'Curiosity' exposes low CO2 level in Mars' primitive atmosphere

February 06, 2017

The CO2 level in Mars' primitive atmosphere 3.5 billion years ago was too low for sediments, such as those found by NASA's Curiosity exploration vehicle in areas like the Gale Crater on the planet's equator, to be deposited. This and other conclusions are drawn from a paper written with the participation of researchers from the Spanish National Research Council (CSIC) and published in the latest issue of the journal, Proceedings of the National Academy of Sciences (PNAS).

The area Curiosity has been analysing since 2012, as part of NASA's Mars Science Laboratory mission, is composed primarily of sedimentary sequences deposited at the bottom of a lake 3.5 billion years ago. These sediments contain various secondary minerals, such as clays or sulphates, which indicate that the primitive surface was in contact with liquid water.

The existence of liquid water requires a warm surface temperature brought about by a minimum content of CO2 in the atmosphere. Yet this was not the case with Mars in its beginnings. "This contradiction has two possible solutions. Either we have not yet developed climatic models which explain the environmental conditions on Mars at the beginning of its history, or the Gale sedimentary sequences really did form in a very cold climate", explains CSIC researcher Alberto Fairén, who works at the Centre for Astrobiology near Madrid (a joint centre run by CSIC and Spain's National Institute of Aerospace Technology).

A very cold environment

"However, the rover has not found carbonates, thereby confirming the results of studies by all previous probes: carbonates are very scarce on the surface of Mars and, therefore, the CO2 level in the atmosphere was very low", adds. Fairén.

Specifically, the direct analysis of samples on the surface of Mars carried out by these researchers shows that the level of CO2 in the atmosphere at the time the Gale Crater sediments were deposited was between 10 and 100 times less than the minimum required for the surface temperature to be above the freezing point of the liquid water.

On Earth, carbonate deposits form on lake and sea beds when CO2 in the atmosphere interacts with liquid water. Carbon dioxide is a gas capable of generating a powerful 'greenhouse effect' and, therefore, of heating the planet.

According to the scientists, an image that maybe would describe Gale in the early days of Mars would be that of a glacial lake, surrounded by huge masses of ice, which would be partially or seasonally frozen. "The environment would have been similar to the Canadian Arctic or to Greenland today," says the CSIC researcher.

In addition, although ice would have dominated, it would also have been common to find liquid water present in abundance. The formation of clays and sulphates would have occurred at specific places and times, seasonally, or under an ice cap in liquid water lakes.
-end-


Spanish National Research Council (CSIC)

Related Mars Articles from Brightsurf:

Water on ancient Mars
A meteorite that originated on Mars billions of years ago reveals details of ancient impact events on the red planet.

Surprise on Mars
NASA's InSight mission provides data from the surface of Mars.

Going nuclear on the moon and Mars
It might sound like science fiction, but scientists are preparing to build colonies on the moon and, eventually, Mars.

Mars: Where mud flows like lava
An international research team including recreated martian conditions in a low-pressure chamber to observe the flow of mud.

What's Mars made of?
Earth-based experiments on iron-sulfur alloys thought to comprise the core of Mars reveal details about the planet's seismic properties for the first time.

The seismicity of Mars
Fifteen months after the successful landing of the NASA InSight mission on Mars, first scientific analyses of ETH Zurich researchers and their partners reveal that the planet is seismically active.

Journey to the center of Mars
While InSight's seismometer has been patiently waiting for the next big marsquake to illuminate its interior and define its crust-mantle-core structure, two scientists, have built a new compositional model for Mars.

Getting mac and cheese to Mars
Washington State University scientists have developed a way to triple the shelf life of ready-to-eat macaroni and cheese, a development that could have benefits for everything from space travel to military use.

Life on Mars?
Researchers from Hungary have discovered embedded organic material in a Martian meteorite found in the late 1970s.

New evidence of deep groundwater on Mars
Researchers at the USC Arid Climate and Water Research Center (AWARE) have published a study that suggests deep groundwater could still be active on Mars and could originate surface streams in some near-equatorial areas on Mars.

Read More: Mars News and Mars Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.