Asteroid Sample-Return Mission MUSES-C (Hayabusa)
- Part 1: Touchdown Outline -


Click here to go directly to the touch down movies

MUSES-C (Mu Space Engineering Satellite-C) or Hayabusa, the first worldwide mission for asteroid sample-return, has been launched from the Kagoshima (Uchinoura) Space Center, Japan, on
 May 9th 2003. The probe will try to collect samples from the surface of asteroid Itokawa (1998SF36) in 2005 and then return to the earth in 2007.

The target is asteroid 1998SF36, a small celestial body with largest dimension of about 500 m. Unlike other major celestial bodies such as Moon or Mars, minor bodies such as asteroids are considered to conserve original material compositions which did not undergo any substantial alterations since the time the solar system was formed. Thus, if MUSES-C is able to collect and bring back even just a few grams of material, we could significantly deepen the knowledge about the origin and formation of our solar system.

In Japanese language the probe has been called Hayabusa, while the target asteroid has been named Itokawa, in honor of Dr. Hideo Itokawa, the father of the Japanese space program.

Officials information about this mission are available from JAXA web pages.


To realize this mission, four main technology fields have been involved:

·  Propulsion using ion engines

·  Autonomous navigation using optical sensors and cameras

·  Sample collection technology from a small celestial body

·  Technology for terrestrial atmospheric re-entry

Space Robotics Lab (led by Professor Kazuya Yoshida) at Tohoku University has been involved since the beginning in the working group for the design and development of the sample collection technology, the 3rd topic in the above listed fields. Involvement included numerical analysis as well as experimental verifications of the different phases of the touch down maneuver (descent, contact, ascent).


The below picture represents some of the strategies that can be used for sampling on a minor celestial body. Hayabusa will employ the last one depicted, i.e. it will use a bullet-like projectile to crush the surface and collect the fragments that are generate by the high velocity impact (click here for more information, in Japanese).

The small-sized projector (gun) used to fire the projectile has been studied by the Shock Wave Research Center  at Tohoku University.


Since the physical properties and geometry of the asteroid surface are not known exactly, numerical simulations and experimental verification have been carried out in different conditions. In particular, surface roughness, inclination of the contact area, and coefficient of friction have been extensively analyzed.

The experimental verifications have been conducted using a hardware simulator illustrated in the below picture. In the simulated micro-gravity environment, tests with different configurations have been performed on the probe horn, i.e. on the part that will come in contact with the asteroid surface
(click here for more information, in Japanese).


The ascent after the contact will be assured using four of gas-jet thrusters mounted on the bottom surface of the probe. In order to avoid contamination from their exhausted gasses, the thrusters will be fired after the sample collection phase.


Below are animations related to Hayabusa touchdown phase (clicking on the figures will start the movie).

Left: MUSES-C hovering over the surface. Right: the sample collection procedure.

Complete sequence of touch-down (descent, contact, ascent).

Available movies:

·  MUSES-C hovering over the asteroid surface (MPEG, 2.3M)

·  The sampling collection procedure in slow motion (MPEG, 1.9M)

·  Complete sequence of touch-down (MPEG, 2.3M)

·  Example of touch-down on smooth surface (MPEG, 2.8M)

·  Example of touch-down on rough surface (MPEG, 2.8M)

The previous animations have been generated from the numerical simulations, using as data the best estimated values known at the present time. The expected contact time will be between 1 and 2 seconds, and only a few grams of material are expected to be collected. We think that if Hayabusa will be able to make return them to the earth, even though such a small amount, a significant progress in the study of the origin of the solar system can be achieved.  



Part 2: Simulation Update upon Arrival of Itokawa (September 2005)


Part 3: Final Update before Touchdown (November 2005)





The presentation here is our outreach effort of research activities carried out with responsibility of Space Robotics Lab at Tohoku University, and are not official JAXA announcements on the Hayabusa (MUSES-C) mission.

Images and animations in this page can be freely used. But please acknowledge to Dr. Yoshida when used in news or publication medias. If you want an high definition version of the animations (avi), please contact here.




Space Robotics Lab at Tohoku University

Main research topics (in English)

Main research topics (in Japanese):

Dynamics and Control of a Space Free-Flying Robot
Robotics on the International Space Station
Design and Control of Lunar/Planetary Rovers
Dynamics and Control of an Asteroid Sample-Return Probe


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All right reserved.

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