Spirit Sol 497

We're planning two sols today, and my part could hardly be simpler: just a single tool change from APXS to MB. Less than twenty-five minutes after I arrive on Lab, I'm done for the day.

Or I should be. But I have to stick around and play both my part and Ashitey's, since he's been asked to look into Spirit's RAT anomaly. This happened some weeks ago: the teeth on Spirit's RAT finally wore away (after 15 grindings, five times as many as its design required). While this was disappointing, in itself it was neither surprising nor worrisome. But what was worrisome was what happened afterward: as the bare metal below the worn-away grind head contacted the rock, the IDD lost contact with the rock face and started skipping around, vibrating the entire arm. This went on for an hour and is extremely dangerous -- it could have broken the arm. Luckily, Spirit survived this event, but we're worried about what could happen if Opportunity goes through the same thing. So Ashitey's looking into ways to keep that from happening.

He's got to be down in the testbed thisol, but he promises to come back for the meetings and for this afternoon's end-of-sol science discussion. (That's no problem. There are sols when we need 1.5 RPs, and sols when we need 2.5. We get 2.0 each sol, so I guess we average right. Thisol is more like 0.5, so Ashitey could go hang out at the beach today for all it really mattered.) "I think we're not going to the summit," he says. "At least, that's my feeling."

"We've got to go to the summit," I exclaim.

"I agree," he nods. "We shouldn't let this thing conquer us." He turns to go. "We should convince the scientists we can get to the top in 25 sols." This is a joke: it'll take considerably longer than that, and we both know it. The only problem is, so do the scientists.

Well, since I've got some spare time, I put it to good use. I know approximately what they're going to want tomorrow, so I go ahead and put together a candidate sequence to do it. That should help my fellow RPs tomorrow. Part of this work involves planning for sol 500. Sol 500! In a few more days, we'll have a combined total of 1000 sols of operations on both rovers.

Between this and other catch-up work, I manage to find ways to keep myself busy until the end-of-sol meeting. The first part of this meeting is an hour of pent-up discussion of science results and what they mean. I haven't been able to attend one in a long time, and usually find these fascinating, but last night I barely slept, and I just can't focus. I snap to when the discussion changes to a strategic one.

Squyres puts the central question to the group: "Where do we go next? Home Plate? The summit? Into the Tennessee Valley?" Basically, this means: do we go around Husband Hill, to its top, or turn our back on it and descend to the valley we can see from here?

I have my strongly held opinion, but I keep it to myself a while. The valley gets more or less ruled out, mainly because there's nothing obviously compelling about it and we might not be able to climb its far side if we went there.

To focus the discussion, Steve asks another question: "The dust storm season is coming. Suppose we had only two to three months to use these vehicles; how would we use them?" The science team's answer to this question revolves around characterizing the local structure and stratigraphy -- basically, wandering around more or less where we are. I can't hold my tongue any longer. If we have only two or three months of life left in this rover, it deserves to go to the top of this hill, and I say so. In his heart of heart, that's what Steve wants, too -- this I'm sure of -- but he's got to be able to make a purely scientific case for it. So he evinces a reserved enthusiasm, and shortly the discussion moves on.

I mainly keep quiet, but I can't resist speaking up when someone asks about our chances of surviving the dust storms. "If we're at the summit," I point out, "there's less dust between us and the sun." This gets a big laugh.

It also gets a serious answer from Steve: "The dust storm season is variable. We could be dead in two weeks from a tau of 5, or we could sail right on through with a tau of 1.2. Both things are possible. Our strategy from the start on this vehicle has been to do as much science as we can, as fast as we can."

I admit I've gotten out of the habit of thinking of our babies that way. They've survived so much, they've come so far, I've been thinking nothing would ever stop them.

But I know something will. I don't know what, but something will.

And, damn it, I want to be on the top of that hill before it happens!

[Next post: sol 502, June 1.]