The Curiosity rover has discovered a spectacular rock structure penetrating Mars' strange surface. Several twisted spires of rock rise among the shallow sands and rocks of the Gale Crater, the spikes of sediment like frozen streams of water poured from an unseen jug in the sky.
Experts believe the columns were most likely made of cement-like material that formerly filled old bedrock fractures. The snaking streams of dense material stayed standing when the softer rock eroded away.
The rock formations were photographed by a camera on the Curiosity rover on May 17, but NASA and specialists from the SETI institute (which stands for the Search for Extraterrestrial Intelligence) only revealed the image last week as part of SETI's planetary picture of the day effort.
The structures, as strange as they appear, are not without precedent.
A hoodoo is a tall and thin spire of rock created by erosion in Earthly geology. It's also known as a fairy chimney, tent rock, or earth pyramid.
Hoodoos are typically found in arid locations, such as Utah's canyons or southern Serbia's mountains, and the columns may reach heights of 10 stories.
A hoodoo in Bryce Canyon, Utah. (Don Graham/Flickr/CC BY SA 2.0)
Hard rock layers that develop up within softer sedimentary rock generate the natural formations. You're left with a gorgeous impression of an old crack in the bedrock while the remainder of the rock erodes away due to rain, wind, or frost.
Hoodoos East Coulee, Alberta, Canada. (Darren Kirby/CC BY SA 2.0)
In comparison to the ones we see on Earth, the two rock towers on Mars appear to be on the verge of collapsing, yet they are definitely strong enough to endure the lesser surface gravity on Mars.
Curiosity discovered another odd rock structure earlier this year that may have been generated in a same manner, but with drastically different effects.
This little rock resembles a piece of coral or a flower, with several small petals extending upwards towards the sun.
According to a NASA news statement at the time, "one notion that has developed is that the rock is a form of concretion generated by minerals deposited by water in fractures or divisions in existing rock."
"These concretions can be compacted together, tougher and denser than the surrounding rock, and can persist even after the surrounding rock has eroded away."
A flower-shaped rock found on Mars. (NASA, JPL-Caltech, MSSS)
Although the Gale crater isn't completely flat, the alien spires observed by Curiosity stand out from the rest of its surroundings, despite the image's lack of height data.
The massive rock tombstones may appear dead now, but their development reveals a great deal about past Martian circumstances and whether life might have thrived there billions of years ago.
The Gale crater is considered to be a dried-up lake bed, albeit it may be shallower and more ephemeral than previously imagined.
The old lake's rock formations are assisting in the discovery of the region's actual past.
