by aichip » Sat Jul 22, 2006 2:21 pm
There are a number of mechanism for getting a meteor of a planet the size of Mars. Most center around a large impact. In some cases, the impact might directly knock material into space, in others it might actually create a shock wave that can travel through the planet, where it is focused (almost like a lens) as it reaches the other side of the planet. Rock is then thrown off in a process called spalling.
Of course, it would take a huge impact, but in theory it is possible.
Now, how do they know if a meteorite is from Mars? First, the chemistry of a meteorite is a clue. We have a lot of information about what Mars is made of and we have found meteorites that match that chemistry. But that is only part of the story.
Next, they look for trapped bubbles of gas in the meteorite and test them to see if they match the Martian atmosphere's chemistry. If they do, then you have a good candidate for a meteorite from Mars.
Then the outside of the meteorite is checked for cosmic ray trails. This tells you how long it was in space. And, analysis of the isotopes can also be used to help confirm or refute the idea it is from Mars.
If the meteorite matches the chemistry, isotope ratios, atmospheric gas, and shows that it has been in space for a few million years, then it is almost certainly a Martian rock. After all, there are only a few terrestrial planets in our solar system, and that helps us a lot by narrowing things down.
There are a number of mechanism for getting a meteor of a planet the size of Mars. Most center around a large impact. In some cases, the impact might directly knock material into space, in others it might actually create a shock wave that can travel through the planet, where it is focused (almost like a lens) as it reaches the other side of the planet. Rock is then thrown off in a process called spalling.
Of course, it would take a huge impact, but in theory it is possible.
Now, how do they know if a meteorite is from Mars? First, the chemistry of a meteorite is a clue. We have a lot of information about what Mars is made of and we have found meteorites that match that chemistry. But that is only part of the story.
Next, they look for trapped bubbles of gas in the meteorite and test them to see if they match the Martian atmosphere's chemistry. If they do, then you have a good candidate for a meteorite from Mars.
Then the outside of the meteorite is checked for cosmic ray trails. This tells you how long it was in space. And, analysis of the isotopes can also be used to help confirm or refute the idea it is from Mars.
If the meteorite matches the chemistry, isotope ratios, atmospheric gas, and shows that it has been in space for a few million years, then it is almost certainly a Martian rock. After all, there are only a few terrestrial planets in our solar system, and that helps us a lot by narrowing things down.