Out of the thousands of meteorites found on Earth, around 188 have been confirmed to have come from Mars. So how did they get here? When asteroids hit Mars with enough force, the debris is blasted into space and eventually finds its way to Earth.
While astronomers once believed only the most powerful impacts could throw rocks from Mars into space, new research suggests it takes much less pressure than previously thought. This means there may be more Mars meteorites floating in space and on their way to Earth than we thought.
A team of planetary scientists from Caltech used a powerful blast gun to simulate an impact on Mars. To avoid using any of the limited and precious supply of Mars meteorites, they used rocks from Earth containing plagioclase, a major component of Martian rocks. Under high pressures, such as an asteroid impact, plagioclase transforms into the glassy material known as maskelynite. Finding maskelynite in a rock indicates the types of pressure the sample came into contact with.
New Research Findings
The scientists found that it takes much less pressure to launch a Mars meteorite than previously thought. Previous experiments showed 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 experiences diving beneath 3 kilometers of ocean water.
With the new and improved blast gun, the recent study showed that the transition actually happens at around 20 GPa, a significant difference from previous experiments. This research helps us identify the impact crater on Mars from which meteorites originated.
This study follows a paper published last year that pinpointed the origins of the “Black Beauty” meteorite from Mars to the Terra Cimmeria – Sirenum region on the Red Planet. Martian meteorites can be traced back to Mars because they contain pockets of trapped gas that match data from missions to Mars.
This new research is important because it not only helps us understand how Mars meteorites get to Earth, but it also sheds light on how we can identify the impact craters on Mars where the meteorites originated.