Saturday, October 1, 2011

Rocks mean stuff, and stuff means science

Since I last wrote an update post, things have been calm in the MER world. I got lucky and landed three shifts in a row this week… right when things got pretty boring. As is well known by the avid MER fan base, MER has been brushing, RAT'ing, APXS'ing, re-brushing, and MB'ing at the Salisbury-1 target on the Chester Lake outcrop, in addition to capturing high-resolution Pancam mosaics of the Endeavour Crater:

(Thanks to Stu fo the stretch!)

When I arrived back on the tactical shift scene, we had started MB integrations. Which means not driving. Which means not moving the IDD. Which means shifts end earlier. Which means… a lot of things. The item of interest here is the strategic plan of using the MB. It is an instrument best described as a "dim light bulb," since its radiation source has gone through several half lives and longer integrations (collections of data) are required to achieve the same signal-to-noise ratio that was achieved during prime mission. The idea is that we must place the MB and stick around for at least several sols, and we can only integrate for data during warmer parts of the day. We have to balance this with infamous deep sleep behavior, remote sensing requests, and lack of coffee. (Always a problem.)

Chester Lake is, interestingly, a much softer rock than the science team expected. The RAT had no problem grinding right on through the outer layer, making a hole about 3mm deep on the first shot. This is where we left things off last time. What has happened since then? A lot, even though we haven't moved.

Due to a string of unrelated bad luck, we had to use the Runout sequence capability for sols 2724 and 2725. No biggie. This is how we live and breathe, baby. Turns out that space is hard. All we get are (useful) Pancam Taus. On sol 2727, we re-brushed the Salisbury-1 target. Why? The science team was unsure about the content of the extra tailings/rocky bits left over from the RAT grind a week earlier. Although the RAT brush is very worn, they felt that a re-brush would clear things up when we decided to…

Place the Mossbauer and start collecting data on sol 2728! The decision was made to stick around here because, hey, you know, we already made that RAT hole, and we'd be stupid to abandon it now. You hungry data miners will quickly find, however, that another apparent technical hiccup left us going into the Runout for this sol, so the plan got trashed in the end. (I spoke too soon.) Again, no problem here. 

Oh, hey, yeah, let's look at the RAT and a false-color of the RAT hole while we're at it:

MB-centric planning weeks are more low-effort to us because if we left the MB down at the end of the last plan and we don't want to move, we don't need any RPs in the room. This is, really, two sides of the same coin: it's good because then meetings get shorter; it's bad because we don't get fancy animations. (Oh wait! Also the joy of the presence of the RPs! How dare I forget! Although… they might be robots… so… I'm reserving judgement.) We we're in Nominal planning shifts this week, meaning every day we get to plug back in a give it another go. In some sense this is not ideal for a MB campaign. If we were in Restricted planning mode, we could get two or three MB integrations out of a single planning day, resulting in a better results-to-effort ratio.

(An aside: By minor coincidence, the famous Rudolf Ludwig Mossbauer passed away recently at the ripe age of 82. It's on our lien list to get a target named after him for his contributions to science. Per the LTP report: The Nobel Prize in Physics 1961 was divided equally between Robert Hofstadter "for his pioneering studies of electron scattering in atomic nuclei and for his thereby achieved discoveries concerning the structure of nucleons" and Rudolf Ludwig Mossbauer "for his researches concerning the resonance absorption of gamma radiation and his discovery in this connection of the effect which his name.)

So, what do these rocks tell us? What do they mean? Well, they mean stuff. And stuff means science. Trouble is, I'm no geologist. When a geologist uses words like "breccia," "fluvial-aluvial," and "volcaniclastic," I'm just as lost as someone listening to me use words like "space," "is," and "pretty awesome." Our geologists are trying to tell a story, remember. This story is multi-faceted and requires the entire suite of MER instruments to be told. We've captured some nice layering when we MI'd the hell out of Tisdale-2, and we'll have captured some 66 hours of MB data on Salisbury-1 by the end of the weekend. Where's the next part of… the stuff? The science?

Although there is a laundry list of targets that we'd like to visit, the next goal is Shoemaker Ridge:

It was a two-fold reason for landing on this decision. First, Shoemaker Ridge looks rich in targets and appears to contain a lot of… stuff. (Science.) Second, it's got north-facing slopes. Winter fast approaches — winter solstice being March 31, 2012, which is not very far away, and our ability to drive and use the IDD will fall steadily until then.

There were many other places we could have chosen next:

-What about ditching Cape York altogether and going south to Sutherland Point and Cape Tribulation? There's lots of stuff (science) in Botany Bay, which stands between Opportunity and Sutherland Point. 
-But why abandon Cape York, whose stuff (science) we haven't even fully characterized? We'd have to leave as soon as we were done at Chester Lake to get there in time to tilt our solar arrays on the 10-20 degree slopes that we'd find at Sutherland Point. 
-What about heading further north and finding some juicy Noachian on Cape York? There are lots of north-facing "lily pads" on the north side of Cape York, but it'd take some seriously unnecessary heroics to get that far north in a mere 100 sols or so.

There's some serious engineering going on here, but the choice is easy: There's stuff (science) to be done, and it's right under our noses. Shoemaker is where it's at, for now. All told, we've got ourselves a nice strategic plan. Shoemaker ridge will give us a nice view of much of Cape York and nearby north-facing lily pads. The choice was easy. No uncertainty or hesitation. Which there ain't a lot of in MER world. Uncertainty lies only on the tactical timeline — days — and not the strategic timelines — weeks and months. Any apprehensions fall by the wayside when the data from yestersol comes rolling in. Shift gears, take a breath, refill the coffee, and soldier on.

Then, more stuff. (Science.)


This weeks' albums of the day:

Sol 2728: III — Chickenfoot ("They're going to spend a lot of time looking for 2.") Here, take this totally egregious and contrived rock video. Take it. It's yours.
Sol 2730: This Is Spinal Tap — Spinal Tap (Self-referentialism! Again!)

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