How do we know meteorites have landed on Earth from Mars?

13 December 2016

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Question

Just listened to a man from NASA say meteorites have landed on Earth from Mars.

This provoked a few questions:
How to we know it was from Mars? How did it get here.... More importantly, how did it achieve escape velocity from Mars?

Answer

We asked Kerstin Goepfrich Mike's burning question... Kerstin - Yes, we do actually have meteorites here from Mars, even though it is only a small fraction of the meteorites we find on Earth. We've found about 60 thousand meteorites and only just over a hundred of them have come from Mars. And we know they have come from Mars because we have Mars rovers which collected samples from the atmosphere from Mars, and these gases, they have been found enclosed in the meteorites we have found here on Earth. And they can escape the gravity of Mars by being hit by an asteroid that sort of knocks out a meteorite from Mars.

Chris - So something big slams into Mars, ejects material off the surface of Mars, which happens to have trapped in it tiny bubbles of martian atmosphere. Delivers the meteorite over time to Earth and, obviously, because we've got these rovers out there and we know what the Mars atmosphere is made of we can compare the two and say that must have come from Mars?

Kirsten - Precisely.

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