[CarrotAndStick]

HAYABUSA?

[snowsislander]

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		HAYABUSA is currently speeding towards Itokawa. It is scheduled to reach its destination and collect samples in the summer of 2005, returning to Earth a year and a half later, in 2007, with the first-ever samples collected from an asteroid.
				HAYABUSA's return trip from Earth to Itokawa is 2 billion kilometres long. Needless to say, such a long journey requires a large amount of fuel. HAYABUSA is the first long-distance interplanetary probe to use an ion engine as its main propulsion device. Traditionally, propulsion occurs when gas is emitted at high speed. Until now, the main form of propulsion has consisted of super-heated gases created by burning fuel with an oxidant. An ion engine, in contrast, gets thrust from ionized gas accelerated by electricity. Therefore, it can accelerate much faster than by traditional propulsion, and only requires a tenth of the fuel.
				HAYABUSA will approach Itokawa 0.3 billion kilometres from Earth. At this distance, even light takes about 17 minutes to travel, so if HAYABUSA needed an emergency instruction from Earth, it would not reach the probe in time. Therefore, HAYABUSA is designed to pilot itself: to use the on-board camera and laser to read the asteroid's geography and judge when to approach it and where to land.
				It is impossible to land and stick to an asteroid with very low gravity, so the contact lasts only one second. During this brief contact, HAYABUSA will fire a 5-gram metal ball at the surface, at a speed of 300 metres per second, and collect pieces stirred up by the impact. This is a revolutionary method for dealing with an asteroid with low gravity.
				The robot Minerva will detach from HAYABUSA, land on Itokawa, and survey it while moving around its surface. Moving around on wheels works only when gravity is present, so a probe with wheels is of no use on Itokawa. Minerva travels by leaping, using its own momentum by accelerating a weight inside itself. This is an entirely new idea. Minerva will use its camera to take images of Itokawa's surface and also read its temperature.
				The capsule containing samples collected from Itokawa will detach from HAYABUSA at a distance from Earth equal to half the distance to the Moon, and plunge into Earth's atmosphere. Until now, similar capsules or probes have entered the Earth's orbit first, and then re-entered the atmosphere once their speed was reduced. These capsules used different kinds of fuel and propulsion devices than HAYABUSA, which, because of its smaller and lighter body, can re-enter the atmosphere directly. The capsule will enter the atmosphere at a speed of 12 kilometres per second, heating up to 3000°C. To keep it from burning up, a new material was developed specially for it. The capsule is scheduled to land in the Australian desert.