Almost 200 Fragments of Mars Made It All The Way to Earth. But How?

Almost 200 Fragments of Mars Made It All The Way to Earth. But How?
SPACE
05 May 2023
ByNANCY ATKINSON, UNIVERSE TODAY

Artist's impression of Earth viewed from Mars, not to scale.
(Ales_Utovko/iStock/Getty Images Plus)
Of the thousands of meteorites found on Earth, about 188 have been
confirmed to be from Mars. How did they get here?

Over the tumultuous history of our Solar System, asteroids have smashed
into Mars with such force, the debris was blasted into space and then
drifted through space, eventually entering the Earth's atmosphere, and
surviving the journey to the ground.

Astronomers once thought it was a complex process, with only the most
powerful impacts capable of throwing rocks from Mars into space. But new
research shows that it takes much less pressure than previously
believed, which means there could be more chunks of Mars floating in
space and on their way to Earth.

Black sharp rock with lighter details.
A Martian meteorite, designated Northwest Africa (NWA) 7034 and
nicknamed "Black Beauty," weighing approximately 11 ounces. (NASA)
A team of planetary scientists from Caltech used a new and powerful
blast gun to simulate an impact on Mars. So not to harm any of the
limited and precious supply of Mars meteorites, they used rocks from
Earth containing plagioclase, which is a major component of Martian rocks.

Under high pressures, such as an asteroid impact, plagioclase transforms
into the glassy material known as maskelynite. According to the
researchers, finding maskelynite in a rock indicates the types of
pressure the sample came into contact with.

"We're not on Mars, so we can't watch a meteorite strike in person,"
says Yang Liu, a planetary scientist at JPL and a co-author on the
study. "But we can recreate a similar kind of impact in a lab setting.
By doing so, we found it takes much less pressure to launch a Mars
meteorite than we thought."

Liu and Caltech professor Paul Asimow said that previous experiments had
shown that plagioclase turns into maskelynite at a shock pressure of 30
gigapascals (GPa), which is 300,000 times the atmospheric pressure
experienced at sea level, or 1,000 times the pressure a submersible
comes into contact with while diving beneath 3 kilometers of ocean water.

Smooth warm grey rock with carved out random pale patches.
Meteorite Elephant Moraine 79001, also known as EETA 79001, was found in
Antarctica. (NASA)
But with the new and improved blast gun, this new study showed that the
transition actually happens at around 20 GPa – a significant difference
from previous experiments.

"It has been a significant challenge to model an impact that can launch
intact rocks from Mars while shocking them to 30 GPa," Asimow said in a
press release.

"In this context, the difference between 30 GPa and 20 GPa is
significant. The more accurately we can characterize the shock pressures
experienced by a meteorite, the more likely it becomes that we can
identify the impact crater on Mars from which it originated."

This new research follows a paper published last year that was able to
pinpoint the origins of the "Black Beauty" meteorite from Mars (pictured
above), as from an impact crater in the Terra Cimmeria – Sirenum region
on the Red Planet.

How do we know these meteorites are from Mars? Martian meteorites can be
traced to the Red Planet because they contain pockets of trapped gas
that matches data from missions to Mars.

In particular, an experiment performed by the two NASA Viking spacecraft
that landed on Mars in 1976 measured the amounts of different gases in
the thin Martian atmosphere. Those same gases were then found in 1983
trapped within shock glass veins and pockets in a meteorite called
Elephant Moraine 79001, and now in other meteorites, as well.

The new research was published in Science Advances.

This article was originally published by Universe Today. Read the
original article.