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Mars Rovers Threatened By Dust Storms
mrcgran writes "Space.com is reporting a new potentially deadly weather condition threatening the Mars rovers: 'The first and largest dusty squall has reduced direct sunlight to Mars' surface by nearly 99 percent, an unprecedented threat for the solar-powered rovers. If the storm keeps up and thickens with even more dust, officials fear the rovers' batteries may empty and silence the robotic explorers forever. "This thing has been breaking records the past few days. The sun is 100 times fainter than normal. We're hoping for a big break in the storm soon, but that's just a hope." '"
They have. The problem is that the batteries also are providing power for heaters to keep the rover warm during the night. They probably won't (especially the batteries) survive a deep-freeze to -40C, so when sun starts shining again there may be too many things broken to start the rover up again.
So, its not that the battery won't come alive again later. Its that the cold will do serious damage to the electronics on board. Without power, there's no way to keep them warm. Nights on mars go well below -25C (in the winter, the southern hemisphere can get as cold as -120C).
From TFA:
The difference being that almost no light for too long of a period of time, not allowing the rovers to keep warm. They've always used batteries & solar power to keep the circuitry just warm enough to keep them from being damaged. Without that warmth, circuits can crack.
wire wrap is nice if weight is not a problem. In a launch, every gram matters, and wire wrap adds a lot of weight for several reasons. You have to have posts to wrap around, you have to use fat solid wire instead of thin traces, and the runs of wire are longer than the traces.
Size is also important. Wire wrap boxes are usually very large by comparison with a soldered PCB, especially where there are dense electronics. These rovers probably have several surface mount ICs on them, and you can't wire wrap that.
Also, correct me if I'm wrong here, but the longer the connecting traces/wires are, the more likely they are to be hit by EMI etc? So longer runs of wire, in addition to adding weight and bulk, could also invite unwanted and potentially damaging inducted power.
It appears they made all the right choices with the amount of information they had to go on and the design goals they had to meet. I can't think of any other possible way to explain the level of their success as discussed by numerous previous posts.
iirc, the rovers were scheduled for three months, and that's before ANY winters. The thing was designed to work for less than 1/2 yr, in the summer, but they engineered it with the "possibility" of surviving a winter or two. How may winters have they made it through so far? If it finally breaks, think of it like your car lasting you 40 years before you have to replace it. It owes you nothing, be happy for what you got, it's more than you deserved.
I work for the Department of Redundancy Department.
At Mars Exploration Rover Mission there is still no official statement that the Rovers are no longer operating normal. It seems that this site is not always up to date, but if I count correctly, images from the Rovers are still arriving. The last status report of Spirit is from June 2, for sols 1234-1239. The last Spirit images are from Sol 1247. The last Opportunity images are from Sol 1226. If I counted correctly, that must have been yesterday or today.
Age is compounding the problem. JPL has a good article up at http://marsrovers.jpl.nasa.gov/spotlight/20070612. html.
What you do with a computer does not constitute the whole of computing.
Actually, no. It was designed for three months. They, of course, made any changes that might make it last longer that didn't effect the budget, but they very definitely avoided any design improvements intended to lengthen it beyond 90 days, unless those improvements cost no money. The budget was very tight and many potential design improvements to make the rovers last longer were specifically rejected. (See the book by the project lead.)
The cake is a pie
The next rover mission will no longer rely on solar panels. It will have nuclear reactors as the main source of power. http://en.wikipedia.org/wiki/Mars_Science_Laborato ry#Power_source/
Lunokhod-2 lasted for four months and explored 37 km in 1973.
National Geographic reported a day later that the storms are not a threat: http://news.nationalgeographic.com/news/2007/07/07 0706-rovers-dust.html.s -selling-solar.html
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Rent solar power: http://mdsolar.blogspot.com/2007/01/slashdot-user