Page last updated at 11:47 GMT, Monday, 14 June 2010 12:47 UK
By Jonathan Amos
Science correspondent, BBC News Jaxa says preliminary inspection indicates the capsule is intact
The Japanese space capsule which landed in the Australian Outback on Sunday night local time (3:08 AM EDT Monday, June 14) has been recovered.
The Hayabusa pod was picked up by a helicopter team and transferred to a control centre on the Woomera Prohibited Area.
The canister, which is believed to hold the first samples ever grabbed from the surface of an asteroid, will now be shipped to Tokyo.
The Japanese space agency (Jaxa) says the capsule looks to be intact.
The return was the culmination of a remarkable seven-year adventure, which saw Hayabusa visit asteroid Itokawa in 2005 and attempt to pluck dust from its surface before firing its engines for home.
The $200m mission encountered many technical problems, from being hit by a solar flare to experiencing propulsion glitches. But each time an issue came up, the Japanese project team found an elegant solution to keep Hayabusa alive and bring it back to Earth - albeit three years late.
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Dr Michael Zolensky Nasa Johnson Space Center
The re-entry on Sunday, at 1351 GMT = 9:51 AM EDT June 13 , produced a spectacular fireball in the Australian night sky.
The main spacecraft broke apart in a shower of light.
As these bright streaks faded, a single point could then be seen racing to the ground. This was the capsule protected against the 3,000-degree heat generated in the fall by its carbon shield.
It took about an hour to locate the capsule by helicopter, its position tracked by radar and a beacon that was transmitting from inside the canister.
It was only when daylight came up on Monday, however, that a recovery team began to approach the 40cm-wide pod which was lying on the ground still attached to its parachute.A helicopter found the capsule about an hour after the return
The heat-shield, which was dumped by the canister in the final moments before touch-down, was also located. Engineers will be keen to see how well it stood up to the 12km/s descent.
In the coming days, the capsule will be prepared for its transfer out of the country. Japanese, American and Australian scientists will open the canister in an ultra-clean, evacuated environment.
"The retrieved capsule will be transported to the Jaxa Sagamihara Campus in Kanagawa," Dr Keiji Tachikawa, the president of Jaxa, said in a statement.
"First, the sample container will be inspected, and then the content will be extracted for analysis. We hope to find the Itokawa's surface material in the capsule, and contribute to understanding the origin and evolution of the Solar System."
Even now, there is still some uncertainty as to whether the capsule really does contain pieces of Itokawa.
The Hayabusa spacecraft's capture mechanism was supposed to shoot a ball bearing at Itokawa when it landed to kick up rock inside a collection horn. An analysis of telemetry data suggests this mechanism may have malfunctioned at the crucial moment.
Nonetheless, scientists connected with the mission remain confident of success.
"It may have worked, it may not; we just don't know," said Dr Michael Zolensky from Nasa's Johnson Space Center.
"But even if it didn't work, the spacecraft landed for half an hour on the surface, and during that landing - it was a hard landing - it should have collected a sample even without firing anything. So, we're pretty confident there'll be something inside the spacecraft," he told BBC News.
BBC science correspondent Jonathan Amos describes the dramatic re-entry
If that is confirmed, it would be the first time fragments of rock have been picked up off the surface of an asteroid and returned to Earth, and only the fourth extraterrestrial sample brought to our planet by a spacecraft.
Those other materials include the Moon rocks recovered by US and Soviet missions; cometary dust captured by the American Stardust probe; and particles in the "solar wind" returned by the Genesis spacecraft, also operated by the US.The capsule is unloaded from the recovery helicopter in a packing box
But scientists caution it could be some weeks before the presence of any dust in the Hayabusa capsule can be established.
Professor Monica Grady, from the UK's Open University, said she hoped to get to work on some of the material.
"One of the great things about this type of science is that it is very collaborative," she told BBC News.
"Preliminary investigation teams will look to see what minerals the dust is made from, whether there is any carbon in there or any organics. And then scientists all over the world will be assigned very, very tiny amounts - just a few grains.
"Because the instruments we now have are so sophisticated, we only need a few grains to find out an awful lot of information."
Scientists hope the Itokawa samples will give them new insights into the make-up of asteroids and help them understand better the early history of the Solar System, which formed more than 4.5 billion years ago.
Rocks on Earth are useless for this purpose because they have been recycled many times through weathering and plate tectonic processes. Many asteroids, on the other hand, contain materials that have been altered little over the course of the past few billion years.
The Hayabusa (はやぶさ?, literally peregrine falcon) was an unmanned spacecraft developed by the Japan Aerospace Exploration Agency to return a sample of material from a small near-Earth asteroid25143 Itokawa (dimensions 540 meters by 270 meters by 210 meters) to Earth for further analysis. named
The 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, colour, composition, density, and history. In November 2005, it landed on the asteroid and attempted to collect samples but it is not clear whether the sampling mechanism worked as intended. Nevertheless, there is a high probability that some dust was trapped in the sampling chamber during contact with the asteroid, so the chamber was sealed, and the spacecraft returned to Earth on June 13, 2010.
The spacecraft also carried a detachable minilander, MINERVA, but this failed to reach the surface.
In addition, Hayabusa was the first spacecraft designed to deliberately land on an asteroid and then take off again (NEAR Shoemaker made a controlled descent to the surface of 433 Eros in 2000, but it was not designed as a lander and was eventually deactivated after it arrived). 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 contact with the surface of an asteroid.
Despite its designer's intention of a momentary contact, Hayabusa did land and sit on the asteroid surface for about 30 minutes (see timeline below).
The Hayabusa spacecraft was launched on 9 May 2003 at 04:29:25 UTC on an M-V rocket from the Uchinoura Space Center (still called Kagoshima Space Center at that time). 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 (four separate units), 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 20 km, the "gate position". After this the spacecraft moved closer to the surface (the "home position"), 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 second Hayabusa touchdown with its deployable collection horn, the spacecraft was programmed to fire tiny projectiles at the surface and then collect the resulting spray. Any samples that were collected are now held inside a separate re-entry capsule. However, it is currently uncertain whether the metal projectiles were fired during contact.
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, June 13, 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.
Hayabusa carried a tiny minispacecraft (weighing only 591 g, and approximately 10 cm tall by 12 cm in diameter) named "MINERVA" (short for MIcro/Nano Experimental Robot Vehicle for Asteroid). Unfortunately, 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 November 12, 2005. The lander release command was sent from Earth, but before the command could arrive, Hayabusa's altimeter measured its distance from Itokawa to be 44 m and thus started an automatic altitude keeping sequence. As a result, when the MINERVA release command arrived, MINERVA was released while the probe was ascending and at a higher altitude than intended, so that it escaped Itokawa's gravitational pull and tumbled into space.
Had it been successful, MINERVA would have been the first space hopper to see action. Instead it joins ranks with the hopper carried on the failed Phobos 2 mission, which also never saw use.
Scientists' current 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 would solve this problem by bringing back pristine samples from a specific, well-characterized asteroid. Accordingly, Hayabusa "will bridge the gap between ground observation data of asteroids and laboratory analysis of meteorite and cosmic dust collections," says mission scientist Hajime Yano. Also in 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 allows 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 (the NEAR Shoemaker landing on 433 Eros was not preplanned) it has enormous influence on further asteroid missions.
The Hayabusa mission profile has been modified several times, both before and after launch.
In 1986–1987, ISAS 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 the asteroid sampling as an engineering demonstration mission, MUSES-C, Nereus as the first choice of target, 1989 ML as the secondary choice. MUSES-C project started in fiscal year 1996. In early development phase, Nereus was considered out of reach and 1989 ML became the primary target. July 2000 failure of M-V forced a delay in the launch from July 2002 to November/December, putting both Nereus and 1989 ML out of reach. As a result, the target asteroid was changed to 1998 SF36. 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 specification. On May 9, 2003 04:29:25 UTC, MUSES-C was launched by M-V rocket, and the probe was named "Hayabusa".
Ion thruster checkout started on May 27, 2003. Full power operation started on June 25. On August 6, Minor Planet Circular reported that the target asteroid 1998 SF36 was named Itokawa. On March 31, 2004, ion thruster operation was stopped to prepare for the Earth swing-by. Last manoeuvre operation before swing-by on May 12. On May 19, Hayabusa performed Earth swing-by. On May 27, ion thruster operation was started again. On February 18, 2005, Hayabusa passed aphelion at 1.7 AU. On July 31, the X-axis reaction wheel failed. On August 14, Hayabusa's first image of Itokawa was released. The picture was taken by the star tracker and shows a point of light, believed to be the asteroid, moving across the starfield. Other images were taken from August 22 to August 24. On August 28, Hayabusa was switched over from the ion engines to the bi-propellant thrusters for orbital maneuvering. From September 4, Hayabusa's cameras were able to confirm Itokawa's elongated shape. From September 11, individual hills were discerned on the asteroid. On September 12, Hayabusa was 20 km from Itokawa and JAXA scientists announced that Hayabusa had officially "arrived".
On September 15, a 'colour' image of the asteroid was released (which is, however, grey in colouring). On October 4, JAXA announced that the spacecraft had successfully moved to its 'Home Position' 7 km from Itokawa. Closeup pictures were released. It was also announced that the spacecraft's second reaction wheel, governing the Y-axis, had failed, and that the craft was now being pointed by its rotation thrusters. On November 3, Hayabusa took station 3.0 km from Itokawa. It then began its descent, planned to include delivery of a target marker, and release of the Minerva minilander. The descent went well initially, and navigation images with wide-angle cameras were obtained. However, at 1:50 am UTC (10:50 am JST) on November 4, it was announced that due to a detection of an anomalous signal at the Go/NoGo decision, the descent, including release of Minerva and the target marker had been canceled. The project manager, Jun-ichiro Kawaguchi, explained that the optical navigation system was not tracking the asteroid very well, probably caused by the complex shape of Itokawa. A few days delay was required to evaluate the situation and reschedule.
On November 7, Hayabusa was 7.5 km from Itokawa. On November 9, Hayabusa performed a descent to 70 m to test the landing navigation and the laser altimeter. After that, Hayabusa backed off to a higher position, then descended again to 500 m and released one of the target markers into space to test the craft's ability to track it (this was confirmed). From analysis of the closeup images, the Woomera Desert site (Point B) was found to be too rocky to be suitable for landing. The Muses Sea site (Point A) was selected as the landing site, for both first and if possible second landings.
On November 12, Hayabusa closed in to 55 m from the asteroid's surface. MINERVA was released but due to an error failed to reach the surface. On November 19, Hayabusa landed on the asteroid. There was considerable confusion during and after the maneuver about precisely what had happened, because the high-gain antenna of the probe could not be used during final phase of touch-down, as well as the blackout during handover of ground station antenna from DSN to Usuda station. It was initially reported that Hayabusa had stopped at approximately 10 meters from the surface, hovering for 30 minutes for unknown reasons. Ground control sent a command to abort and ascend, and by the time the communication was regained, the probe had moved 100 km away from the asteroid. The probe had entered into a safe mode, slowly spinning to stabilize attitude. However, after regaining control and communication with the probe, the data from the landing attempt were downloaded and analyzed, and on November 23, JAXA announced that the probe had indeed landed on the asteroid's surface. Unfortunately, the sampling sequence was not triggered since a sensor detected an obstacle during descent; the probe tried to abort the landing, but since its attitude was not appropriate for ascent, it chose instead a safe descent mode. This mode did not permit a sample to be taken, but there is a high probability that some dust may have whirled up into the sampling horn when it touched the asteroid, so the sample canister currently attached to the sampling horn was sealed. On November 25, a second touchdown attempt was performed. It was initially thought that this time, the sampling device was activated; however, later analysis decided that this was probably another failure and that no pellets were fired. Due to a leak in the thruster system, the probe was put in a "safe hold mode".
On November 30, JAXA announced that control and communication with Hayabusa had been restored, but a problem remained with the craft's reaction control system, perhaps involving a frozen pipe. Mission control was working to resolve the problem before the craft's upcoming launch window for return to Earth. On December 6, Hayabusa was 550 km from Itokawa. JAXA held a press conference about the situation so far. On November 27, the probe experienced a power outage when trying attitude correction, probably due to a fuel leakage. On December 2, an attitude correction was tried, but the thruster did not generate enough force. On December 3, the probe's Z-axis was found to be 20 to 30 degrees from the sun direction and increasing. On December 4, as an emergency measure, xenon propellant from the ion engines was blown to correct the spin, and it was confirmed successful. Attitude control was commanded using the xenon gas. On December 5, attitude was corrected enough to regain communication through the medium gain antenna. Telemetry was obtained and analyzed. As the result of telemetry analysis, it was found that there was a strong possibility that the sampler projectile had not penetrated when it landed on November 25. Due to the power outage, the telemetry log data was faulty. On December 8, a sudden attitude change was observed, and communication with Hayabusa was lost. It was thought likely that the turbulence was caused by evaporation of 8 or 10cc of leaked fuel. This forced a wait of a month or two for Hayabusa to stabilize by conversion of precession to pure rotation, after which the rotation axis needed to be directed toward the Sun and Earth within a specific angular range. The probability of achieving this was estimated at 60% by December 2006, 70% by spring 2007.
On March 7, 2006, JAXA announced that communication with Hayabusa had been recovered in the following stages: On January 23, the beacon signal from the probe was detected. On January 26, the probe responded to commands from ground control by changing beacon signal. On February 6, an ejection of xenon propellant was commanded for attitude control to improve communication. The spin axis change rate was about two degrees per day. On February 25, telemetry data was obtained through low-gain antenna. On March 4, telemetry data was obtained through medium-gain antenna. On March 6, Hayabusa's position was established at about 13,000 km ahead of Itokawa in its orbit with a relative speed of 3 m per second.
On June 1, Hayabusa project manager Jun-ichiro Kawaguchi reported that they confirmed two out of four ion engines work normally, which will be sufficient for return journey. On January 30, 2007, Jaxa reported that 7 out of 11 batteries are working and the return capsule was sealed. On April 25, JAXA reported that Hayabusa started the return journey. On August 29, it was announced that Ion Engine C onboard Hayabusa, in addition to B and D, has been successfully re-ignited. On October 29, JAXA reported that the first phase of trajectory maneuver operation has finished and the spacecraft is now put in spin-stabilized state. On February 4, 2009, JAXA reported success in reignition of ion engines and starting second phase of trajectory correction maneuver to return to the Earth. On November 4, 2009, the ion engine D automatically stopped working due to the anomaly from degradation.
On November 19, 2009, JAXA announced that they managed to combine the ion generator of ion engine B and the neutralizer of ion engine A. It is suboptimal but expected to be sufficient to generate the necessary delta-v. Out of 2,200 m/s delta-v necessary to return to the earth, about 2,000 m/s had been performed already, and about 200 m/s still necessary. On March 5, 2010, Hayabusa was on a trajectory that would have passed within the lunar orbit. Ion engine operation was suspended to measure the precise trajectory in preparation to perform Trajectory Correction Maneuver 1 to the Earth-rim trajectory. On March 27, 06:17 UTC, Hayabusa was on a trajectory which would pass 20,000 km from Earth center, completing the orbit transfer operation from Itokawa to Earth. By Apr 6, completed first stage of Trajectory Correction Maneuver (TCM-0) which controlled coarsely to Earth rim trajectory. It was planned to be 60 days before reentry.
Full size high bitrate video here (details)
By May 4, completed TCM-1 maneuver to control precisely to Earth rim trajectory. On May 22, TCM-2 started, continued for about 92.5 hours, and finished on May 26. TCM-3 from June 3 through June 5 to change the trajectory from the Earth rim to Woomera, South Australia, TCM-4 was performed on June 9 for about 2.5 hours for a precision control to Woomera Prohibited Area. The reentry capsule was released at 10:51 UTC of June 13.
The reentry capsule and the spacecraft reentered to the Earth atmosphere at 13:51 UTC. The capsule made a parachute landing in the South Australian outback while the spacecraft broke up and incinerated in a big fireball.
An international team of scientists observed the 12.2 km/s entry of the capsule from 39,000ft on board NASA's DC-8 airborne laboratory, using a wide array of imaging and spectrographic cameras to measure the physical conditions during entry.
Since the reaction control system no longer functioned, the 510 kilograms (1,124 lb) space probe re-entered the Earth's atmosphere similar to the approach of an asteroid along with the sample re-entry capsule, and, as mission scientists expected, the majority of the spacecraft disintegrated upon entry.
The return capsule was expected to land in an area of 20 km by 200 km in the Woomera Prohibited Area, South Australia. Four ground teams surrounded the area to
locate the re-entry capsule by optical observation and a radio beacon.
Then a team on board a helicopter was dispatched, which located the
capsule and recorded the position with GPS. The capsule was successfully
retrieved at 7:08 UTC of June 14.
The heat shield, which was jettisoned during the descent, was also