It’s one of the most profound questions in science – did life ever exist on Mars?
Now, experts have unearthed evidence that the Red Planet was once habitable.
Scientists have found carbon residue in Martian rocks, indicating that an ancient carbon cycle existed.
And it means the Red Planet was likely once warm enough to sustain life.
Researchers have long believed that, billions of years ago, Mars had a thick, carbon dioxide-rich atmosphere with liquid water on its surface.
This carbon dioxide and water should have reacted with rocks to create carbonate minerals.
However, rover missions and analysis from satellites so far haven’t detected the amounts of carbonate on the planet’s surface predicted by this theory.
But that’s all just changed, thanks to data collected by NASA’s Curiosity Mars rover.
The NASA Curiosity rover (pictured) found large deposits of a carbon-rich mineral on Mars. Here, it can be seen exploring the Red Planet’s surface
NASA’s Curiosity Mars rover sees its tracks receding into the distance at the ‘Ubajara’ site. This site is where the rover made the discovery of siderite, a mineral that may help explain the fate of the planet’s thicker ancient atmosphere
Information recovered from three drill sites reveals the presence of siderite, an iron carbonate mineral.
It was picked up within the sulfate-rich rocky layers of Mount Sharp in Mars’ Gale Crater.
‘The discovery of abundant siderite in Gale Crater represents both a surprising and important breakthrough in our understanding of the geologic and atmospheric evolution of Mars,’ said Benjamin Tutolo, associate professor at the University of Calgary and lead author of the paper.
To study the Red Planet’s chemical and mineral makeup, Curiosity drills three to four centimetres down into the subsurface then drops the powdered rock samples into its CheMin instrument, which uses X-ray diffraction to analyse rocks and soil.
‘Drilling through the layered Martian surface is like going through a history book,’ said Thomas Bristow, research scientist at NASA Ames and coauthor of the paper.
‘Just a few centimetres down gives us a good idea of the minerals that formed at or close to the surface around 3.5 billion years ago.’
The discovery of carbonate suggests that the atmosphere contained enough carbon dioxide to support liquid water existing on the planet’s surface.
Carbon is vital for life on Earth because it’s the fundamental building block of all living organisms, forming the basis of their molecules, including DNA, proteins, and carbohydrates.
NASA’s Curiosity rover has collected 42 powderised rock samples with the drill on the end of its robotic arm
Mars is called the Red Planet primarily due to the presence of iron oxide, or rust, on its surface. Experts say the new findings suggest it was likely once warm enough to sustain life
It also regulates the planet’s temperature.
As the atmosphere thinned – which is thought to have happened around 4 billion years ago – the carbon dioxide transformed into rock form.
‘The abundance of highly soluble salts in these rocks and similar deposits mapped over much of Mars has been used as evidence of the ‘great drying’ of Mars during its dramatic shift from a warm and wet early Mars to its current, cold and dry state,’ Dr Tutolo added.
‘It tells us that the planet was habitable and that the models for habitability are correct.
‘The broader implications are the planet was habitable up until this time, but then, as the CO2 that had been warming the planet started to precipitate as siderite, it likely impacted Mars’ ability to stay warm.’
He said it’s clear that small changes in atmospheric CO2 can lead to huge changes in the ability of the planet to harbour life.
‘The most remarkable thing about Earth is that it’s habitable and it has been for at least four billion years,’ he added.
‘Something happened to Mars that didn’t happen to Earth.’
NASA’s Curiosity rover landed on Mars on August 5, 2012, and has travelled more than 20 miles (34 kilometres) on the Martian surface.
The findings were published in the journal Science.
THE NASA MARS CURIOSITY ROVER LAUNCHED IN 2011 AND HAS IMPROVED OUR UNDERSTANDING OF THE RED PLANET
The Mars Curiosity rover was initially launched from Cape Canaveral, an American Air Force station in Florida on November 26, 2011.
After embarking on a 350 million mile (560 million km) journey, the £1.8 billion ($2.5 billion) research vehicle touched down only 1.5 miles (2.4 km) away from the earmarked landing spot.
After a successful landing on August 5th, 2012, the rover has travelled about 11 miles (18 km).
It launched on the Mars Science Laboratory (MSL) spacecraft and the rover constituted 23 per cent of the mass of the total mission.
With 80 kg (180 lb) of scientific instruments on board, the rover weighs a total of 899 kg (1,982 lb) and is powered by a plutonium fuel source.
The rover is 2.9 metres (9.5 ft) long by 2.7 metres (8.9 ft) wide by 2.2 metres (7.2 ft) in height.
The Mars curiosity rover was initially intended to be a two-year mission to gather information to help answer if the planet could support life, has liquid water, study the climate and the geology of Mars an has since been active for more than 3,700 sols
The rover was initially intended to be a two-year mission to gather information to help answer if the planet could support life, has liquid water, study the climate and the geology of Mars.
Due to its success, the mission has been extended indefinitely and has now been active for over 3,700 sols.
The rover has several scientific instruments on board, including the mastcam which consists of two cameras and can take high-resolution images and videos in real colour.
So far on the journey of the car-sized robot it has encountered an ancient streambed where liquid water used to flow, not long after it also discovered that billions of years ago, a nearby area known as Yellowknife Bay was part of a lake that could have supported microbial life.
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