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Back from the PIT, off to Mars

by Mark Lemmon

May 05, 2008 - Another week, another project test. Last week we held ORT 10 in Tucson, Pasadena, and Denver. ORT 10 is the last Operational Readiness Test (unless you count “ORT 11,” which starts on Mars in 19 sols). For ORT 10, we simulated Approach, Entry, Descent and Landing (AEDL), for which I was just a spectator. Then we continued on to a dress rehearsal of surface operations from landing through the evening of sol 2. This was a chance to test our response to many of the lessons learned earlier. I was extremely happy with the results. We’re still learning and still working to get better, but we did a very good job getting the information we needed on the ground quickly.

Sol 0 was nominal. (That’s the understated NASA way of saying we survived the “7 minutes of terror” of EDL, and have a healthy spacecraft in Mars.) We got all of the images taken on sol 0 during the first downlink after landing. There was still plenty of data from EDL stored, for not
only the sol 1 AM downlink but for the next few AM downlinks). From an imaging point of view, it was even better than real flight operations will be, with no missing parts of images whatsoever.

There was one exception to getting at all the information quickly. After sol 1, we did not have confidence in the resolution of conflicting information about the robotic arm temperatures. (This was all made up -- the conflicting temperatures hovered around -25 C…in Tucson…in
May…) The decision was to gather more information before using the robotic arm
motors. So, on sol 2 we took more pictures and did some MECA activity that had been scheduled for a few sols in the future. After we got the sol 2 data, we were go to use the RA, and we planned sol 3 accordingly before ending the ORT.

At the end of the ORT, we got a special treat -- a bonus downlink of all the data still on the lander. Prior to that, we had about 1/3 of a panorama of the site, a look at the RA workspace just in front of the lander, and assorted images of things on the deck. But since we completed the pan on sol 2 (instead of 3, as planned), we got a good look at the PIT.

The image below is the SSI view of the PIT, rendered as a vertical projection. That is, it does not use any stereo information, it just shows all the SSI images painted onto a surface as if everything were from the ground. So, tall rocks get stretched out. The lander also looks big compared to its surroundings. The walls of the PIT sort of make it look like you are
looking into a tube at the lander. With all that, it still conveys a great deal about the immediate environment of the lander -- I’m really looking forward to this view from Mars. Some of the imperfections will remain (there are lighting discontinuities since we had to take parts at different times of sol, and there are missing areas). Some will go away (ignore the passageway in on the left, and the light behind the rock at top, etc.) On Mars, we probably will see less tilt; here the lander is tilted 9 degrees to the South (down in the image). We will likely also see fewer big rocks, polygonal terrain that looks a little less like overlapping tarps, and -- oh yeah -- no panoramas taken by the Spirit rover on walls around us!