Mars Meteorite Found in Desert Suggested Planet Was Habitable 30m Years Later Than Thought

A Martian meteorite discovered in northern Africa has revealed that the Red Planet was impacted by potentially planet-sterilizing asteroids later in its early history than previously believed.

The results, obtained by researchers at Curtin University in Australia, could mean that the planet was habitable later than current estimates suggest by 20-30 million years, meaning the habitability window coincides with the presence of liquid water on Mars.

The team examined the rare sample of Mars surface NWA 7034, nicknamed "black beauty" found in the Western Sahara region in 2011. They discovered evidence in zircon grains that indicate damage that could only be caused by large meteorite strikes.

Ph.D. candidate from Curtin's Space Science and Technology Centre (SSTC) in the School of Earth and Planetary Sciences, Morgan Cox, said in a press release: "This grain is truly a one-off gift from the Red Planet. High-pressure shock deformation has not previously been found in any minerals from Black Beauty.

"This discovery of shock damage in a 4.45-billion-year-old Martian zircon provides new evidence of dynamic processes that affected the surface of early Mars."

Cox is the lead author of a paper documenting the team's findings published in the journal Science.

The shock damage is represented by the sharing of crystal lattice between two separate crystals known as "twinning." This effect, not discovered in Black beauty before, is something that has been found in rock at sites that experienced massive asteroid impacts here on Earth.

This includes samples from the Chicxulub impact in the Yucatán Peninsula in Mexico that occurred around 66 million years ago and wiped out most of the dinosaurs.

Because the zircon in the sample is 4.45 billion years old the shock damage provides evidence that late in its early history the Red Planet was experiencing the kind of asteroid strikes associated with mass extinctions here on Earth.

SSTC researcher and co-author of the paper Aaron Cavosie explains the consequences this has for the habitability of Mars during its relative infancy as these impacts had previously been believed to be in decline on Mars around 4.48 billion years ago.

He said: "Prior studies of zircon in Martian meteorites proposed that conditions suitable for life may have existed by 4.2 billion years ago based on the absence of definitive shock damage.

"Mars remained subject to impact bombardment after this time, on the scale known to cause mass extinctions on Earth."

Cavosie continued by explaining that the zircon uncovered by the team in the 11-ounce meteorite provides evidence of these impacts. It also highlights the possibility that the habitability window may have occurred later than previously thought.

The significance of this is, Cavoise said, that it now perhaps coincides with the evidence of the existence of liquid water on Mars by 3.9 to 3.7 billion years ago.

Space and planetary science researcher at Imperial College London, Sara Motaghian, who was not involved in the study was impressed with the team's findings.

She told Newsweek: "These results are really cool, it's the first instance of shocked zircon from another planet that has been found."

Motaghian, part of a team working on some of the instruments on board the ExoMars 2022 mission, which is designed to find signs of past or present life on Mars, continued: "Meteorites with evidence of these really high shock levels tell us that large scale impact cratering has gone on.

"So for NWA 7034 and Mars, it has gone on longer than we previously thought.
And that has a knock-on effect on when life might have been able to emerge as heavy bombardment can affect the ability of life to develop."

Motaghian added that these results help researchers like herself narrow down the potential window of habitability on Mars by about 20 million years and revisit how the interplay of cratering and life evolving might occur.

She concluded: "So in future locations for missions can be selected to better investigate the surfaces with the most suitable age ranges and conditions and with the highest chance of finding life. "