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."

Comments

obligatory

[President_Camacho]

Hayabusa To Begin Long Journey Back to Earth
I'm sure Ken and Guile miss him.

Re:obligatory

[stratjakt]

Ryu Hyabusa is the Ryu from Ninja Gaiden, not related to the Ryu from Street Fighter.

Maybe we need a 40 page Wikipedia entry to clear this up.

Re:Why not park it in high orbit?

[biocute]

Maybe to test if the re-entry works.

Re:Why not park it in high orbit?

[The MAZZTer]

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.

Re:Why not park it in high orbit?

[LiquidCoooled]

Because they spent however million building a ship capable of a return voyage.
It will be wasted if they just give up.
I think this is invaluable research and has taken a tremendous effort by the crew to even get this far.
There may not be humans on-board this time but years in the future someone may end up being saved by lessons learnt in the Hayabusa incident.

(yes, it does sound star trekkish)

Why not another attempt?

[ClayJar]

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. :)

By chance?

[Actually, I do RTFA]

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?

Heh.

[Funkcikle]

"My God...it's full of...nothing..."

Ha.

[Assassin bug]

2010 is the next solar maximum! Who wants to place bets that the nav circuits on this thing get scrambled on its way back!?

embarrassment reduction

[2ms]

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.

Correction

[kahrytan]

Ion Drives are not slow. And Japan is probably most interested in how the drives perform.

From Deep Space 1;

The ultimate speed of a spacecraft using ion thrust depends upon how much propellant it carries; indeed, the same principle applies to chemical propulsion systems, although they are much less efficient. The ion propulsion system on Deep Space 1 carries about 81.5 kilograms of xenon propellant, and it takes about 20 months of thrusting to use it all. It increases the speed of the spacecraft by about 4.5 kilometers per second, or about 10,000 miles per hour. If we had the same amount of chemical propellant, it would provide only one tenth as much velocity increment. If DS1 carried a larger solar array, it certainly would have a slightly higher acceleration, and if it carried more Xe propellant it could reach a much higher final velocity by simply thrusting longer. But DS1 is testing ion propulsion solely to find out if it works as well as predicted. Future missions that use it likely will carry more propellant to achieve still higher speeds.