Comet Link

Charles Morris's Comet Site
Hale-Bopp Webpages
The Why Files - Information on Comets
Comet Hyakutake Near the Sun
Stardust Mission to Comet Planned
Caroline Herschel, Discoverer of Many Comets
astronomylinks.com/comets/
Planetary Society's Descriptions of Comet and Asteroid Missions
Comet Hale-Bopp Webpage at the European Space Agency
Maria Mitchell Page
Comet Crash of Shoemaker-Levy 9 with Jupiter homepage
Comet Borrelly

Rosetta to Be Launched to a Comet

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

Mission objectives

* 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.

Mission Firsts

Launch and Flight

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.

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.

American Participation in Rosetta

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.

Rosetta Ready to Explore a Comet's Realm

Stardust Mission Encounters a Comet

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.

Background information

Wild-2 is pronounced Vilt-2. The comet is named after the Swiss discoverer.

Stardust Mission Encounters a Comet

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.

Background information

Wild-2 is pronounced Vilt-2. The comet is named after the Swiss discoverer.

New Explanation of the Kuiper Belt's Mass

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."

Hubble Observations of Rosetta's Target; February 2004 Launch

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.

Halley's Comet Photographed Right Now

See:
http://www.eso.org/outreach/press-rel/pr-2003/phot-27-03.html

New Destination for ESA's Rosetta Spacecraft

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

Send Your Name to a Comet on a Spacecraft

People worldwide may celebrate July 4, 2005, as the day their names reach a comet. NASA is launching a campaign to send hundreds of thousands of names to comet Tempel 1.

The names will be carried on board NASA's Deep Impact spacecraft, the first deep-space mission designed to really reach out and touch a comet. Mission scientists are confident an impact on a comet's nucleus will answer basic questions about the nature and composition of these celestial wanderers.

"This is an opportunity to become part of an extraordinary space mission," said Dr. Don Yeomans, an astronomer at JPL, a member of Deep Impact's science team. "When the craft is launched in December 2004, yours and the names of your loved-ones can hitch along for the ride and be part of what may be the best space fireworks show in history."

Deep Impact's larger flyby spacecraft will carry a smaller impactor spacecraft to Tempel 1 for release into the comet's path for a planned collision. The flyby spacecraft will take pictures as the 370-kilogram (816 pound) copper-tipped impactor plunges into Tempel 1 at about 37,000 kilometers (22,990 miles) per hour. The impactor is expected to make a spectacular, football field-sized crater, seven to 15 stories deep, in the speeding comet. Carried aboard the impactor will be a standard mini-CD containing the names of comet, space, and other enthusiasts from around the world.

"This campaign will allow people from around the world to become directly involved with Deep Impact and through that get them thinking about the scientific reasons for the mission," said University of Maryland (UM) astronomy professor Michael A'Hearn, Deep Impact's principal investigator. "We particularly hope to capture the interest of young students, as they will become the explorers of the next generation."

People may submit their names for this historic one-way mission by visiting NASA's Deep Impact Web site, from May 2003 to February 2004, at:
http://deepimpact.jpl.nasa.gov

The collision between the impactor and Tempel 1 is not forceful enough to make an appreciable change in the comet's orbital path around the sun. The comet poses no threat to Earth.

Deep Impact was selected in 1999 as a NASA Discovery mission. The goal of the Discovery Program is to launch many smaller missions with fast development times, each for a fraction of the cost of NASA's larger missions. The main objective is to enhance our understanding of the Solar System by exploring the planets, their moons, and small bodies, such as comets and asteroids.

http://deepimpact.jpl.nasa.gov
A mirror site is available at: http://deepimpact.umd.edu

Rosetta Mission Postponed Indefinitely

Rosetta to Be Launched in January 2003

Royal Astronomical Society Press Release, 4 December 2002

The launch of the European Space Agency's pioneering Rosetta mission to explore Comet Wirtanen is currently scheduled for the night of 12-13 January 2003.

After launch from Kourou spaceport in French Guiana on board a heavy-lift Ariane 5 rocket, Rosetta will spend almost nine years travelling around the inner Solar System until it finally rendezvous with Comet Wirtanen in November 2011.

In order to catch up with the fast-moving comet, Rosetta will receive gravitational boosts during close flybys of Mars (26 August 2005) and Earth (28 November 2005 and 28 November 2007). It will also make two excursions into the main asteroid belt, when it will gather the first close-range observations of two contrasting chunks of primitive rock, a 110 km wide asteroid named Siwa and a tiny asteroid named Otawara.

In the summer of 2012, when the Rosetta Orbiter is circling within one kilometre (0.6 miles) of Wirtanen's nucleus, the 100 kg Lander will drop gently onto its coal-black surface to make the first in situ measurements of one of these 'dirty snowballs.'

The Orbiter will then spend another 12 months chasing the comet during its headlong plunge towards the Sun. Rosetta will examine at close quarters the dramatic changes that take place as Wirtanen's ices vaporise in the warmth of the Sun, generating bright jets of gas and dust that feed an all-enveloping coma. The 11-year odyssey will end when the comet and spacecraft return to the vicinity of Earth's orbit in July 2013.

Deep Impact is a smaller, less ambitious NASA mission which is designed to discover the secrets of what comets are made of. Its two components - a flyby spacecraft and a 350 kg (771 pound) impactor - will be launched together in early 2004 and travel to Comet Tempel 1, where they will separate and operate independently.

CONTOUR spacecraft failed, perhaps exploded

August 20, 2002

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

Spectacular Split Comet (57P/DU Toit-Neujmin-Delporte)

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 Launched

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 until Aug. 15, when it's scheduled to fire its main engine and enter a comet-chasing orbit around the sun. The mission's flexible four-year plan includes encounters with comets Encke (Nov. 12, 2003) and Schwassmann-Wachmann 3 (June 19, 2006), though it can add an encounter with a "new" and scientifically valuable comet from the outer solar system, should one be discovered in time for CONTOUR to fly past it. CONTOUR's four scientific instruments will take detailed pictures and measure the chemical makeup of each comet's nucleus -- a chunk of ice and rock -- while analyzing the surrounding gas and dust.

The 8-sided solar-powered craft will fly as close as 62 miles (100 kilometers) from each nucleus, protected by a 10-inch-thick, layered dust shield of heavy Nextel and Kevlar fabric. Scientists expect the data to reveal the differences between comet nuclei and answer questions about the role comets had in shaping the Earth and other planets. "We're looking forward to a fantastic mission," says APL's Edward L. Reynolds, who at launch assumed the role of CONTOUR project manager from Mary C. Chiu, who is retiring from the Applied Physics Laboratory. "From mission design and operations at APL, to the navigation group at NASA's Jet Propulsion Laboratory, to the science effort headed by Cornell University, this team includes the talent and expertise needed to capture and deliver the best data yet on a comet's nucleus."

The $159 million CONTOUR is the sixth mission in NASA's Discovery Program of lower cost, scientifically focused exploration projects. APL manages the mission, built the spacecraft and its two cameras, and will operate CONTOUR during flight. NASA's Goddard Space Flight Center, Greenbelt, Md., provided CONTOUR's neutral gas/ion mass spectrometer and von Hoerner & Sulger, GmbH, Schwetzingen, Germany, built the dust analyzer. NASA's Jet Propulsion Laboratory, Pasadena, Calif., will provide navigation and Deep Space Network (DSN) support. Dr. Joseph Veverka, CONTOUR's principal investigator from Cornell University, Ithaca, N.Y., leads a science team of co-investigators from universities, industry and government agencies in the U.S. and Europe.

For more information about the CONTOUR mission or to view images of the spacecraft, visit www.contour2002.org.

Comet Borelly's Surface Is Dry

Press Release, April 5, 2002

PASADENA, Calif., April 5 (AScribe Newswire) -- Comets are sometimes described as "dirty snowballs," but a close flyby of one by NASA's Deep Space 1 spacecraft last fall detected no frozen water on its surface.

Comet Borrelly has plenty of ice beneath its tar-black surface, but any exposed to sunlight has vaporized away, say scientists analyzing data from Deep Space 1, managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif.

"The spectrum suggests that the surface is hot and dry. It is surprising that we saw no traces of water ice," said Dr. Laurence Soderblom of the U.S. Geological Survey's Flagstaff, Ariz., station, lead author of a report on the Borrelly flyby results appearing in the online edition of the journal Science.

"We know the ice is there," he said. "It's just well- hidden. Either the surface has been dried out by solar heating and maturation or perhaps the very dark soot-like material that covers Borrelly's surface masks any trace of surface ice."

The Deep Space 1 science team released pictures and other initial findings days after the spacecraft flew within 2,171 kilometers (1,349 miles) of the comet's solid nucleus on September 22, 2001. This week's report provides additional details about the nucleus and the surrounding coma of gases and dust coming off of the comet as measured by one of Deep Space 1's scientific instruments.

"Comet Borrelly is in the inner solar system right now, and it's hot, between 26 and 71 degrees Celsius (80 and 161 degrees Fahrenheit), so any water ice on the surface would change quickly to a gas, " said Dr. Bonnie Buratti, JPL planetary scientist and co-author of the paper. "As the components evaporate, they leave behind a crust, like the crust left behind by dirty snow."

Borrelly is unusually dark for an object in the inner solar system. The comet's surface is about as dark as a blot of photocopy toner, possibly the darkest surface in the solar system. It is more like objects in the outer solar system such as the dark side of Saturn's moon Iapetus and the rings of Uranus.

"It seems to be covered in this dark material, which has been loosely connected with biological material." Buratti said. "This suggests that comets might be a transport mechanism for bringing the building blocks of life to Earth." Comets may have played an important role in supplying organic materials that are required for life to originate.

Soderblom points out that Borrelly's old, mottled terrain with dark and very dark spots -- different shades of black - -- are apparently inactive. Ground-based observations estimated that 90 percent of Borrelly's surface might be inactive, and the observations taken by Deep Space 1 show that this is indeed true.

"It's remarkable how much information Deep Space 1 was able to gather at the comet, particularly given that this was a bonus assignment for the probe," said Dr. Marc Rayman, project manager of the mission. Deep Space 1 completed its original goal to test 12 new space technologies and then earned extra credit by achieving additional goals, such as the risky Borrelly flyby. "It's quite exciting now as scientists working with this rich scientific harvest turn data into knowledge."

Images of comet Borrelly from Deep Space 1 are available at http://www.jpl.nasa.gov/images/ds1/ds1_borrelly.html .

More information on the Deep Space 1 mission is available at http://nmp.jpl.nasa.gov/ds1/ .

Deep Space 1 was launched in October 1998 as part of NASA's New Millennium Program, which is managed by JPL for NASA's Office of Space Science, Washington, D.C. The California Institute of Technology, Pasadena, manages JPL for NASA.

Stardust En Route to Comet Wild 2 in 2004

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.

CONTOUR Mission to Be Launched to Two Comets in Summer 2002

Capping nearly two years of detailed development and assembly, engineers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, are putting the last touches on the CONTOUR spacecraft, which will provide the closest and most detailed look ever into the icy heart of a comet.

Slated to launch July 1, 2002, CONTOUR (Comet Nucleus Tour) will encounter at least two diverse comets as they zip through the inner solar system. From as close as 100 miles (160 kilometers) away, the spacecraft will snap high-resolution photos of the comet nucleus, map the types of rock and ice on the nucleus, and analyze the composition of the surrounding gas and dust. CONTOUR's targets include comet Encke in November 2003 and Schwassmann-Wachmann 3 in June 2006 - though the mission team can send the spacecraft to an as-yet undiscovered comet should such a valuable opportunity arise.

Currently parked in an APL clean room, CONTOUR has had all onboard systems tested, including all four of its scientific instruments - two cameras, a dust analyzer and a mass spectrometer. Over the next week, APL technicians will attach solar panels and the final layers of the resilient Kevlar-and-Nextel dust shield designed to protect CONTOUR from speeding bullet-like particles around the comets.

Environmental testing on the craft begins Jan. 14 on APL's large vibration tables. On Jan. 28, CONTOUR will ship to NASA's Goddard Space Flight Center in Greenbelt, Maryland, for nearly three months of additional tests in Goddard's expansive facilities.

"These rigorous checks will verify that CONTOUR can stand up to the shaking during launch and the harsh conditions of outer space," says Edward Reynolds, CONTOUR mission system engineer at APL.

In May, CONTOUR will leave Goddard for Kennedy Space Center, Florida, in final preparation for launch aboard a Boeing Delta II rocket.

CONTOUR is the next launch in NASA's Discovery Program of low-cost, scientifically focused missions. APL manages the CONTOUR mission for NASA and will operate the spacecraft. Dr. Joseph Veverka of Cornell University, Ithaca, New York, is CONTOUR's principal investigator. For more information, visit the CONTOUR Web site at www.contour2002.org.

Photos are available on the Web at
http://www.jhuapl.edu/public/pr/020104.htm.

Deep Space 1 Images Comet Borrelly's Nucleus

In a risky flyby, NASA's ailing Deep Space 1 spacecraft successfully navigated past a comet, giving researchers the best look ever inside the glowing core of icy dust and gas.

The space probe's close encounter with comet Borrelly provided the best-resolution pictures of the comet to date. The already-successful Deep Space 1, without protection from the little-known comet environment, whizzed by just 2,200 kilometers (1,400 miles) from the rocky, icy nucleus of the 10-kilometer-long (more than 6-mile-long) comet.

Exceeding the team's expectations of how this elderly spacecraft would perform, the intrepid spacefarer sent back black-and-white photos of the inner core of the comet. It also measured the types of gases and infrared waves around the comet, and how the gases interacted with the solar wind.

"Deep Space 1 plunged into the heart of comet Borrelly and has lived to tell every detail of its spine-tingling adventure!" said Dr. Marc Rayman, the project manager of Deep Space 1 at the Jet Propulsion Laboratory (JPL), Pasadena, Calif. "The images are even better than the impressive images of comet Halley taken by Europe's Giotto spacecraft in 1986."

Rayman added, "After years of nursing this aged and wounded bird along -- a spacecraft not structured to explore comets, a probe that exceeded its objectives more than two years ago - -- to see it perform its remarkably complex and risky assignment so well was nothing short of incredible."

"It's mind-boggling and stupendous," said Dr. Laurence Soderblom, the leader of Deep Space 1's imaging team, and a geologist with the U.S. Geological Survey, Flagstaff, Ariz. "These pictures have told us that comet nuclei are far more complex than we ever imagined. They have rugged terrain, smooth rolling plains, deep fractures and very, very dark material."

Scientists also realized that Borrelly was different than they expected as Deep Space 1 flew through the coma, the cloud of dust and gas surrounding the nucleus. They had expected that the solar wind would flow symmetrically around the cloud, with the nucleus in the center.

Instead, they found that though the solar wind was flowing symmetrically around the cloud, the nucleus was off to one side shooting out a great jet of material forming the cloud that makes the comet visible from Earth. "The formation of the coma is not the simple process we once thought it was," said Dr. David Young of the University of Michigan, Ann Arbor, leader of the team that made the measurements. "Most of the charged particles are formed to one side, which is not what we expected."

Deep Space 1 completed its primary mission testing ion propulsion and 11 other advanced, high-risk technologies in September 1999. NASA extended the mission, taking advantage of the ion propulsion and other systems to undertake this chancy but exciting encounter with the comet.

Deep Space 1, launched in October 1998 as part of NASA's New Millennium Program, is managed by JPL for NASA's Office of Space Science in Washington. The California Institute of Technology manages JPL for NASA.

More information can be found on the Deep Space 1 Internet home page at:

http://nmp.jpl.nasa.gov/ds1/

In this highest resolution view of the icy, rocky nucleus of comet Borrelly, (about 45 meters or 150 feet per pixel) a variety of terrains and surface textures, mountains and fault structures, and darkened material are visible over the nucleus's surface. This was the final image of the nucleus of comet Borrelly, taken just 160 seconds before Deep Space 1's closest approach to it. This image shows the 8-km (5-mile) long nucleus about 3417 kilometers (over 2,000 miles) away.

Smooth, rolling plains containing brighter regions are present in the middle of the nucleus and seem to be the source of dust jets coma. The rugged land found at both ends of the nucleus has many high ridges along the jagged line between day and night on the comet. This rough terrain contains very dark patches that appear to be elevated compared to surrounding areas. In some places the dark material accentuates grooves and apparent faults. Stereo analysis shows the smaller end of the nucleus (lower right) is tipped toward the viewer (out of frame). Sunlight is coming from the bottom of the frame.

Contour mission

NASA has approved the Comet Nucleus Tour, "Contour," for launch in July 2002. it will go first to Comet Encke, a periodic comet with a short period. It will then go on to Comet Schwassmann-Wachmann-3, which split into three parts in 1995. Then it will proceed to Comet d'Arrest, where it will arrive in 2008.

Deep Impact Collision To Be Observable from Earth on July 4, 2005

U. Maryland Press Release

The Deep Impact mission to penetrate deep into the nucleus of a comet and uncover secrets about the origin of the solar system has won approval by NASA. The $240 million mission --- which was conceived by University of Maryland astronomy professor Michael A'Hearn --- will be the first to study the interior of a comet, which astronomers believe contains material unchanged since the formation of the solar system.

"We are excited that NASA selected "Deep Impact" from among five strong mission proposals," said A'Hearn, principal investigator for the mission and one of the world's leading experts on comets. "And we are even more excited about the scientific potential of this mission. It promises to greatly further our understanding of the composition of comets and of the materials and processes that led to the formation of the planets and other bodies in our solar system. Learning more about the composition of comets also should help us better understand the past history and future risks of comet impacts with the earth."

The launch of the Deep Impact mission is planned for January 20, 2004. The schedule calls for the mission to reach its target, comet Tempel 1, at the beginning of July, 2005 with impact on July 4. The spacecraft will actually consist of two craft that will separate when the comet is reached. The first craft is an instrument platform that will fly slowly by the comet and record data and images of the impact, crater formation, and comet interior. The second craft is the "impactor," which upon reaching Tempel 1 will separate from the flyby craft and be propelled at 10 kilometers per second into a target site on the sunlit side of the comet. The kinetic energy of the 500 kilogram copper impactor is expected to create a large (120 meters diameter), deep (25 meters) crater and vaporize the impactor in the process.

Optical and infrared instruments on the flyby craft will provide visual images and infrared spectral mapping of the impact and crater. In the visual range, a high resolution camera will provide detailed images while a medium resolution one will provide targeting information and views of the complete crater and nucleus. The craft will have redundant storage of data to guard against any data loss.

"Because the impact will be spectacular and observable from Earth, the mission should be of great interest to the public and will provide a tremendous opportunity for students and others to learn more about comets, the formation of the solar system and the role of comets in the history of Earth," said Lucy McFadden, an associate research scientist in the University of Maryland's department of astronomy and director of education and public outreach for the Deep Impact mission.

According to McFadden, the public will have opportunities to be directly engaged in the mission by viewing the July 4th impact both through small telescopes and in nearly real time images from the flyby craft that will be received on earth minutes after the impact occurs.

Amateur and professional astronomers around the world will be enlisted to host viewing parties that will provide the public with a chance to directly participate in the mission and see the impact. Millions of people will likely be able to view the impact at home on their TV sets as well, since images from the flyby craft will be made available via satellite to television stations and other media outlets around the world.

In addition, information and images about the mission and its findings will be made available to students and the public through a mission web site and educational materials that will be provided to schools.

(http://www.ss.astro.umd.edu/deepimpact/).