‘Spiders’ on Mars are far more common than first thought, researchers have revealed.
Named for their arachnid-like appearance, they are a type of land erosion where networks of cracks form on Martian soil, completely different to anything on Earth.
The features were previously thought only to exist in a region known as the South Polar Layered Deposits (SPLD), banded layers of dust and water ice.
However, in a recent publication, citizen-science volunteers spotted the ‘spider’ formations in other areas of the Martian polar surface.
A high resolution image from the HiRISE camera onboard NASA’s Mars Reconnaissance Orbiter of one of the new Martian araneiform ‘spiders’
The discovery was made by volunteers working on behalf of Planet Four: Terrains, an online project hosted by Zooniverse, the world’s largest and most popular people-powered research platform.
Araneiforms – the scientific name for these features – occur at the planet’s South Pole and form when carbon dioxide turns to ice during the Martian winter.
As the seasons change, direct sunlight penetrates the translucent ice, warming the land beneath.
The land surface then gets eroded as the gas races out and rips off little bits of dirt, forming spindly branches which resemble spider legs.
The sightings were later confirmed using high resolution imaging from HiRISE (High Resolution Imaging Experiment) camera aboard NASA’s Mars Reconnaissance Orbiter.
Planet Four: Terrains started in June 2015, and was one of the first citizen science projects to launch using the Zooniverse’s Project Builder platform.
Led by Professor Chris Lintott of the Department of Astrophysics at Oxford University, the Zooniverse now hosts over 100 projects.
The online platform runs on support from volunteers, of whom there are now over 1.6 million worldwide.
The volunteers act as armchair scientists, helping the team with their online research from their own homes.
The troughs are believed to be formed by gas flowing beneath the seasonal ice to openings where the gas escapes, carrying along dust from the surface below.
10,000 citizen scientists contributed to the ‘spider’ research, viewing and classifying over 20,000 images derived from observations made by the Context Camera (CTX), aboard the Mars Reconnaissance Orbiter.
These images contained many spiders as well as other land forms known as ‘Swiss cheese terrain’, and craters.
Dr Meg Schwamb, from the Gemini Observatory and lead author of the paper, said: ‘This was a totally unexpected find. By having so many eyes scouring the images, we know now that the SPLD is not the only place where spiders form. This will help us better understand the carbon dioxide jet formation process.
‘The carbon dioxide jet process that forms ‘spiders’ is a completely un-Earthly phenomenon.
‘The only other body suspected of having these jets is Neptune’s moon Triton.
‘The Rise & Fall of Ziggy Stardust’ by David Bowie and the spiders from Mars, released in 1972
‘By studying these spiders and jets we’re learning more about how Mars differs from Earth.
‘The jet process is linked to the Martian seasons and is returning carbon dioxide to the atmosphere, studying these new locales will give new insights into the Martian atmosphere.‘
Based on these exciting new results, the hunt for Martian spiders continues. ‘We have added new CTX images of Mars’ South Polar region to the Planet Four: Terrains website in need of review to see how far north these features may extend,’ Dr Schwamb added.
Nasa has previously revealed a stunning image of springtime on Mars.
The radial troughs have been referred to as spiders, simply because of their shape, and are caused by the thawing of carbon dioxide ice.
Since 2006, the Mars Reconnaissance Orbiter has been charting the red planet’s terrain. This image shows defrosting of the crests of ‘Inca City’. This is the informal name given to a set of intersecting ridges that are located among the layered materials of the south polar region of Mars. Their origin has never been understood
‘Mars’ seasonal cap of carbon dioxide ice has eroded many beautiful terrains as it sublimates (goes directly from ice to vapor) every spring,’ said NASA.
‘In the region where the High Resolution Imaging Science Experiment (HiRISE) camera on Nasa’s Mars Reconnaissance Orbiter took this image, we see troughs that form a starburst pattern.
‘In other areas these radial troughs have been refered to as spiders, simply because of their shape.’
In this region the pattern looks more dendritic as channels branch out numerous times as they get further from the center.
The troughs are believed to be formed by gas flowing beneath the seasonal ice to openings where the gas escapes, carrying along dust from the surface below.
The dust falls to the surface of the ice in fan-shaped deposits.