Emily LakdawallaMay 15, 2014

Curiosity update, sols 610-630: Drilling work at Windjana

Finally, a new drill site! For the first time in nearly a year, Curiosity has put drill bit to rock and acquired a new sample of Martian material for her analytical instruments to chew on. The full-depth drill was achieved on sol 621. The new sample site is called Windjana, and is the fourth location from which Curiosity has sampled Mars, after Rocknest (sol 69), John Klein (182), and Cumberland (279). It's clearly a different rock from John Klein; the powdered tailings from the drill hole are substantially darker. It's amazing how well a thin coating of Martian dust obscures these color differences.

Comparison of John Klein and Windjana mini-drill holes
Comparison of John Klein and Windjana mini-drill holes Comparison of the two test drill holes Curiosity performed at John Klein on sol 180 (left) and Windjana on sol 615 (right) shows how Mars' red dust obscures differences between rock colors. The dust drilled out of John Klein is much lighter in color than that at Windjana.Image: NASA / JPL / MSSS / Emily Lakdawalla

Here's how the drill site looked on sol 627. This is a mosaic of MAHLI images. They were taken in such a way that they can be swapped in for pictures taken as part of the massive self-portrait mosaic from sol 613.

Windjana site after drilling, Curiosity sol 627
Windjana site after drilling, Curiosity sol 627 A MAHLI mosaic of the Windjana drill site taken on sol 627. The major drilling activity happened on sol 621. Note the cascades of fine sand that have slumped due to the percussive activity of the drill.Image: NASA / JPL / MSSS / Emily Lakdawalla

Here's a zoom view on the drill site, taken by MAHLI after sunset on sol 628; MAHLI has LED flashlights for such nighttime imaging. You can see the scorch marks from the Chemcam analyses down the drill hole. Pew pew!

Windjana drill hole at night, Curiosity sol 628
Windjana drill hole at night, Curiosity sol 628 After drilling at Windjana, Curiosity used MAHLI's flashlights to image the interior of the drill hole at night. On the far wall of the drill hole are seven black dots, the marks of ChemCam laser shots. This image is actually a composite of many MAHLI images at different focus positions. Such "focus merging" is performed automatically onboard the rover, reducing the amount of data that needs to be sent to Earth: only one focus-merged image is returned, rather than a dozen or so images focused at different depths.Image: NASA / JPL / MSSS / Emily Lakdawalla

This was how I'd learned they successfully obtained a sample from Windjana:

The sign taped to a cubicle in mission operations is only sort of a joke. Now that they have sample inside the CHIMRA sample handling system in the turret, it's a lot more complicated for the rover engineers to plan arm operations, because they have to manage how the powdered sample moves inside the turret as they rotate it to place the turret-mounted instruments in position. They will keep the Windjana sample in CHIMRA until they're sure they've performed all the analyses on it with SAM and CheMin that they want to -- unless, of course, they drill at the Kimberley a second time, in which case they'll have to spit the remaining Windjana sample out first.

From the time that they selected the drill location, to the time that they wrapped up work, took, in total, about three weeks. Here's how the whole process unfolded, as documented in Hazcam images. There are two things I love about this animation. First, before drilling, there is a "preload" step, where the arm pushes down on the drill site in order to brace the two prongs on either side of the drill against the rock and prevent slipping. This downward push exerts an upward force on the rover, so the rover lifts. But because the Hazcams are bolted to the rover, the camera lifts too. In the animation, it winds up looking like Curiosity is pushing Mars down! The other thing I enjoy is the cascading of loose sand during the two drilling activities. That stuff is near its angle of repose, and the powerful percussion of the drilling activity shakes it downhill. I made the animation small in order to keep its file size manageable; click to enlarge.

Curiosity's work at Windjana, sols 609-629
Curiosity's work at Windjana, sols 609-629 Hazcam images document three weeks of work at Windjana, the drill site at the Kimberley, from sols 609 to 629 (April 23 to May 14, 2014). Activity included a "mini-drill" on sol 615 and a full drill -- Curiosity's third -- on sol 621. APXS and MAHLI images of the Windjana drill site and another location named Stephen occurred throughout.Image: NASA / JPL / Emily Lakdawalla

Here's a list of all the activities. For the most part, this list is based upon what I could deduce from looking at the raw images, because unfortunately Ken Herkenhoff has taken a break from blogging and there is only one very brief update from him covering this entire time period. Ken represents the public's only connection inside mission operations apart from rare JPL press releases; it's a big loss to public understanding of mission operations when he's too busy. (I'm begging you, Ken, please keep writing!!)

There's a funny sort of gap in the middle of the action, almost a week between the mini-drill on sol 615 and the full drill on sol 621, beginning with a skipped sol (which is sometimes an indicator of activity with SAM), and then checkouts of the turret combined with four solid sols of remote sensing, acquiring what will be a truly awesome 3D Mastcam mosaic of the site (I haven't checked, but it seems big enough to be the full 360 degrees). But once they drilled last Monday, they've worked pretty rapidly at sample deliveries and initial analysis, taking a little extra time to analyze a second spot next to Windjana that Ashwin Vasavada told me is named "Stephen." This photo shows you how effective the ChemCam laser can be as a dust removal tool. It looks a lot like Stephen has been brushed, but if you look through all the photos you'll see they never put the brush on Stephen, only MAHLI and APXS. It's been dusted off by the blast of vapor that spreads outward from the ChemCam laser shot points. It makes me wonder if you could do analysis of rock colors and how they relate to composition by using ChemCam as a remote rock duster and taking multispectral Mastcam-100 images after ChemCam shots....

Stephen site before and after ChemCam zapping, sols 610 and 627
Stephen site before and after ChemCam zapping, sols 610 and 627 The ChemCam instrument on Curiosity shoots a laser at a target to vaporize some of it, and "reads" the elemental makeup of the target from the wavelengths of light visible in the plasma. The vaporization causes an outward blast of air, which can very effectively dust off a Martian rock. The inset image was taken with Mastcam on sol 610 and shows the Windjana drill site and Stephen ChemCam target before any activity was performed there. The main image was taken with MAHLI on sol 627 and shows Stephen's surface blasted mostly clean except for the visible ChemCam shot points.Image: NASA / JPL / MSSS / Emily Lakdawalla

Last night, Curiosity left Windjana.

Windjana in the rear view, Curiosity sol 630
Windjana in the rear view, Curiosity sol 630 After spending three weeks performing drilling activities at Windjana, Curiosity departed the site on the edge of the Kimberley waypoint.Image: NASA / JPL / Emily Lakdawalla

I can't say whether this means they're done at the Kimberley or not. They could still drill one of the other two rock units in this location. On the other hand, they are under a lot of pressure to keep driving toward Mount Sharp. I suppose it depends upon what the team sees in the early CheMin and SAM analyses.

EDIT: JPL has now announced that "The rover team has decided not to drill any other rock target at this waypoint. In coming days, Curiosity will resume driving toward Mount Sharp, the layered mountain at the middle of Mars' Gale Crater. The rover is carrying with it some of the powdered sample material from Windjana that can be delivered for additional internal laboratory analysis during pauses in the drive."

Some of you may be wondering when we are going to get the science results from the Kimberley: what is in the stuff that they drilled out of Windjana? I counsel patience. There are two things that control when we hear about the science from the Curiosity mission: the timing of scientific meetings where they present the results to their peers, and the timing of public release of Curiosity data. In general, the Curiosity science team is forbidden from sharing and discussing scientific data from the mission until after the data are publicly available. Of course, JPEG versions of images are available instantly, but they're not science data; the science data from all instruments are released roughly 4 to 8 months after they're acquired, in batches three times a year. This has caused very awkward conversations between me and mission scientists at science meetings. Because I know what the rover has been doing (because I can see what it has been doing in the released raw images), and the scientists know that I know, they know they can discuss rover actions that are obvious in photos, but they can't discuss science, and there are lots of pauses in conversation and there is much staring off into space as they think about what they're allowed to say.

So far, data have been released through sol 449; Curiosity was at Cooperstown then. Drilling at Windjana happened on sol 621, and the first CheMin and SAM analyses happened on sols 623 and 624. SAM analysis will likely continue for weeks, as Curiosity continues chewing on samples while on the road. Here are the upcoming dates of meetings and data releases. As you can see, the next data release covers up to just before they got to Windjana. So the science team is not allowed to discuss the results from the drilling campaign at the Kimberley until December unless the mission leadership chooses to discuss it earlier. But the good thing about that is that the next data release will cover enough time after Windjana that it should cover all the SAM analyses that will be done on the newly drilled sample. So although we could hear some science results from Windjana earlier, we'll definitely hear about them at the American Geophysical Union meeting.

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