Curiosity update, sols 764-781: Work complete at Confidence Hills; puzzling arm issues
Posted by Emily Lakdawalla
17-10-2014 12:53 CDT
Curiosity spent a total of four weeks at Confidence Hills, feeding samples to SAM and CheMin several times. On two weekends during this period, the rover's activities were interrupted by faults with the robotic arm that canceled the rest of the weekend's arm activities and left the MAHLI camera's cover open, potentially exposing it to dust contamination. To prevent contamination, the mission is now not using MAHLI except with the arm stowed until they understand the arm faults well enough to prevent them from recurring. Curiosity drove away from Confidence Hills on sol 780, moving farther up the Pahrump Hills outcrop. The rover is ready to attempt to observe comet Siding Spring with cameras -- including ChemCam -- over the weekend. Early next week, mission scientists will be presenting some results at the annual Geological Society of America meeting in Vancouver, and I'll be attending, so stay tuned for reports from that.
As usual, you can read a detailed play-by-play of the last two weeks of activity in the USGS Astrogeology blog, which I've embedded below. Despite the problems with the robotic arm, it was a productive couple of weeks of data gathering. They performed repeated APXS and MAHLI observations of the Confidence Hills drill hole, drill tailings pile, and dump pile. They also looked very closely at several cool-looking "rosettes" located near the drill site, including ones named Mammoth, Moenkopi, and Morrison. They repeatedly returned to Morrison, hitting it with ChemCam, brushing it, and analyzing it with MAHLI and APXS.
Sadly, this is the first drill location where they did not use MAHLI to get a self-portrait of the rover along with the drill spots in context. That may have to do with the desire to protect MAHLI from arm faults, but not entirely. I am pretty sure they cannot do a MAHLI self-portrait with powdered sample stored in the sample handling mechanism. So going straight to drilling upon arrival prevented them from shooting a MAHLI portrait before drilling, and they drove away before dumping the remaining sample. One hopes that they will be drilling frequently enough, now that they are at Mount Sharp, for it to be overkill to shoot a self-portrait from every drill site!
They would like to be able to use the spectrometer in ChemCam to observe Siding Spring when it flies by on October 19. In order to be able to get the comet in the narrow ChemCam field of view, they have to know the position and orientation of ChemCam's mount -- which is to say, the whole rover -- much more precisely than usual. On sol 777, they performed an update to their attitude estimation in which they determined local vertical due to gravity with their inertial measurement unit, and a Navcam image of the Sun to determine their yaw. This is a common activity for the rover (they perform it regularly, particularly after a series of drives), but they used some tricks to make this particular measurement more precise than usual. As a result, Curiosity deputy project scientist Ashwin Vasavada told me, they had one of the most accurately pointed high-gain antenna communications passes ever. The high-gain antenna is the hexagon-shaped steerable dish; the rover uses it each morning to receive its commands from Earth. It tolerates a couple of degrees of mispointing, so it's just a cool fact that the precision update to the rover's self-awareness of its orientation manifested itself in a particularly clean communication session. They have also been doing nighttime and twilight star imaging to figure out the best exposure settings and improve pointing accuracy for their Siding Spring observations. Even with all of these preparations, they will have to take several ChemCam images in a raster pattern to guarantee they will get the comet in the field of view.
Following a 22-meter drive on sol 780, the rover is in a lovely new location, near an outcrop called "Book Cliffs." This is where the rover will sit for the weekend observations of Siding Spring.
And here is the detailed breakdown from the USGS Astrogeology blog. I haven't embedded USGS blog content for a while, so this summary goes back a little farther than the subject line of the blog post, to the beginning of Confidence Hills drill activities. I thought it would be useful, later, to have all of this concatenated into a single post.
Sol 755-758 Update from Ryan Anderson: Mini-Drilling Pahrump Hills (22 September 2014)
Curiosity has had a busy weekend! We arrived at the location called Pahrump Hills, which has a nice flat expanse of bedrock for us to drill and get our first taste of Mt. Sharp rocks. On Sol 755 we took pictures of the outcrop with MAHLI, brushed it with the Dust Removal Tool (DRT), and measured its composition with APXS. Then, on Sol 756 we did a “mini-drill” to test the stability of the rock before doing a full drill. We used Sol 757 to recharge after all of the arm activity of the previous sols.
In the sol 758 plan today, we have a lot going on. ChemCam will be zapping the targets Mammoth and Morrison, and Mastcam will take images of those targets, plus the tailings from the mini-drill. Then we will use MAHLI to take pictures of Mammoth and Moenkopi, we will use the DRT to brush off Moenkopi, and then do some more MAHLI imaging afterward. Finally, APXS will measure the composition of the targets Moenkopi and Mammoth.
Sol 759-760 Update from Ryan Anderson: Drill Baby, Drill! (23 September 2014)
It’s time to drill! The mini-drill over the weekend showed that the Pahrump Hills outcrop is nice and stable, so the main activity in the sol 759 plan is a full drill and the associated images from Mastcam and MAHLI. While the arm is out, we will also make some APXS measurements of the tailings from the mini-drill. We won’t have an uplink tomorrow, and the rover will be low on energy after the drilling activity, so Sol 760 will be a less eventful day, with just standard environmental monitoring.
Sol 761 Update from Ken Herkenhoff: Software patch (25 September 2014)
The Sol 759 drill hole looks good, but there was a problem with one of the rover's gyroscopes that halted the transfer of drill sample to the scoop. This did not significantly affect Sol 761 planning, which is dominated by patching flight software and SAM preconditioning. Completion of the sample handling will be planned later. As MAHLI/MARDI uplink lead today I therefore concentrated on planning the images we would like to take of the drill tailings and perhaps other targets.
Sol 762-764 Update from Ken Herkenhoff: Sample Handling (26 September 2014)
Arm activities will resume on Sol 762, starting where they left off on Sol 759, with transfer of the drill sample to the scoop and Mastcam imaging of it. Then the APXS will be placed on the drill tailings (target dubbed "Paradox") for an overnight integration. In addition, ChemCam will observe targets "Panum" and "Stovepipe Wells" and Mastcam will image the drill tailings through all filters. Finally, SAM will heat a sample from the previous drill target "Windjana" ( still held in a sample cup) and measure evolved noble gases overnight on Sols 763 and 764. As MAHLI/MARDI PUL1 again today, I focused on planning MAHLI observations of the drill tailings, but they were deleted because of concerns about the overall complexity of the weekend plan. We hope to take these MAHLI images on Sol 765.
Sol 765 Update from Ryan Anderson: Feeding CheMin (29 September 2014)
After our successful drill last week, the main event in today’s sol 765 plan is dropping off the drilled sample in CheMin, which will tell us what minerals are in the rocks of Pahrump Hills. CheMin works by shining a beam of X-rays through the sample and recording how the X-rays reflect off of the structure of the crystals in the sample. To make sure that every possible orientation of the crystals is measured, the sample holder vibrates, causing the powdered rock to mix around in the sample cell.
The drill sample has been sieved so that only particles smaller than 150 microns will go to CheMin. The rover will dump out the particles that are coarser than 150 microns, take pictures of them with Mastcam and MAHLI, and measure their composition with APXS. Not all of the fine-grained sample will go to CheMin: some will be saved for analysis by SAM, and in case we want to re-analyze it with CheMin.
Sol 766 Update from Lauren Edgar: Confidence Hills (30 September 2014)
Curiosity is currently investigating the Pahrump Hills outcrop. This Navcam image from Sol 762 shows part of the workspace with the arm down, analyzing the Confidence Hills drill tailings. While we wait for CheMin to tell us what minerals are present in the drilled sample, we will spend Sol 766 doing targeted remote sensing. The two-hour science block includes ChemCam observations of the interior wall of the Confidence Hills drill hole, as well as nearby fractures (“Straight Cliffs”) and upcoming MAHLI and APXS targets named “Comb Ridge” and Morrison. There are also several Mastcam observations to document the ChemCam targets and image the nearby sand ripples. The plan also includes a number of atmospheric observations to monitor the opacity and search for clouds and dust devils. On Sol 767 we’re planning to do contact science on the target Morrison, and prepare for possible SAM activities.
Sol 767 Update from Lauren Edgar: Dump Pile (1 October 2014)
Curiosity continues to investigate the Pahrump Hills outcrop. The Sol 767 plan includes MAHLI and APXS observations of the target Morrison, as well as MAHLI images of the drill hole and dump pile (the dump pile consists of the part of the drilled sample that did not make it through the 150-micron sieve). Today’s plan also includes ChemCam and Mastcam observations of the targets “Paoha,” “The Maze,” and “Quartz Spring,” to characterize the drill tailings and other rock features. There is also an atmospheric observation to look for clouds, along with standard RAD and REMS activities. In addition to the science observations, the Sol 767 plan includes SAM cup conditioning to prepare for upcoming SAM activities. Tomorrow will be a soliday, and then we are looking forward to upcoming SAM and CheMin activities.
Sol 768-770 Update from Ken Herkenhoff: Preparing SAM (3 October 2014)
[Editor's note: The arm activities described below did not complete, but the SAM ones did. --ESL]
The tactical team took a day off Thursday to make the transition from restricted (every other day) to nominal (daily) planning. That meant that, to complete all of the planning for the weekend in time to send the commands to the rover by the start of Sol 768 (at 7 PM PDT), planning had to start 1.5 hours earlier than usual (at 6:30 AM PDT). It's good that we started early, because the weekend plan is full: After SAM preconditioning during the day, MAHLI will image the "Confidence Hills" drill hole after sunset on Sol 768 using its LEDs to illuminate the hole and tailings. SAM activities typically require lots of power and are best done during the night, so the rover will recharge during the day on Sol 769 before performing a 10-hour overnight SAM evolved gas analysis without sample. This analysis will provide a good baseline for the upcoming SAM measurements of the drill sample, currently planned to begin on Sol 771. In preparation for those measurements, SAM will perform another preconditioning late on Sol 770, after the rover recharges during the day.
Sol 771 Update from Ken Herkenhoff: Arm recovery (6 October 2014)
During the nighttime MAHLI imaging on Sol 768, there was a problem with arm positioning that prevented the subsequent arm activities from completing. The problem is understood, and the arm is in a safe configuration. So the Sol 771 plan includes arm recovery activities as well as ChemCam and Mastcam observations of nearby targets named "Pink Cliffs," "Comb Ridge," "White Cliffs," "Crowley," and "Fairyland Point." Overnight (into the morning of Sol 772), CheMin will analyze the new drill sample again, to improve the quality of the mineralogic measurement.
Sol 774 Update from Ken Herkenhoff: APXS raster on Morrison (9 October 2014)
I'm scheduled to support MAHLI/MARDI uplink tomorrow, so today I'm getting familiar with recent results and near-term plans after spending a couple days focusing on other projects. The "Confidence Hills" campaign continues to go well, with a successful dropoff of drill sample to SAM on Sol 773. The rover will recharge its batteries after the overnight SAM sample analysis, then use the arm instruments after sunset on Sol 774. APXS will take 4 measurements of the target "Morrison", then MAHLI will image the bottom of the drill hole using its LEDs for illumination. MAHLI received merges of the nighttime images of the sides of the drill hole on Sol 771 (one of which shows bluish ChemCam laser spots down one side of the hole), but has not acquired nighttime images of the bottom of the hole yet.
Sol 775-777 Update from Ken Herkenhoff: Weekend Planning (10 October 2014)
[Editor's note: The arm activities described below did not complete, but the CheMin ones did. --ESL]
The Sol 775 MAHLI activities were planned in advance, so it was an easy day for me as uplink lead--I only had to make minor changes to the plan. MAHLI will take another image of the drill hole from 25 cm above it, similar to the image acquired on Sol 759, but later in the day when the sun will illuminate the entire scene. Then MAHLI will take images of the 5 locations on "Morrison" that will be measured by the APXS. All of the images will be taken late enough in the day that they should be fully illuminated by the Sun. On Sol 776, ChemCam and Mastcam will observe several targets at various distances from the rover, then CheMin will analyze the drill sample again overnight. The CheMin analysis requires a fair amount of power, so the rover will recharge most of the following day. Finally, after sunset on Sol 777, Mastcam, and ChemCam will observe the bright star Vega to help refine plans to observe comet Siding Spring next weekend.
Sol 778 Update from Lauren Edgar: MAHLI recovery (13 October 2014)
Over the weekend, Curiosity was supposed to perform a number of MAHLI activities to image the drill hole and the target Morrison, along with APXS on Morrison, but unfortunately an arm fault occurred during the observation of the drill hole. This left MAHLI with its cover open. Fortunately, some JPL engineers came in on Saturday to make a recovery plan and successfully closed the MAHLI cover. A team of engineers is working to better understand the arm faults before we use MAHLI again. And even though today is a holiday, the rover doesn’t have the day off so we are planning some remote sensing and CheMin analysis. The Sol 778 plan includes ChemCam of the targets “Whirlwind,” “Kings Peak,” “Red Rock” and “Bald Mountain,” to characterize the nearby rocks and sand ripples. The plan also includes Mastcam imaging of the southwest valley walls to investigate the local stratigraphy, along with some Navcam observations to monitor the atmosphere.
Sol 779 Update from Ken Herkenhoff: Using the arm (14 October 2014)
The Sol 778 data show that the arm instruments are safe, and the arm is ready for more activities. MAHLI will not be used until the recent arm problems are better understood, to ensure that MAHLI's lens does not get dirty if the dust cover is left open again. However, the APXS can be used, so the Sol 779 plan includes another attempt to measure the chemistry of "Morrison" (see Sol 777 blog). In addition, ChemCam and Mastcam will observe several targets at various distances from the rover. I'm scheduled as MAHLI/MARDI uplink lead tomorrow, so I'm spending some time today to get up to speed on the near-term plans.
Sol 780 Update from Ken Herkenhoff: MARDI video (15 October 2014)
We were originally planning to perform some arm tests on Sol 780 to help diagnose the fault that occurred last weekend, but it was decided that they were too risky. So a drive toward a target dubbed "Book Cliffs" was planned instead. During the drive, MARDI will acquire images of the surface just behind the left front wheel to show what the Pahrump Hills rocks look like all along the rover traverse. As MAHLI/MARDI uplink lead, I was busy today planning the details of this MARDI "video." We also planned a MAHLI stowed image at the end of the drive, which is safe because no arm motions are involved.
Sol 781 Update from Ken Herkenhoff: Dumping Sample (16 October 2014)
The 22-meter Sol 780 drive completed as planned, placing the rover near "Book Cliffs" (visible at the right side of this image). Sol 781 planning was interrupted this morning by the "Great Shakeout" earthquake drill, but the tactical team recovered and stayed on schedule the rest of the day. After making ChemCam and Mastcam observations of "Delta," "San Rafael Swell," and "Castle Valley" (all named after places in Utah), the drill sample will be dumped onto the ground and CHIMRA cleaned out. Then the APXS will be placed on the dump pile for an overnight integration. Finally, before dawn on Sol 782, Mastcam will attempt observations of Comet Siding Spring and Mars' satellites Phobos and Deimos.