August 7, 2000


The MUSES-C project, a joint effort of Japan's Institute of Space and Astronautical Sciences (ISAS) and NASA to explore an asteroid and return a sample to Earth, has announced that the asteroid target of the project and the launch date have been changed.

The launch is now slated for November or December 2002, arrival at the asteroid in September 2005 and return to earth in June of 2007. Its previous schedule included launch in July 2002, arrival at its previous target in 2003, and return to Earth in June 2006.

The new target is the asteroid 1998 SF36. The NASA-built science payload is a rover that will gather and transmit science data to the Japanese spacecraft. The spacecraft will then gather and return to Earth samples of the asteroid. The ISAS-built spacecraft will stay at the asteroid for three months.

The launch date and subsequent target asteroid changes are due to delays in the provision of the Japanese MV launch vehicle, which will carry the MUSES mission to space.

Asteroid 1998 SF36, whose orbital period is about 1.5 years, will approach to within 6.4 million kilometers (4 million miles) of the Earth on March 29, 2001 and to within about 2.09 million kilometers (1.3 million miles) on June 25, 2004. Extensive ground-based observing campaigns will be planned near these close approach times to determine the asteroid's approximate size, shape, rotation state, and some surface characteristics.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., is managing the U.S. portion of the mission, which is called MUSES- CN, and includes the rover and various support services for the ISAS mission. ("MUSES-C" stands for Mu Space Engineering Spacecraft C, "N" refers to NASA.) The JPL MUSES-CN project has also arranged for the testing of the MUSES-C reentry heat shield at NASA's Ames Research Center, Moffett Field, Calif. JPL will also arrange for supplemental tracking of the spacecraft by NASA's Deep Space Network, and will assist in navigating the spacecraft to the asteroid. Japanese and U.S. scientists will collaborate on the investigations of the asteroid and the returned samples.

More information (pdf file).

MUSES CN is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory, Pasadena, Calif. JPL is a division of the California Institute of Technology in Pasadena.

03 August 2000

By Andrew Bridges

Hopping Rover: Bound for New Asteroid in 2002

PASADENA, Calif. - A launch delay has forced the selection of a new target for a joint Japanese-U.S. mission that will make an unprecedented docking with an asteroid, where the probe will gather rock samples for return to Earth and release a tiny rover to roam its surface.

The launch date for the Muses C mission has now slipped to November or December 2002, prompting planners to fix their sights on the asteroid 1998 SF 36 as the spacecraft's new target destination.

"The change is significant, in the sense the arrival date also slips to September 2005 and we'll stay not six months but just three months," said Donald Yeomans, of NASA's Jet Propulsion Laboratory (JPL), project manager for the NASA portion of the mission.

Full story

August 1, 2000

Forwarded from Don Yeomans, NASA MUSES-CN Project Scientist

Change in MUSES-C Target Body Announced

As a result of a tight launch schedule, the Japanese MUSES-C project has announced that their target asteroid has been switched from 10302 (1989 ML) to 1998 SF36.

The new mission time line is:

Launch:              Nov. - Dec. 2002
Earth Swingby:       May 2004
Asteroid arrival:    Sept. 2005
Asteroid departure:  Jan. 2006
Earth sample return: June 2007

Information on the new target body:  1998 SF36
Orbit (J2000)
Epoch of osculation:        2000 Feb. 26.0  ET
Perihelion passage time:    1999 Oct. 25.01552 ET
Perihelion distance:        0.953828 AU
Aphelion distance:          1.69567 AU
Semi-major axis:            1.32475 AU
Orbital period:             1.525 years
Eccentricity:               0.2799948
Arg. Of perihelion:       160.10020  deg.
Long. Asc. Node:           71.61882  deg.
Inclination:                1.71649  deg.

Absolute magnitude:  18.8
  Diameter ~ 1.2 km if albedo = 0.04
             0.7 km if albedo = 0.11
             0.5 km if albedo = 0.20

This asteroid is classified as a "Potentially Hazardous Object" since its orbit approaches that of the Earth to within 0.05 AU (less than 7.5 million km). The orbit is still uncertain since it is based upon a data interval of 46 days only. The next two Earth close approaches are in 2001 and 2004.

   Date               Close Approach     Brightest App. Magn.
   2001 Mar. 29       0.043 AU            14.2
   2004 June 25       0.014 AU            12.7

Before, during, and after these Earth close approaches, we hope that observers will make an effort to characterize this asteroid's rotation rate, rotation pole direction, albedo, thermal properties, size, shape, and spectral classification. Astrometric observations will also be necessary to update its orbit.

For asteroid 1998 SF36, an interactive orbit animation as well as an ephemeris generation capability is located at:

Don Yeomans
NASA MUSES-CN Project Scientist

University of Hawaii
Honolulu, HI 96822

July 1, 1999

NASA taps UH astronomer David Tholen for asteroid mission

David Tholen, an astronomer at the University of Hawai'i Institute for Astronomy, is one of a half-dozen U.S. scientists selected by the National Aeronautics and Space Administration (NASA) for the world's first expedition to place a robotic lander on an asteroid and return pieces of the space rock to Earth for in-depth study. The U.S. scientists selected will collaborate with Japanese colleagues on the MUSES-C project, the world's first asteroid sample return mission.

"MUSES-C" stands for Mu Space Engineering Spacecraft, with the "C" signifying it is the third in a series. The mission is a cooperative venture of Japan's Institute of Space and Astronautical Science (ISAS) and NASA.

Asteroid Nereus, a one kilometer-diameter (about one-half mile) object, is the preferred target of the mission. (An alternative target is the asteroid 1989 ML.) "Nereus is one of Earth's closest neighbors, easily accessible for a spacecraft rendezvous and an object of key scientific interest," according to Donald K. Yeomans, NASA's MUSES-C mission project scientist.

David Tholen is an internationally recognized authority on the categorization of asteroids. He will use data from the spacecraft camera to determine the asteroid's rotational state, to estimate the age of the asteroid and its shape and size, as well as other properties such as density.

Nereus is thought to be a relatively unaltered asteroid, having changed little since Earth and the other planets of the inner solar system formed some 4.6 billion years ago. Detailed studies of Nereus and other asteroids are expected to provide scientists with crucial information about Earth's initial chemical composition and the conditions under which it and the other inner planets originally formed.

The MUSES-C spacecraft, provided by the Japanese, will be launched on a Japanese M-5 launch vehicle in January 2002 from Kagoshima Space Center, Japan, toward a touchdown on the asteroid Nereus in April 2003. The Japanese spacecraft will deliver a NASA-provided miniature robotic rover to the surface of Nereus to study the asteroid up close. The MUSES-C spacecraft will gather samples of the asteroid and depart for Earth, leaving the rover behind. The asteroid samples will be returned to Earth in January 2006.

Nereus has a gravity field estimated to be about 100,000 times weaker than Earth's. This presents an unusual challenge for engineers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, where the miniaturized rover is being developed. The cigar box-size rover is being designed to take advantage of the low gravity field and will be able to hop tens of meters above the surface by drawing its wheel struts together, then springing them outward. This would give the cameras and other instruments onboard a bird's-eye view of the asteroid terrain, and would allow the rover to cover much more ground overall. The weak gravity would pull the rover back to land gently on the surface. Solar panels on the rover's back and belly allow it an uninterrupted flow of electricity, no matter which way it lands. Like an agile cat, the rover is also equipped to right itself if necessary.

The MUSES-C spacecraft will carry a camera, an infrared spectrometer and a lidar instrument (a laser-based altimeter) that will be used by Japanese scientists and their NASA colleagues to study the asteroid from a distance of about 20 kilometers. An X-ray spectrometer will also be onboard to study the asteroid's bulk chemical composition. The NASA rover will carry a camera, an infrared spectrometer and an alpha X-ray spectrometer for analyzing the composition of the asteroid surface.

Up to three asteroid samples will be collected after small pellets are fired into the asteroid's surface. Ejecta from the pellets' impact will be collected through an inverted funnel and stored in a sample-return capsule onboard the orbiter. The capsule will parachute to Earth's surface when the orbiter re-approaches the planet in January 2006.

In addition to David Tholen, the scientists selected for the mission's U.S. team are: Beth Clark of Cornell University, a UH alumna (PhD '93) who will use the rover camera and infrared spectrometer to study the physical and light- scattering properties of the surface of Nereus. This will aid in differentiating between data that characterizes the asteroid's chemical composition and data that shows optical effects of the surface.

Faith Vilas of the NASA Johnson Space Center, who will use the spacecraft infrared spectrometer to determine the nature of the minerals on the surface of Nereus through the comparison of spectral features with laboratory spectra of meteorites and terrestrial rocks.

Peter Smith of the University of Arizona, who will use the rover camera to study the surface characteristics of Nereus to understand how the surface and its structures evolved over time. Smith has worked with the cameras on numerous NASA missions including the Mars Pathfinder mission and the Cassini-Huygens mission to Saturn and Titan.

Andrew Cheng of the Johns Hopkins University Applied Physics Laboratory, who will use the spacecraft lidar (a laser-based altimeter) instrument to determine the size, shape, mass and rotation of Nereus. Cheng is the project scientist for NASA's Near-Earth Asteroid Rendezvous mission, which will encounter the asteroid Eros in February 2000.

Michael Zolensky of the NASA Johnson Space Center, who will participate in the preliminary petrologic, mineralogic, and compositional analysis of the asteroid samples returned to Earth by the MUSES-C spacecraft. Zolensky is a leader in the development and application of sample analysis techniques to extra-terrestrial samples and is a co-investigator on NASA's Stardust mission to collect a comet sample and return it to Earth.

The alpha X-ray spectrometer for the rover, which will be used to determine the chemical composition of many surface rocks, is being supplied by Thanasis Economou of the University of Chicago. Economou supplied a similar instrument for the Sojourner rover on the Mars Pathfinder mission and for many other NASA missions.

JPL is managing the U.S. contribution to the MUSES-C mission for NASA's Office of Space Science. For the NASA portions of the MUSES-C mission, Ross M. Jones of JPL is the NASA project manager, and Brian Wilcox of JPL is the lead engineer for the asteroid roving vehicle. The Institute of Space and Astronautical Science (ISAS) manages the MUSES-C project for Japan's Ministry of Education, Science, Sports and Culture, where Jun'ichiro Kawaguchi is the MUSES-C project manager and Akira Fujiwara the project scientist.

Beta SP video is available from JPL; high-res images at JPL website:


March 5, 1998


Astronomer Dr. Donald K. Yeomans has been named project scientist for the NASA portion of a joint U.S.-Japanese mission that will be the first ever to send a lander and robotic rover to an asteroid, and return an asteroid sample back to Earth.

Yeomans is a senior research scientist at JPL and supervisor of the Laboratory's Solar System Dynamics Group, which is responsible for tracking all the planets, natural satellites, comets and asteroids in the solar system. He specializes in identifying the orbital paths of comets, asteroids and other bodies. Yeomans will lead the work of the U.S. science team in utilizing the scientific instruments on the tiny book-size rover being built at JPL for the asteroid lander mission, which is called MUSES-C. The U.S. and Japanese science teams will collaborate on the analysis of scientific data returned by the spacecraft, including work on the asteroid sample that will be brought back to Earth.

Scheduled for launch from Kagoshima, Japan on a Japanese M5 rocket in January 2002, MUSES-C will be the world's first asteroid sample return mission and will be the first space flight demonstration of several new technologies. "MUSES-C" stands for Mu Space Engineering Spacecraft (the "C" signifies that it is the third in a series). It is part of a series of flight technology and science missions managed by the Institute of Space and Astronautical Science of Japan (ISAS). NASA's Jet Propulsion Laboratory (JPL) in Pasadena, CA, is managing the U.S. portion of the mission. Ross M. Jones is the project manager at JPL.

Asteroid 4660 Nereus, a small, near-Earth asteroid nearly one mile in diameter, is the target of the MUSES-C mission that will set a lander down on the asteroid's surface, let loose a miniature rover to gather photos of the terrain, and collect and return to Earth three samples from the asteroid's surface. The lander and sample return vehicles are provided by Japan and the rover is being provided by JPL. All three vehicles will be combined as one package for flight to the asteroid.

Asteroids are thought to be remnants of the material from which the inner solar system was formed 4.6 billion years ago. They are representative of the fundamental building blocks that coalesced into the terrestrial planets -- Mercury, Venus, Earth and Mars. Scientists want to study asteroids because of the clues these small bodies may hold to the origin and evolution of the solar system. Eventually, metal-rich asteroids could also serve as resources for space mining and human exploration.

Yeomans is well-known for his precise orbit determinations of solar system objects. He provided the accurate position predictions that led to the first telescope sighting of comet Halley on its return visit to the inner solar system in 1982. He provided the predictions that led to the successful flybys of five international spacecraft past comet Halley in March 1986. Yeomans also provided the position predictions for asteroids 951 Gaspra and 243 Ida that helped the Galileo spacecraft to make the first close-up images of an asteroid. More recently, he worked with Dr. Paul Chodas, also of JPL, to provide the accurate predictions for the impacts of comet Shoemaker-Levy 9 with Jupiter in July 1994. Yeomans is currently a science investigator on a NASA mission to fly past three different comets. He is also the radio science team chief for NASA's Near-Earth Asteroid Rendezvous (NEAR) mission, a spacecraft headed for an encounter with the asteroid Eros.

Yeomans has been given seven NASA awards including an Exceptional Service Medal in 1986. In addition, he was presented with a Space Achievement Award by the American Institute of Aeronautics and Astronautics, an award of appreciation by the Goddard Space Flight Center, Greenbelt, MD. Asteroid 2956 was re-named 2956 in Yeomans' honor. He has authored four books and more than 80 technical papers on comets and asteroids.

A native of Rochester, NY, Yeomans received his bachelor's degree in mathematics in 1964 from Middlebury College in Middlebury, VT, and a master's degree in 1967 and doctorate in astronomy in 1970 from the University of Maryland. Yeomans and his wife, Laurie, have two adult children and reside in La Canada-Flintridge, CA.

JPL is a division of the California Institute of Technology.

NASA Headquarters, Washington, DC
Japan Institute of Space and Astronautical Science

May 14, 1997


NASA and Japan's Institute of Space and Astronautical Science (ISAS) have agreed to cooperate on the first mission to collect samples from the surface of an asteroid and return them to Earth for in-depth study.

Known as MUSES-C, the mission will be launched on a Japanese M-5 launch vehicle in January 2002 from Kagoshima Space Center, Japan, toward a touchdown on the asteroid Nereus in September 2003. A NASA-provided miniature robotic rover will conduct in- situ measurements on the rocky surface.

The asteroid samples will be returned to Earth by MUSES-C via a parachute-borne recovery capsule in January 2006, just weeks after a NASA mission named Stardust is expected to return collected comet dust samples to Earth.

NASA and ISAS will cooperate on several aspects of the mission, including mission support and scientific analysis. Dr. Atsuhiro Nishida, Director General of ISAS, and Dr. Wesley T. Huntress Jr., NASA Associate Administrator for Space Science, signed a summary of discussions outlining the cooperation on MUSES-C during a May 2 meeting in Washington, DC.

"This ambitious mission is an opportunity for two spacefaring nations to combine their expertise and achieve something truly fantastic," said Dr. Jurgen Rahe, director of Solar System Exploration at NASA Headquarters. "The rover will be the smallest ever flown in space. With a successful mission, we will have the first direct insight into the composition of the materials that helped form the rocky inner planets more than four billion years ago."

With a mass of less than 2.2 pounds, the asteroid rover technology experiment would be a direct descendant of the technology used to build the Sojourner rover due to land on Mars with the Mars Pathfinder lander on July 4 of this year. The rover will carry two science instruments: a visible imaging camera and a near-infrared point spectrometer. It will be designed and built by NASA's Jet Propulsion Laboratory, Pasadena, CA.

Other U.S. contributions to MUSES-C include testing of its reentry capsule heat shield at NASA's Ames Research Center, Mountain View, CA, and navigation and tracking support from the ground-based Deep Space Network. NASA also will provide co- investigators to join in the mission's science, and the Agency will share in access to the asteroid samples.

Nereus is a small, near-Earth asteroid roughly one mile in diameter. It was discovered in 1982. At its closest point to the Sun, its orbit takes it just inside the orbit of the Earth.

MUSES-C will continue a recent string of missions focused on asteroids. NASA's Galileo mission, now in looping orbit around Jupiter, flew by two asteroids -- Gaspra and Ida -- on its way to the giant gas planet, discovering a small moonlet around one of them. The Near Earth Asteroid Rendezvous spacecraft, a NASA Discovery Program mission built and operated by the Johns Hopkins University's Applied Physics Laboratory, will fly by the asteroid Mathilde on June 27 on its way to orbit the large asteroid Eros in 1999.

Back to ASTRONET's home page
Terug naar ASTRONET's home page