (more so, in fact, than to many professional astronomers with little or no interest in solar-system astronomy who just happen to be serving on a committee), we feel that it is appropriate for us to solicit advice in this way. Your early response is desirable. It is not necessary that you actually subscribe to these Circulars in order to respond. Appropriate responses will be examined and considered in connection with the responses will be examined and considered in connection with the deliberations by the Small Bodies Names Committee by their deadline of Feb. 26.
-- The above is the Editorial Notice that appears on MPC 33615-33616, dated 1999 Feb. 2
Brian G. Marsden
(C) Copyright 1999 MPC
[An IAU Statement, 2/3/1999]
Recent news reports have given much attention to what was believed to be an initiative by the International Astronomical Union (IAU) to change the status of Pluto as the ninth planet in the solar system. Unfortunately, some of these reports have been based on incomplete or misleading information regarding the subject of the discussion and the decision making procedures of the Union.
The IAU regrets that inaccurate reports appear to have caused widespread public concern, and issues the following corrections and clarifications:
1: No proposal to change the status of Pluto as the ninth planet in the solar system has been made by any Division, Commission or Working Group of the IAU responsible for solar system science. Accordingly, no such initiative has been considered by the Officers or Executive Committee, who set the policy of the IAU itself.
2: Lately, a substantial number of smaller objects have been discovered in the outer solar system, beyond Neptune, with orbits and possibly other properties similar to those of Pluto. It has been proposed to assign Pluto a number in a technical catalogue or list of such Trans-Neptunian Objects (TNOs) so that observations and computations concerning these objects can be conveniently collated. This process was explicitly designed to not change Pluto's status as a planet.
A Working Group under the IAU Division of Planetary Systems Sciences is conducting a technical debate on a possible numbering system for TNOs. Ways to classify planets by physical characteristics are also under consideration. These discussions are continuing and will take some time. The Small Bodies Names Committee of the Division has, however, decided against assigning any Minor Planet number to Pluto.
3: From time to time, the IAU takes decisions and makes recommendations on issues concerning astronomical matters affecting other sciences or the public. Such decisions and recommendations are not enforceable by national or international law, but are accepted because they are rational and effective when applied in practice. It is therefore the policy of the IAU that its recommendations should rest on well-established scientific facts and be backed by a broad consensus in the community concerned. A decision on the status of Pluto that did not conform to this policy would have been ineffective and therefore meaningless. Suggestions that this was about to happen are based on incomplete understanding of the above.
The mission of the IAU is to promote scientific progress in astronomy. An important part of this mission is to provide a forum for debate of scientific issues with an international dimension. This should not be interpreted to imply that the outcome of such discussions may become official IAU policy without due verification that the above criteria are met: The policy and decisions of the IAU are formulated by its responsible bodies after full deliberation in the international scientific community.
Johannes Andersen
General Secretary, IAU
For more information, contact the IAU Secretariat (URL: http://www.iau.org and address below), or the Division President, Prof. Michael A'Hearn, University of Maryland, USA (Tel: (301) 405 6076; Fax: (301) 314 9067; E-mail: ma@astro.umd.edu).
[from the Division of Planetary Sciences of the American Astronomical Society]
Colleagues,
No doubt, you are aware of the recent media attention implying that Pluto has been "officially" downgraded from planetary status. This was stimulated in large part by a suggestion by the Minor Planet Center to assign the minor planet number 10000 to Pluto in conjunction with the numbering of some Trans-Neptunian Objects. The Small Bodies Names Committee (SBNC) of IAU Commission 20 has been discussing this issue for several months, as has the Executive Committee of IAU Division III (Planetary Systems Sciences). It should be emphasized that, in spite of media perceptions, no action or decision has yet been taken. The number 10000 will likely be reached for the numbered asteroids within a few weeks. Mike A'Hearn, as President of IAU Division III, has established a web page with background information which also solicits input from the astronomical community:
http://www.ss.astro.umd.edu/IAU/div3/pluto.shtml
The DPS committee believes that this situation is harmful to our profession and will become more so if not put quickly to rest. The public is confused, acrimonious rifts are being created within our community and many of our colleagues are being diverted from productive work to counter what they perceive to be an alarming and unnecessary crisis. We have therefore adopted the following brief position statement, which will be forwarded to the appropriate IAU committees:
"The Committee of the Division for Planetary Sciences of the American Astronomical Society is opposed to assigning a minor planet number to Pluto. This action would undoubtedly be viewed by the broader scientific community and the general public as a "reclassification" of Pluto from a major planet to a minor planet. We feel that there is little scientific or historical justification for such an action."
We urge DPS members to visit the above web page and express your opinions. Michael A'Hearn (ma@astro.umd.edu) is President of IAU Div. III and Chair of the Small Bodies Nomenclature Committee, and can relay messages to appropriate others in the IAU.
Don Yeomans, Division of Planetary Sciences/Am Astron Soc Chairman and the other members of the DPS Committee
[Postscript from another message from Don Yeomans: Many of us have been asked when the Planet Pluto will once again have the largest heliocentric distance of any of the nine planets. JPL's Myles Standish notes that on 1999 Feb. 11 at 10:09 ET, Pluto's distance will exceed that of Neptune's. This result is based upon JPL's Planetary ephemeris DE405 and the time refers to Pluto and Neptune themselves rather than their respective barycenters (the latter time would be 09:40).]
Note the additional objection from Deborah Pasachoff:
We can now note the nine planets from the initial letters of "My Very Educated
Mother Just Sent Us Nine Pizzas." If we demote Pluto, the mnemonic would become
"My Very Educated Mother Just Sent Us Nothing,"
which is obviously undesirable.
Gary Kronk's site for comet and meteor
showers
Gary Kronk's site for comets
Mini-Comets
Hitting Earth All the Time?
Some Comet WWW Links
Hale-Bopp Webpages
The Why Files - Information
on Comets
Comet Hyakutake Near the Sun
Stardust mission to comet planned
Caroline
Herschel, discover of many comets
Comet Borrelly
In a week's time the European Space Agency's pioneering Rosetta mission will begin its 12-year expedition to orbit and land on Comet 67P/Churyumov-Gerasimenko. This is one of the most ambitious and complex robotic space projects ever undertaken and the UK has made a significant contribution to the scientific instruments on the orbiter and lander.
Following the launch on an Ariane 5 rocket from Kourou in French Guiana on 26th February (0736 GMT) the spacecraft will make 3 flybys of Earth and one of Mars before reaching the comet in 2014. For much of its journey the spacecraft will be placed in hibernation mode to limit power and fuel consumption. There will be some science observations taking place on the journey and crucially on approach to the comet the onboard camera will provide images which will help improve calculations of the comet's position, orbit, size and shape.
Once in the comet's vicinity around May 2014 the spacecraft will edge closer to the nucleus, as the comet moves towards the sun, before deploying the Philae lander in November 2014. Once on the surface of the comet a whole range of scientific experiments will be conducted in situ with the 10 instruments on board.
As the oldest and most primitive bodies in the solar system comets provide the key to unlocking the secrets of the Universe. Comets have remained unchanged in comparison to other bodies within our solar system and provide the earliest record of materials in a pristine form. In addition comets brought "volatile" light elements to the planets and played an important role in forming oceans and atmospheres. They are also space "carriers" of complex organic molecules that may have been involved in the origin of life on Earth.
The Particle Physics and Astronomy Research Council [PPARC] have funded the development and construction of two key instruments: the Ptolemy experiment on the Rosetta lander [Open University and CCLRC-Rutherford Appleton Laboratory] and the Plasma Interface Unit [PIU, Imperial College, London] built for the Rosetta Plasma Consortium instrument package on the orbiter.
Commenting on the mission and the UK scientific involvement Prof. Ian Halliday, PPARC Chief Executive, said," This mission will turn science fiction into science fact. Every aspect of comet Churyumov-Gerasimenko will be analysed, resulting in the most comprehensive set of scientific measurements ever obtained of a comet - and the UK can be justly proud of the significant part it has played".
He adds, "This ground-breaking mission benefits from considerable involvement by talented scientists from several UK universities. Their contribution endorses the UK's world-leading expertise in the development of technologies needed for planetary landers and miniaturised instrumentation for space missions".
Dr Ian Wright from the Open University is Principal Investigator on PTOLEMY instrument. The size of a shoe box PTOLEMY will analyse samples from the surface of the comet.
He explains "Ptolemy will analyse the nature and distribution of the most important cometary surface materials. From samples of ices extracted by drilling and coring, Ptolemy will use a variety of chemical processing techniques to reduce the samples to their constituent parts, making key measurements of molecules such as water, carbon, monoxide, carbon dioxide and organic compounds."
He adds, "The overall experiment is based around a coupled gas chromatograph and mass spectrometer - together these will determine the abundance and stable isotopic compositions of elements such as hydrogen, carbon, nitrogen and oxygen. The study of these biologically important elements is strongly implicated in humankind's quest to understand the origin of life on Earth".
Dr. Chris Carr from Imperial College is Principal Investigator for the Rosetta Plasma Consortium. "We are extremely pleased to be playing a major role in the Plasma Consortium on Rosetta. The consortium is an international team involving instrumentation from the US, France, Germany, Sweden and the UK, and the whole team has worked really well together to get the instruments ready for launch. Understanding how the comet interacts with the solar wind is a very important part of the Rosetta science objectives, and an area in which the UK is particularly strong. We're really looking forward to some great new results from this mission."
Images
PPARC website
* Global characterisation of the nucleus, determination of dynamic properties, surface morphology and composition;
* Determination of the chemical, mineralogical and isotopic compositions of volatiles and refractories in a cometary nucleus;
* Determination of the physical properties and interrelation of volatiles and refractories in a cometary nucleus;
* Study of the development of cometary activity and the processes in the surface layer of the nucleus and the inner coma (dust/gas interaction);
* Global characterisation of asteroids, including determination of dynamic properties, surface morphology and composition.
UK Science Involvement
In total there are 21 instruments/experiments on Rosetta (11 on orbiter and 10 on the lander Philae). UK scientists are involved in 10 of these (7 on orbiter and 4 on Philae).
The institutes involved are:
Armagh Observatory, Cardiff University (Cardiff Centre for Astrobiology), CCLRC, Imperial College, Mullard Space Science Laboratory, UCL, Open University, Oxford University, Queen Mary University of London, University of Sheffield.
Imperial College of Science, Technology and Medicine
As part of the Rosetta Plasma Consortium (RPC), the Space and Atmospheric Physics Group at Imperial College has provided the data processing and plasma interface unit (PIU) for the RPC sensors.
The role of the PIU is to act as an interface between the five plasma instruments and the spacecraft by providing a single path for the transmission of scientific data to the ground and commands sent from the ground. The PIU also provides a safely managed power supply to the instruments. It incorporates a number of novel technical solutions to ensure that the scientific output of the RPC instruments is maximised. These solutions also ensure that the risks of malfunction during the mission are minimised by a failure tolerant design. This ensures the required robustness to survive on a long mission and in the cometary environment.
Dr. Chris Carr is the Principal Investigator for RPC/PIU at ICL and is the current spokesman for the Consortium. Dr Chris Lee is the technical manager for the RPC-PIU and will be the operations manager for the Consortium during the mission.
Professor Andre Balogh is a Co-Investigator on the Fluxgate Magnetometer, one of five sensors in the Rosetta Plasma Consortium experiment on the Rosetta Orbiter. The experiment aims to measure the magnetic field in the region where the charged particles of the solar wind plasma interact with the comet. It is also designed to study a possible remnant magnetic field of the nucleus by taking measurements in close co-operation with the Lander magnetometer experiment ROMAP.
Ptolemy is the first example of a new concept in space instrumentation, which has been devised at PSSRI to tackle the analytical challenge of making in situ isotopic measurements of Solar System bodies. The scientific goal of Ptolemy is to understand the geochemistry of light elements, such as hydrogen, carbon, nitrogen and oxygen, by determining their nature, distribution and stable isotopic compositions. The size of a shoebox and weighing just 4.5 kg, Ptolemy will use gas chromatography / mass spectrometry techniques to investigate the comet surface and subsurface.
Samples of material supplied by the Lander's Drilling and Distribution system (SD2) will be placed in a small oven and heated in stages up to 800C. Gases released from the ices will then be analysed to determine their composition.
Ptolemy is the brainchild of Dr. Ian Wright and Prof. Colin Pillinger of the Planetary and Space Sciences Research Institute (PSSRI) based at the Open University in Milton Keynes. The instrument represents the culmination of many years' work by members of the PSSRI along with the Space Sciences Department at the Rutherford Appleton Laboratory. Some of the technological aspects of the experiment have been developed in partnerships with commercial companies (mostly in the UK).
PSSRI has also been involved in the development of the MUPUS experiment on the Rosetta Lander. Dr. Andrew Ball, who is a Co-Investigator for MUPUS, worked with Austrian colleagues on development of the accelerometry experiment built into the harpoon that will anchor the Lander to the comet's nucleus. Dr. Ball helped to develop data analysis tools - by studying the way the harpoon penetrates the surface - the science team will be able to draw conclusions about the strength, texture and layering of the sub-surface material. Dr. John Zarnecki is also a Co-Investigator for both MUPUS and SESAME, another Lander experiment that will investigate the nature of the comet's surface. Professor Tony McDonnell is a Co-Investigator for the GIADA dust analyser instrument on the Orbiter.
Oxford University (Department of Physics, Sub-department of Atmospheric, Oceanic and Planetary Physics). Professor F.W Taylor and Dr P.G Irwin are part of the science team for the VIRTIS imaging spectrometer on the Rosetta Orbiter.
University of Sheffield
The Space Systems Group at the University of Sheffield has helped to develop the Atomic Force Microscope of the MIDAS dust analysis experiment on the Rosetta Orbiter. Dr. Hugo Alleyne of the Space Systems Group is a Co-Investigator for MIDAS.
Professor David Hughes of the University's Department of Physics is a Co-Investigator for the Ptolemy instrument on the Rosetta Lander, which will analyse the composition of the comet's nucleus.
Contacts:
Dr. Hugo Alleyne
Space Systems Group
Department of Automatic Control & Systems Engineering
Rutherford Appleton Laboratory
RAL was also responsible for the design and manufacture of the thermal insulation for the whole Rosetta Lander, as well as the insulation for the GIADA and VIRTIS instruments.
The Particle Physics and Astronomy Research Council (PPARC) is the UK's strategic science investment agency. It funds research, education and public understanding in four broad areas of science - particle physics, astronomy, cosmology and space science.The European Space Agency's Rosetta spacecraft is scheduled to lift off on Feb. 26, 2004, at 2:16 am EST, from the Kourou spaceport in French Guiana, on the northeastern coast of South America. The launch will be the beginning of a ten-and-a-half year odyssey to comet Churyumov-Gerasimenko that includes flybys of Mars (2007) and the Earth (2005, 2007 and 2009).
Among the instruments aboard the Rosetta spacecraft are three instruments funded by NASA and a key component of a fourth. The NASA instruments will examine Churyumov-Gerasimenko from the orbiter.
"This comet has only about three-hundred-thousandths the gravity of Earth," said Dr. Claudia Alexander, project scientist for the U.S. role in the mission, from NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. "The Rosetta spacecraft will be able to make observations from as close as 2 kilometers (1.2 miles). The data from our state-of-the-art instruments will be amazing," she added.
Rosetta will reach Churyumov-Gerasimenko, a four-kilometer (2.5-mile) diameter comet, in May 2014. When this rendezvous occurs, Churyumov-Gerasimenko will be about three times as far from the sun as the Earth is. Over the next 18 months Rosetta will study how the comet changes as it moves closer to the sun. In November 2014, Rosetta will drop its experiment-laden, harpoon-firing lander on Churyumov-Gerasimenko's icy nucleus.
"What you have to understand is that comets are primordial remnants of the early solar system," explained Dr. Paul Weissman of JPL. "They are the keys to understanding the way the whole solar system, the Earth, and how even we came into being. And with Rosetta we will be able to observe, study and analyze this primordial material up close for more than a year," he said.
JPL supplied the Microwave Instrument for Rosetta Orbiter, the first of its type on any interplanetary mission. This instrument can reveal the abundances of selected gases, their temperatures, the speed at which they are coming off the nucleus, and the temperature of the nucleus. Scientists will use it to monitor changes in how vapors are released from the nucleus as the coma and tail grow. They will be studying water, carbon monoxide, ammonia and methanol, four of the most abundant gases from comets. Dr. Samuel Gulkis of JPL's Earth and Space Sciences Division is principal investigator.
The Southwest Research Institute, based in San Antonio, supplied two NASA instruments for Rosetta. One is an imaging telescope/spectrometer capable of analyzing the composition both of gases released by the comet and of the comet's surface. A goal of scientists using the instrument is to learn about the temperatures at which comets form and evolve, by determining the relative abundance of noble gases, such as helium, neon and argon. Principal investigator for the ultraviolet instrument is Dr. Alan Stern of the institute's Space Studies Department in Boulder, Colo.
Dr. James Burch, of the Institute's Instrumentation and Space Research Division, San Antonio, is principal investigator for Rosetta's Ion and Electron Spectrometer. This device will measure the environment of charged particles surrounding comet Churyumov-Gerasimenko. It will also study the interaction between that environment and the solar wind of charged particles speeding outward from the sun.
Key electronics for a fourth instrument, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis, have been supplied by Lockheed Martin Advanced Technology Center, Palo Alto, Calif. This instrument will examine gases surrounding the comet.
JPL, a division of the California Institute of Technology in Pasadena, manages the microwave instrument for NASA's Office of Space Science, Washington, D.C.
For information about the Rosetta mission visit:On January 2nd 2004 the NASA space mission, STARDUST, will fly through comet Wild 2, capturing interstellar particles and dust and returning them to Earth in 2006. Space scientists from the Open University and University of Kent have developed one of the instruments which will help tell us more about comets and the evolution of our own solar system and, critical for STARDUST, its survival in the close fly-by of the comet.
Launched in February 1999, STARDUST is the first mission designed to bring samples back from a known comet. The study of comets provides a window into the past as they are the best preserved raw materials in the Solar System. The cometary and interstellar dust samples collected will help provide answers to fundamental questions about the origins of the solar system.
Scientists from the Open University and University of Kent have developed one set of sensors for the Dust Flux Monitor Instrument (DFMI) built by the University of Chicago, and the software to analyse the data. The DFMI, part funded by the Particle Physics and Astronomy Research Council (PPARC) will record the distribution and sizes of particles on its journey through the centre, or coma, of the comet.
Professor Tony McDonnell and Dr Simon Green from the Open University's Planetary and Space Science Research Institute (PSSRI), will be at the mission command centre, the Jet Propulsion Laboratory in California, when the encounter with Wild 2 begins.
Dr Green explains "By combining the information about each of the tiny grains of dust captured by STARDUST we will discover more about the formation of stars, planets and our solar system."
Professor Tony McDonnell said "The information derived from the signals will tell us on the night if the dust shield has been critically punctured."
Cometary particles will be captured on a tennis racket like grid which contains a substance called aerogel - the lightest solid in the Universe! This is a porous material that allows the particles to become embedded with minimum damage. This means that on their return to Earth they will be as near as possible to their original state.
Once the samples are captured a clam-like shell closes around them. The capsule then returns to Earth in January 2006 where it will land at the US Air Force Utah Test and Training Range. Once collected, the samples will be taken to the planetary material curatorial facility at NASA's Johnson Space Centre, Houston, where they will be carefully stored and examined.
The Open University team hope to be involved in analysing the samples that return to Earth in January 2006.
UK scientists, including a team from the Open University, are also involved with the European Space Agency's Rosetta Mission which will follow and land on Comet Churyumov-Gerasimenko. This mission is due to be launched on 26th February 2004.
Wild-2 is pronounced Vilt-2. The comet is named after the Swiss discoverer.
STARDUST, is part of NASA's Discovery Programme of low cost, highly focused science missions, was built by Lockheed Martin Astronautics and Operations, Denver, Colorado, and is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington D.C.Boulder, Colorado -- November 26, 2003 -- A new study by researchers at Southwest Research Institute (SwRI) and the Observatoire de la Cote d'Azur provides an explanation for one of the more mysterious aspects of the population of objects beyond Neptune. In doing so, it provides a unique glimpse into the proto-planetary disk from which the Solar System's planets formed. Results will be published in the November 27 issue of Nature.
The Kuiper belt is a region of the Solar System that extends outward from Neptune's orbit, containing billions of icy objects from kilometers to thousands of kilometers across. It was discovered in 1992 and, since that time nearly 1,000 objects have been cataloged. Some of these objects are very large -- the largest having a diameter of more than 1,000 kilometers.
As astronomers have studied this structure, a mystery has unfolded. Like most of the planets in the Solar System, the large Kuiper belt objects are believed to have been formed from smaller objects that stuck together when they collided. For this process to have worked in the distant regions beyond Neptune, the Kuiper belt would have to contain more than 10 times the amount of material than is in the Earth. However, telescopic surveys of this region show that it currently contains roughly one-tenth the mass of the Earth, or less.
To solve the puzzle, researchers have been searching for several years for a way to remove more than 99 percent of the Kuiper belt's material. However, Dr. Harold Levison (SwRI) and Dr. Alessandro Morbidelli (Observatoire de la Cote d'Azur of Nice, France) describe in their article, "Forming the Kuiper Belt by the Outerward Transport of Objects During Neptune's Migration," that the Kuiper belt may not have lost much mass at all.
"The mass depletion problem has been sticking in our throat for some time," says Levison, a staff scientist in the SwRI Space Studies Department. "It looks like we may finally have a possible answer."
Levison and Morbidelli argue that the proto-planetary disk from which the planets, asteroids and comets all formed had a heretofore unanticipated edge at the current location of Neptune, which is at 30 astronomical units (AU, the average distance between the Sun and Earth), and that the region now occupied by the Kuiper belt was empty. All the Kuiper belt objects we see beyond Neptune formed much closer to the Sun and were transported outward during the final stages of planet formation.
Researchers have known for 20 years that the orbits of the giant planets moved around as they formed. In particular, Uranus and Neptune formed closer to the Sun and migrated outward. Levison and Morbidelli show that Neptune could have pushed all the observed Kuiper belt objects outward as it migrated. "We really didn't solve the mass depletion problem, we circumvented it," says Levison. "According to our work, the void beyond Neptune was probably devoid of objects."
However, in this model, the region interior to 30 AU contained enough material for the Kuiper belt objects to form. The mechanisms employed by Neptune to push out the Kuiper belt only affected a small fraction of the objects. These became the objects seen by astronomers; the rest were scattered out of the Solar System by Neptune. This new theory explains many of the observable features of the outer Solar System, including the characteristics of the orbits of the Kuiper belt objects and the location of Neptune.
"One of the puzzling aspects of Neptune's migration is why it stopped where it did," says Morbidelli. "Our new model explains this as well. Neptune migrated until it hit the edge of the proto-planetary disk, at which point it abruptly stopped."
NASA, the National Science Foundation and the Centre National de la Recherche Scientifique in Paris funded this research.Results from NASA's Hubble Space Telescope played a major role in preparing ESA's ambitious Rosetta mission for its new target, comet 67P/Churyumov-Gerasimenko (67P/C-G). For the first time in history, Rosetta will land a probe on a comet and study its origin. Hubble precisely measured the size, shape, and rotational period of comet 67P/C-G.
Hubble's observations revealed that comet 67P/C-G is approximately a three-by-two mile, football-shaped object on which it is possible to land. Mission scientists were concerned that the solid nucleus could be nearly 3.6 miles (6 km) across. The higher gravity on a comet that size might make a soft landing more difficult. "Although 67P/C-G is roughly three times larger than the original Rosetta target, its elongated shape should make landing on its nucleus feasible, now that measures are in place to adapt the lander package to the new configuration before next year's launch," says Dr. Philippe Lamy of the Laboratoire d'Astronomie Spatiale in France. Lamy is presenting the Hubble results on comet 67P/C-G on Sept. 5, 2003 at the annual meeting of the Division of Planetary Sciences of the American Astronomical Society in Monterey, Calif.
Mission scientists began considering the new target when the Rosetta mission's launch date was postponed. The delay made the original target comet, 46P/Wirtanen, no longer easily reachable. But scientists did not have enough information on the new target, comet 67P/C-G, and sought data from the largest telescopes. Using a technique developed over the past decade by Lamy, Imre Toth (Konkoly Observatory, Hungary), and Harold Weaver (Johns Hopkins University Applied Physics Laboratory, Laurel, Md.), the team snapped 61 Hubble images of comet 67P/C-G over an interval of 21 hours between March 11 and 12, 2003. Hubble's Wide Field Planetary Camera 2 isolated the comet's nucleus from the coma, the diffuse cloud of dust and gas surrounding the nucleus, and quickly provided the missing figures. The telescope showed that the nucleus has an ellipsoidal shape. Hubble also measured its rotation rate of approximately 12 hours. Rosetta's launch is currently planned for February 2004, with a rendezvous with the comet about 10 years later.
The Hubble observing team members are P.L. Lamy and L. Jorda (Laboratoire d'Astronomie Spatiale, France), I. Toth (Konkoly Observatory, Hungary), and H.A. Weaver (Johns Hopkins University Applied Physics Laboratory). The movie simulation of the Hubble results is provided by Mikko Kaasalainen (University of Helsinki, Finland) and Pedro Gutierrez (Laboratoire d'Astronomie Spatiale, France). The observations were made possible through a special program approved by the Director of the Space Telescope Science Institute, S. Beckwith.
Electronic images, a movie, and additional information are available at:
See:
http://www.eso.org/outreach/press-rel/pr-2003/phot-27-03.html
8/20/02
The CONTOUR spacecraft was launched into Earth orbit on July 1 to begin its Comet Tour. But on July 15, when its rocket engine was fired to take it on its orbit to Comet Encke, it apparently broke apart. It did not establish radio contact, and telescopes in Arizona, Hawaii, and elsewhere have been able to follow 3 pieces of something moving rapidly in the orbit that the spacecraft would have followed. Apparently, the rocket-engine burn was about 4% short and then something exploded. Some faint hope remains that the extra pieces are merely unimportant parts that broke off and that the spacecraft will resume radio contact following some automatic sequences, including one with relatively favorable antenna contact scheduled for December 2002, but that seems unlikely. It is a sad ending for a promising mission.
I am writing this note from Mauna Kea Observatory, where our Pluto occultation group of David Ticehurst, Bryce Babcock, and me has been helping David Tholen of the University of Hawaii obtain images using the 2.2-m telescope. Tholen has worked out sun-centered orbits for the three components he has imaged.
Jay M. Pasachoff
Institute of Astronomy, U. Hawaii, Press Release, 24 July 2002
SUMMARY
New observations from Mauna Kea with the University of
Hawaii's 2.2-meter telescope by Institute for Astronomy
astronomers Yanga R. Fernandez, Scott S. Sheppard and
David C. Jewitt have revealed a zoo of tiny mini-comets
strung out in a line trailing behind the comet 57P/du
Toit-Neujmin-Delporte. This comet has apparently
suffered a significant catastrophe, violent enough to break
off many pieces of its nucleus. The event was
probably triggered by thermal stresses within the nucleus
due to it being warmed by sunlight. While it
is not uncommon for one or two companions to be seen
near a comet that has fragmented, our observations
reveal at least 19 companions, a rare finding.
Monitoring of these fragments over the coming weeks
and months should reveal much about the constitution
and fragility of cometary material.
DETAILS
Motivated by an earlier report of a previously-unknown
companion associated with Comet 57P/du Toit-Neujmin-Delporte,
we obtained deep imaging to search for any population of
fragments that might exist near the comet. We used the
University of Hawaii 2.2-m telescope on Mauna Kea and a
charge-coupled device (CCD) to make a digital map of the
sky around the comet. The observations were performed on
the nights of July 17/18 and July 18/19, 2002 (Hawaii
Standard Time).
We found a zoo of fragments strung out in a line extending almost 30 minutes of arc away from the comet itself (for comparison, the diameter of the full Moon also covers 30 minutes of arc). So far we have confirmed the existence of 19 fragments, and the discovery has been announced by the Central Bureau for Astronomical Telegrams, the internationally- recognized official clearinghouse for reporting cometary discoveries. We identified the fragments by taking successive images of a field and detecting their motion against the background stars. A mosaic of the relevant mapped region is shown at
http://www.ifa.hawaii.edu/~yan/57p.html,
with the location of the fragments circled. At the distance of the comet, the mosaic spreads over about 1,000,000 kilometers (about 620,000 miles).
We cannot be sure of the sizes of the fragments but the brightest ones are probably less than a few hundred meters (few hundred yards) across. The smallest fragments are probably no more than a few tens of meters across, roughly the size of a house. A gallery of our 18 new objects is shown on the above WWW site.
FREQUENTLY ASKED QUESTIONS
* What are comets?
Comets are conglomerates of water ice and rocky
material formed in the early days of the solar system.
When a comet is within roughly 400,000,000 kilometers
(250,000,000 miles) of the Sun, the sunlight is strong
enough to start evaporating the ice in large
quantities. (For comparison, Earth is 150,000,000 km
(93,000,000 miles) from the Sun.) Since the ice and
rock are intimately mixed, the warming and
evaporating ice produces great thermal and physical
stresses on the body of the nucleus. Under normal
circumstances, only vapor and tiny dust grains are
all that fly off the surface of the nucleus -- and
here on Earth we see a comet with a long tail, for
example as widely seen in the late 1990s with comets
Hyakutake and Hale-Bopp.
* Why do comets split?
Occasionally thermal stresses become great enough
that entire chunks of the nucleus are ejected.
Now while the basic idea is thought to be understood,
the details are still uncertain, basically because
we do not know many fundamental structural properties
of cometary nuclei. In the case of this comet we
cannot yet determine even when the fragmentation
took place; further observations are necessary.
With sufficient data fragmenting comets can provide
a laboratory for us to witness major evolutionary
events and can help us understand a comet's basic
constitution.
* What will happen to the fragments?
We expect that most will fade to the point of
invisibility, but we don't know how long that will
take. A few might last for years.
* Why that name?
Comet 57P/du Toit-Neujmin-Delporte is named for the
3 people who discovered it in 1941.
* Why 57P?
The "57P" means it is the 57th comet in the list of
comets that have been seen on two of their passages
around the Sun. (The first comet in this list, "1P",
is the famous Halley's Comet.)
* Why didn't somebody see the 19 companions before?
Nobody looked hard enough.
* Can I see this comet by eye?
No, it is 15th magnitude and much too faint to see,
even with binoculars.
CONTOUR Spacecraft Is Launched for Its Comet Tour
JHU APL Press Release, July 3, 2002
NASA's Comet Nucleus Tour (CONTOUR) spacecraft -- set to provide the closest look yet at the "heart" of a comet -- was successfully launched on July 3 aboard a Boeing Delta II rocket from Cape Canaveral Air Force Station, Fla.
Designed and built by The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., the 2,138-pound (970-kilogram) spacecraft was placed into an elliptical Earth orbit 63 minutes after launch. About 19 minutes later the mission operations team at APL acquired a signal from the spacecraft through the Deep Space Network antenna station in Goldstone, Calif., and by 5:45 a.m. EDT Mission Director Dr. Robert W. Farquhar of the Applied Physics Lab confirmed the craft was operating normally and ready to carry out its early orbit maneuvers.
"CONTOUR's launch was a spectacular start to an important project," says Dr. Stamatios M. Krimigis, head of the APL Space Department. "CONTOUR is next in the growing lineup of missions to explore small planetary bodies -- such as comets and asteroids -- and we expect it will add much to what little we know about these ancient samples of the solar system's original materials."
CONTOUR will orbit Earth un
