As the first of three landers to land on the moon, the Mars Reconnaissance Orbiter was designed to find signs of life.
But now, it has also found something that it thinks might be the key to understanding the planet’s past.
It is an ancient crater that is now filled with a mysterious liquid that can be seen only through a special telescope.
As part of the Mars Science Laboratory (MSL) mission, the rover is set to fly by the crater on Wednesday to search for traces of life that could help the search for ancient microbial life on the Red Planet.
But in the meantime, a group of scientists are exploring the liquid to try and see if they can find any traces of water or minerals.
“We think we can find traces of minerals that could be present on Mars,” said Dr Peter Smith, a researcher with the Australian Space Agency (AUSA) at the Jet Propulsion Laboratory (JPL) in Pasadena, California.
“The fact that it is so small and so remote from the planet, we think we could probably find a mineral there.”
“What you see is just the tip of the iceberg” The liquid, which is composed of methane and ethane, is so cold that it does not react with oxygen and water to form carbon dioxide, the main component of water.
This means that the liquid is mostly water and carbon dioxide and could have been produced during an impact with the surface of Mars, or by ancient microbes.
The presence of a liquid in a crater is not the only indication of ancient microbial activity.
“What we are finding is a kind of liquid,” said lead author of a paper published in the journal Nature Geoscience, Dr David Pemberton, a postdoctoral fellow at the University of Melbourne in Australia.
“This is a very old liquid that is not very hot and does not have any oxygen and has a very high pH level.”
This means it is likely to be a very stable liquid, meaning that it could be preserved in situ for billions of years without decomposing.
“There is no sign of microbial life or any trace of organic material on it,” Dr Pemberthton said.
“So we are looking for signs of organic molecules.”
“This liquid is composed mostly of methane, which means it has a pH level that is much lower than water and a very low oxygen content, so it is a relatively stable liquid.”
However, the presence of traces of carbon dioxide on the surface is not a conclusive sign of life, as the amount of carbon is so low that the carbon dioxide could not have formed on the crater floor.
In addition, the water on the ground has also been detected by the rover, which could also be indicative of an ancient organic source.
The researchers also noted that the material is very similar to the organic material found on Mars that would have been deposited by an impactor.
“As we are not looking for life, the carbon is not really indicative of life,” Dr Smith said.
However, Dr Piverton and Dr Smith added that it was important to keep an open mind about what they are seeing.
“In a sense, it’s just the bottom of the ocean of things we’re looking for,” Dr Martin Koopmans, an associate professor at the Australian National University (ANU) at Canberra, said.
If the liquid has a carbon-rich surface, the organic molecules may have come from a source in the ocean.
“That would be interesting,” he said.
It could be that there was some water and the organic molecule was washed away from the surface, or that it just happened to be in the right spot to attract the organic water.
However if the organic source is not there, it is unlikely that the organic chemical signature is indicative of ancient microbes, which are considered a threat to the planet.
“You can have organic chemistry in the subsurface, but if it’s not in the atmosphere, then that’s where the threat comes in,” Dr Koopman said.
In other words, organic chemicals can easily be deposited by microbes, but it is not clear whether there is a large enough microbial population on Mars to be able to support life.
“If there’s a large amount of organic chemistry on Mars, then you could potentially have an atmosphere with that organic chemistry,” Dr Bong Nguyen, a planetary scientist at the ANU, said in a statement.
“But there is so much to understand about Mars that we don’t really know what we’re going to find.”
However if there is evidence of microbial activity, the researchers could potentially use this evidence to help with future Mars missions.
“I think this is a great example of the power of science, which can actually be applied to Mars,” Dr Nguyen said.
Read more about the Mars rover mission, including what it is looking for, how it is designed, and where it is headed, here.
Follow Al Jazeera’s coverage of the landing