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Hayabusa Probe Arrives at Destination
david.given writes "The Japanese space probe Hayabusa has just arrived at its destination, the asteroid Itokawa, and is taking pictures. The largely autonomous ion-drive powered vehicle was launched in 2003 and was supposed to have arrived last year, but a solar flare damaged the solar panels causing a reduction in power. It will study the asteroid for two months before collecting a sample from the surface and departing for Earth, which it should reach in 2007. It's a pity that NASA's asteroid rover, which Hayabusa was going to drop off, got cancelled due to budgetry constraints..."
Hayabusa includes the Minerva hopper - gravity on asteroids is so slight that you can get around on springs - no rockets or NASA rovers required. That's the key - that's why planetary exploration makes so little sense - when you can get to an asteroid and mine it - and return for a small fraction of the delta-V required to get back from the moon, or Mars.
There's lots of good reasons to study deep space objects like asteroids and comets. Some of these are purely scientific while others are far more practical. Finding the exact composition of an asteroid for instance helps tell us where in the solar system it formed. Knowing where it began existance and comparing that position to its current one gives us clues on how the solar system has evolved from its accretion disk state. Studying asteroids up close also lets us test our theories on planetary formation, if an asteroid of a particular class is expected to have a particular composition and indeed does it lends weight to that formation theory. It also provides ground truth for other forms of observation and measurement.
From a practical standpoint it is highly beneficial to know what asteroids are made out of. They're prime targets for space mining ventures at some point. Unlike materials mined from the Moon or Mars there's very little surface gravity to fight to get the material from the asteroid back to Earth. Hence it would be far easier to grab raw silicon or some such off a NEA and return it to Earth than get it off the Moon.
It also pays off to practice sending craft to rendevous with deep space objects. While current missions are exploratory, at some point they might be defensive. If we see an Earth crossing comet or asteroid in enough time there's a good chance we can alter its trajectory or outright destroy it (if its small enough) if we can successfully put spacecraft in striking distance of it. It is desirable to have a lot of people well versed in that sort of mission. It's also another area where knowing the composition of such objects is useful. Knowing what would be needed to destroy or deflect such an object is much easier when you know how it is going to behave. A rocky dense asteroid will act far differently than a loosely clumped dustball when hit with a nuclear blast.
I'm a loner Dottie, a Rebel.