In The Field

Phoenix landing: Humpty Dumpty and all the king’s men

workspace.jpg The Mars Odyssey orbiter is going to be Phoenix’s twice-a-day radio link until engineers figure out what happened to the UHF radio on Mars Reconnaissance Orbiter, the Phoenix team announced this morning at a press conference here in Tucson. As I reported yesterday, MRO’s did come back on before the afternoon’s downlink, and so the Phoenix team was able to get some data down last night. But until they figure out what happened to MRO, Phoenix will use Odyssey. “This is a contingency that we have always planned for,” said JPL’s Barry Goldstein, Phoenix project manager. He said he had no worries about Odyssey being a much older spacecraft than MRO, noting that it was built the same time as Phoenix itself.

Also at the press conference, Mark Lemmon, Surface Stereo Imager lead, discussed what I tried to explain in my post this morning – how the SSI uses stereo vision to get depth perception, which allows for the determination of heights. He released a cool graphic of the digital elevation model that SSI has built up so far in the north workspace – the areas reachable by the robotic arm. Reds are low lying areas, the other colors are higher. So you can see that the arm has great access to a polygon directly in front.

“The red swath you see at the 10 and 11 o’clock postion is a trough between a polygon,” Lemmon said. "The yellows and greens and blues are the polygons themselves.”

The team has already started to divvy up the workspace. The area to the left of the robotic arm in the image is going to be used for digging and dumping. The high ground in yellow — nicknamed “Humpty Dumpty” — is going to be the start of a trench that will be dug from out to in, from the center of the polygon and across a trough. (Transects like this are really useful, as any geologist will tell you.)

Just to the right of Humpty Dumpty is a low trough area being called “Sleepy Hollow.” The arm will dig another trench there, but along the axis of the trough. Other areas have been preserved for the spiky electrical conductivity instrument. The robotic arm will have to dodge rocks that are already being given names such as “King’s Men” and “Headless.”

It will be fun to watch these names enter the Martian lexicon, as the stories that lie beneath these little patches of ground unfold.


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