February 4, 2012
Mars Has Been Suffering Through 600 Million Year Drought
According to new research, Mars may have been arid for over 600 million years, making it inhospitable for life to survive.
Researchers spent three years analyzing data on Martian soil that was collected during the 2008 NASA Phoenix mission to Mars.Phoenix touched down in the northern arctic region of the Red Planet to look for signs that it was habitable to support life by analyzing ice and soil on the surface.
They found that the surface of Mars has been arid for hundreds of millions of years, despite the presence of ice and the fact that previous research has shown that the planet may have had a warmer and wetter period in its earlier history 3 billion years ago.
The team also believes the soil on Mars had been exposed to liquid water for at the most, 5,000 years ago since its formation billions of years ago.
Satellite images and previous studies show that the soil on Mars is uniform across the planet, suggesting that the results from the team's analysis applies to all of Mars.
"We found that even though there is an abundance of ice, Mars has been experiencing a super-drought that may well have lasted hundreds of millions of years," Dr Pike, from the Department of Electrical and Electronic Engineering at Imperial and lead author on the study, said in a press release.
"We think the Mars we know today contrasts sharply with its earlier history, which had warmer and wetter periods and which may have been more suited to life. Future NASA and ESA missions that are planned for Mars will have to dig deeper to search for evidence of life, which may still be taking refuge underground."
The scientists formed one of 24 teams based at mission control in the University of Arizona, operating part of the spacecraft's onboard laboratories.
By using an optical microscope to produce images of larger sand-sized particles of soil samples dug up by a robot arm, they were able to produce 3D images of the surface of particles as small as 100 microns.
The team has been cataloging individuals particles sizes to understand more about the history of the Martian soil.
They looked for microscopic clay particles in the study that are formed when rock is broken down by water. These particles are an important marker of contact between liquid and water and the soil.
The researchers calculated that even if the few particles they saw in this size range were clay, they made up less than 0.1 percent of the total proportion of the soil in the samples.
Clay on Earth can make up 50 percent or more of the soil content, so such a small portion on Mars suggests that the soil has had a very arid history.
The team estimated that the soil they were analyzing had only been exposed to liquid water for a maximum of 5,000 years by comparing their data with the slowest rate that clays could form on Earth.
They also found evidence to support the idea that the soil on Mars has been largely dry throughout its history by comparing soil data from Mars, Earth and the Moon.
They concluded that the soil was being formed in a similar way on Mars and the Moon because they were able to match the distribution of soil particle sizes.
On Mars, they determined that physical weathering by the wind and meteorites breaks down the soil into smaller particles.
On the Moon, they found that meteorite impacts break down rocks into soil, because there is no liquid water or atmosphere to wear the particles down.
The study was published in the journal Geophysical Research Letters.
Image Caption: This is a false color image of the Martian terrain and rock called "Winkies" (rock "Quadlings" in foreground) taken by the Surface Stereo Imager camera on NASA's Phoenix Mars Lander on Sol 151 of the mission (Oct. 27, 2008). This frosty image is among the last taken by the lander before the mission's final communications on Nov. 2, 2008. Image NASA/JPL-Caltech/University of Arizona/Texas A&M University
On the Net:
- Imperial College London
- European Space Agency (ESA)
- Dr Tom Pike
- Geophysical Research Letters
- Phoenix mission
- University of Arizona