ESA Scientists Reveal Mysterious Image of Thousands of ‘Black Spiders’ Crawling on Mars’ Surface

Mars has long captivated scientists and space enthusiasts alike with its alien landscapes and dramatic climate shifts. Now, fresh images from ESA’s Mars Express and the ExoMars Trace Gas Orbiter have unveiled one of its most intriguing natural phenomena: sprawling, dark formations resembling giant spiders crawling across the planet’s icy terrain.

But these eerie structures aren’t the work of extraterrestrial arachnids—they’re the result of an explosive process happening beneath the Martian surface.

A Seasonal Spectacle: How ‘Spiders’ Emerge on Mars

Despite its barren landscape, Mars experiences extreme seasonal changes similar to Earth, driven by its tilted axis. During the frigid Martian winter, carbon dioxide from the atmosphere freezes, coating the ground in a layer of dry ice. But when spring arrives, things take a dramatic turn.

Instead of melting like water ice, carbon dioxide sublimates—jumping directly from a solid to a gas. Trapped beneath the surface, this gas builds up pressure until it bursts through the ice, carrying dark dust from below and spraying it into the thin Martian air.

The result? Large, black blotches stretching up to a kilometer wide, with spindly, vein-like channels carved into the ground beneath—the ‘spider’ effect.

This Image Shows Features Known As Spiders Near Mars’s South Pole — This image shows features known as “spiders” near Mars’s south pole, as seen by the CaSSIS (Colour and Stereo Surface Imaging System) instrument aboard ESA’s ExoMars Trace Gas Orbiter. The data for this image were captured by CaSSIS on 4 October 2020. The image is centred at roughly 323°E/75°S. Credit: ESA/TGO/CaSSIS

Capturing the Phenomenon: Mars Express and Exomars Trace Gas Orbiter

These bizarre formations have been closely observed by two of ESA’s most advanced spacecraft.

The Mars Express orbiter, equipped with the High Resolution Stereo Camera (HRSC), captures the dark spots on the surface left behind by escaping gas and dust.
Meanwhile, the Colour and Stereo Surface Imaging System (CaSSIS) aboard ExoMars TGO takes things a step further, revealing the full web-like channels beneath the ice.

One of the most striking images comes from an area called Inca City, a grid-like network of ridges that looks eerily like the ruins of an ancient civilization.

While some have speculated about alien involvement, scientists believe it’s the result of natural geological processes, possibly linked to ancient impact craters.

This Rectangular Image Shows Part Of The Martian Surface As If The Viewer Is Looking Down And Across The Landscape — This rectangular image shows part of the Martian surface as if the viewer is looking down and across the landscape, with the irregular, mottled ground appearing in swirled tones of brown and tan. Credit: ESA/DLR/FU Berlin

Could Humans Witness This Event Firsthand?

If astronauts ever set foot on Mars, they might see this spectacular natural show in real time—ice cracking open, dark dust erupting into the air, and the landscape shifting beneath their feet. Unlike anything found on Earth, these ‘spiders’ highlight the Red Planet’s dynamic and unpredictable environment.

For now, spacecraft like Mars Express and ExoMars TGO continue to provide stunning evidence of Mars’ geological activity, inching us closer to understanding its alien world—and perhaps one day, setting foot on its surface.