Published results from Curiosity as it traversed Vera Rubin Ridge

The science results from American Mars rover Curiosity during its traverse of Vera Rubin Ridge at the base of Mount Sharp in Gale Crater have now been released to the public.

This link takes you to the overview paper, available online for free. The abstract notes the key finding, which confirms previously released research:

We conclude Vera Rubin ridge formed because groundwater recrystallized and hardened the rocks that now make up the ridge. Wind subsequently sculpted and eroded Mount Sharp, leaving the harder ridge rocks standing because they resisted erosion compared with surrounding rocks. The implication of these results is that liquid water was present at Mount Sharp for a very long time, not only when the crater held a lake but also much later, likely as groundwater.

The fundamental geological mystery of Mars remains. The evidence strongly says that liquid water must have existed for long periods on the surface of Mars. At the same time, other evidence strongly says that the climate and atmosphere of Mars has never been warm enough or thick enough to allow for liquid water on the planet’s surface.

So far, no global model proposed by any theorist that allows liquid water in the past on Mars has been accepted with any enthusiasm by the planetary community. While possible, the models carry too many assumptions and are based on what is presently far too limited data. We simply do not yet know enough about Mars and its past history to explain this conundrum.

The paper also outlines a number of models for allowing liquid water in the localized area of Gale Crater alone. As with the global models, none fits all the facts, or is entirely satisfactory for explaining the data.

Regardless, the results from Vera Rubin Ridge confirm once again that enough liquid water once did exist on Mars to have allowed it to be habitable for life, even if we have so far found no evidence of any past life.

Another failed drilling attempt by Curiosity

The second attempt by Curiosity to drill into Vera Rubin Ridge was a failure, the rock once again being too hard using the rover’s new improvised drilling technique.

They are now in search of “softer rock.” The scientists very much want to get at least one drill hole in the hematite unit on Vera Rubin Ridge. However, it does appear that the new drill technique, that uses the robot arm to push the drill bit down as its drills, does not provide enough force for some hard geological features.

The failure to drill is in itself not a complete scientific washout. Knowing the hardness of a rock can tell a geologist a great deal about it. Nonetheless, the Curiosity science team seems determined to find something they can drill into on Vera Rubin Ridge.

Mars rover update: April 27, 2018

Summary: Curiosity’s exploration of Vera Rubin Ridge is extended, while an attempt by Opportunity to climb back up Perseverance Valley to reach an interesting rock outcrop fails.

For a list of past updates beginning in July 2016, see my February 8, 2018 update.

Curiosity

Curiosity's traverse map, Sol 2030

For the overall context of Curiosity’s travels, see Pinpointing Curiosity’s location in Gale Crater.

Since my March 21, 2018 update, it has become apparent that the Curiosity science team has decided to extend the rover’s research on Vera Rubin Ridge far beyond their original plans. They have continued their travels to the northeast well past the original nominal route off the ridge, as indicated by the dotted red line on the traverse map above. Along the way they stopped to inspect a wide variety of geology, and have now moved to the north and have actually begun descending off the ridge, but in a direction that takes the rover away from Mount Sharp and its original route. As noted in their April 25 update,
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Mars rover update: July 12, 2017

Summary: Curiosity looks at some big dune ripples, then creeps up hill. Opportunity tests its wheels.

Curiosity

For the overall context of Curiosity’s travels, see Pinpointing Curiosity’s location in Gale Crater.

The interior of a dune ripple

Since my last update on June 23,, Curiosity has worked its way around and, for a few days, even into the small sandy field at the base of Vera Rubin ridge. The scientists noticed that the sandy here had a series of large ripples, and they wanted to take a close look at at least one. The image on the right, cropped to show here, was taken shortly after they had the rover drive through one ripple in order to expose its interior. You can see the robot arm directly above the cut created by the rover’s wheels. On the cut’s wall several distinctly different toned layers are visible. A close look reveals that they are wavy, and probably indicate numerous and repeated overlays as the wind brushes a new layer of dust on top of old layers, time after time. The different tones indicate a change in the material’s composition, which could reveal something about some past events in either Mars’ weather or geology.

In order to decipher this information, however, they will need to be able to date the layers, and figure out when each tonal change happened. I am not sure Curiosity can do this, especially since they have not scooped up any of this dust for later analysis.

They are now approaching Vera Rubin Ridge, and should climb up onto in the coming weeks. At that point they will move off the Murray Formation, where they have been since March 2016, made up of dried and ancient crushed mud, and up onto a lighter, yellowish layer of rock, dubbed the Hematite Unit. This October 3, 2016 press release. gives a good outline of the geology of these regions.
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