Timble2
Imaginary Person
- Joined
- Feb 9, 2003
- Messages
- 6,047
- Location
- In a Liminal Zone
Rust never sleeps...on Mars
Another article about whether there were ever oceans on Mars, the colour may be meteor dust, not rust.
Ties in with Rynner's post about the missing carbonates.
Full New Scientist article at:
http://www.newscientist.com/news/news.jsp?id=ns99994120
Another article about whether there were ever oceans on Mars, the colour may be meteor dust, not rust.
Ties in with Rynner's post about the missing carbonates.
Full New Scientist article at:
http://www.newscientist.com/news/news.jsp?id=ns99994120
Red planet's hue due to meteors, not water
18:28 04 September 03
Why is Mars red? The generally accepted explanation that liquid water rusted its rocks may be wrong. Lab experiments that mimic the environment on Mars suggest that the planet's reddish hue came from a dusting of tiny meteors falling on the surface. The result is fuelling the debate about whether Mars was ever hospitable to life.
The mineral that gives the planet its colour is a reddish iron oxide. Until now, astronomers thought that it probably formed in a chain of chemical reactions as iron in rocks dissolved into pools and rivers on the warm young planet. The iron oxidised, precipitated, and was then blown all over the planet.
But Albert Yen of NASA's Jet Propulsion Laboratory in Pasadena, California, began to doubt this after the Mars Pathfinder mission reached the Red Planet in 1997. The mission revealed that there is more iron and magnesium in Martian topsoil than within its rocks. This suggests the minerals actually came from the small, metal-rich meteors and dust particles that constantly fall onto Mars, says Yen. Calculations suggest they deposit five centimetres of surface layer every billion years.
If that is the case, Mars might not have been so wet after all. To test whether this topsoil would have needed water to oxidise and turn red, Yen exposed metallic iron to ultraviolet light, simulating sunlight, in a chamber containing gases similar to the Martian atmosphere at temperatures as low as -60 °C.
Red iron oxides started to form within a week. No water was necessary, Yen told this week's meeting of the American Astronomical Society's planetary science division in Monterey, California....
Yen does not claim water never flowed on Mars - the planet's networks of dry valleys and channels are good evidence that it did, he says. But flowing water seems to have played only a small role in weathering the surface.....