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One of the most remarkable explorations in space is Japan’s microwave ion propulsion Hayabusa spacecraft. (Hayabusa is falcon in Japanese — an interesting coincidence of names with the “Millenium Falcon” in Star Wars, which was depicted as having ion drives also.) The Hayabusa has the amazing goal of landing on the asteroid Itokawa and returning approximately one gram of the asteroid’s surface to a landing site in Australia.
Launched May 9th last year atop the Japanese M-5 rocket, in May of 2004 Hayabusa successfully completed a very precise swing-by of the Earth to develop acceleration that will take it out into the asteroid belt between Mars and Jupiter. There it will approach Itokawa and spend five months in its vicinity. During this time, it will make contact with the surface of the asteroid and via a unique collection system, fire a “bullet” into the surface, and collect the fragments in a “horn.” It will then return to Earth, and in 2005, if all goes well, the first bits of another heavenly body since the Moon rocks will be recovered.
Hayabusa is the first spacecraft to use microwave ion propulsion as its main system. The NASA Deep Space probe, launched in 1998, had a somewhat rocky initial use of its auxiliary ion propulsion when the unit stopped after a short initial use, and was only restarted after several weeks. The European Space Agency SMART-1 spacecraft, the second to use ion propulsion as its main propulsion, had a great adventure when its initial lift system failed far below where it should have delivered SMART-1. The ESA decided to use the main system far earlier than scheduled to power SMART-1 up to its proper orbital height, and SMART-1 is still in the process of using its ion propulsion system to take SMART-1 up to its original orbital height.
The Hayabusa is a remarkable achievement. Its engines have done well, and it is on track with its amazingly ambitious schedule. It is currently travelling at around 33 kilometers per second, or about 20 miles per second — 72,000 miles per hour. That’s an amazing 1/9000 of the speed of light, and about 3000 times faster than the zippiest bullet. This is among the fastest man-made objects of all time — Pioneer 11, the fastest of all, only reached a maximum of 107,000 miles per hour during its acceleration through Jupiter’s gravity well. (This assertion ignores any items that, for instance, reached higher terminal velocities when they were deorbited into large bodies such as the Sun, or for that matter, the acceleration of man-made particles.)
