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Phoenix set to land May 22, 2008

Posted by aquillam in Astronomy.
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The big news in my circles these days is the immenent landing of the Phoenix craft of Mars. 3 days to go, and all looks well.  The spacecraft is so close to perfectly on target that mission planners may not have to do the final course courection.  Orbiter images of the landing site show it’s clear of debris and large rocks that could pose a hazard.

The very fact that it has made it this far is actually what impresses me.

In 1998 NASA had a mission called the Mars Polar Lander.  It was the cheapest, smallest mission NASA had ever run, and we (the taxpayers) got what we paid for.  The program was rife with errors.  There were planning errors, programming errors, instrumentation errors.  All things that weren’t found because they didn’t put the money into the testing that was needed.

But NASA did get something from the faiure: knowlege. I don’t just mean the knowlege gleaned from the phyical failures either, though there was plenty of that.  Probably more important is the understanding of what steps you have to go through to make sure you have all the problems worked out, to make sure you’ve really covered everything you can cover.

Mars comes into a favorable position for a mission roughly every 2 years, thus we generally plan Martian missions about 2 years apart.  The next mission after Polar Lander was Mars Surveyor Lander, which was to piggyback on Mars Global Surveyor (MGS).  When Polar Lander crashed, it took months to figure out what went wrong. In fact, it wasn’t until images came back from MGS that they really had the whole story There wasn’t enough time to make all the fixes and do all the testing for a new lander, so Surveyor was sent out as an orbiter only, and the lander instruments were packed away.

Eventually, NASA leaders decided it was time to try for the poles again. The poles are particularly good targets because there is more water detectable at or near the surface. Polar Lander was supposed to head for the southern pole, but the angle of Mars to us on this orbit makes the north pole a better target.   So Phoenix rose out of the ashes of Mars Polar Lander and Mars Surveyor Lander and is headed for Mars’ north pole.

And if you want to know how nerve-wracking it can be for the mission planners, you should check out the entry-descent and landing videos at http://www.nasa.gov/mission_pages/phoenix/main/index.html

And if you’re  wondering what happened to the rovers, they’re still going,  They’ve been working every day for over 4 years now, and they were only supposed to operate for 90 Matian days. Both are having some trouble with their wheels, but as I’m writing this they’re both still digging holes and taking pictures.



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