Opportunity Sol 768 (Spirit Sol 789)

I'm RP-1, so I get in about half an hour early -- 07:30. Turns out I needn't have bothered. As I'm walking in, Emily's telling folks on the telecon that ODY's in safe mode. That means we didn't get any data from the pass.

Indeed, we haven't heard from Opportunity at all for about 24 hours, because we didn't get a beep acknowledging yesterday's uplink. That's not terribly unusual, though it would be an odd coincidence that it happened at more or less the same time as ODY went into safe mode. Still, nobody seems able to think of a plausible connection between those two events, so a coincidence may be all it is.

We're left with three likely possibilities, ranked in descending order of goodness:

  1. Opportunity is healthy. The drive went fine, we just didn't hear the beep that said she heard us.

  2. Opportunity's healthy, but we didn't get a beep because she didn't get our uplink. So she didn't drive, but she's fine.

  3. Opportunity underwent a FSW reset and is now in automode.

#3 is actually more likely than #2, as spacecraft resets have been more common than missed uplinks. Still, the top candidate is #1, and there's no reason to panic.

Assuming Opportunity is indeed healthy, we at least won't have to ask her to retransmit any data. ODY entered safe mode about an hour before our uplink, and the uplink is two-way -- she doesn't just beam a signal into the air and hope someone's listening, she has to actually get a confirmation that ODY is there before sending the data. So when she talks to us next, she'll know just what we want to hear, without having to be told. She's smart.

The plan for today is basically to ping Opportunity. We'll command a DTE comm window for sometime around 12:00 her time, which will be something like 20:00 our time, and she'll talk to us. I don't know how much data we'll get, but I think it'll be at most something like 40 Mbits, which will be plenty for health assessment but might or might not be enough to support a drive. (We could work within a 40 Mbit limit, but we generated about 60 Mbits because that's what ODY was supposed to relay, and that's how much Opportunity will send.) We always prioritize our drive-related data pretty well, though, so even if we don't get all the data we'd wanted, we'll probably be able to do something.

They consider asking Opportunity to do more than talk to us -- we could have her do some untargeted remote sensing as well. The problem is that we don't know she's not in automode, or why she entered that mode if she did, so the less we ask her to do, the better.

ODY plans to be down for at least several days; they hope to resume UHF relay Saturday. In the meantime, we've got a rover to drive, and DTE really won't cut it in the long term. So Emily also wants to investigate using an MGS relay. But as our TDLs, Kirk and Bill, tell her, something's messed up with the hardware or software involved in the MGS relay, something that corrupts data pretty badly.

"Corrupted data would be better than no data, right?" she asks.

"The last time we tried an MGS relay, we got something like 60 Mbits, of which about 2 Mbits was usable," Kirk replies.

"Oh," says Emily.

No MGS relay is planned.

What with trying to track all of this, it almost doesn't even occur to me that the loss of the ODY relay is very bad news for Spirit. Spirit can't afford to lose drive sols, and she's going to lose two or three of them -- maybe more -- over just this. We can't even command her at all before tomorrow, because there's no uplink window scheduled until then -- she won't be listening. And she still has something like 65-90m to go (depending on whom you ask) before she reaches a safe haven. The perfect storm continues to gather strength, I fear.

They don't need me at the (very brief) SOWG meeting, but I sit through it anyway, just in case. Afterward, I listen to Albert Haldemann and Tim Parker discussing the latest results from Mars. Albert mentions that the rovers have taken enough observations that they're now able to confidently predict what a dust-free sky on Mars would look like.

"Blue-black," he says. "In the daytime, you'd probably be able to see the stars."

I want Spirit to make it to the safety of McCool Hill. But if she doesn't, I hope she gets one last glimpse of those stars before she goes. It sounds glorious.

[Next post: sol 792, March 26.]

No comments: