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Hayabusa To Begin Long Journey Back to Earth
Sparky writes "Japan is planning to set the Hayabusa spacecraft on a trajectory back to Earth next month after a delay of more than a year, but it's far from certain that it will get back safely. It was supposed to retrieve asteroid debris, but it's thought that a computer error prevented that from happening. A fuel leak means that its chemical thrusters are out of action, and the craft is relying on its weaker ion engines. The journey back will take 3 years, and the capsule will be on Earth in June 2010 — even if it is empty."
As the summary clearly indicates, they're not 100% sure wtf is up with it. Bringing it back allows them to figure that out, as well as collect any asteroid debris it might have successfully picked up. In addition, they'll be able to track down the computer error to avoid it occurring in future craft. Same with the fuel leak.
Basically, the technology to retrieve a satellite from where it is now is likely just as hard as the original mission. Additionally, by the time retrieval would be possible, what would be the point? Technology marches ever on; even if they could retrieve Hayabusa, it's old technology now.
:)
Additionally, such probes are one-shot devices. The components are built to specs to survive hard solar radiation, exposure to space, and all the extreme temperatures involved. I'd venture to guess they'd have to basically rebuild the satellite almost completely to be able to make another attempt with it. It's cheaper to just start from scratch and include the advances available to you.
Now, why bother trying to get it home? It's by no means as important as Apollo 13 (in that no lives are depending on it), but to take a probe that's seen better days and get it all the way back home in the face of what appear to be nearly insurmountable odds has quite a bit of sentimental value. For Japan to get Hayabusa home even in such a depleted state, it would be a great honor to their scientists. (And the fact that there's still *some* chance, albeit very small, that there may have been some material captured just makes it that much better.)
It's the "Incredible Journey" of satellites, or perhaps more apropos, it's the wounded samurai doing everything he can to make it back home before he dies. Very Japanese, and quite a good potential story, too.
The navigation systems shut down for 13 months, only 2/16 engines work reliably, 2/3 of the wheels failed and pellet gyn failed to fire. Yet they're bringing it back to Earth "in case some asteroid dust had slipped into its collection chamber by chance." Because they're feeling lucky?
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"My God...it's full of...nothing..."
If you read the timeline of hayabusa's journey it has just been incredible how many things failed. I mean, practically everything imaginable went wrong with this thing. I wouldn't be surprised if their primary purpose in bringing it back was simply to salvage a modicum of dignity. Seriously. They able to upload and download its software. That should be enough to tell a lot about what was wrong with it. I mean, it's not as if they can't tell probably 90% of what they problems were just through data. I'm guessing they're just bringing it back for the sake of at least being able to claim that they got a spacecraft, that was designed to go somewhere and then come back, to actually come back, even if it didn't fulfill any of the purposes for which its coming back was to be useful.