* Astronomy

Blobrana · L

RE: HAYABUSA (MUSES-C) mission

Blobrana · L

Hayabusa to start return trip to Earth in mid April
The asteroid explorer "Hayabusa" which landed on the asteroid "Itokawa" November 2005, delivered its probe container for acquired samples to the re-entry capsule, stored it in the capsule, then tightly shut the lid (with latches and seals.)
Since February, JAXA tried a new attitude control method to operate the ion engine, and engine running trials in phases have been underway since late March.
It is scheduled to start fully fledged engine operations in mid April to return to Earth.
The operation of the Hayabusa is still undergoing difficulties, but JAXA will do its utmost to make the explorer return home in June 2010.

Source

Blobrana · L

Japan's problem-plagued Hayabusa spacecraft will attempt to return to Earth at the end of March, mission controllers say.
If the craft does return as planned in 2010, researchers would finally find out whether it collected the first-ever samples from an asteroid during its two landings on the tiny space rock Itokawa.

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Blobrana · L

The asteroid probe "Hayabusa," which landed on the asteroid "Itokawa" last November, successfully turned on its ion engine, and it is now aiming to return to Earth in June 2010. The U.S. eminent scientific journal Science features the results of Hayabusa's scientific investigations in its June 2 edition. The "Hayabusa" observed Itokawa's shape, geographical features, reflectance, mineral composite, and gravity from an altitude of three to 20 km, and clarified the Itokawa's structure as a "pile of rubble." Science published seven Hayabusa-related essays, the first time for the magazine to feature a Japanese asteroid probe project. The Hayabusa project also received a "Space Pioneer Award" from the National Space Society of the United States at the International Space Development conference held in Los Angeles in May.

Source JAXA

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Blobrana · L

With the help of Hideo Fukumori at JSpace, I've received an update on the status of Hayabusa, the Japanese mission to retrieve a sample from an asteroid, from the Japanese science journalist Shin-ya Matsuura. Matsuura said (translated from the Japanese by Fukumori):

Preparation for the return trip is currently under way. From what I heard, recharging the damaged battery, which has been considered to be the most risky part, is almost done. The next critical step will be closing the sample capsule using power supply from recharged battery. Successful execution of that step will move Hayabusa a lot closer to the return trip to the Earth. Considering that the return trip operation should be started in February, I guess they will attempt to close sample capsule by the end of this month(January) and make a press release. Or, Prof. Kawaguchi might hold a press conference in February to announce the start of return operation instead.

Blobrana · L

Title: TECHNOLOGIES FOR FUTURE ASTEROID EXPLORATION: WHAT WE LEARNED FROM HAYABUSA MISSION.
Authors: M. Yoshikawa, H. Yano, J. Kawaguchi, A. Fujiwara, M. Abe, T. Iwata, Y. Kawakatsu, S. Tanaka, O. Mori, T. Yoshimitsu, Y. Takagi, H. Demura, T. Noguchi, H. Miyamoto

Hayabusa spacecraft, which is the asteroid sample return mission of Japan, finally arrived at its destination Asteroid (25143) Itokawa in September 2005. We were surprised to see the image of Itokawa, because we found a lot of boulders instead of craters. We discovered many new things about the very small-sized asteroid Itokawa from the in situ observations. Also we have had many experiences and learned a lot about exploration of small asteroid. Although Hayabusa is still on the way to the Earth, we are now considering future asteroid sample return missions.

Read more (75kb, PDF)

Blobrana · L

As already reported, Hayabusa was restored at the end of January and had completed the attitude control to make its antenna aperture pointed to the Earth by the beginning of March, using its Xenon cold gas thrusters (neutralisers of the ion engines) aboard.

Since then, Hayabusa has maintained the attitude slightly offset to the Sun but kept to the Earth within communication coverage via the above mentioned Xenon thrusters. It has worked very well and the radio communication with the ground stations has been established through the medium gain antenna everyday by now.
From March to April, the spacecraft performed a `baking operation` to exclude any volatile liquid potentially left inside the spacecraft by making the temperature as highest as possible. There had not been confirmed any gas that came out, however, the project team was sure that the baking operation was completed practically.
From the end of April to the middle of May, Hayabusa had undergone the ion engines functional verification to make sure if the performance of the engines are in order toward the return cruise. The engines B & D were driven and the results showed they are in very good shape and retained the nominal performance as that before arrival to Itokawa. The engine C test was postponed to next January when the distance to the Sun becomes closer, since the high voltage power supply as well as TWTA for the thruster have high sensitivity to the temperature. The project team thinks the engine C should also work normally. The engine A has been and will be left for reserve.
The return cruise is possible even by two engines. And the Xenon gas left aboard satisfies the Xenon gas required for the cruise.
For two weeks, Hayabusa lowered its spin rate down to 0.2 rpm whose period is about 5 minutes now, aiming at reducing the Xenon gas consumption required for the attitude control.

Currently, there is no problem for the communication as well as the operation. However, the project team is anticipating a few issues that need to be clarified through ground experiment and flight history. As soon as it becomes more clear, the project will make another news release about it in a few months.
The spacecraft was seriously injured and operating it and steering it are still very hard to do. Nevertheless, the project team is sure to try it as best as they can.

Source

Blobrana · L

The near-Earth asteroid named Itokawa is just a pile of floating rubble, probably created from the breakup of an ancient planet, according to a University of Michigan researcher was part of the Japanese space mission Hayabusa.

The finding suggests that asteroids created from rubble would be pristine records of early planet formation.

Photo courtesy Japan Aerospace Exploration Agency, Institute of Space and Aeronautical Science.

Daniel Scheeres, University of Michigan associate professor of aerospace engineering, was part of the team that determined the asteroid's mass, surface environment, and gravitational pull and helped interpret the images that were taken of the asteroid from the spacecraft. Some of the findings will be discussed in a special issue of the journal Science on June 2. The mission is led by the Japan Aerospace Exploration Agency.
The Hayabusa space probe arrived at asteroid Itokawa last fall and orbited for three months. During that time it descended twice to the surface of the asteroid, which is named for the father of Japanese rocketry, to collect samples. In 2010 the probe will return to Earth and eject a sample canister that will re-enter the atmosphere and land in central Australia. Researchers hope this will be the first asteroid sample brought back to Earth.
The confirmation of Itokawa's makeup as rubble rather than a single rock has large implications for theories of how asteroids evolved, and will lead to a better understanding of the early solar system. Asteroids are thought to be the remnants of material that formed the inner planets, which include Earth, and could bear the record of events in the early stages of planet formation. It is a significant finding that Itokawa is a pile of rocks ranging in size from tiny sand grains all the way up to boulders 50 meters wide, because it verifies a number of theories about the makeup and history of asteroids.
The existence of very large boulders and pillars suggests that an earlier "parent" asteroid was shattered by a collision and then re-formed into a rubble pile, the researchers conclude in the paper.
It's likely that most asteroids have a similar past.

"Analysis of the asteroid samples will give us a snapshot of the early solar system, and provide valuable clues on how the planets were formed" - Daniel Scheeres.

Also, knowing if an asteroid is a single, big rock or a pile of rubble will have a major influence on how to nudge it off course, should its orbit be aimed at Earth. An asteroid collision with Earth, while unlikely, could have disastrous consequences. It's widely thought that an asteroid collision caused the mass extinction of dinosaurs 65 million years ago, so some have discussed ways to demolish or steer an approaching asteroid, should we see one coming.

Another striking finding, is that regions of Itokawa's surface are smooth, "almost like a sea of desert sand" and others are very rugged. This indicates that the surfaces of asteroids are, in some sense, active, with material being moved from one region to another. Gravity holds the mass of rubble together.

"These are the first such detailed observations of an asteroid from this close" - Daniel Scheeres.

Source

Blobrana · L

New data acquired by Japan's Hayabusa spacecraft from the high-resolution images, spectra and density measurements of the 550-metre-long space rock were presented at the Lunar and Planetary Science Conference in Houston, Texas, US.

Most asteroids appear to be covered largely by fine regolith. But Itokawa contains only small amounts – its finest-grain material appears to be gravel-sized particles whose distribution is concentrated in flat expanses that cover about one-fifth of Itokawa's surface. The rest of the surface is "rough" terrain littered with metre-sized boulders, which suggests that some process is moving the gravel into the flat zones.
It seems that impacts by other space rocks may have shaken the asteroid for several hours, and moved the expected regolith around the surfaces.
Assuming that this is the case, Chikatoshi Honda of the Japan Aerospace Exploration Agency (JAXA) in Kanagawa, Japan, estimates it is between 10 million and 100 million years old.
Estimates of its density reveal it is 39% empty space. That suggests it coalesced from the debris of an ancient asteroid impact.
Spectral observations taken by Hayabusa suggest the rock was not altered by heat in its past. But those from ground-based telescopes in Hawaii suggest it partially melted after being heated to more than 1000°C.

Blobrana · L

Japan's space agency, JAXA, has re-established partial contact with the Hayabusa probe, but a fuel leak could cut communications again.
The Japan Aerospace Exploration Agency said it had established sufficient contact with the Hayabusa probe to assess its condition and position.

JAXA has been gradually restoring communications with Hayabusa since January, after a thruster malfunction the previous month put the probe into a spin that caused a break in contact
It said it now has learned that a fuel leak that also occurred in early December apparently caused Hayabusa to lose most of the fuel for the chemical engine controlling its positioning.
The agency plans to use solar batteries to charge up an ion engine in order to control the probe's attitude and keep it properly oriented to maintain communications with Earth, but contact could be lost again if the operation fails.

JAXA lost contact with Hayabusa during a faulty touchdown in November. A second landing days later but experienced trouble with its thruster after takeoff, forcing JAXA to shut down the probe's engines.
Data from the probe did not show that it had fired a metal projectile onto the asteroid's surface during landing, as previously believed. The probe was to have collected dust particles shot up by the projectile's impact.
If Hayabusa does return to Earth with extraterrestrial material, it would be the first successful mission to bring back asteroid samples from space