NASA scientists have successfully replicated spider-like shapes found on the surface of Mars in a laboratory setting for the first time.
The planetary phenomenon known as “spiders” — scientifically referred to as “araneiform terrain” — is unique to Mars and created by processes involving carbon dioxide ice.
Researchers’ findings, published in The Planetary Science Journal, reveal the experiment to recreate those “spider” formations in simulated Martian temperatures and air pressure.
What are Mars ‘spiders’?
Mars spiders are landforms found primarily in the planet’s south polar regions. They consist of branched, circular spots on the surface resembling spider legs that can stretch more than one kilometre.
In the study, scientists say when the planet’s carbon dioxide ice caps begin to sublimate — transition directly from solid to gas — pressure builds up beneath the surface and bursts through to create these radial patterns.
This process, described as the Kieffer model, is unique to Mars due to the planet’s thin atmosphere and cold temperatures.
Recreating Mars ‘spiders’
To better understand how these spiders form, NASA scientists conducted lab experiments simulating the conditions found on Mars.
In their experiments, researchers used a specialized wine-barrel-size chamber to replicate the low-pressure and cold environments of Mars. A Martian soil simulant was chilled in the container, which was submerged in liquid nitrogen.
Here’s a look inside of JPL’s DUSTIE, a wine barrel-size chamber used to simulate the temperatures and air pressure of other planets – in this case, the carbon dioxide ice found on Mars’ south pole. Experiments conducted in the chamber confirmed how Martian formations known as “spiders” are created. (NASA/JPL-Caltech)
CO2 gas was introduced, and ice formed over three to five hours. The study said it took many attempts before researchers found the right conditions for the ice to become thick and translucent.
A heater was used to warm the simulant, causing the ice to crack and release gas plumes similar to those seen on Mars.
The dark plumes created holes in the soil and spewed dust for up to 10 minutes.
Scientists said it came as a surprise that ice formed between the grains of the soil, cracking it open. This may explain why spiders have a more “cracked” appearance.
“These experiments will help tune our models for how they form,” lead researcher Lauren Mc Keown in a news release on NASA’s website.
Mc Keown is said to have been working to make a plume for five years.
What is next?
According to the study, the next step is to try the same experiment with simulated sunlight from above rather than a heater below.
This could reveal the conditions under which plumes and soil ejection might occur.
Spider-shaped features called araneiform terrain are found in the souther hemipshere of Mars, carved into the landscape by carbon dioxide gas. This 2009 image by NASA’s Mars Reconnaissance Orbiter shows several of these distinctive formations within an area three-quarters of a mile (1.2 kilometres) wide. (NASA/JPL-Caltech/Unversity of Arizona)
Scientists admit that some questions remain unanswered, including why the spiders form in some places on Mars and not others and don’t grow in size or number.
The study also acknowledges that these spider-like shapes could have existed for a long time and were created when the climate on Mars was different.
