AN American mission to Mars will focus on three key areas where alien life may once have thrived and gather samples to be returned to Earth, scientists have been told.
The Mars 2020 mission will launch a rover to the Red Planet in three years’ time to look for chemical relics of Martian bugs.
ExoMars Rover, a European mission also launching in 2020, will use similar techniques to search for life biosignatures.
The Nasa craft will also collect 30 to 40 rock samples and seal them in titanium tubes on the Martian surface for future retrieval.
Deputy project scientist Dr Ken Williford said: “Our objective is to collect a diverse set of samples from our landing site with the best potential to preserve records of the evolution of Mars — including the presence of life if it was there.”
The first landing site for Mars 2020 will be at Columbia Hills in Gusev crater. It was previously visited by the Nasa Spirit rover and features silica deposits thought to be evidence of hydrothermal springs, which on Earth are havens for life.
The two other sites are located on the edge of Isidis Planitia, one of the solar system’s largest craters.
Northeast Syrtis contains ancient exposed Martian crust that bears signs of alteration in the presence of liquid water. Scientists believe the site could have hosted sub-surface life. The remaining site, Jezero crater, is thought to be the location of an ancient river delta and lake which could have been a prime spot for living organisms.
Williford added: “We’ve got some hard decisions in front of us.
“Because of the possibility of sample return, the selected site could have an outsized impact on the future of Mars science, compared to a typical mission.”
Meanwhile, new evidence suggests as ice age known as Snowball Earth triggered the development of complex life 650 million years ago.
Glaciers covered the planet and pounded entire mountain ranges to powder, releasing life-sustaining nutrients, scientists believe.
When the snow and ice finally melted, the nutrients were washed into the oceans to fuel the rapid development of algae. The primitive plant organisms marked the transition from aeons of bacterial life to complex ecology and multitudes of animal species, without which humans might never have existed on Earth.
Scientists say they have solved the mystery of how complex life first appeared after analysing ancient sedimentary rocks from central Australia. Dr Jochen Brocks, from the Australian National University, said: “We crushed the rocks to powder and extracted molecules of ancient organisms. This told us things really became very interesting 650 million years ago. It was an ecosystems revolution.”
Scientists linked the change to a destiny-shaping event 50 million years earlier when virtually the entire planet was covered in glaciers and ice sheets. The Snowball Earth theory is controversial, but has been supported by the discovery of glacial deposits in tropical regions.
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