The chances of early life on Mars faced a meteorite problem

Craters on Mars (between Acidalia Planitia and Tempe Terra) show evidence of past meteorite crashes on the Red Planet.
(Image credit: ESA/DLR/FU Berlin (G. Neukum))

Early chances for life on Mars might have been diminished by meteorites.

A new study suggests that a period of heavy cratering on the Red Planet (and elsewhere in the solar system) persisted 30 million years longer than thought. Studies of the Late Heavy Bombardment, as this period is called, also has implications for the rise of life on Earth.

The new study is largely based upon a meteorite known as Northwest Africa (NWA) 7034, nicknamed "Black Beauty." The meteorite includes part of the ancient crust of Mars during the period considered for study, which is nearly 4.5 billion years ago.

Related: Scientists spot water ice under the 'Grand Canyon' of Mars

A fresh look at the meteorite (first found in 2013) found signs of "shocking", or very high-intensity damage during a meteorite impact. A proxy of such shocking is an element called zircon, which only occurs during the largest and most powerful meteorite impacts.

"The type of shock damage in the Martian zircon ... has been reported from all of the biggest impact sites on Earth, including the one in Mexico that killed off the dinosaurs, as well as the moon, but not previously from Mars," study lead author Morgan Cox, a Ph.D. candidate at Curtin University in Australia, said in a statement.

The interiors of zircons are visualized using an specialized electron microscope.

(Image credit: Michael Ackerson/Smithsonian)

Black Beauty is about 4.45 billion years old, which has larger implications for the rise of life on Mars. Previously, a majority of studies suggested that large meteorite impacts on Mars ceased 30 million years before that period, or roughly 4.85 billion years ago.

Early Mars was considered a warmer and wetter environment, with a thicker atmosphere that may have allowed life to persist on the surface. Over the eons, however, the Red Planet lost most of its atmosphere and today is very arid. 

The amount of water available on the surface or underground today is highly debated; a study released just weeks ago, for example, suggests that a purported polar underground water reserve may just be volcanic rock. Meanwhile, an independent study of NASA Mars Reconnaissance Orbiter images suggests water may have persisted on the surface longer than previously suggested.

Artist's illustration of a Mars with Earth-like surface water. The Red Planet was a wet world in the ancient past.

An artist's illustration of a Mars with Earth-like surface water. The Red Planet was a wet world in the ancient past. (Image credit: NASA Earth Observatory/Joshua Stevens; NOAA National Environmental Satellite, Data, and Information Service; NASA/JPL-Caltech/USGS; Graphic design by Sean Garcia/Washington University)

Water is one metric that might suggest a life-friendly environment, but meteorites would also be important. If an area is continually pummeled by space rocks, that provides a less stable spot for microbes to persist.

"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," co-author and planetary scientist Aaron Cavosie, who is also from Curtin, said in the same statement.

"Mars remained subject to impact bombardment after this time, on the scale known to cause mass extinctions on Earth. The zircon we describe provides evidence of such impacts, and highlights the possibility that the habitability window may have occurred later than previously thought, perhaps coinciding with evidence for liquid water on Mars by 3.9 to 3.7 billion years ago."

It is likely that other Martian meteorites will need to be examined or re-examined for evidence of zircon, in an effort to further support the findings, however. A study based on the research was published in Science Advances on Wednesday (Feb. 2).

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: