NASA has finally uncovered the truth behind the mysterious “spider” formations on Mars, which have puzzled scientists for decades. These features, known as araneiform terrain, are not actual spiders but rather unique geological structures predominantly located in the planet’s southern hemisphere. Their branching, spider-like channels can extend over a kilometre in length, raising numerous questions about their origin. After years of analysis and satellite observations, NASA researchers have now recreated these fascinating formations in laboratory experiments, shedding light on their formation process.
For years, scientists have observed these peculiar, spider-like features on Mars‘ surface via satellite imagery. These formations, known as araneiform terrain, have sparked curiosity due to their unique, branching structure, which closely resembles a spider’s legs. Found primarily in the southern hemisphere, these formations are grouped with other features such as dark spots and fan-shaped structures. Collectively, they have been dubbed the “Kieffer zoo”, named after Hugh Kieffer, who first suggested a theory about their formation two decades ago.
NASA’s Jet Propulsion Laboratory (JPL) has long suspected that these features form as a result of carbon dioxide (CO2) sublimation during the Martian spring. However, until recently, no direct observations could confirm this. The lack of in-situ investigations left a significant gap in our understanding, pushing researchers to conduct Earth-based experiments to mimic the Martian environment.
Earth-Based Experiments Unravel the Mystery
To investigate the formation of these Martian spiders, NASA scientists embarked on a groundbreaking experiment. Led by Lauren McKeown at JPL, the team aimed to recreate the Martian environment here on Earth. The challenge was immense: Martian conditions include extremely low temperatures, dropping to -185°C (-301°F), and a thin atmosphere, unlike anything on Earth. To overcome this, the researchers used JPL’s DUSTIE test chamber, which simulates these harsh conditions using liquid nitrogen to cool the chamber and replicate Mars’ freezing environment.
Using a substance that mimics Martian soil, the team pumped CO2 into the chamber, allowing it to freeze over several hours. After numerous trials, they successfully recreated the spider-like channels, proving that CO2 sublimation, coupled with gas pressure, could carve out these distinct formations on Mars. This finding confirms Kieffer’s original hypothesis, marking a significant milestone in planetary science.
How Do Martian Spiders Form?
The driving force behind these spider formations is the seasonal sublimation of CO2 ice. During the Martian winter, much of the planet’s atmosphere—made primarily of carbon dioxide—freezes, creating a frost that blankets the surface. When the spring sun returns, sunlight penetrates the translucent CO2 ice, warming the dark soil beneath. As the ground heats up, the ice sublimates directly into gas, creating pockets of trapped gas beneath the surface.
As the pressure builds, the gas eventually escapes through cracks in the ice, creating high-velocity jets of CO2 and dust. These jets carve out the intricate, spider-like channels we see today, making these formations a product of Mars’ seasonal carbon dioxide cycles.
Multiple Formation Processes at Play
While the experiment confirmed the CO2 sublimation model, researchers found some surprises along the way. In some cases, the cracks in the ice formed due to thermal stresses, rather than gas build-up alone. This suggests that multiple processes could be responsible for creating these formations, adding a layer of complexity to their origin. These variations could offer clues about past climate changes on Mars, providing scientists with invaluable information about the planet’s geological history.
What Makes These Spiders Unique?
Interestingly, not all spider-like formations are identical. Their appearance depends on subtle factors such as gas release intensity and ice thickness. In some instances, dark spots formed where gas broke through the ice, while surrounding areas exhibited bright halos, likely caused by frost deposition from gas plumes. Despite extensive studies, questions remain about why these formations appear in certain areas and not others, and why they don’t seem to grow over time.
These unanswered questions hint that Martian spiders could be relics from a time when Mars had a very different climate. Understanding their origins could provide a window into the planet’s distant past, unlocking secrets about Mars’ geological and climatic history.
NASA’s findings offer an exciting glimpse into the dynamic processes shaping the Martian surface. Thanks to cutting-edge experiments, scientists are now closer than ever to understanding these strange and beautiful formations. As exploration of Mars continues, researchers will undoubtedly uncover even more secrets hidden within the Red Planet’s enigmatic landscape.
