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MeteoritesNASA think this is a meteorite. What do you think?

1st Sep 2014 22:54 UTCDavid Baldwin

I came across this while browsing the NASA website. Here is a link to an article on a 'Meteorite' found on Mars back in May by the Curiosity rover.

http://www.nasa.gov/jpl/msl/pia18387/#.VATfvfn4dKN

(If you click on the image, it can be blown up to a 37m pixels for more detail).

I personally think this looks like a large chunk of basalt, which shows typical pitting of weathering/erosion patterns for cold, arid conditions.

Ironically, similar rocks have been encountered on Mars before, photographed by other craft in the early 90's, and studies have been carried out comparing the rocks to weathered dolerites from Antarctica ( http://adsabs.harvard.edu/abs/1991LPSC...21..711A ). These photos were obviously of a far lower resolution and quality compared to what we see here, where the rock appears to be almost polished and very well defined, detailing bubbles/cavities of various sizes. And would two iron meteorites really come to rest like this side by side?

Here on earth, meteorites are not 'allowed' to have bubbles in them, yet now, scientists are hypothesising over this one to come up with reasons why it can have bubbles. Erm, because it's basalt?

What do you guys think?

1st Sep 2014 23:13 UTCAlfredo Petrov Manager

I personally can't say whether this is a meteorite or not just by looking at the photo, but I don't see any reason yet to doubt NASA's "iron meteorite" ID. Keep in mind that you aren't looking at the original surface shape of the meteorite (or basalt rock) but rather at the surface structure left after sand-blasting (often wrongly called "wind abrasion"), like ventifacts from Earth deserts. So, if indeed it is a meteorite, very soft material (like graphite), and harder but brittle material (like troilite and forsterite), got abraded out, leaving the cavities you see on the photo. The cavities were not necessarily present yet right after the meteorite fell.

1st Sep 2014 23:53 UTCBob Harman

So, while I have very little "real" knowledge of meteors and meteorites, I do think of several comments and questions. Firstly since Mars is so much smaller than Earth and has a verrrry thin atmosphere, the actually fall characteristics would be quite different than a fall to Earth. Am I correct? Would the max speed be different and might there be less "burn up" and disintegration during the fall? After all, a meteor falling into the Moon would fall totally intact and only break up upon impact with the Moon's surface.

After the landing, the meteorite might last quite unchanged for many millennia, perhaps even 1 - 3 billion years, yes??

As the Martian atmosphere is so thin, a 100 mph wind would only feel like a gentle breeze and billions of years would be needed to actively weather the rock surface, yes??. That is unless the atmosphere of Mars was denser into the quite recent past. Also, I am surprised that a thin layer of very fine Martian dust seemed not to be adherent to the meteorite surface (static electricity??) lying there on the Martian surface.

Am I correct with all my comments and suppositions?

BTW, Alfredo, nice meeting you at the East Coast Show! CHEERS…….BOB

2nd Sep 2014 00:47 UTCAlfredo Petrov Manager

Hi Bob, nice to meet you on Mindat too!

I'm no expert on atmospheres, but I think meteorites start glowing in the lower ionosphere (100km up) when they hit Earth, and the gas pressure there is only a 1/100,000 or even only a few millionths or so of what it is at sea level, and Mars' atmosphere is 1/100 or 1/200 of Earth's at sea level, so the air on Mars, even though way too thin to keep you alive without a pressure suit, is still more than thick enough to burn up a small meteor, and give a bigger one a nice fusion crust.

Likewise, when you look at NASA's photos of rocks on Mars, many of the small ones look like typical Dreikanter, a classic ventifact shape, so the wind + dust must have done a good job of abrading them despite the thin air. One NASA spokesperson told the press that it was a "mystery" why so many of the smaller rocks were pyramid-shaped. Mystery? Duh! He obviously had not visited any windy deserts on Earth and seen the fields of dreikanter. (Easy for me to say, since I'm in a very windy desert now ;-) )

2nd Sep 2014 10:09 UTCUwe Kolitsch Manager

Well, NASA analysed this iron meteorite of course with the equipment available on the Curiosity Mars rover.

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