curiosity Rover has a confirmed nemesis on Mars: Ventifacts. These razor-sharp rock formations, honed to a deadly degree by the Martian winds, nearly killed Curiosity’s wheels five years ago. And now NASA is revealing that these old enemies have once again dramatically stopped the Mars rover as it searches for clues to Mars’ past and whether it once harbored life.
What’s new – In an April 7, 2022, rover blog Curiosity post, NASA reveals that Curiosity has had to abandon its current exploration route on the Greenheugh Pediment, an area of scientific interest of the aptly named Mount Sharp on Mars that may contain evidence of the red wet past of the planet.
The setback came after weeks of the rover slowly rolling up the scrubby southern face of the Gable, a steep terrain region on Mars. According to NASA, the rover’s path became intractable on March 18. The rover’s cameras showed its ground-based drivers that the trail is littered with ventifacts, also known as “gator-back” rocks — so called because they resemble the hard scales on an alligator’s back.
“It was obvious from Curiosity’s photos that this would not be good for our wheels,” says Curiosity project manager Megan Lin in a statement on NASA’s website. “It would have been slow and we wouldn’t have been able to implement best practices for driving rovers.”
These windblown rocks are so sharp that they could irreparably damage the rover should it attempt to struggle on. Surprisingly, this is the largest number of ventifacts Curiosity has ever found on Mars, despite having explored the planet for almost a decade.
Here is the background – In March 2020, Curiosity briefly made it to the top of the pediment — beating its own record for the steepest hill it had climbed on Mars.
The summit of the Greenheugh Pediment is covered in red sandstone debris. It is part of a larger peak called Mount Sharp, a 3.4 mile high mountain on the Red Planet. Since 2014, Curiosity has been working its way up the hill for almost eight years.
The area is of interest to NASA as there is evidence that water once flowed over the site. Where surface water once flowed on Mars, there may also have been life.
“From afar, we can see car-sized boulders being carried down from higher levels of Mount Sharp — perhaps by water relatively late in Mars’ wet era,” Ashwin Vasavada, Curiosity project scientist at NASA’s Jet Propulsion Laboratory, says in the same statement.
“We don’t really know what they are, so we wanted to see them up close.”
But ultimately, to detect signs of past habitability on Mars, the Curiosity rover must be able to function — and that means protecting itself from harm.
In March 2017 (what’s the meaning of March?), Curiosity fell when its tire treads were damaged by alligator rock. The rover also suffered a puncture in 2013 while driving over difficult terrain. Today the team is trying to avoid driving Curiosity over any terrain that could further damage its tires to try to maintain the mission.
What’s next – Having turned around again, Team Curiosity is now trying to stabilize the rover Curiosity and guide it on a new path to success. On April 7, Curiosity team member and planetary geologist Michelle Minitti published a diary entry detailing the current status of the mission:
We successfully continued down the ‘Greenheugh Gable’ while making our way downhill onto gentler tracks. However, the chaotic jumble of terrain we encountered on the final rolls of our wheels left a couple of our wheels sitting awkwardly…our Rover drivers wanted to push the Rover out of the offending terrain to get all six wheels on firm ground (or the Mars equivalent) before attempting another ride. Therefore, today’s drive aims to reposition the rover for weekend observations.
Minitti also posted a picture of Curiosity taken during the descent:
With this new path, Curiosity will have more opportunities to explore a region of Mount Sharp where the surface material is rich in clay – a signature of the waters of the past. This is a region Curiosity has traversed before, but another observation opportunity could reveal new clues about the Red Planet’s past.
“It was really cool to see rocks that preserved a time when lakes dried up and were replaced by streams and dry sand dunes,” says Abigail Fraeman, Curiosity’s associate project scientist at JPL, in the April 7 statement.
“I’m really excited to see what we find as we continue climbing this alternative route.”