Organic molecules have been found in ancient rocks under the surface of Mars. The discovery was made by NASA’s Curiosity Rover by drilling into sedimentary rock called mudstone. Mars’ early climate would have allowed water to exist on the surface and as the rivers and lakes dried it would have deposited vast amounts of muddy sand which eventually turned to a form of soft rock about 3.5 billion years ago.
The molecules found include sulphur-rich thiophenes, aromatic hydrocarbons, such as benzene, and aliphatic hydrocarbons such as propane. While the presence of these “tough” organic molecules does not on its own prove that life once existed on Mars, there are other signs that add to the notion that it was a living planet.
(For example, in a second paper in Science, NASA’s Christopher Webster and an international team describe how they have used instruments on-board Curiosity to measure a seasonal variation in methane levels in the Martian atmosphere. Levels of methane within Gale Crater repeatedly peak in warm, summer months and drop in the winter every year, suggesting a methane-generating activity somewhere beneath the surface. Webster and colleagues say that the variation cannot currently be explained by processes known to occur on Mars. Some argue that it has distinct similarities with variations on Earth cause by increased levels of micro-organisms in warmer seasons. )
“This is the first time we’ve seen something repeatable in the methane story, so it offers us a handle in understanding it,” said Chris Webster of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, lead author of the second paper. “This is all possible because of Curiosity’s longevity. The long duration has allowed us to see the patterns in this seasonal ‘breathing.'”
Water-rock chemistry might have generated the methane, but scientists cannot rule out the possibility of biological origins. Methane previously had been detected in Mars’ atmosphere in large, unpredictable plumes.
The discovery of complex molecules in the rock samples is reported in the journal Science by NASA’s Jennifer Eigenbrode and an international team of scientists. They used Discovery’s Sample Analysis at Mars (SAM) instrument to examine samples that had been gathered from Mars’ Gale crater using a drill that can probe 5 cm below the surface. The rocks were analysed using an oven to heat the samples (to in excess of 900 degrees Fahrenheit, or 500 degrees Celsius) to release organic molecules from the powdered rock.
SAM measured small organic molecules that came off the mud-stone sample – fragments of larger organic molecules that don’t vaporise easily. Some of these fragments contain sulphur, which could have helped preserve them in the same way sulphur is used to make car tires more durable, according to Eigenbrode, lead author of one of the two new Science papers.
“The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter,” said Eigenbrode. “Finding ancient organic molecules in the top five centimetres of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.”
Earlier headlines talking about finding these sorts of complex molecules were soon tempered by reports of possible contamination and experiment-procedural errors. The recent tests have apparently resolved these problems to the satisfaction of the science team in charge.
While such organic compounds could have been produced by ancient life – or could have provided a food source for ancient organisms – it is also possible that the molecules were created in the complete absence of life. “Curiosity has not determined the source of the organic molecules,” explains Eigenbrode.
Apparently barren and devoid of life today, scientists increasingly believe that Mars may have once been a more hospitable environment. Data gathered by Curiosity in 2015 suggested that the Gale Crater was once home to streams and lakes of liquid water. Now, scientists know that some of this water contained molecules that could be associated with life.
Finding methane in the atmosphere and ancient carbon preserved on the surface gives scientists confidence that NASA’s Mars 2020 rover and ESA’s (European Space Agency’s) ExoMars rover will find even more organics, both on the surface and in the shallow subsurface.
These results also inform scientists’ decisions as they work to find answers to questions concerning the possibility of life on Mars.
“Are there signs of life on Mars?” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program, at NASA Headquarters. “We don’t know, but these results tell us we are on the right track.”
TMT Editorial Comment
Meanwhile….back on Comet 67P/Churyumov-Gerasimenko, otherwise known as the Rubber Duck visited by spacecraft Rosetta……..
In a study published on the 1st December 2017 in Monthly Notices of the Royal Astronomical Society, the Rosetta team found that organic molecules make up about half of the dust emitted by Comet 67P. “Rosetta’s comet thus belongs to the most carbon-rich bodies we know in the solar system,” said co-author, MPS scientist and COSIMA team member. Dr. Oliver Stenzel i.
Comet 67P visited by Rosetta. Photo: ESA
“Our analyses show that the composition of all these grains is very similar,” according to MPS researcher Dr. Martin Hilchenbach, Principal Investigator of the COmetary Secondary Ion Mass Analyser (COSIMA) team. They concluded that the comet’s dust consists of the same “ingredients” as the comet’s nucleus and thus can be examined in its place.
As the study showed, organic molecules are among those ingredients at the top of the list. These account for about 45 percent of the weight of the solid cometary material. “Rosetta’s comet thus belongs to the most carbon-rich bodies we know in the solar system,” says Dr. Stenzel.
A previous paper by the COSIMA team also showed that the carbon found in Comet 67P mainly comes in the form of large, organic macro-molecules. After combining the data, it seems that complex organic molecules make up a significant chunk of Comet 67P. Therefore, if comets were responsible for seeding the early Earth with organic matter (as many researchers suggest), then these seeds may have already been somewhat complex by the time they reached Earth.
It follows that, if both Earth and Mars were being bombarded by carbon-rich molecules from meteorites at about the same time in the history of the solar system, then both planets would have had the ingredients for life to have developed as long as conditions on the surface were favourable. As we now know, Mars’ conditions changed to become hostile to life as we know it and ended up as the apparently “lifeless” place we see today.
Our own Milky Way galaxy with between 200 and 400 Billion star system revolving around multiple Black Holes. Photo: NASA
However, and taking the argument back one stage, if Earth and Mars were being struck by molecules with complex organic molecules, then so, presumably, were all the other planets in the system. That being the case, those “Seeds of life” were not formed on a planet as such but by some much older and much more widely spread process. If that is the case, then it is very likely that those processes, and the resultant carbon-rich, complex molecules, have been formed – and are forming – in most of the approximately 200,000,000,000-plus star-systems in our galaxy.
And there are billions of galaxies on the Universe.
That’s quite a thought !
How do they take those “self-portraits” on Mars ?
This low-angle self-portrait of NASA’s Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called “Buckskin” on lower Mount Sharp.
The selfie combines several component images taken by Curiosity’s Mars Hand Lens Imager (MAHLI) on Aug. 5, 2015, during the 1,065th Martian day, or sol, of the rover’s work on Mars. For scale, the rover’s wheels are 20 inches (50 centimeters) in diameter and about 16 inches (40 centimeters) wide. This view is a portion of a larger panorama available at PIA19807.
A close look reveals a small rock stuck onto Curiosity’s left middle wheel (on the right in this head-on view). The rock had been seen previously during periodic monitoring of wheel condition about three weeks earlier, in the MAHLI raw image at http://mars.nasa.gov/msl/multimedia/raw/?rawid=1046MH0002640000400290E01_DXXX&s=1046.
MAHLI is mounted at the end of the rover’s robotic arm. For this self-portrait, the rover team positioned the camera lower in relation to the rover body than for any previous full self-portrait of Curiosity. This yielded a view that includes the rover’s “belly,” as in a partial self-portrait (/catalog/PIA16137) taken about five weeks after Curiosity’s August 2012 landing inside Mars’ Gale Crater.
The selfie at Buckskin does not include the rover’s robotic arm beyond a portion of the upper arm held nearly vertical from the shoulder joint. With the wrist motions and turret rotations used in pointing the camera for the component images, the arm was positioned out of the shot in the frames or portions of frames used in this mosaic. This process was used previously in acquiring and assembling Curiosity self-portraits taken at sample-collection sites “Rocknest” (PIA16468), “John Klein” (PIA16937), “Windjana” (PIA18390) and “Mojave” (PIA19142).
MAHLI was built by Malin Space Science Systems, San Diego. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington. JPL designed and built the project’s Curiosity rover.
More information about Curiosity is online at http://www.nasa.gov