O Jezero crater del Mars was chosen as the landing site for the wanderer perseverance because images from orbiters (such as NASA’s Mars Global Surveyor and Mars Reconnaissance Orbiter, or ESA’s Mars Express mission) suggested that it hosted a lake billions of years ago. In fact, there are still indications that there was a delta at the end of one of its inlet channels.
This week are published in Science Y Advances in Science three articles that present new results collected by Perseverance in this martian crater and all point to the possibility of having been habitable in the past🇧🇷 Data were collected with three instruments: the Mastcam-Z camera system and the PIXL and SHERLOC spectrometers.
Illustration of what Jezero Crater, the landing site of the Perseverance rover, could have looked like. / NASA/JPL-Caltech
One of the authors of the three articles, Alberto González Fairenresearcher at the Center for Astrobiology (CSIC-INTA) and Cornell University, in New York (USA), explains to SINC that the analysis on site of wanderer on Jezero “revealed a great number of details that were not appreciable from the orbiters” and which can be summarized in five points.
On the one hand, the long distance images made by Mastcam-Z confirmed that the Jezero delta is Gilbert type, that is, with three parts: a wedge-shaped upper one with fine and flat sediments, an intermediate one with a pronounced slope and a lower one with finer and flat sediments. These types of deltas are typical of lakes, where river water and lake water have the same density.
Igneous rocks at the bottom of the crater and sedimentary rocks in the delta
“Second, data from PIXL indicate that the rocks at the bottom of the crater are igneous [se originan cuando se enfría y solidifica el magma, como las volcánicas] and that formed before there was a river, a lake and a delta there,” says González Fairén. Therefore, by combining Mastcam-Z and PIXL data, two types of materials were identified in Jezero: igneous rocks at the bottom of the crater and sedimentary deposits in the delta”.
The new Perseverance analyzes support the image that Jezero Crater formed a habitable site more than 3 billion years ago, containing liquid water and carbonate precipitation in a sedimentary geological environment rich in organic compounds.
Cameras on the Mastcam-Z instrument also confirm that the igneous rocks at the bottom of the crater formed by two different processes: a deep subsurface piece of magma that slowly cooled, forming olivine crystals🇧🇷 and the other, from volcanic activity on the surface.
“Large olivine crystals exhibit fractured textures, and the PIXL data suggest they were exposed to at least two different periods of interaction with water”, explains the astrobiologist as a fourth point, and clarifies: “In the beginning, the interaction was with the Sparkling water that circulated filling the lake, that dissolved the olivine and precipitated in the form of carbonates. Much later, different periods of interaction (at least two) with small brine they left patches of concentrated salts as the fluids evaporated, and this aqueous alteration led to the production of amorphous silicates, sulfates, and chlorine salts.
The SHERLOC instrument made it possible to identify aromatic organic compounds in Jezero rocks from two different ancient aqueous environments
Finally, the spectroscopic analyzes carried out with the instrument SHERLOC allowed to identify the presence of aromatic organic compounds in the rocks of the Jezero crater. Their distribution is spatially correlated with that of secondary minerals, and they appear associated with both carbonates and sulfates, suggesting two periods of mineral formation. organic compounds: two different ancient aquatic environments.
“Therefore, the Perseverance analyzes now published support the image that Jezero formed a habitable enclave more than 3 billion years ago, in which liquid water and carbonate precipitation existed in a sedimentary geological environment rich in organic compounds”, concludes González Fairén.
Bringing Martian Samples to Earth
now he wanderer Perseverance is collecting samples of the different types of rocks in this Martian crater to bring back to Earth for analysis. The fragments collected from igneous rocks will serve to accurately date the age of the Jezero materials and the temporal sequence of its geological events.
On the other hand, the sedimentary samples will help to search for potential indicators of biological activity on Mars in the past. Specifically, establish the formation processes of the identified organic compounds. O wanderer Perseverance will therefore continue to provide new information about the red planet and its habitability.
Perseverance Scientific Instruments. Three were used in the new studies: Mastcam-Z, a camera system for capturing panoramic, stereoscopic, and zoomed images; PIXL, a fluorescent X-ray spectrometer to accurately analyze the chemical composition of Martian surface material; and SHERLOC, an ultraviolet laser Raman spectrometer for detecting organic compounds and other substances. The latter also includes a high-resolution camera for taking color microscopic images of the Martian soil. / NASA/JPL-Caltech
References:
Eva L. Scheller et al. Science. 🇧🇷Aqueous alteration processes in Jezero Crater, Mars – implications for organic geochemistry”. Science2022.
James Bell et al. 🇧🇷Geological, multispectral and meteorological imaging results of the Mars 2020 Perseverance Rover in Jezero Crater.” advances in science2022
Michael Tice et al. 🇧🇷History of alteration of the Séítah formation rocks inferred by PIXL X-ray fluorescence, X-ray diffraction, and multispectral imaging on Mars”. advances in science2022