View Full Version : Discussion: NASA Updates Software on FUSE ...

2003-Jul-22, 09:05 PM
SUMMARY: NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite got a complete software upgrade this week to improve the precision of its observations. Software engineers from several groups have been working for two years to upgrade the software for the Attitude Control System, the Instrument Data System, and the processor on the Fine Error Sensor guide camera. The new software will even let the observatory work if some or all of its gyroscopes fail.

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2003-Jul-23, 09:15 AM
How exactly do they go about upgrading the software?

2003-Jul-24, 10:12 PM
Once again, I went to the source, and talked to Dr. Bill Blair at John Hopkins University.

Here's what he had to say:

The software is upgraded and tested on the ground prior to uplink to the satellite. Most space missions have ground facilities known as "simulators", which are themselves some combination of software and engineering components (hardware) assembled to mimic the "real thing." Depending on budget, these simulators can be either high or low fidelity. In the case of FUSE, which is a relatively low-cost (and
cost constrained) mission, I'm pleased to say that we were still able to cobble together a pretty fair ground test capability.

So the idea is, you put together a top-level plan for how you think the changes will work. Then you change the software, compile it, and run tests on the simulator to see if it works the way you expect it to. Ultimately, after however many iterations, you say it is ready to fly on the "real bird." At that point, you uplink the revised flight
software to the satellite (into "backup" buffers), switch the satellite over to using the new software, and then do "on-orbit" testing to make sure it works the way it is expected to. (Remember, the simulator is only an approximation to the real satellite.)

An additional complication in the case of FUSE was that we really had to revise the code operating each of three separate processors onboard, making sure not only that each worked properly, but that they all "talked" to each other properly, too. A very tricky set of operations.

In some sense, it took some "guts" to do this, because the satellite was still working just fine. We were fixing a potential (but likely) future problem here, so we had to do this pre-emptively. I for one have to admit that, while I was confident in the testing we had done, I still had a bit of a knot in my stomach when we did it. Thank
goodness all went as expected.

Thanks for your interest!

Dr. Bill Blair,
Johns Hopkins University,
FUSE Chief of Observatory Operations

Hope that answers the question.