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Touchdown!

by Mark Lemmon

March 14, 2008 - Today was an interesting day in the Phoenix operations world. We are ending one test as we begin another. Operational Readiness Test #9 (ORT-9) ended with a successful entry, descent, and landing (EDL). It was a tense situation on the ground due to some communications
delays, but telemetry from Phoenix was regained after entry about 30 seconds before landing.

About two hours earlier, Phoenix had a successful EDL in what we call the Characterization Dry Run. While ORT-9 was about getting Phoenix onto Mars, the Dry Run was about operating on Mars. Specifically, it was about testing what we hope to be our actual command sequences for use during the first week, to the extent they are predictable. Many things are predictable:
the Characterization Phase will last around a week, and will be geared toward understanding the spacecraft’s behavior in the Martian environment. Does everything work? How well? How much power are we getting and how are the batteries doing?

So, on Sol 0 on simulated Mars, Phoenix opened the solar arrays and then deployed some instruments. Specifically, the meteorology (MET) mast went up and started its task of measuring pressure and temperature through the mission, the biobarrier deployed, and the Surface Stereo Imager (SSI) popped up. SSI then took a set of images of the solar arrays in case we need to diagnose any problems; a set of images to confirm the biobarrier deployed completely and the Robotic Arm (RA) is free to move; a pair of images of the one footpad that is visible to SSI; and than started a “postcard” panorama looking north.

Sometime during the postcard, the lander reached the time when it needed to sleep to conserve energy. SSI was shutdown, then the lander. Later, Phoenix woke up and phoned home (via communications relay). So far, all is well. The solar arrays look good, we got all the lander images, and we got a handful of images of Mars -- actually more than we should have, since most should have waited for the next Martian morning.

So, we set upon the task of planning Sol 1 activities. We still do not know much. We haven’t seen much of what’s around us (polygons? rocks?). We have almost no information on the weather (moderately dusty conditions, based on the first horizon images), or on spacecraft temperatures in the cold environment. The Robotic Arm Camera will take a picture to verify it is still working. The lidar checkout includes the first lidar measurements ever from the surface of another planet, and SSI will monitor the lidar check-out. Phoenix will take a bunch of SSI pictures, so we can look for dust on some deck targets, map out the workspace of the robotic arm, and measure atmospheric dust with Sun images. We also will begin a low resolution black and white panorama of the whole site, so we can judge the lay of the land. It will take a while to get all this information back. There is so much new info that downlink of MET data is being delayed some, since we need to focus on the things that affect the next sol’s plan.

Essentially, we’re following the plan very closely so far. We are very constrained by data availability -- we have to use a low bandwidth transmission until we characterize the Phoenix
antenna performance. We are constrained in time of day we can use -- it is especially cold in the mornings and we need to gather data on what temperatures the lander experiences. As we characterize these things, the scope of what we can accomplish will grow, and we can move to more complex things to characterize. Ultimately, we will demonstrate that the lander can safely acquire a sample from the surface and deliver it to TEGA (Thermal Evolved Gas Analyzer). But it will be a slow path to safely do that. But when we have reached the end of that path, we will be ready to proceed on an exciting exploration down to Martian water ice and an analysis of what secrets the ice and soil hide.

Note: You will probably notice a bias toward imaging in my posts -- I am acting as science lead for this dry run, but am more generally the lead investigator for the SSI.