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ToSeek
2004-Oct-26, 05:33 PM
Yale Lock on Martian Ages (http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid= 1263&mode=thread&order=0&thold=0)


A Yale geology team has tested an isotope method to correlate the age of martian meteors to how uranium and thorium decay to form helium. An important byproduct is a profile of how the rock may have been heated during its ejection or atmospheric entry.

Candy
2004-Oct-27, 07:47 AM
The timeline proposed for Lafayette showed a lineage that began around 700 million years ago on Mars, when some saline began to seep into it and change the rock's mineral content. About 11 million years ago, the fragment blasted off of Mars as debris and then landed on Earth [originally in Illinois] about 2,900 years ago. Could some explain to me, in layman's terms, how the Mars' debris got to Earth? :-?

Maksutov
2004-Oct-27, 08:08 AM
The timeline proposed for Lafayette showed a lineage that began around 700 million years ago on Mars, when some saline began to seep into it and change the rock's mineral content. About 11 million years ago, the fragment blasted off of Mars as debris and then landed on Earth [originally in Illinois] about 2,900 years ago. Could some explain to me, in layman's terms, how the Mars' debris got to Earth? :-?

In brief, the escape velocity for Mars is 5.02 km/s (Earth's is 11.18 km/s). This is how fast an object would have to be moving away from Mars in order to escape from the martian gravity and go into orbit around the Sun.

When large bodies impacted Mars in the past, some of the material was thrown up at speeds in excess of 5.02 km/s. This material then left Mars and went into orbit around the Sun.

Some of these orbits intersected the orbit of the Earth, and eventually some of this Earth orbit intersecting material collided with the Earth. Some pieces were large enough to survive the plunge through Earth's atmosphere and landed.

Those pieces, which were now called meteorites, had interiors that were undisturbed since leaving Mars. Once we determined in the 1970s what the typical atmospheric composition of Mars was, then it was possible to open these meteorites, examine the trapped atmosphere inside them, and determine analytically if there was a match.

Those that provided matches were classified as Martian meteorites. ALH 84001 (http://www.lpi.usra.edu/lpi/meteorites/The_Meteorite.html) is a prime example of one of these Martian meteorites.

Candy
2004-Oct-27, 08:27 AM
When large bodies impacted Mars in the past, some of the material was thrown up at speeds in excess of 5.02 km/s. This material then left Mars and went into orbit around the Sun. Thanks, Maksutov. When I read the article, it didn't explain very well why the 'fragment's blasted' off of Mars. I should have figured as much. #-o

Maksutov
2004-Oct-27, 08:37 AM
BTW, I've dated a few Martian Meteorites myself.
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At least that's how I later referred to those gals. Personalities from the depths of space. No matter how "warm" the restaurant, play, concert, etc., being around them was like being in a meat locker. Uncomfortable even for a guy from New England who loves winter! No second dates, of course! :D

Candy
2004-Oct-27, 08:42 AM
BTW, I've dated a few Martian Meteorites myself.
.
.
.
.
.
.
.
At least that's how I later referred to those gals. Personalities from the depths of space. No matter how "warm" the restaurant, play, concert, etc., being around them was like being in a meat locker. Uncomfortable even for a guy from New England who loves winter! No second dates, of course! :D As long as you don't let a meteorite hit you in the head! :lol:

Maksutov
2004-Oct-27, 08:48 AM
BTW, I've dated a few Martian Meteorites myself.
.
.
.
.
.
.
.
At least that's how I later referred to those gals. Personalities from the depths of space. No matter how "warm" the restaurant, play, concert, etc., being around them was like being in a meat locker. Uncomfortable even for a guy from New England who loves winter! No second dates, of course! :D As long as you don't let a meteorite hit you in the head! :lol:

I know that joke. Too bad it can't be told on the BABB! :D

George
2004-Oct-31, 01:42 AM
BTW, I've dated a few Martian Meteorites myself.

I wondered who was gonna say this. Odd, Candy even posted before this. :)