For years, NASA‘s Perseverance and Curiosity rovers have been traveling across Mars, exploring different parts of the Red Planet that are hundreds of kilometers apart. However, over the past few months, both robots have been struggling to complete an important part of their missions.
Perseverance is embarking on its fifth scientific campaign, but the rover is unable to reach the edge of an ancient crater and often has to spend twice as much time traveling through Martian terrain. As for Curiosity, it also faces obstacles: recently, the rover was forced to turn off from exploring a dried-up canal after its wheels got stuck on a rock.
Perseverance’s journey
For nearly three months, the Perseverance rover has been climbing the rim of Jezero Crater to investigate whether life once existed on Mars. This is the most challenging terrain for a six-wheeled robot, and it is proving to be more difficult than the mission team expected.
Percy has been on Mars for almost four years now, and at the end of August, the rover began its fifth science campaign. This is a major event in Perseverance’s journey on Mars, and it requires exploration of the western rim of Jezero Crater, which shows signs of ancient hydrothermal activity. To do this, Perseverance must overcome slopes of up to 23 degrees and climb about 1,000 feet (300 meters) to the edge of Jezero, which contained a huge lake billions of years ago. However, as the rover recently showed, it was not easy.
“My journey to the rim of Jezero Crater has not been easy,” NASA’s Perseverance rover wrote on the X network. But thanks to my team and the autonomous navigation system, I’m avoiding major dangers as I slowly make my way up.”
The path to the crater rim turned out to be more slippery than originally anticipated, and this slowed Perseverance’s journey. The area around the crater turned out to be loosely packed dust and sand with a thin and brittle crust, forcing the rover to cover half the distance it normally travels during normal driving, according to NASA Spaceflight. There was a day when Perseverance traveled about 20% of the planned route.
“Rovers have traveled over steeper terrain and more slippery terrain, but this is the first time we’ve had to deal with both, and on this scale,” Camden Miller, a rover route planner at NASA’s Jet Propulsion Laboratory (JPL) in California, told NASA Spaceflight. “For every two steps forward that Perseverance takes, we’ve taken at least one step back.”
The team behind the mission is coming up with various ways to make Perseverance’s journey on its wheels easier, including making the rover drive along the crater’s rim backwards, as its suspension maintains better traction when it moves in that direction. For now, the team has decided to direct the rover to the northern rim of the crater, as there are larger rocks closer to the surface in this region, which will reduce slippage, according to NASA Spaceflight.
NASA’s Curiosity rover has captured this image of its middle and right rear wheel. Image: NASA/JPL-Caltech
Curiosity’s problems
Hundreds of kilometers away, NASA’s Curiosity rover, Percy’s predecessor, is also having trouble navigating the bumpy road on Mars. This week, NASA announced that Curiosity has traveled only halfway to its destination. Curiosity’s movement was stopped early after it exceeded one of the suspension limits, and the rover ended up with one wheel in the gutter and the other on a rock.
“Curiosity is currently in Gediz Valles, a channel at the foot of Mount Sharp that may have contained liquid water in the past. With the rover stuck in an awkward position, the team focused on a remote sensing plan, collecting all possible observations of Gediz Vallis while figuring out how Curiosity could turn west to exit the channel. The awkward position also meant that the team didn’t want to extend the rover’s arm, which remained attached to its side.
The Gediz Vallis channel is carved into the underlying rock and filled with boulders and other debris. The mission team is looking for clues as to how the channel was formed: whether it was carved by an ancient river, wind, or dry avalanches. The study of Gediz Vallis not only provides a glimpse into the ancient history of Mars, but also suggests that water on Mars may have appeared and disappeared in stages, rather than gradually disappearing as the planet became increasingly dry.
“When I joined the mission in 2020, I would occasionally look at Gediz Vallis on our HiRISE maps and imagine what it must have looked like between those tall, steep walls of canals,” Conor Hayes, a PhD student at the University of York, wrote in his blog. “It therefore seems almost unbelievable that we will soon be leaving Gediz Valles behind as we continue our trek to Mount Sharp.”
Mars can be an unforgiving environment for a pair of car-sized robots just trying to do their job.
