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Dry run sol 2-3

by Mark Lemmon

March 16, 2008 - It’s now a little after midnight on simulated sol 3 of the characterization dry run. We’ve finished the plan, and it is on its way to Mars -- well, on its way down the hall to the PIT (Payload Interoperability Testbed). We are moving forward quite nicely, but we are also
learning from our mistakes.

So what happened? Well, the news from Mars is good. TEGA and part of MECA have had their checkout. The lidar unlatched and fired successfully (well, it didn’t really fire since there is no laser in the PIT unit). MECA has some minor problems, but they are related to the test unit. The Robotic Arm unstowed properly and is poised over the workspace on the northwest side of the lander. Normally the workspace would be closer to north, but we
“landed” turned to the west a bit more than expected. Having the workspace north keeps it in the shade during midsol, optimal for working with ice that we do not want to go away after we uncover it.

One big problem from the science (and probably public) point of view is that we have seen little of Mars so far. We have dug ourselves into a bit of a hole in terms of having so much data coming down that is needed to move ahead with characterizing the lander, that images of Mars are sitting up there. It impacted the plan for sol 3 -- we had expected to take an image of a part of the workspace. The image was to be “multispectral” using color and infrared filters on the SSI. The point was to document in detail what we can see in the area where we will soon do a touch test and a test dig. It turned out that we didn’t have the right images to decide where this test would be. So, for this test we delayed the images until tomorrow -- for real life we’re taking the lesson that in the give and take between various priorities, seeing
Mars needs to come back up. It would be nice if we could do everything at the highest quality and do it now, if not sooner. But trades need to be made. So we’ll look at where we can use lower resolution or higher compression, or where we can wait for some images in order to get others more quickly. Scheduling what we’ll get is complicated, and this is one of the reasons to do a test like this. For now, we’re in a hole, so we stop digging; for later, we will be testing several options for making sure that by this point in the real mission we’ll have seen more. And by “seen more,” I really mean “gotten more information.” Not only have images of Mars suffered, the meteorology data is still sitting up on the lander waiting to come down.

Sol 3 still has an ambitious plan that has been implemented. Atmospheric monitoring continues and even intensifies, with the first regular telltale wind measurements and coordinated lidar and imaging. MECA and TEGA checkouts continue, including use of the MECA’s TECP on the Robotic Arm to measure winds. Some basic characterization of the Robotic Arm is followed by moving the RAC in to image a blind spot (where SSI cannot see) near one of the lander’s footpads. That allows imaging under the lander of the other two footpads the following sol, which in turn allows the use of the RA to touch the surface (we
need a stable lander for that). SSI will complete the site panorama, and it was arranged that this new piece would be set to come down sooner (an unfortunate side affect was possibly delaying the MET data by a sol -- it is all about trade-offs).

Looking ahead, things are increasingly busy as more of our payload becomes OK to use, and more times of day are acceptable for using the payload. The latter part means that we will soon start going beyond the plan with “drop-ins”: observations not strictly needed as characterization, but that are needed as part of the Phoenix mission. Personally, I am looking forward to the color pan of the site, but there will be many great projects competing for time and for data volume.