Hayabusa -- Japanese Sample Return Mission

Hayabusa (translation: Falcon), formerly known by the acronym MUSES-C, returned a tiny sample of an near-Earth asteroid to Earth which has been examined in laboratories, though the spacecraft had several serious problems and failures.

A follow-on probe, Hayabusa-2, is under construction as of 2012, for a launch in 2014.

The Hayabusa-1 spacecraft is the project of the Japanese space agency (now called JAXA). Various asteroid missions had been comtemplated from the mid-1980s until this one was approved in 1995. Development started the next year and it was launched in 2003. The probe arrived at the near Earth asteroid 25143 Itokawa in 2005 using an ion drive propulsion system, orbited the satellite to study its composition, topography, and other physical attributes, and then attempted to have a lander called MINERVA drop to the surface and hop around (similar to the Russian designed hoppers of the 1980s). The main Hayabusa probe was also designed to touch the asteroid's surface briefly twice in order to collect two samples.

Hayabusa was the first probe designed to land on an asteroid since the failed Russian hopper probes to Mars' asteroid-like moon Phobos. The US NEAR-Shoemaker probe landed on an asteroid as its final resting place but was not designed to do so.

The MINERVA lander (MIcro/Nano Experimental Robot Vehicle for Asteroid) weighed only half a kilogram and of size just 10 cm high and 12 cm diameter. It was a solar powered device designed to hop around the surface and send images back to the main Hayabusa craft when they were within line of sight. However, an error in deployment resulted in MINERVA being flung out into space above escape velocity due to the release command arriving at the same time that Hayabusa had automatically executed an altitude raising command of its own.

The Hayabusa probe was designed to collect two samples in separate cannisters by briefly touching the surface and firing pellets which would spray material into the cannisters, which would then be sealed.

Due to the distance to the asteroid from Earth, the sequences had to be automated.

On the first approach, there were blackouts and a lot of confusion as to whether or not the probe had actually touched down, with the original conclusion being that it had not made contact, and a command was sent to abort. Afterwards, from a data downloaded, it was found that the probe had made contact, but no pellet had fired. Since there was a chance that material had gone up the cannister horn anyway by contact, a decision was made to seal the first cannister rather than try again. (Why?)

On the second approach, contact was made normally and then the second cannister was sealed, but then it was found out that no pellets were never fired for that sample, either.

The cannisters were eventually returned to Earth in 2010, where they underwent far greater re-entry heating than any other manmade object had to date (as expected), and eventually parachuted down to the Australia desert where they were recovered.

About 1500 fine grains were recovered, mostly under 10 micrometers in size. It was determined that Itokawa is apparently broken off from another body with its surface exposed to space for about 8 million years. It is an S type asteroid with a composition matching an LL chondrite meteorite.

The Hayabusa probe was plagued by many problems before and after its arrival at the asteroid. Two attitude control wheels failed (and which had been made in the USA and imported to Japan). There were fuel leaks. Two of the four ion engines failed, as did 4 of 11 batteries. Plus various other problems.

Nonetheless, many subsystems worked very well, and the Japanese space agency personnel gained a whole lot of experience in dealing with an asteroid and its environment, as well as extensive troubleshooting of a misssion and finding solutions to problems.

Older reports on Muses-C had the probe going to the near Earth asteroid 4660 Nereus, which has been of interest by many groups (including the private sector SpaceDev NEAP probe which was never developed) because it takes very little energy to reach and there are spectroscopic indications that it might be a volatile rich body. However, failure of another Japanese rocket caused a delay in the launch of Hayabusa, resulting in a change in the target.

The near Earth asteroid targeted was initially catalogued under its automatically assigned 1998 SF36, but after the Japanese targeting this asteroid for the mission, they contacted its discoverer, the NASA supported LINEAR program, to request that it ask to name it after the recently deceased Japanese rocket and space agency pioneer, Hideo Ikokawa, a request which was granted.

As of 2012, Hayabusa-2 is under development by the Japanese company NEC, and the German company DLR will build a surface lander called MASCOT (Mobile Asteroid Surface Scout) with assistance from the French space agency (CNES).

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