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

By: JJ Smith

JJ Smith — Fri, 05 Oct 2012 03:03:29 +0000

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.

By: Matt B.

Matt B. — Thu, 04 Oct 2012 22:49:57 +0000

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

By: Jeanette

Jeanette — Thu, 04 Oct 2012 04:35:25 +0000

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.

By: amphiox

amphiox — Thu, 04 Oct 2012 00:48:27 +0000

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.

By: Hainish

Hainish — Wed, 03 Oct 2012 20:50:07 +0000

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

By: Brian

Brian — Wed, 03 Oct 2012 20:21:43 +0000

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).

By: Jonathan

Jonathan — Wed, 03 Oct 2012 16:18:59 +0000

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.

By: Nigel Depledge

Nigel Depledge — Wed, 03 Oct 2012 12:12:10 +0000

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

By: Chris

Chris — Tue, 02 Oct 2012 18:14:59 +0000

@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

By: Keith Hearn

Keith Hearn — Tue, 02 Oct 2012 17:17:54 +0000

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.