NASA’s Mars Reconnaissance Orbiter Finds Hydrated Silica in Jezero Crater

Using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument aboard NASA’s Mars Reconnaissance Orbiter, researchers have detected hydrated silica — a mineral good at preserving biosignatures — in Jezero Crater, the landing site of the agency’s upcoming Mars 2020 rover mission.

This image from NASA’s Mars Reconnaissance Orbiter shows Jezero Crater on Mars, the landing site for NASA’s Mars 2020 mission. On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins. Examination of spectral data acquired from orbit show that some of these sediments have minerals that indicate chemical alteration by water. Here in Jezero Crater delta, sediments contain clays and carbonates. Image credit: NASA / JPL-Caltech / MSSS / JHU-APL.

This image from NASA’s Mars Reconnaissance Orbiter shows Jezero Crater on Mars, the landing site for NASA’s Mars 2020 mission. On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins. Examination of spectral data acquired from orbit show that some of these sediments have minerals that indicate chemical alteration by water. Here in Jezero Crater delta, sediments contain clays and carbonates. Image credit: NASA / JPL-Caltech / MSSS / JHU-APL.

NASA announced last year that its Mars 2020 rover would be headed to Jezero Crater, which appears to have been home to an ancient lake.

The crater contains a large delta deposit formed by ancient rivers that fed the lake. The delta would have concentrated a wealth of material from a vast watershed.

“Deltas on Earth are known to be good at preserving signs of life. Adding hydrated silica to the mix at Jezero Crater increases that preservation potential,” said lead author Jesse Tarnas, a Ph.D. student at Brown University, and colleagues.

One of the silica deposits was found on the edge of the delta at low elevation. It’s possible that the minerals formed in place and represent the bottom layer of the delta deposit, which is a great scenario for preserving signs of life.

For the study, the researchers used data from the CRISM instrument that flies aboard NASA’s Mars Reconnaissance Orbiter.

The team’s technique applied to the CRISM data used big data analysis methods to tease out the weak spectral signature of the silica deposits.

“Using a technique we developed that helps us find rare, hard-to-detect mineral phases in data taken from orbiting spacecraft, we found two outcrops of hydrated silica within Jezero Crater,” Tarnas said.

“We know from Earth that this mineral phase is exceptional at preserving microfossils and other biosignatures, so that makes these outcrops exciting targets for the rover to explore.”

While the geologic context of the deposits suggests they could have formed at the base of the delta, it’s not the only possibility.

The minerals could have formed upstream in the watershed that fed Jezero and been washed subsequently into the crater, by volcanic activity or later episodes of water saturation in the Jezero crater lake.

The Mars 2020 rover should be able to isolate the real source.

“The material that forms the bottom layer of a delta is sometimes the most productive in terms of preserving biosignatures,” said Brown University’s Professor Jack Mustard.

“So if you can find that bottomset layer, and that layer has a lot of silica in it, that’s a double bonus.”

The study was published in the journal Geophysical Research Letters.

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J.D. Tarnas et al. Orbital identification of hydrated silica in Jezero crater, Mars. Geophysical Research Letters, published online November 6, 2019; doi: 10.1029/2019GL085584

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