Slashdot Mirror
Mars Rover Spirit Back Online
Skyshadow writes "Just in time for the arrival of its twin, the Spirit Mars Rover is back in working order. Programmers at the JPL have traced the problem to the rover's flash RAM, which it uses to maintain its filesystems. They are using a ramdisk in the rover's RAM to bypass the bad flash memory, and are working on a workaround for the bad flash. Good news, but the rover is still potentially weeks away from full operational status."
During all of the "Spirit is broken" columns, I kept reading /. comments saying that it was likely a memory error due to the non-consistent errors...I guess a million monkeys with a typewriter can be correct :-)
Doh!
Is there a chance that the problem could've been caused by electrostatic discharge? Rover bounces on rubber airbags on sand, bags fold up, Rover rolls off, Rover touches rock - zap!??
Ive been unable to find any hard information on the design of the MER memory systems. If anyone can point me to a technical brief id be very happy.
From what ive pieced together the MER system is something like this:
One RAD6000 powerpc cpu.
Connected via probably compact pci to 128 mb of ecc sdram.
256 mb of flash. No info on what make of flash, but likely Intel since they are the biggest. There was some info from the press conference that there are actually two flash chips and that the flight software is redundantly stored on each. So does this mean that there is actually 128mb of redundant flash? Also it was said that they had problems even with the redundancy, could they possibly have overwritten something? We all know that even a redundant raid does not stop filesystem corruption.
No information on how the flash is connected, parallell / serial? How the redundancy works?
Btw, I guess flash is rather radiation hard since they require 10 - 20V to erase / write.
Funny you mention that. I'm taking a class on design of digital systems at my university, and my professor works for JPL. He helps design the control systems onboard space vehicles such as the Mars rover. Anyway, a majority of the class grade is based on an end-of-the-quarter project, which we complete in groups of 2 to 4. On Wednesday he expressed interest in a group developing some sort of redundancy for FPGAs that would be suitable in spacecraft. You see, on Mars, you're not shielded from huge doses of radiation as you are on earth. A healthy dose of radiation bombardment could easily reprogram an FPGA chip on the surface of Mars; ASICs chips are used to overcome this problem.
Maybe he was gung-ho about anti-radiation redundancy because he already knew the likely problem of the Spirit. Who knows?
- sm