posted on Mar, 28 2010 @ 01:41 PM
Sorry for the delay in posting this, I had hoped to have it ready last week. Work has been very hectic. I am still not finished typing everything
up, so I will post this installment while I finish the rest. I've needed to consult my journal more than expected, and that has been a tedious
process from which I've allowed myself to be easily distracted. I find the process of re-reading my own history very emotionally draining.
For those who don't want the suspense of not knowing where this is going, and may feel my posting in installments is manipulation instead of slow
fingers attached to a slow brain, you can read my post last week where I tell you in advance what we discovered.
This experience marked the beginning of the end of my NASA work, and the end of the beginning of my awakening; they were hiding something, and the
mostly transparent organization I thought I worked for was no more.
Last January I was at JPL on a project when a colleague of mine in the unrelated MER program was working a Spirit glitch. Spirit is one of the two
rovers still operating on Mars. Spirit's expected mission was for a little over 90 days long, but six years later the rover is still operating.
Spirit has performed well beyond expectations, but even the best robot is going to have its off days. One of these off days was in late January 2009.
My friend and colleague, who I'll call Rich, was a senior software engineer on the team tasked with maintaining the mobility flight software, the
code that controlled the rover's movements and experiments.
Spirit had refused an instruction. It had been sent instructions to move, it acknowledged receipt of those instructions, but it did not move. In and
of itself that was not highly unusual, the rover is given license to ignore move requests it does not believe it can fulfill successfully or safely.
But not only did Spirit not move, its non-volatile flash memory was missing data about its motionless hours. Through a separate subsystem they were
able to estimate that it had been awake for at least an hour during the gap, but what it had been doing or why it had decided not to move was unknown.
Imaging before and after the event showed no change, cameras, IDD, suspension values, terrain; all were the same. This was the mystery my colleague
and his team were engaged in solving. Why did the rover ignore its command to move? Why did the rover record nothing? Presumably the one question
would answer the other.
They ran a battery of system checks and all appeared nominal. A refusal to comply can have its origins in the rover having lost track of its
orientation, so they attempted to recover this with an onboard program that uses the panoramic camera and accelerometers to locate the sun and
determine its own orientation from that. After an initial unrelated failure in this procedure (the accelerometer package was off) they were able to
reacquire orientation. After a bit more testing and investigation, with more nominal results, the rover driver (RP) once again prepared move orders
that were vetted and ultimately uplinked. This time the rover moved as expected, and recorded its activities to flash.
The most probable explanation for the initial faults (the failure to move, memory loss, loss of orientation) was cosmic rays. Cosmic rays are
energetic particles, usually protons, capable of disrupting electronic systems they come in contact with. With all systems once again performing as
they should, it would be hard to explain any other way. And this can happen, cosmic rays have been suspected in the transitory failure of other
satellites, orbiters, and landers. The potential for problems has been amply demonstrated in labs on earth, and as a result Spirit's electronics are
somewhat hardened, to the degree reasonable for its expected exposure.