12 June 2018
On Earth we have multiple means of communication-cell phone, text messages, land line, e-mail, and good old snail mail. On Mars the rover basically has three-a UHF antenna that communicates with satellites orbiting Mars, a low-gain antenna (LGA) that does not need to be pointed but only handles a low data flow, and a high-gain antenna (HGA) that requires accurate knowledge of Earth’s position to receive or send commands directly. The two antennae on the left side of the rover are shown in the image above, taken early in the mission. The LGA is the pointy object near the left, and the HGA is the paddle-shaped object near the center of the image. The UHF antenna (not shown) is a can-shaped object on the back right side of the rover. Over the weekend the HGA was left unavailable to receive commands due to an error during a test, so the team had to do the next best thing yestersol, skipping most of the normal plan in order to reset the HGA-a bit like someone on Earth having to resort to a text message on an intermittent cell connection when an hours-long conversation was desired. As of today, it looks like Curiosity is back on track with normal communications.
Just to continue the discussion, on the downlink side, thanks to the combination of the HGA, orbiting satellites, and the Deep Space Network on Earth, we have received an average of about 60 megabytes of data each day from Curiosity over the last several years. We take that data link for granted when all is working well!
Back on the ground, Curiosity is resuming its drill-related activities with the plan to dump the tailings that are remaining in the drill. The sample dump is scheduled to take place in the early afternoon. Afterwards, the dump pile will be observed by Mastcam and MAHLI, and APXS will do an overnight integration on the pile. These analyses allow the rover team to determine the chemical composition of the drill material for comparison with the mineral composition obtained by CheMin. Having both chemical and mineral compositions helps us understand the origin of the rock and the conditions prevailing at the time of its formation much better than one data set by itself. Also happening during the day: ChemCam will shoot a couple of unrelated targets, ‘Robinson Lake’ (nearby pebbles) and ‘Tofte’ (a vein), both of which will also be observed by Mastcam. Imagers will also perform observations looking for dust devils and day-to-day changes in the nearby surface, as well as viewing the sky and the crater rim to characterize the increasing haze due to the dust storm. Observations of the environment by REMS, RAD, and DAN will continue.
Written by Roger Wiens, Geochemist at Los Alamos National Laboratory, ChemCam PI