The Rovers That Just Won't Quit

smooth wombat writes "Like the Energizer bunny, the two martian rovers just won't quit. Spirit, after climbing to the top of Husband Hill during the past year, spent two months examining rocks at the top of the hill and scientists confirmed that those rocks were similar to rocks found along the side of the hill indicating that Husband Hill is probably the result of an impact crater. It will take about two months for Spirit to make its way down the hill after which the next target will be a feature called Home Plate located about a half mile away. Opportunity is exploring the northern rim of Erebus Crater, the largest crater between already-explored Endurance Crater and its next destination, Victoria Crater. The rovers were only supposed to last three months but have been operating for almost two years. NASA has also released a 360 degree panorama of images taken by Spirit as it explored Gustav Crater."

Comments

Read this book.

[grub]

I read Roving Mars a few months ago. It was written by Steven Squyres, the principal investigator for the Mars missions. A very good book with some behind the scenes scoop on the politics and squabbling involved in getting these things build and sent. Highly recommended.

Re:Read this book.

[grub]

There's quite a bit of coverage of roving the planet. Boring into rocks, getting samples, etc. The reviews are incomplete.

Larger version...

[JoeLinux]

Not to be cruel and kick up their bandwidth, but is a larger version

Re:One thing no one is really talking about...

[Sockatume]

Well, look at it this way: the rovers were designed with redundancy and robustness so that if things go somewhat wrong they can still provide their target lifespan. A side effect of this is that when things don't go wrong, they exceed their target lifespan.

Gustav Crater?

[utexaspunk]

It's called Gusev crater.

Re:conversion error?

[Hussman32]

That is pretty funny, and not untrue.

One of the designers gave a presentation to our conference the day after they landed. It's easy to say they sandbagged their estimate, but they have had a host of challenges such as

• In addition to the dust, they had concerns about the batteries freezing. They have a very small bit of plutonium included to keep them warm, but it was a very real possibility that they would lose too much heat and be dead in the water.
• The firmware for one of the rovers (Opportunity, I think) had to be completely uploaded and rebooted remotely (that's when it was lost for a while).
• Leaving the landing foam was a pain, I think one of the Rovers was stuck for a while before it got out.
• The terrain itself is unpredictable, and even though they have six wheel independent suspension traveling at a slow pace, one wrong crater and they are screwed. One of them did get stuck for a while, they wiggled their way out.

So yeah, say they sandbagged it, but in reality, it was entirely possible that they could have worked only for a day (or not at all) and they would have been ostracized for being incompetent when they actually did a fine job. Congratulations to them.

Re:Any ideas?

[stickytar]

These babies are solar powered and NASA figured that dust from the atmosphere would render the solar panels useless after two months. The wind kept pushing the dust off the panels so.. there they go again.

Re:conversion error?

[Guysmiley777]

They both had a flaw that when their flash memory got too full a buffer overflow in the memory management software would reboot the machine. Spirit had been operating and collecting data first and thus encountered the problem before Opportunity ran into it too. The fix was to disable the flash memory from a safe mode so they could point the high gain antenna and send a fixed software version (once they figured out what was causing the problem). It really was a close call.

There was no landing foam. There were inflated bags that cushioned the impact as the lander bounced. The bags had cords attached to them that were retracted after landing to pull the deflated bags under the lander out of the way. The retraction didn't work 100%, and there was concern that the rover's wheels would get tangled up in the bags or the cords (which turned out not to happen).

The rover actually got stuck on mostly flat terrain. It was crossing some low wind swept dunes which the wheels eventually just dug into (think a car on the beach). By wiggling back and forth they were able to back out, and they added some movement rules for the auto drive that if a lot of slippage occurs the move stops so as not to dig so deep into loose sand.

Re:Low Resolution Images....

[cplusplus]

Actually, they are MASSIVE 1 megapixel cameras. The reason I said MASSIVE (in CAPS!) is that the CCD on them is .5 inches square, which is HUGE for a 1 megapixel camera. That means it captures a lot of light and there is very little 'bleed' from one pixel to the next, and it cuts down on the noise in the image. Not only that, each pixel is single color and there are ELEVEN (!!) color filters that can be put in front of the CCD to capture different wavelengths and generate amazing true color images. Their cameras are very very cool.