Wednesday, January 06, 2010

Happy Geek Year!

Okay, time to get the new year started. Considering that the old one was pretty crappy, it seemed wise to get the new one off on a more fun footing. So - geek news!

Actually, it's a bit sad as geek news goes: NASA is concerned that the upcoming Martian winter could spell the end of the career of Spirit, the Mars rover whose planned 90-day mission is now a few days over six (Earth) years long.

It's not the first time the end has been feared: Just 18 days after landing, even before its twin rover Opportunity came down, it stopped transmitting data. It recovered from that near-death experience two weeks later, only to have a problem with a steering brake crop up some months later. Its right front wheel stop working in 2006, so since then it's been driving backwards. In the fall or 2007 a dust storm left the solar panels so covered with dust that it was feared Spirit could no longer function - and the same thing happened again in 2008.

But this is bad: Nine months ago one of its wheels broke through a crust layer and sank into loose sand. It has been stuck ever since. Every effort to get the rover free has failed; the last attempt actually would up with it sunk deeper into the sand. Remember that the rover uses solar power to operate. Unless the team can get the rover free or at the very least improve its tilt to angle the solar panels toward the sun, Spirit may well not survive.

However, science is not short on serendipity, and Spirit has provided some.
"Spirit had to get stuck to make its next discovery," says [Ray] Arvidson[, deputy principal investigator for the rovers].
The very churning of the wheels in the loose soil has uncovered sulfates,
"minerals just beneath the surface that shout to us that they were formed in steam vents, since steam has sulfur in it[," Arvidson explained. "]Steam is associated with hydrothermal activity – evidence of water-charged explosive volcanism. Such areas could have once supported life."

"And most amazingly, the boundary between the sulfate-rich soil and the soil with just the generic concentration of sulfates runs right down the middle of the stranded rover."
By getting stuck and by getting stuck just where it did, Spirit
has given scientists material evidence of past water on Mars on two time scales: ancient volcanic times, and cycles ongoing to the present day.
Even if the rover can't get loose, if its tilt can be improved enough to get enough sun to keep working, it can provide double serendipity: It could use radio transmissions to measure the wobble of Mars's axis of rotation, which would tell scientists things about the interior of the planet - something that is only possible for a rover which is no longer a rover, that has a reliable fixed position. And it could still provide additional information about Martian weather.

Still, Arvidson says, "we’re ready to leave." Now it just remains to be seen if they can.

Footnote: Meanwhile, on the other side of Mars, Opportunity just keeps on keepin' on. NASA's rover mission page is here.

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