Big Push

Sorry I dropped off for a couple of weeks - I got busy with a couple of real things. I wrapped up a paper and an LPSC abstract based on the work I did for my MER team proposal. The science that I'm interested in relates to large impact events, what they do to rocks, and what information we can pull out from the rocks about the impacts that created them. So far in my career, I've been able to get some interesting impact information from terrestrial rocks, lunar rocks and from meteorites - but all by picking up the rock and taking it into the lab for analysis. Mars is a whole different story. These rovers are strictly in-situ instruments. They can't pick up rocks and turn them over. They can't break open the rocks to look inside. And they certainly can't launch the rocks back to Earth for me to be able to put them in the lab! So it's required a change of reference frame for me.

The first thing I did was to try to determine how much material at the MER landing sites might have been thrown there by large impact events - no sense trying to look for things that don't exist! Using some simple equations, I estimated that at least at the Spirit landing site, we should expect to see a couple of horizons of interesting impact ejecta. So I worked up that first attempt into a paper and an abstract that I'm sure will generate some discussion at our next meeting in March. But, this isn't a straightforward exercise. Though we understand quite a bit about lunar and terrestrial craters, Mars is more complicated in a lot of ways. Mars probably has water ice in much of its subsurface and when a meteorite slams into the rock + ice mixture, strange things happen. So now I have to take the next step and try to understand more about Martian crater forms.

Now that I have more access to data and more importantly, to knowledgeable scientists, I'm also diving into trying to identify the rocks that might be products of impacts and to be able to get information out of them. That's my 2-year plan, though, so that's a big mountain of learning ahead of me. :)

Science vs Survival

It's autumn in Gusev Crater, and the sun is moving lower in the sky. Opportunity is near the equator and doesn't see much of a change, but Spirit is feeling the chill in the air. The power we are getting from the solar panels is steadily decreasing - not enough to make a difference to our science activities now, but enough that we can see when we're going to have to start worrying about it. Last winter, the clever team got Spirit onto north-facing slopes to tilt the solar panels toward the low sun. This autumn, we are moving off Husband hill on a south-facing slope and into a basin, so there's some urgency we feel in getting into a position to be on north-facing slopes come winter.

Fortunately, because the year on Mars is twice as long as on Earth, it's not winter yet (though in Santa Fe, temperatures have been in the single digits F and there's been snow!). So, we have a couple of months yet before winter really sets in. But a couple of months to the rover is not so long when it takes a whole day to drive 30m! Just as I came on as a new science team member, one of the first telecons I attended addressed this issue. It was decided that we needed some serious discipline to get us where we needed to go, into the basin, with some margin, so that we could find safe haven for the winter months. To me, this was a huge blow - bring new, excited team members on to the rovers and then tell them you're going to have to rein in a lot of your scientific curiosity?!? But that's the reality of the situation if we want to keep these amazing little machines in good health for future discoveries.

This issue came up again this week, as we saw a spectacular outcrop and half the team wanted to go there to see what it is and half the team wanted to press on to make sure we get to safer ground. It's a really difficult discussion to have, because realistically, there are only so many science stops we can make. It comes down to trading an interesting science goal in front of us for possibly *more* interesting science activities in the future, and I think it's espeically hard to come in new and want to do something immediately. Though we bring fresh perspectives, we might also lack the experience to know when something's not worth stopping for. This time, we're stopping, and I'm glad for now. If it turns out to be a stop for something we've already seen, everyone will be disappointed and we might have to skip something later too. But that's the nature of science, some roads lead to fabulosity and others dead-end unexpectedly.

Documenting Spirit's weekend

I meant to post this on Friday - I spent a long first day on the job. Every day that we do planning for a rover, there is someone on the job taking notes. The idea is so take detailed enough notes that 100 days later, or a year, or ten years, someone can look at the notes and figure out what we were thinking and why we wanted the rover to do this particular activity.

After a week of "shadowing," I had my first real day on Friday. It actually started Thursday afternoon, with a pre-meeting to outline what we expected to do. On Friday, we were planning 3 sols of activities to take us through the weekend, so it was a long list of what people wanted to do and the pre-plan gets things in order so we only need to hash out the details later. On Friday morning, I came in at my usual 7:30 am, looked at all the data that had come down, read all the emails from people that were circulating, and made sure I had all the random pieces of software running. I tagged-up with the day's planners and managers at 8:30 to make sure we were all present and on the same page. Then I got the various reports and listened in to the morning's science telecon at 9, where all the interested scientists dial in and decide what we want to do.

I summarized the morning meeting around 10 am. I'm a terribly poor typist, so it's not easy to keep up with detailed notes, but I am keenly interested in the details, so it's not that hard to remember things from my misspelled notes. Then, I got on a different telecon line and listened in all day to our incredibly talented engineering staff, who take the list of activities the scientists want and spend all day turning it into lines of code the rover can understand and execute. My job there is to make sure the science activities do actually make it in, note when any changes are made and why, and be an extra brain to double-check on everything.

The activities go through several iterations of turning into more and more detailed engineering-speak, and there are three meetings during the day where various people get together to comb through the latest iteration and double-check it. This is where tiny improvements are made or tiny mistakes get caught. Finally, at about 6 pm, we concluded our meetings for the day and left it to the dedicated JPL staff to turn our requestes into a long code to radiate to the rovers. I finalized my report and posted it for everyone to refer to at about 6:30.

So, it was a long day, but at the end I knew, to the most minute detail, everything Spirit was going to do over the weekend. It was an exhilirating feeling. Several times over the weekend, at home, I could look up at the bright orange point of Mars and imagine, very accurately, whre Spirit was headed and what it might be seeing.