NASA's Mars rover Curiosity acquired this image using its Mars Hand Lens Imager (MAHLI) on Sol 809 Credit: NASA/JPL-Caltech/MSSS
As Curiosity continues to mend, I've been looking forward to our next drill sample of gray rock. Some interesting features we've seen on Vera Rubin Ridge are small "swallowtail crystals" often associated with the boundary between gray and red rocks on the ridge top. In thinking about these features, I wanted to take the opportunity to reflect on past results from when Curiosity was just beginning to explore Mt. Sharp at the Pahrump Hills region. Readers of this blog may remember that back on sol 809, after we brushed away the dust on target "Mojave," the team was surprised and excited to discover hundreds of millimeter-sized, rice-shaped crystals on its face. These crystals are geologic clues to what happened in the past. What were these unique features made of? How and when did they form?
Swallowtail Crystals Close to Drill Attempt at Inverness
This image was taken by ChemCam: Remote Micro-Imager (CHEMCAM_RMI) onboard NASA's Mars rover Curiosity on Sol 2163 (2018-09-06 12:10:38 UTC). Image Credit: NASA/JPL-Caltech/LANL
Curiosity scientist Linda Kah and colleagues address these questions in a new paper available in the journal Terra Nova titled "Syndepositional precipitation of calcium sulfate in Gale Crater, Mars." For this study, Kah and colleagues carefully studied the sizes, shapes, and orientations of the unusual crystals at Mojave and several nearby targets. They integrated these findings with the geologic setting, chemistry, and mineralogy of the Pahrump Hills area to infer the presence of shallow, salty, and sometimes ephemeral waters during this period in Gale's history.
Kah and co-authors explain that the crystal shapes are distinctive of gypsum salts that precipitate in lake, playa, and near-shore ocean environments. Interestingly, Curiosity did not detect any large differences in the composition of rocks containing crystals versus nearby, non-crystal-containing rocks. This result suggests the calcium sulfate that originally formed the crystals had either been dissolved at a later time and/or that the crystals had incorporated a lot of the original rocks around within them when they formed.
The shapes, sizes, and orientation of crystals give clues to how they grow. Kah and authors showed the crystals at Pahrump were randomly oriented and occurred between and within cemented layers. Combined with the crystals' elongated shapes, this suggests that they grew at the interface between loose, water-logged sediment and either shallow water or air. Interestingly, small amounts of organic (carbon-bearing) material can cause crystals to have shapes similar to those observed at Mojave, which is consistent with Curiosity findings of organic material in the Mojave drill sample.
The swallowtail crystals on Vera Rubin Ridge are also known shapes of gypsum crystals. Why are these crystals so different in form from what we saw back at Mojave? What does this all tell us about ancient environments at Gale Crater?
These blog updates are provided by self-selected Mars Science Laboratory mission team members who love to share what Curiosity is doing with the public.
Dates of planned rover activities described in these reports are subject to change due to a variety of factors related to the Martian environment, communication relays and rover status.
Contributors
Sterling Algermissen
Mission Operations Engineer; NASA/JPL; Pasadena, CA
Atmospheric Scientist; Texas A&M University; College Station, TX
Kristen Bennett
Planetary Geologist; USGS; Flagstaff, AZ
Fred Calef
Planetary Geologist; NASA/JPL; Pasadena, CA
Brittney Cooper
Atmospheric Scientist; York University; Toronto, Ontario, Canada
Sean Czarnecki
Planetary Geologist; Arizona State University; Tempe, AZ
Lauren Edgar
Planetary Geologist; USGS; Flagstaff, AZ
Christopher Edwards
Planetary Geologist; Northern Arizona University; Flagstaff, AZ
Abigail Fraeman
Planetary Geologist; NASA/JPL; Pasadena, CA
Scott Guzewich
Atmospheric Scientist; NASA/GSFC; Greenbelt, MD
Samantha Gwizd
Planetary Geologist; University of Tennessee; Knoxville, TN
Ken Herkenhoff
Planetary Geologist; USGS; Flagstaff, AZ
Rachel Kronyak
Planetary Geologist; University of Tennessee; Knoxville, TN
Sarah Lamm
Planetary Geologist; LANL; Los Alamos, NM
Michelle Minitti
Planetary Geologist; Framework; Silver Spring, MD
Claire Newman
Atmospheric Scientist, Aeolis Research; Pasadena, CA
Catherine O’Connell
Planetary Geologist; University of New Brunswick; Fredericton, New Brunswick, Canada
Melissa Rice
Planetary Geologist; Western Washington University; Bellingham, WA
Mark Salvatore
Planetary Geologist; University of Michigan; Dearborn, MI
Susanne Schwenzer
Planetary Geologist; The Open University; Milton Keynes, U.K.
Ashley Stroupe
Mission Operations Engineer; NASA/JPL; Pasadena, CA
Dawn Sumner
Planetary Geologist; University of California Davis; Davis, CA
Vivian Sun
Planetary Geologist; NASA/JPL; Pasadena, CA
Lucy Thompson
Planetary Geologist; University of New Brunswick; Fredericton, New Brunswick, Canada
Ashwin Vasavada
MSL Project Scientist; NASA/JPL; Pasadena, CA
Roger Wiens
Geochemist; LANL; Los Alamos, NM
Tools on the Curiosity Rover
The Curiosity rover has tools to study clues about past and present environmental conditions on Mars, including whether conditions have ever been favorable for microbial life. The rover carries:
Some days just give me goose bumps. First, looking at yesterday's plan I realized that we did something really unusual overnight: Wrap up the drill activity on one site and start the drill activities on the next in the same sol.
Curiosity is finishing up at "Aberlady" and ready to move on to our next drill target. We are preparing to drill a second hole in the clay bearing unit.
Yesterday's discussions with the science team focused on determining which target in the vicinity of "Aberlady" will become the focus of the next drill campaign: target 2, or target 3 (pictured in the Sol 2379 Mission Update).
With our time at Aberlady coming to a close, the search for our next drill target is in full swing. On Friday, the team discussed two different "bump" options that are near our current workspace and may be drillable.
This week's drill activities have been very power-intensive for Curiosity. So we'll spend today, Sol 2374, catching up on some remote science observations while waiting for data from yesterday's CheMin run to arrive.
After looking at our exciting new drill hole, "Aberlady," a few interesting observations were made: the drilled block lifted up a centimeter or two as the drill was retracted, there might be some evidence of a horizontal calcium sulfate (i.e. gypsum) vein within the drill hole, the drill went into the rock very easily (no percussion required), and the drill tailings look clumpier than usual.
Our drill attempt at target "Aberlady" this weekend was a success! In today's plan we are continuing our investigation of Aberlady and the surrounding areas and preparing to deliver our drilled sample to our onboard instruments.
One of the primary goals of the Curiosity mission, to determine the composition of a region which appears to be rich in clays (informally known as "Glen Torridon") is getting closer to being achieved.
Curiosity is getting close to the area in which we next want to drill. We are possibly as close as 2-3 drives (including today's) away from our next drill target!
We are continuing to find interesting new things in Glen Torridon. One of my favorite new images was taken this weekend (Mars sol 2356) on target "Stonebriggs."
At the start of Sol 2359, Curiosity found herself parked in front of some layered bedrock outcrops, a rarity in the rubbly landscapes that we've explored so far in the clay-bearing unit.
As Curiosity makes her way to the site where the science team would like to drill next, there is no shortage of observations to make of the many different lithologies of the clay-bearing unit.
In the current plan, we start with a dust devil survey to look for them while they are still in season. This is followed by a ChemCam investigation "Schiehallion" and an RMI mosaic on "Motherwell." Mastcam will finish off the investigation with multispectral images on the block in front of us, which contain the previous APXS targets "Fife" and "Arbuthnott." So far, so routine, but then there was the look in the rear-view mirror!
Today we planned Sol 2338 chock full of science activities to finish up our observations at the "Midland Valley" outcrop. We'll primarily use our Mastcam and ChemCam instruments to take a closer look at some interesting rock targets in our workspace.
Curiosity returned to science planning today after a two week hiatus because of a technical issue. Our most recent science plan, described in the blog for Sols 2320-2323, included a drive towards a blocky outcrop called "Midland Valley."
Today was a very busy planning day for the Curiosity operations team. We planned a 3-sol plan, with contact science, imaging, environmental monitoring and a drive.
Similar to its namesake in Scotland, the Glen Torridon area on Mars affords us stunning vistas, but in our case, of the relatively low-lying clay bearing (from orbit) unit flanked to the north by the higher ground of the Vera Rubin Ridge and to the south, by Mount Sharp.
The accompanying image shows the target "Brent" in the lower right corner; it was analyzed with ChemCam and APXS, and imaged with MAHLI over the weekend.
Curiosity successfully completed her drive yesterday and is currently parked on top of one of the ridges ("Knockfarril Hill") in the clay-bearing unit.
This weekend's plan started off on Sol 2301 with some Mastcam atmospheric observations, followed by ChemCam analysis of "Loch Ness" and "Loch Skeen," examples of brown and gray bedrock.
Curiosity is continuing the first phase of its journey to the "clay-bearing unit," the low elevation portion in the middle distance of this Navcam image with a series of "touch-and-go" driving sols.
Curiosity has moved for the first time since December 13, 2018. More importantly, Curiosity is moving to a new geological unit that we have so far called the "Clay-Bearing Unit".
Sometimes the best laid plans of rovers go astray. After wrapping up at the Rock Hall drill site yesterday, the plan was for Curiosity to start driving towards the clay-bearing unit, starting with a series of small bumps so that MAHLI could take images of the full outer circumference of the wheels.
Today was our last day at "Rock Hall," so it was our final chance to get every last bit of science at this location. We had a 2.5 hour science block filled with Mastcam change detection imaging of the Rock Hall drill fines and alternating ChemCam RMI and LIBS observations of the Rock Hall dump pile, drill tailings, and target "St.Cyrus 2."
Today we planned a single sol of activities, Sol 2291. As we begin to wrap up our activities at the Rock Hall drill site, Sol 2291 is chock full of science observations. We'll begin the sol with an hour-long science block.
We will soon be leaving the Rock Hall area, thus this one last look at the drill site from a hazard camera perspective. Seeing those holes always is special, even for #19!
Our onboard instruments SAM (Sample Analysis at Mars) and CheMin (Chemistry and Mineralogy) have come to the end of their investigation of the Rock Hall target, likely to be our last drill location on the Vera Rubin Ridge, so this 2-sol plan is the beginning of the drill operation wrap up.
Today was a very smooth planning day on Mars, with the first scheduled science block in the plan being entirely filled by various spectroscopic ChemCam observations. The ChemCam instrument has the capabilities to be used in both passive and active modes, both of which were included in today's plan.
Today we are continuing the drill campaign at our red Jura target "Rock Hall." The focus of this weekend's plan is the dropoff of the Rock Hall sample to the SAM instrument, which will occur on Sol 2281.
The holiday planning completed successfully and included 10 sols of five-hour-long morning meteorological observations by REMS, during the period when more complex activities were precluded.
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