kottke.org posts about Mars Express

Enhanced Color Mars

posted by Jason Kottke   Jun 15, 2023

an enhanced color photo of Mars

Using data from the ESA's Mars Express probe, the German Aerospace Center has released an enhanced color image of Mars that shows off the planet's geology and mineral content better than the usual dusty red photos do. Here's part of what you're seeing:

It is well known that most of Mars is reddish in colour, due to the high amount of oxidised iron in the dust on its surface, earning it the nickname the 'Red Planet'. But it is also immediately noticeable that a considerable region of Mars is rather dark, appearing bluish in colour in image 1. These regions represent greyish-blackish-bluish sands, which are volcanic in origin and form large, dark sand layers on Mars. They were primarily piled up by the wind to form imposing sand dunes or enormous dune fields on the floor of impact craters. These unweathered sands consist of dark, basaltic minerals, of which volcanic lava on Earth is also composed. Basalt is the most widespread volcanic rock on Earth — and in the Solar System. Earth's ocean floor is made of basalt, as are the extinct volcanoes of the Eifel, Mount Etna in Sicily and volcanoes of the Hawaiian archipelago.

In my mind, the best bit is how much clearer you can see the various geographical features of the planet. (via bad astronomy)

A Massive Ice-Filled Crater on Mars

posted by Jason Kottke   Dec 26, 2018

Korolev Crater

Korolev Crater

ESA's Mars Express mission recently photographed the Korolev crater on Mars, filled almost to the brim with water ice.1 When I first saw this image I thought, oh cute!, assuming the crater was maybe a few dozen feet across. But no, it's about 51 miles across and the thickest part of the ice is over a mile thick.

This ever-icy presence is due to an interesting phenomenon known as a 'cold trap', which occurs as the name suggests. The crater's floor is deep, lying some two kilometres vertically beneath its rim.

The very deepest parts of Korolev crater, those containing ice, act as a natural cold trap: the air moving over the deposit of ice cools down and sinks, creating a layer of cold air that sits directly above the ice itself.

Behaving as a shield, this layer helps the ice remain stable and stops it from heating up and disappearing. Air is a poor conductor of heat, exacerbating this effect and keeping Korolev crater permanently icy.

Update: Just to clarify slightly, the top image was generated using photographs taken by Mars Express and a terrain map, so it's technically not a photograph but is like the oblique view in Google Maps. The bottom image is a composite of five photographs. (via @ryanguill)

  1. Mars also has CO2 ice, so you have to specify.