On Fri, 23 Jan 2004 00:43:24 GMT, (Henry Spencer)
wrote:

Probably SEU, Single Event Upset, where a bit gets flipped by a particle
hit on a chip. If it's an important bit, a mess can result. :-)

The good news is that an SEU is a transient error, not a permanent failure,
assuming you have some way of resetting and restarting.

Well there appears to be some good news at least concerning this
matter. As they sent a command to Spirit assuming that it was in safe
mode following a failure, simply saying if you receive this, then
please respond.

And sure enough Spirit went "beep" indicating that it did.

This means that the X-band system is working, the SSPA, the
multi-space transponder and all the rest. However, Spirit has detected
a serious fault and so has gone into safe mode.

That means that it could still be screwed, where they have to find
this out for themselves, but at least this is good news in that it
lives on and is at minimum somewhat alive.

I have been thinking a bit about this, where I expect that this system
is divided up into two layers (at least). One is the control software
that could well have malfunctioned somehow, where on a second level,
where this beep comes from, is a more hard coded program.

And under my knowledge on how such a system should be designed, then
at this low level they should be able to do a lot of things, like
restarting the system or even loading in a fault detection program to
check it all out.

We will have to see what has gone on, but there is a fair chance that
it could make a good recovery.

Fingers crossed.

Just two days left now before Opportunity touches down.

Cardman
http://www.cardman.com
http://www.cardman.co.uk