Hayabusa
Hayabusa was a robotic spacecraft developed by the Japan Aerospace Exploration Agency to return a sample of material from a small near-Earth asteroid named 25143 Itokawa to Earth for further analysis.
Hayabusa, formerly known as MUSES-C for Mu Space Engineering Spacecraft C, was launched on 9 May 2003 and rendezvoused with Itokawa in mid-September 2005. After arriving at Itokawa, Hayabusa studied the asteroid's shape, spin, topography, color, composition, density, and history. In November 2005, it landed on the asteroid and collected samples in the form of tiny grains of asteroidal material, which were returned to Earth aboard the spacecraft on 13 June 2010.
The spacecraft also carried a detachable minilander, MINERVA, which failed to reach the surface.
Mission firsts
's Galileo and NEAR Shoemaker spacecraft had visited asteroids before, but the Hayabusa mission was the first one to return an asteroid sample to Earth for analysis.Hayabusa was the first spacecraft designed to deliberately land on an asteroid and then take off again. Technically, Hayabusa was not designed to "land"; it simply touches the surface with its sample capturing device and then moves away. However, it was the first craft designed from the outset to make physical contact with the surface of an asteroid. Junichiro Kawaguchi of the Institute of Space and Astronautical Science was appointed to be the leader of the mission.
Despite its designer's intention for momentary contact, Hayabusa landed and sat on the asteroid surface for about 30 minutes.
Mission profile
The Hayabusa spacecraft was launched on 9 May 2003 at 04:29:25 UTC on an M-V rocket from the Uchinoura Space Center. Following launch, the spacecraft's name was changed from the original MUSES-C to Hayabusa, the Japanese word for falcon. The spacecraft's xenon ion engines, operating near-continuously for two years, slowly moved Hayabusa toward a September 2005 rendezvous with Itokawa. As it arrived, the spacecraft did not go into orbit around the asteroid, but remained in a station-keeping heliocentric orbit close by.Hayabusa surveyed the asteroid surface from a distance of about, the "gate position". After this the spacecraft moved closer to the surface, and then approached the asteroid for a series of soft landings and for the collection of samples at a safe site. Autonomous optical navigation was employed extensively during this period because the long communication delay prohibits Earth-based real-time commanding. At the instant Hayabusa touched down with its deployable collection horn, the spacecraft was programmed to fire tiny projectiles at the surface and then collect the resulting spray. Some tiny specks were collected by the spacecraft for return to Earth and analysis.
After a few months in proximity to the asteroid, the spacecraft was scheduled to fire its engines to begin its cruise back to Earth. This maneuver was delayed due to problems with attitude control and the thrusters of the craft. Once it was on its return trajectory, the re-entry capsule was released from the main spacecraft three hours before reentry, and the capsule coasted on a ballistic trajectory, re-entering the Earth's atmosphere at 13:51, 13 June 2010 UTC. It is estimated that the capsule experienced peak deceleration of about 25 G and heating rates approximately 30 times those experienced by the Apollo spacecraft. It landed via parachute near Woomera, Australia.
In relation to the mission profile, JAXA defined the following success criteria and corresponding scores for major milestones in the mission prior to the launch of the Hayabusa spacecraft. As it shows, the Hayabusa spacecraft is a platform for testing new technology and the primary objective of the Hayabusa project is the world's first implementation of microwave discharge ion engines. Hence 'operation of ion engines for more than 1000 hours' is an achievement that gives a full score of 100 points, and the rest of the milestones are a series of world's first-time experiments built on it.
| Success criteria for Hayabusa | Points | Status |
| Operation of ion engines | 50 points | Success |
| Operation of ion engines for more than 1000 hours | 100 points | Success |
| Earth gravity assist with ion engines | 150 points | Success |
| Rendezvous with Itokawa with autonomous navigation | 200 points | Success |
| Scientific observation of Itokawa | 250 points | Success |
| Touch-down and sample collection | 275 points | Success |
| Capsule recovered | 400 points | Success |
| Sample obtained for analysis | 500 points | Success |
MINERVA mini-lander
Hayabusa carried a tiny mini-lander named "MINERVA". An error during deployment resulted in the craft's failure.This solar-powered vehicle was designed to take advantage of Itokawa's very low gravity by using an internal flywheel assembly to hop across the surface of the asteroid, relaying images from its cameras to Hayabusa whenever the two spacecraft were in sight of one another.
MINERVA was deployed on 12 November 2005. The lander release command was sent from Earth, but before the command could arrive, Hayabusa
Had it been successful, MINERVA would have been the first hopping space rover. The Soviet mission Phobos 2 also encountered a malfunction while attempting to deploy a hopping rover.
Scientific and engineering importance of the mission
Scientists' understanding of asteroids depends greatly on meteorite samples, but it is very difficult to match up meteorite samples with the exact asteroids from which they came. Hayabusa helped solve this problem by bringing back pristine samples from a specific, well-characterized asteroid. Hayabusa bridged the gap between ground observation data of asteroids and laboratory analysis of meteorite and cosmic dust collections. Also comparing the data from the onboard instruments of the Hayabusa with the data from the NEAR Shoemaker mission will put the knowledge on a wider level.The Hayabusa mission has a very deep engineering importance for JAXA, too. It allowed JAXA to further test its technologies in the fields of ion engines, autonomous and optical navigation, deep space communication, and close movement on objects with low gravity among others. Second, since it was the first-ever preplanned soft contact with the surface of an asteroid it has enormous influence on further asteroid missions.
Changes in mission plan
The Hayabusa mission profile was modified several times, both before and after launch.- The spacecraft was originally intended to launch in July 2002 to the asteroid 4660 Nereus. However, a July 2000 failure of Japan's M-5 rocket forced a delay in the launch, putting both Nereus and 1989 ML out of reach. As a result, the target asteroid was changed to 25143 Itokawa|, which was soon thereafter named for Japanese rocket pioneer Hideo Itokawa.
- Hayabusa was to deploy a small rover supplied by NASA and developed by JPL, called Muses-CN, onto the surface of the asteroid, but the rover was canceled by NASA in November 2000 due to budget constraints.
- In 2002, launch was postponed from December 2002 to May 2003 to recheck the O-rings of its reaction control system since one of them had been found to be using a different material than specified.
- In 2003, while Hayabusa was en route to Itokawa, the largest solar flare recorded in history damaged the solar cells aboard the spacecraft. This reduction in electrical power reduced the efficiency of the ion engines, thus delaying the arrival at Itokawa from June to September 2005. Since orbital mechanics dictated that the spacecraft still had to leave the asteroid by November 2005, the amount of time it was able to spend at Itokawa was greatly reduced and the number of landings on the asteroid was reduced from three to two.
- In 2005, two reaction wheels that govern the attitude movement of Hayabusa failed; the X-axis wheel failed on 31 July, and the Y-axis on 2 October. After the latter failure, the spacecraft was still able to turn on its X and Y axes with its thrusters. JAXA claimed that since global mapping of Itokawa had been completed, this was not a major problem, but the mission plan was altered. The failed reaction wheels were manufactured by Ithaco Space Systems, Inc, New York, which was later acquired by Goodrich Company.
- The 4 November 2005, 'rehearsal' landing on Itokawa failed, and was rescheduled.
- The original decision to sample two different sites on the asteroid was changed when one of the sites, Woomera Desert, was found to be too rocky for a safe landing.
- The 12 November 2005, release of the MINERVA miniprobe ended in failure.
Mission timeline
Up to the launch
The asteroid exploration mission by the Institute of Space and Astronautical Science originated in 1986–1987 when the scientists investigated the feasibility of a sample return mission to Anteros and concluded that the technology was not yet developed. Between 1987 and 1994, joint ISAS / NASA group studied several missions: an asteroid rendezvous mission later became NEAR, and a comet sample return mission later became Stardust.In 1995, ISAS selected asteroid sample return as an engineering demonstration mission, MUSES-C, and the MUSES-C project started in fiscal year 1996. Asteroid Nereus was the first choice of target, 1989 ML was the secondary choice. In early development phase, Nereus was considered out of reach and 1989 ML became the primary target. A launch failure of M-V in July 2000 forced MUSES-C's launch to be delayed from July 2002 to November/December, putting both Nereus and 1989 ML out of reach. As a result, the target asteroid was changed to 25143 Itokawa|. In 2002, launch was postponed from December 2002 to May 2003 to recheck O-rings of reaction control system since one of it was found using different material than specified. On 9 May 2003 04:29:25 UTC, MUSES-C was launched by an M-V rocket, and the probe was named "Hayabusa".