2009-02-24

Spirit Sol 51

Today will be relatively easy. This is one of the days when my shift overlaps with Chris Leger's, and this time it's my turn to take it easy. As it happens, Chris and I arrive simultaneously, and talk some on the way in. He's a morning person and is hoping Mars time goes away eventually -- my very opposite.

As we exit the elevator, we run into Ray Arvidson, who says simply, "Eighteen meters!"

Cool! That means we got through the whole blind drive. It turns out to be even better news than that; we actually got a few steps of autonav, which added about 1.25m to the drive. The day's total distance was 18.86m, about twice what we'd been officially shooting for. Mark will be happy, since this will get him some memory statistics to play with; I'm happy, because we didn't just drive the rover, we drove the heck out of it.

Not everyone is as happy as I am. Bill Dias is depressed about yestersol's activity plan. In a desperate attempt to come in under the resource limits, they ended up cutting scientific observations that had real merit, and didn't consume much time or energy. He particularly laments cutting a MTES experiment that would have generated all of 5KB of data -- practically nothing at all. Part of the problem is that our system assigns simple numeric priorities to experiments, and we're supposed to cut things in priority order. This simplifies many decisions (and simplifies the code), but it also means that sometimes we'll cut ten lower-priority experiments for the sake of a single higher-priority experiment, even when that's not a good trade overall. Maybe a better way (I reflect) would have been to start with a fixed number of "points" -- say, 1000 points -- and allocate them to the different experiments however you like. The goal of the revised game would be to maximize the number of points in the final plan. Oh, well: this is one of those things we'll have to try next time.

The scientists are stunned by yesterday's performance, little thinking we'd cover this much ground. The main question at the downlink assessment meeting is (with apologies to the Rolling Stones): should we stay, or should we go now? The rocks visible from here are, morphologically speaking, nothing new. Everything on Mars is interesting, Ray points out, but we should drive! When we reach Middleground, we can explore the local area. Ray wants to reach the crater rim in time for the March 10 stand-down, when they'll upload new navigation software to the rover. There will be a lot to explore and remotely sense there. Ray is not especially subtle in appealing to the scientists' sense of competition with their Opportunity counterparts: "Because this crater rim view is going to be certainly better than Marsberries."

So Ray asks directly, do we stay or boogie? The consensus: boogie.

The usual poll on instrument health contains one point of concern: the PANCAM came dangerously close to overheating yestersol. The instrument's safe temperature limit is 70C, and it got up to 65C somehow. Even as the instrument PUL is reporting this, the explanation arrives: a heating sequence inadvertently was run twice. That would account for it, the PUL says dryly.

We got in-focus MI images! I've been very worried about this. Correct instrument placement is my responsibility, so I was very concerned by the out-of-focus images we initially got from the trench. But it looks like it's OK now. Apparently I wasn't the only one who was worried -- word of the new in-focus images prompts applause. Which is nice, but I'd rather have gotten it right the first time.

Ray is warming to the term "antepenultimate." "I promised I'd learn how to pronounce it ... 'antepenultimate' is now my favorite part of the drive sol," he says.

Tomorrow we'll touch-and-go, and we've long since decided that the "go" should take us to Middleground, which is about another 30m from our new location. So the only discussion is on what to do with the touch. The question is whether to MI only, or both MI and MB. But we've got a lot of ground to cover -- 30m will set a new record -- and the MB will cut too much into the drive. So no MB tomorrow.

There's some resistance to this decision, because they want to characterize the changes (if any) to soil and rock composition as we drive, and the MB is crucial to doing that. What other mechanisms are available? One person points out that we've shown that the MTES can effectively see through the dust, so we can do some of the work with remote sensing. Another question arises because there's a small rock in reach: should we MI the soil, or the rock?

Steve Squyres, who's hanging out with us for some reason, pops up with a suggestion: since we're trying to characterize the rock's composition, how about doing a RAT brush and a PANCAM of the resulting spot? I tell him that we've been told that, until further notice, all RAT activities require a ground go/no-go. The time delay resulting from this will make it impossible for us to drive. Squyres thinks requiring a go/no-go for the RAT this far into the mission is ridiculous, but the directive comes from higher up, so he can't override it. (But he leaves the meeting and talks the mission managers and the mechanical team into allowing a brush. By the time he returns, the discussion has moved on, but he's made it possible for us to do it that way next time.)

The discussion starts to trend against doing a touch-and-go at all. Maybe we should keep things simple and just have a pure driving sol. Ray takes a vote, and the touch-and-go wins, though there's more dissent than for most votes. Then Chris reports that there's only 76W-hr available for the drive, and this gives Ray an opening to try again. "I really don't see a compelling argument for a touch-and-go at this site, especially since it might jeopardize the drive." He asks for consensus, and gets agreement.

The atmospheres guys have a "special treat" for us, in Ray's words. They propose an unusual experiment, waking the rover up in the middle of the night to take a PANCAM image of the Earth. They have some scientific justification for this, but mainly it's for outreach. Pathfinder tried this but it didn't work for some reason, so we're going to give it a shot. If we're to do this, we should do it soon, because the Earth is slowly disappearing from the Martian sky: as seen from Mars, Earth is lower and lower in the sky each night, visible only in the early mornings. If the rover lives until next December, he says, we'll get it as an evening object. This is a joke: there's no hope of that. So, he says, we'd better get it now. It will be a sizable power hit to wake up the rover and warm it up enough to do this, but despite that, there are no objections.

Ron Li has been working on localization. After each drive, we take pictures looking back at the lander, and Ron uses this and other information to precisely reconstruct the rover's path. He shows one of the backward-looking NAVCAM images, on which he's overlaid bright yellow lines illustrating our path to the present position, as seen from a rover's-eye view. This is somehow very emotional, and a great source of pride. When we started, we had no idea whether we'd even land safely, much less crawl off the lander. Now here we are, a hundred meters from the lander and moving fast. Before long, the lander -- our cradle -- will simply disappear. We'll never see it again.

That meeting over, I run into Squyres. He's been scarce in Gusev lately -- all the good science is halfway around the planet in Meridiani, I guess. "What are you doing down here with us lesser mortals?" I kid him. He's trying to stay awake, as it turns out, to give a presentation at 8AM. I check my watch -- it's 7:30. He's really drooping, so I give him a jocular pep talk: "You're almost there! You can do it!" What's the presentation? It's for Firouz Naderi, the head of JPL's Mars Program Office. The purpose of the presentation: to justify an extended mission for the rovers. Well, good luck! I don't think there will be much resistance to the idea of funding an extended mission, but it's a form we have to go through. The scientists have to line up and say yes, the rovers are doing great science, keep it coming; then NASA can say, well, okay, if the scientists want it .... So Squyres is doing his part in the little dance.

Since I'm the shadow today, I start catching up on other things. When I'm the primary rover driver, I don't have time for much else, so requests accumulate. ("One of the pleasures of reading old letters is the knowledge that they need no answer," wrote the poet Byron. The same, sadly, cannot be said of email. Email is too often a source of bad news in the form of new work. Old email is worse, because it's work you've had to put off, and which has generally become more urgent.) I've taken to handling this stuff on my time off. A shadow shift, with much lighter responsibilities, gives me that much more time to get things done.

I start with something fun: making a list of proposed rover wakeup songs. In order to sell the songs, I accompany each one with a light-hearted reason why they should use it. The Red Hot Chili Peppers's cover of the Stevie Wonder song "Higher Ground," for instance, has enough energy to power a Mars rover all by itself -- and so I tell the mission managers. I don't have a lot of hope that any of the songs will be used, but putting the list together is fun anyway.

Most of the rest of the work is not fun, but it's all stuff that needs to get done. Adding automated checks of our sequences, to take pressure off of the RP-2. Creating a way to run RSVP with a single click on the toolbar. (Which would be a no-brainer, except that running an instance of RSVP kills the existing instance -- which means that the naive solution leaves you with a way to accidentally kill the running instance with a single click.) Writing up what we learned from the first attempt at doing a megadrive. Stuff like that.

I'm still working on it when John Wright shows up. Because there is not a surplus of machines in the sequencing room, I do this stuff at (what is supposed to be) his machine, which means I'm always in his way. He's very polite about it, but I've started trying to get out of his way earlier. Today he has a new tactic: he comes in and tells Chris (within my hearing) that he's here, is going up to his office, and will be back shortly. I decide to let this be a good tactic; I've logged out and ensconced myself in someone else's temporarily available workstation before he returns. I need to start thinking of things like that.

One of the items stacked up in my email is a request for another interview with WBBB, the Raleigh radio station I've been on a couple of times already. They want to do this interview live, which means no sleeping in for me tomorrow. I could just ignore it -- but I don't. They were nice to me.

A couple of hours later, the usual user of the workstation I've moved to needs it, so I log out of that one. All of the others are occupied, and my shift is almost over anyway. So I fiddle around for a few minutes, annoy Chris by suggesting sequencing changes he's already made, and go home.





Courtesy NASA/JPL-Caltech. In-focus images of the trench, including the impression made when we probed the side of the trench with the MB. Gorgeous!


Courtesy NASA/JPL-Caltech. Ron Li's traverse map, showing the zig-zag path we followed from the lander to our then-present spot.


Courtesy NASA/JPL-Caltech. Looking back at the trench, midway through yestersol's drive.


4 comments:

jordigomezsuay said...

I don't remember how I discovered this blog, but I'm getting sticked to it. With the rovers and this blog Mars doesn't look anymore like something distant and unknown. Congratulations!

Anyway, if you let me a little and unfair "but", with just two rovers running a record of 30 meters in one day, maybe we're discovering Mars like the blind men discovered the elephant: the blind who touched the trunk said that the elephant was long and soft like a snake, the one of the leg said it was cylindrical like a tree, and the one of the tail said it was small and furry.

BTW: "Should I stay or should I go" is a song by The Clash, not the Rollings.

jordigomezsuay said...

On another sort of things, a possible wakeup song would be "La meva terra ├ęs el mar", that means "My land is the sea", but changing "mar" (sea) for Mars the lyrics seem made for the planet exploration:

http://www.youtube.com/watch?v=8u4RnaDWFoE
My land is the [Mars]

I'm a lonely navigator, I'm sailor without harbor, I've never had calendar, my clock is myself, who doesn't have seconds and have longer hours.
Old rudder that helps me, my address are you and the wind, get me out from this storm, get me out because I can't more, following a star maybe I missed the sky, and I lost my mind...
Give me power to shout: that I'm not from here, and I'm not from there, my land is the [Mars]. Give me power to shout: that I belong to me, I belong to nobody, and it will be this way forever.
I was born without frontiers, I don't believe in possessions, as I think that there are too much things that separate us, and we all are from the same world, I don't believe in nations nor duties, nor duties...
Give me power to shout: that I'm not from here, I'm not from there, I'm part of the ocean.
Give me power to shout: that I belong to myself, I belong to nobody.
My land is the [Mars] made of water and salt. Under the water there's no money, nor flags, nor nations, the silence that surrounds me is the beat that makes me live, live and be free, free!
Give me power to shout, that if the water is love, I'm not made of stone, wet me again.
Give me power to shout, that if the water is love, I'm not made of stone, wet me again inside the heart...

Sludge said...

"If the rover lives until next December, he says, we'll get it as an evening object. This is a joke: there's no hope of that."

And, although not for the reason intended, the joke ended up being quite funny :)

Scott Maxwell said...

@jordigomezsuay I'll add your suggestion to the list of songs for the next rover. And ... well, I'll be damned. Somehow I always thought that The Clash's awesome "Should I Stay or Should I Go" was a cover of a Rolling Stones song. I'm quite embarrassed to learn that I was wrong, but I appreciate the correction!