Salts could possibly be an necessary piece of the Mars bio-puzzle, NASA scientists discover out – Watts that?

From NASA

May 20, 2021

A NASA team has found that organic salts are likely to be present on Mars. Like shards of ancient pottery, these salts are the chemical residues of organic compounds previously discovered by NASA’s Curiosity rover. Organic compounds and salts on Mars could be a result of geological processes or remnants of ancient microbial life.

In addition to adding more evidence to support the idea that organics once existed on Mars, direct evidence of organic salts would also aid modern Mars habitability, as on Earth some organisms can use organic salts such as oxalates and acetates for energy .

“If we find that organic salts are concentrated somewhere on Mars, we want to investigate these regions further and ideally drill deeper below the surface where organic matter can be better preserved,” said James MT Lewis, a senior organic geochemist on the research. published March 30 in the Journal of Geophysical Research: Planets. Lewis works at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Lewis’ laboratory experiments and analysis of data from sample analysis on Mars (SAM), a portable chemistry laboratory in the belly of Curiosity, indirectly indicate the presence of organic salts. However, with instruments like SAM, which heat Martian soil and rocks to release gases that reveal the composition of these samples, it is difficult to identify them directly on Mars. The challenge is that when organic salts are heated, only simple gases are produced that could be released by other ingredients in the Martian soil.

What do you do when you have a sample from another planet and want to find out if it contains a particular molecule? Maybe even one that shows whether the planet can sustain life? When faced with such a situation, scientists use an amazing tool: the mass spectrometer. It separates materials and allows scientists to look very closely at a sample and see what is inside. Credits: NASA / Goddard Space Center
Download the video here

However, Lewis and his team suggest that another Curiosity instrument that uses a different technique to look at Martian soil, the Chemistry and Mineralogy Instrument, or CheMin for short, could detect certain organic salts if they are present in sufficient quantities . So far, CheMin has not detected any organic salts.

Finding organic molecules or their organic salt residues is vital to NASA’s search for life on other worlds. However, this is a challenging task on the surface of Mars, where billions of years of radiation have erased or broken apart organic matter. Like an archaeologist excavating pieces of ceramic, Curiosity collects Martian soil and rocks that may contain tiny pieces of organic compounds, and then SAM and other instruments identify their chemical structure.

Using data that Curiosity radiates to Earth, scientists like Lewis and his team are trying to put these broken organic pieces together. Their aim is to infer what kind of larger molecules they once belonged to and what these molecules could say about the ancient environment and the potential biology on Mars.

“We’re trying to unravel billions of years of organic chemistry,” said Lewis, “and in this organic record there could be the ultimate prize: evidence that life once existed on the red planet.”

While some experts have predicted for decades that ancient organic compounds would be preserved on Mars, it took experiments from Curiosity’s SAM to confirm this. For example, NASA astrobiologist Jennifer L. Eigenbrode of Goddard led an international team of scientists on the Curiosity mission in 2018 who shared evidence of countless molecules that contain an essential element of life as we know it: carbon. Scientists identify most carbon-containing molecules as “organic”.

The scientist Dr. Jennifer Eigenbrode discusses the discovery of ancient organic molecules on Mars.
Credits: NASA’s Goddard Space Flight Center / Dan Gallagher
Download this video in HD formats from NASA Goddard’s Scientific Visualization Studio

“The fact that organic matter is preserved in 3 billion-year-old rocks and that we have found them on the surface is a promising sign that we may be able to obtain more information from better-preserved samples below the surface,” said Eigenbrode. She worked with Lewis on this new study.

Analysis of organic salts in the laboratory

Decades ago scientists predicted that organic compounds could break down into salts on Mars. These salts, they argued, were more likely to linger on the Martian surface than the large, complex molecules associated with the way living things work.

If organic salts were present in Martian samples, Lewis and his team wanted to find out how heating in the SAM furnace could affect the type of gases they would release. SAM heats samples to over 1,000 degrees Celsius. The heat breaks down molecules and releases some of them as gases. Different molecules release different gases at certain temperatures. By examining which gases are released at which temperatures, scientists can deduce what the sample is made of.

“When Mars samples are heated, many interactions between minerals and organic matter can occur that could make it more difficult to draw conclusions from our experiments. So we’re trying to break these interactions apart so that scientists can do analysis on Mars can use that information, ”said Lewis.

Lewis analyzed a number of organic salts mixed with an inert silica powder to replicate a Martian rock. He also studied the effects of adding perchlorates to the silica mixtures. Perchlorates are salty and oxygenated salts that are common on Mars. Scientists have long feared that they could interfere with experiments looking for signs of organic matter.

This is the first photo ever taken on the surface of Mars. It was captured by NASA’s Viking 1 spacecraft just minutes after it landed on the Red Planet on July 20, 1976.
Credits: NASA / JPL More information here.

In fact, the researchers found that perchlorates interfered with their experiments, and they discovered how. However, they also found that the results they collected from samples containing perchlorate were in better agreement with the SAM data than if no perchlorates were present, which increases the likelihood that organic salts are present on Mars.

In addition, Lewis and his team reported that organic salts could be detected with Curiosity’s instrument CheMin. To determine the composition of a sample, CheMin shoots X-rays at it and measures the angle at which the X-rays are bent towards the detector.

Curiosity’s SAM and CheMin teams will continue to search for signals of organic salts as the rover moves to a new region on Mount Sharp in Gale Crater.

In the near future, scientists will also have the opportunity to study better preserved soil beneath the Martian surface. The European Space Agency’s upcoming ExoMars rover, which is equipped for drilling up to 2 meters, will carry a Goddard instrument that will be used to analyze the chemistry of these deeper layers of Mars. NASA’s Perseverance rover does not have an instrument to detect organic salts, but the rover collects samples for future return to Earth, where scientists can use sophisticated laboratory machinery to look for organic compounds.

Banner image: This review of a dune that NASA’s Curiosity Mars rover drove over was taken on February 9, 2014 by the rover’s mast camera or on the 538th Mars day or sol of the Curiosity mission. For the scale, the distance between the parallel wheel tracks is about 2.7 meters. The dune is about 1 meter high in the middle of its span over an opening called the “Dingo Gap”. This view faces east. Credits: NASA / JPL-Caltech / MSSS. More information here.

By Lonnie Shekhtman
NASA Goddard Space Flight Center, Greenbelt, Md.

Last updated: May 20, 2021

Editor: Svetlana Shekhtman

Like this:

To like Loading…

connected