|
The "Presidential Panorama"
An image of Mars of extraordinary quality. This image was composed over a number of days from image panels taken at approximately the same time on each day. A fine red silt is beginning to accumulate on both the lander and the rover, and the differences in color that the accumulation is beginning to make can be seen in a few places such as the top of the low-gain antenna (left-hand side of image) and on the bottom railing of the right-hand ramp, as well as the rover itself. This red silt is composed in large part of iron oxide. The surface of Mars is literally rusting. Although both Mars and the Earth -- like Venus, Mercury and the Moon -- are described as stony-iron planets, iron is not nearly as freely available on the surface of the Earth as it apparently is on Mars. The very commonality of iron on Mars doesn't bode well for the current active presence of bacteria-like life on the planet. On Earth, iron is a metabolically valuable heavy metal that has been sequestered into the extant biomass, both within the interstices of surface rock and on the surface of the Earth. Indeed, the few truly iron-rich deposits on Earth, such as the Mesabi deposits in Minnesota, are believed to have been biogenically formed by iron-precipitating bacteria 1-3 billion years ago, thus "locking up" Earth's equivalent storehouse of iron.
|