Curiosity at the foot of Mount Sharpe

Over the past six months, the rover has hardly made any progress in its path along Mars, but has made significant progress in its study. NASA scientists continue to follow the covenant given to budget officials: to study more and walk less, and the place has been blessed.

The Pahrump Hills site drew the attention of geologists even in summer, and when they got into it, the situation with Yellowknife Bay repeated - the scientists felt like children in a pastry shop. As a result, for 5 months, Curiosity traveled a small patch of land along and across, examined almost every protruding stone, shot the neighborhood with a laser and drilled the ground twice, and is now looking for a place for another well.


')
Why is Pahrump Hills so interesting?
This area is the very foundation of Mount Sharp, which is called the main goal of the whole expedition. Pahrump Hills turned out to be a hollow, which the wind in layered sandstones “gnawed through”. According to NASA geologists, once there was a lake and a river delta formed by streams of water from a mountain. The rivers carried sand, which subsided, falling into the standing lake water. As a result, any look of the rover stumbles upon plate or thin-bedded rocks.



Outwardly, the landscape seems monotonous, but a careful study of the surface showed that numerous layers of rock have a different composition. A significant difference can be observed quite a short distance, with a slight difference in height, less than half a meter.

But first, I’ll tell you about two important discoveries that were made earlier and told a couple of months ago. Both relate to long-awaited organics on Mars.



If we recall the events of two years ago (how time flies), then the first analysis using the SAM instrument for organic compounds in the Martian soil gave contradictory results. At first they seemed to be found, and then, it seemed they did not. The reason for the failure was in a bursting vessel with an organic solvent, which was brought from Earth. The solvent should have helped in the study of local soil, but a few drops hit the device by accident, so the first positive results were hasty. Therefore, all subsequent soil analyzes were performed in different modes and several times to determine what effect the pollution has on the results.

During the ten-kilometer run along the mountain, Curiosity also repeatedly carried out drilling operations and analyzed the ground. As a result, scientists were able to figure out where the local organic matter is, and where the earth is. Now, in fact, there are no more traces of the terrestrial pollutant left - weathered and cleaned up by previous samples, and scientists have learned to distinguish the remaining minor traces from the rest. After all the work done, they were able to state with confidence that there is organic matter on Mars.



The SAM gas analyzer was able to determine the release of chlorobenzene by heating the Martian soil in a microwave oven. However, it is not known whether such a form contained hydrocarbons in the soil or whether this substance turned out to be already in the oven, after combining with chlorine, which is also sufficient in the samples. Chlorobenzene turned out to be only in one well, which was distinguished by the bluish color of the rock and an abnormally high water content - up to 6% of the total mass.

After Yellowknife Bay, there were no organic matter deposits for the rover across the 8-kilometer route. But a regular analysis of the atmosphere has made a new discovery - periodic methane emissions.



Here it is necessary to clarify that “emissions” is too loud a name for the absolutely insignificant concentration of methane molecules that were recorded. In fact, these “emissions” barely exceeded the sensitivity threshold of the gas analyzer. But repeated tests allowed more or less confidently to say that there is methane, albeit of very low concentration.

NASA drew a detailed scheme to explain the possible origin of methane, but most likely, gas emissions are associated with seasonal activity, just as water-related activity is observed in mid-latitudes. Probably in the crater of Gale, somewhere in the depths remains ice, which gradually melts with the onset of spring. Or, in the season of winds, gas brings from somewhere else.



Reaching Pahrump Hills, Curiosity began a detailed study of the terrain. The first borehole revealed brownish rocks. This color is traditionally associated with iron oxides.



This means that this soil was formed during the “acid” geological period of Mars - Hesperides, when powerful volcanic eruptions led to the saturation of the atmosphere with sulfur and acid rain. That is why the bluish layer found earlier attracted the attention of geologists - it meant that we managed to get to the bottom of more ancient rocks.

After wandering a couple of months on Pahrump Hills, the rover is almost back to the well done earlier. Just a few meters away, a new type of breed was found, which Curiosity has not yet encountered. But he turned out to be very similar to those layers that Opportunity studied ten years ago.



Then, the found oblong cavities in the rock allowed us to express hypotheses about the formation of sediments in the aquatic environment. The oblong salt crystals remained at the bottom of a drying lake, and then collapsed with time.

Curiosity was more fortunate and he was able to find similar deposits, but in them crystals of a familiar shape had not yet crumbled.



Therefore, geologists could not refrain from laying a new well.



Surprisingly, this breed was again gray, not brown, although, according to Opportunity, it should have been formed during that very acidic period, unfavorable for life.



No detailed drilling results have yet been published, but Curiosity continues to work at Pahrump Hills. Judging by the colorful landscapes that he regularly sends, there is still something to do.


Large image size (13 mb) .

Although the mountain ahead beckons with its uncertainty.