Scott had it easy. All he had to contend with was weather, scurvy, crevasses, bad logistics and the hierarchical tyranny of British command. Here? We’ve got to deal with faulty serial buses and SSPA overtemp power faults.
The current trouble started yesterday afternoon, when we failed to have a power failure. The FEMC team had been doing repairs on Generator 3 as part of the recovery from our previous power failure, and were ready to switch back to our primaries. On the theory that it was better to under- promise and over-deliver, they told us to expect a brief power failure during the switchover.
Being good IT guys, we powered everything down that wasn’t protected by a UPS circuit. Waited for the lights to blink, and waited, until suddenly, nothing happened. The switchover hadn’t even caused a flicker. Eh – we powered everything back on, and went about our business.
Until the TDRS satellite failed to sync 30 minutes later, at which point much hilarity ensued. Not. It got even better when GOES, our “reliable” satellite link, also failed to sync this morning. By the time I rolled in at 7:00 a.m., Ben, Daniel, Stephen and James looked like they’d spent the night manually hauling buckets of electrons between the RF shed and geosynchronous orbit. I silently said a little word of thanks for my lack of any training that could have been of use in debugging the problem.
Finally, around 10 a.m., they thought they’d found it. The flux capacitor needed recalibration. No, wait – wrong movie. No, as I understand it, when a particular controller out in the shed had rebooted, it failed to recognize that was connected to a couple of devices, namely a temperature sensor embedded in the SSPA, and a little vent it could open and close above it. The SSPA (solid state power amplifier) is a honking big metal box that directly drives the signal we use to
blast space junk out of orbit talk to the satellites. So as you might imagine, it might generate a bit of heat, and gets a wee bit unhappy if it isn’t being properly vented.
|Stephen debugs the TDRS uplink. Those little red boxes over
on the left? They probably shouldn’t be red. Shackleton couldn’t
have done any better.
The good news is that we probably didn’t fry the entire SSPA. We’ve probably only fried one little piece of it. The bad news, is that we don’t appear to have any working spare for that one little piece. And getting a replacement from the states would require a week, minimum. If, of course, everyone in the US weren’t already taking a long weekend for Thanksgiving.
So. The serial controller has been spanked and reconfigured and told that it damn well better monitor the SSPA temps and open the vent when things get toasty. James and Stephen have manually set the gains on the SSPA power divider in hopes that it wasn’t entirely fried, and can still hobble along if we keep it below egg-frying temperatures. And they’re dissecting our non-working spare, seeing if they can figure out how to fix what part of it might have been fried.
In the meantime, we’ve resynched GOES (and by “we”, of course, I mean the folks on our team who understand this electromagnetic-crazy-foo), so I’m able to at least post this. I guess the upside of all this is that, if I’m going to fail to make a blog post, I’ve got a better excuse than simply “the dog ate my homework”.
Why does the vent close at all? Wouldn't all the equipment run more efficiently if it were the same temperature as the outside air?