Friday, September 9, 2011

Story and Context

(Had to go ixnay on the Juno-post-ay for now. There were fish of larger volumetric proportions to dip in hot oil this week.)

Every Wednesday, there's a placeholder in the SOWG (the team, not the meeting) schedule for something called the "End-of-Sol" (EOS). It comes from Prime Mission days, when the SOWG and sometimes the engineering teams would gather after a nice, long planning day and… talk about stuff. Stuff, meaning, "What's going on with the rover? What science are we collecting? Why?"

When I joined MER a year ago, the EOSs were few and far between. They've had a weekly placeholder for some time now (I'm not sure how long it's been this way) and it definitely hasn't had the pace of Prime Mission, or even the first few extended missions. We expect this: we weren't capturing a lot of interesting stuff along the way to Endeavour. An impact crater here, a meteorite there, but mostly dusty dunes and cruise control. The LTP report would frequently say "No EOS Wednesday." When we hit Santa Maria in December of 2010, EOSs picked up in frequency, only to drop off again when we hit Earth-Mars conjunction in late January. 

Since we hit Cape York, EOSs are happening every week with strong consistency. Not only are there EOSs in the first place, but they are ripe with material. The organizer has to balance four or five extensive PowerPoint presentations. Fitting them in within some time allotment (an hour, say) is a challenge. CY is screaming results at the science team, and it's placing some unique demands on the engineering team. At last week's EOS, there were so many callers on the line listening in that the system started booting people — the meet-me lines can only so many callers, and we had apparently exceeded the limit without a sweat.

Two words that I've heard with such great reliably as to, as the kids say, "take it to the bank," are the following:

1) Story
2) Context

They are synonymous in their use here. Let me, in turn, propose two simple facts:

1) Geologists are storytellers. 
2) MER is a geology mission.

Conclusion: MER is about stories. Really cool, science, geology-y stories. 

Cape York was selected as the landfall point at Endeavour for the simple reason that, from the sky above, it appears to represent an entirely new geology compared to both what Opportunity and Spirit had seen thus far in their respective missions. The extensive remote sensing told the MER science teams that, hey, maybe there's an interesting story here, maybe this material is really Noachian and maybe it's hiding something wonderful, let's head there first.

By opening Cape York to our in situ instrument suite on Oppy, we've been able to collect a fantastic story so far. One example is the now-famous Tisdale 2, which contained a variety of elements that did not correlate to rocks we've already encountered:

Courtesy NASA/JPL/Cornell

The ratios of Zinc and Bromine in Tisdale 2 were much higher -- take careful note of that log scale on the y-axes. ("Everything is linear if plotted log-log with a fat magic marker."). According to the science team, this possibly tells us a story about some kind of water flow, which deposits only certain stuff, stuff that we can see and touch and virtually feel right now with a hunching piece of metal on wheels. Cool.

Once we decided we had poked and prodded Tisdale 2 enough, we wanted to move on to the Northeast. Our next target: The Noachian. The multiple drives took us past the Tisdales:

Through sol 2710, which just passed by, here's our map:

Courtesy NASA/JPL/OSU/Cornell/AU

Interestingly, per the drive plan proposed by RP Frank and the science team several hundred meters before we hit Cape York, we're pretty much right on track. We're on the hunt for the next part of the story, gaining our context along the way to placing that fat Mossbauer spectrometer thingy on a fat piece of Noachian. 

(Ahem... and then sit there forever while we curse whichever god made the concept of half lives. The bastard.)

On 2709, we came on a nice piece of exposed outcrop. This one was playing nice; unlike Tisdale 2, we had a variety of target locations that were unquestionably RAT-able and APXS-able, and unlike Tisdale 2, we didn't have to worry about running the IDD smack into the side of it. This outcrop is just another part of the Cape York context, which, in a larger meta-picture, tells us the story of Endeavour, which, in an even larger meta-story, gives us a piece of the history of Mars. Why a new target? Why not go right for the purported Noachian? Squyres had a great answer. Paraphrased:

The new target should be IDD'd... it looks bright and Noachian itself... Need to build a nice story here and relate it to the Tisdales... We think there might be a coating, so we'll have to choose a target carefully and at least APXS it... Consider RAT'ing it to get into its guts... 
It is something entirely new, or SOS ("Same Old Sulfates")? This is our first major Noachian target, so let's make it count.

Oh. It IS the Noachian!

Our 2709 drive placed Oppy just out of reach of the new outcrop. The SOWG selected a suite of options for possible final approaches:

Then we approached a final target: Chester Lake. The RPs nailed a bump drive to get us right in the IDD sweet spot:


Then, a curveball: We lost a sol due to the GRAIL launch slip. More specifically, we lost our ability to uplink a set of plans for sol 2712, so we're allowing the "runout science" sequence — a Pancam Tau, among other things — to execute. No problem. 2712 was part of a 3-sol plan, so sol 2713 is golden for us. As such, the team planned an IDD placement on Chesterlake. With it, the usual MI stacks and an APXS integration on targets called "Salisbury". 

Images from these will come down sometime this weekend. With that, more context. With that, more story. With that, a healthy amount of 



Quotes of the week:

"Why don't I have any shifts this week?"

"Also, why don't I have any shifts this week?"

"All in all, just another day in paradise."
-Scott Maxwell

No comments: