NASA and SpaceX scientists have found a former lake bed on Mars which would have provided stable conditions for a number of different types of alien life to have developed.
The long-lasting lake had environmental conditions differed significantly from one part of the lake to another, according to a study of the findings from the first three-and-a-half years of NASA’s Curiosity rover mission.
The rover is a 4WD droid exploring the planet remotely and taking samples of the surface for any sign of alien life.
A NASA spokesman said: “Different conditions favourable for different types of microbes existed simultaneously in the same lake.”
Previous work had revealed the presence of a lake more than three billion years ago in Mars’ Gale Crater.
This study defines the chemical conditions that existed in the lake and uses Curiosity’s powerful payload to determine that the lake was stratified.
Stratified bodies of water exhibit sharp chemical or physical differences between deep water and shallow water.
In Gale’s lake, the shallow water was richer in oxidants than deeper water was.
Joel Hurowitz of Stony Brook University, Stony Brook, New York, lead author of a report of the findings in the June 2 edition of the journal Science, said: “These were very different, co-existing environments in the same lake.
“This type of oxidant stratification is a common feature of lakes on Earth, and now we’ve found it on Mars.
“The diversity of environments in this Martian lake would have provided multiple opportunities for different types of microbes to survive, including those that thrive in oxidant-rich conditions, those that thrive in oxidant-poor conditions, and those that inhabit the interface between those settings.”
Although significant, whether Mars has ever hosted any life is still unknown.
Curiosity’s primary goal when it landed inside Gale Crater in 2012 was to determine whether Mars has ever offered environmental conditions favourable for microbial life.
In its first year, on the crater floor at “Yellowknife Bay,” the rover found evidence of ancient freshwater river and lake environments with all the main chemical ingredients, as well as a possible energy source, for life.
Curiosity has since driven to the base of Mount Sharp, a layered mountain inside the crater and inspected rock layers which grow progressively younger as the rover gains elevation on lower Mount Sharp.
Mr Hurowitz said: “We could tell something was going on.
“What was causing iron minerals to be one flavour in one part of the lake and another flavour in another part of the lake?
“We had an ‘Aha!’ moment when we realised that the mineral information and the bedding-thickness information mapped perfectly onto each other in a way you would expect from a stratified lake with a chemical boundary between shallow water and deeper water.”
In addition to revealing new information about chemical conditions within the lake, the report by Hurowitz and 22 co-authors also documents fluctuations in the climate of ancient Mars.
One such change happened between the time crater-floor rocks were deposited and the time the rocks that now make up the base of Mount Sharp were deposited.
Those later rocks are exposed at “Pahrump Hills” and elsewhere.
Curiosity Project Scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory, Pasadena, California, said: “These results give us unprecedented detail in answering questions about ancient environmental conditions on Mars.
“I’m struck by how these fascinating conclusions on habitability and climate took everything the mission had to offer: a set of sophisticated science instruments, multiple years and miles of exploration, a landing site that retained a record of the ancient environment, and a lot of hard work by the mission team.”
In mid-2017, Curiosity is continuing to reach higher and younger layers of Mount Sharp to study how the ancient lake environment evolved to a drier environment more like modern Mars.