Q&BA: How do we know some meteorites come from Mars?

By Phil Plait | October 2, 2012 10:34 am

This Q&BA video’s a bit longer than usual, but what the heck. It’s a fun topic!

First: every now again when I have time I do an interactive live video chat on Google+ where people can ask me questions about space and astronomy. I call it Q&BA, and it’s always fun to hear what questions are on people’s minds.

In this episode of Q&BA, I was asked about Mars meteorites: how do they get to Earth? I talk about their transport mechanism, as well as how they get blasted of the surface of Mars, and how we know they come from the Red Planet at all. It’s a pretty common question, and a pretty cool little slice of science.

[Note: I was having software issues when I recorded this on a Google+ Hangout in January 2012, and the aspect ratio is a bit wonky.]

So there you go. I’ve seen a few Mars meteorites, and they’re pretty nifty. One of these days I’ll have to see about getting one to add to my collection of iron and stony meteorites, too. It’s be nice to have a chunk of actual planet that’s not Earth sitting on my display shelf.

I have an archive of Q&BA links and videos. Take a look and see if there are other ones that tickle your imagination.


Related Posts:

- Q&BA: Can we build a space habitat?
- Q&BA: The Science of Science Fiction
- Q&BA: Which moon has the best chance for life?
- Q&BA: Why spend money on NASA?
- Q&BA: What happens if you are exposed to the vacuum of space?

CATEGORIZED UNDER: Astronomy, Q & BA, Science

Comments (10)

  1. Keith Hearn

    So the rock was formed billions of yeas ago, and was ejected from Mars millions of years ago. When was the gas encapsulated? Wouldn’t this give us a snapshot of what Mars’ atmosphere was like back then? Seems like it would help answer questions about how Mars evolved if we could get decent time estimates for how old these samples are.

  2. Chris

    @1 Keith

    The gas would have had to be encapsulated when that rock was molten, so either when the rock was coming out of the Martian volcano, or perhaps when it got wacked by the asteroid. They aren’t just looking at what gases are present, but also the isotopic composition. I’m sure they could use Uranium dating (or some other long lived radio-isotope) to determine how old the Martian meteorites actually are.

    Here’s an interesting reference http://seismo.berkeley.edu/~manga/nyquist.pdf

  3. Nigel Depledge

    The chances of anything coming from Mars are a million to one, he said . . .

  4. Jonathan

    What are the odds of a piece of Earth ending up on Mars? I suppose the terminal velocity of a rock in Earth’s atmosphere is much lower, but at the same time, the energy imparted by an impact of a rock large enough to form a large crater would be pretty significant. This is a large rock that fell from space, so it seems like it generally could impart enough energy to propel a smaller rock back into space.

  5. Brian

    Our gravity well would require more energy to escape, plus our atmosphere is like a 100 times denser than Mars’, so it would have a lot more energy loss due to friction. My guess is that a rock powerful enough to liberate a piece of Earth would be pretty unpleasant for us. Then again, we know that we’ve had several very unpleasant impact events in our past, so maybe there are pieces of Earth out there.

    Finally, it’s a lower probability for something to make its way to Mars, just because it has such a greater volume of space in its orbit (along with a smaller gravity well).

  6. Hainish

    I have always wondered why some scientists are so eager to get a sample return from Mars if the specimen are delivered to us free of charge. You can even buy them on the web:
    http://www.meteorites-for-sale.com/mars-boxes.html

  7. amphiox

    re #6;

    Because that way we get to know the providence of the sample, ie where on mars it came from, and out of what local geological conditions.

  8. Jeanette

    :) I have a few teeny tiny fragments of Martian Meteorite that I bought from Galactic Stone. (look him up on the web ) :)
    It blows me away, the fact that I’ve actually touched part of Mars. :)

  9. Matt B.

    @3 Nigel – “Million-to-one shots are a dime a dozen.” –Terry Pratchett

  10. Can some body tell me who to contact if you see a meteor fall? My brother and I were fishing the other night and we seen this meteor flying south to north. It was so close you could hear it sizzling like frying bacon. It broke into three large pieces and a few smaller ones. The delay in the sight and sound made it about 1/2 to 1 mile away. It hit the hills across from us about 2 miles away. Nothing to burn in the desert, so there was no fire. But it was sure neat to see.

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