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Craters serve as a Martian chronicle


This natural-color view of the Danielson and Kalocsa craters and their surroundings in the Arabia Terra region was captured by the High-Resolution Stereo Camera on the European Space Agency's Mars Express orbiter on June 19, 2011.

In honor of science-fiction legend Ray Bradbury's passing, here's a totally non-fictional Martian chronicle: a picture of two craters on the Red Planet that record how the climate has changed over the course of billions of years.

The photo, sent back by the European Space Agency's Mars Express orbiter and released today, focuses on the Kalocsa and Danielson craters in Mars' Arabia Terra region. Danielson is the larger crater, measuring roughly 38 miles (60 kilometers) across. Kalocsa is smaller (20 miles, or 33 kilometers across) and about a half-mile (1 kilometer) shallower.

The most noticeable features on Danielson's crater floor are the dark, eroded layers of sediments and streamlined hills known as yardangs. In today's photo advisory, ESA's science team explains that the sediments appear to have been cemented by water, possibly from an ancient deep groundwater reservoir, and then were eroded by the wind.

The orientation of the yardangs suggests that strong north-northeasterly winds initially deposited the sediments, and eroded them during a later, drier period of Martian history. Danielson's layers may chronicle fluctuations in the climate of Mars, triggered by changes in the planet's axis of rotation.

In contrast, Kalocsa's crater floor is smooth, with no layered sediments. This may be because the crater is too shallow to have reached the groundwater reservoir, or because the crater was blasted into the Martian surface after the water in the reservoir was lost.

One of Bradbury's best-known books, "The Martian Chronicles," spins tales about the disappearance of an ancient Red Planet civilization. The disappearance of the Red Planet's ancient water is a story worthy of the Ray Bradbury treatment, and fresh chapters of that story are sure to be written after NASA's Mars Science Laboratory lands in Gale Crater in August.

Someday, a crater on Mars may well bear Bradbury's name — but Mars Society President Robert Zubrin had something even grander in mind when he issued a tribute to the author:

"I was saddened today to hear of the death of Ray Bradbury.  I first read Bradbury's 'The Martian Chronicles' when I was in elementary school.  He was one of those who inspired me, and I'm sure millions of others, with the vision of a new world.  While science has since shown nearly all the details of Bradbury's Lowellian Mars to have little relationship to reality, still, I think on a deeper level he was fundamentally right.  The human future need not be limited to the Earth.  It is from imagination that reality springs.  There are no crystalline cities on Mars, yet, but there will be someday.  Perhaps one of the first should be named after Ray."

I'm certain that "Bradbury" will be a future destination on Mars, whether it's Bradbury Crater or Bradbury City. What do you think? Feel free to leave your tributes as comments below.

More about Ray Bradbury and Mars:

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.