What Are These Blue Spots on Mars?
A wider view of Mars Express image of Arabia Terra. Credit: European Space Agency

FYI.

This story is over 5 years old.

Tech

What Are These Blue Spots on Mars?

The true identity of Arabia Terra’s dark, oasis-like patches.

This morning, the European Space Agency (ESA) released a fascinating satellite image of Mars, taken by the agency's Mars Express orbiter. It depicts the planet's Arabia Terra region, which may ring a bell with fans of Andy Weir's The Martian.

This densely cratered tract of land, which is about 4,500 kilometers wide, made for a handy plot device in Weir's novel. Now the ESA picture demonstrates that its literary cred is far from the only interesting thing about it.

Advertisement

For instance, take the two bluish patches located in Arabia Terra's craters which, at first glance, look almost like water-rich oases in the Martian desert. Alas, this is only a mirage effect of the orbiter's perspective and image processing—in reality, the spots are windswept accumulations of dark, basalt-rich sediments. These minerals are deposited into the craters by the planet's colossal dust storms, which can enshroud the entire planet for weeks at a time, kicking up massive amounts of debris and eroding Martian surface features.

Arabia Terra is a great place to study the geological fallouts of these stormy ragers, because it is among the most ancient regions on the planet. Billions of years of cumulative dust erosion and sedimentary deposits are laid bare across this battered landscape, providing a comprehensive window into Arabia Terra's tumultuous past.

The region's more recent craters—like the one created by a meteorite impact about 12 years ago—boast sharper edges than older impact scars that have been sanded down over time. This diverse collection of young and old surface features distinguishes Arabia Terra as one of the most geologically distinct regions on Mars.

According to a 2007 paper published in the journal Icarus, Arabia Terra boasts mysterious outflow channels with no obvious origins, and evidence of a rich paleotectonic history, while more recent studies suggest it was home to supervolcanoes some 3.7 billion years ago, further upping the region's mystique. In short: Arabia Terra is a bizarre jumble of geological oddities that contextualize Mars's past in ways that few other regions can.

As weird as the area is, however, images like this one from Mars Express hit home that alien worlds are subject to much of the same natural processes as Earth, just with altered parameters. Indeed, Mars isn't the only extraterrestrial environment that has been visibly shaped by winds and storms—Saturn's moon Titan is also sculpted by these processes.

While neither of these worlds are hospitable to humans (for now), the fact that scientists continue to observe familiar phenomena in our own solar system bodes well for finding Earthlike environments elsewhere in the universe.

And though at this point, only fictional astronauts have visited Arabia Terra, that may soon change given NASA's recent ambitious commitments to putting a human on Mars in the 2030s. The region is tantalizing enough from the Mars Express's perspective in outer space. Perhaps it's time we took a closer look.