NASA’s Curiosity Rover Discovers New Clues Of How Mars Became Hostile To Life

While NASA searches for signs of life on the Red Planet, its Curiosity rover has found new details about how the ancient Martian climate went from potentially suitable for life, to the inhospitable terrain it’s known as now.

Scientists believe there are signs that early Mars had an abundance of liquid water on its surface, such as features resembling valleys and deltas, and minerals that only form in the presence of liquid water. They also believe billions of years ago, the atmosphere of Mars was much denser and warm enough to form rivers, lakes, and even oceans of water. However, the Red Planet’s surface today is frigid and hostile to life.

One thought as to how the planet transformed was as it cooled and lost its magnetic field, the solar wind and solar storms eroded away to space a significant amount of the planet’s atmosphere, eventually turning the Red Planet into the dusty and cold planet it is today.

Research using instruments on board Curiosity may lend new insights into how the planet’s ancient climate may have dramatically transformed after measuring the isotopic composition of carbon-rich minerals found in Gale crater.

“The isotope values of these carbonates point toward extreme amounts of evaporation, suggesting that these carbonates likely formed in a climate that could only support transient liquid water,” explained David Burtt of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Our samples are not consistent with an ancient environment with life (biosphere) on the surface of Mars, although this does not rule out the possibility of an underground biosphere or a surface biosphere that began and ended before these carbonates formed.”

According to NASA, isotopes are versions of an element with different masses. As water evaporated from the surface of the Red Planet, light versions of carbon and oxygen were more likely to escape into the atmosphere, while heavier versions were left behind, accumulating into higher abundances, and eventually being incorporated into the carbonate rocks found on Mars today. Scientists have an interest in these rocks, because minerals can retain signatures of the environments in which they formed, including things such as the temperature and acidity of the water, and the composition of the water and the atmosphere.

“These formation mechanisms represent two different climate regimes that may present different habitability scenarios,” remarked Jennifer Stern of NASA Goddard, a co-author of a paper on the find. “Wet-dry cycling would indicate alternation between more-habitable and less-habitable environments, while cryogenic temperatures in the mid-latitudes of Mars would indicate a less-habitable environment where most water is locked up in ice and not available for chemistry or biology, and what is there is extremely salty and unpleasant for life.”

While this is not the first time these climate scenarios have been proposed, the result of the new study is the first to add isotopic evidence from rock samples in support of the scenarios.

“The fact that these carbon and oxygen isotope values are higher than anything else measured on Earth or Mars points towards a process (or processes) being taken to an extreme,” remarked Burtt. “While evaporation can cause significant oxygen isotope changes on Earth, the changes measured in this study were two to three times larger. This means two things: 1) there was an extreme degree of evaporation driving these isotope values to be so heavy, and 2) these heavier values were preserved so any processes that would create lighter isotope values must have been significantly smaller in magnitude.”

According to the space agency, the discovery using Curiosity was made using its Sample Analysis at Mars (SAM) and Tunable Laser Spectrometer (TLS). SAM is said to heat samples up to nearly 1,652 degrees Fahrenheit (almost 900 degrees Celsius), and then the TLS is used to analyze the gases that are produced during the heating phase.