After nearly five years on Mars, NASA's Perseverance rover has traveled almost 25 miles (40 kilometers), and the mission team has been busy testing the rover's durability and gathering new science findings on the way to a new region nicknamed "Lac de Charmes," where it will be searching for rocks to sample in the coming year.
Like its predecessor Curiosity, which has been exploring a different region of Mars since 2012, Perseverance was made for the long haul. NASA's Jet Propulsion Laboratory in Southern California, which built Perseverance and leads the mission, has continued testing the rover's parts here on Earth to make sure the six-wheeled scientist will be strong for years to come. This past summer, JPL certified that the rotary actuators that turn the rover's wheels can perform optimally for at least another 37 miles (60 kilometers); comparable brake testing is underway as well.
Over the past two years, engineers have extensively evaluated nearly all the vehicle's subsystems in this way, concluding that they can operate until at least 2031.
"These tests show the rover is in excellent shape," said Perseverance's deputy project manager, Steve Lee of JPL, who presented the results on Wednesday at the American Geophysical Union's annual meeting, the largest gathering of planetary scientists in the United States. "All the systems are fully capable of supporting a very long-term mission to extensively explore this fascinating region of Mars."
Perseverance has been driving through Mars' Jezero Crater, the site of an ancient lake and river system, where it has been collecting scientifically compelling rock core samples. In fact, in September, the team announced that a sample from a rock nicknamed "Cheyava Falls" contains a potential fingerprint of past microbial life.
More efficient roving
In addition to a hefty suite of six science instruments, Perseverance packs more autonomous capabilities than past rovers. A paper published recently in IEEE Transactions on Field Robotics highlights an autonomous planning tool called Enhanced Autonomous Navigation, or ENav. The software looks up to 50 feet (15 meters) ahead for potential hazards, then chooses a path without obstacles and tells Perseverance's wheels how to steer there.
Engineers at JPL meticulously plan each day of the rover's activities on Mars. But once the rover starts driving, it's on its own and sometimes has to react to unexpected obstacles in the terrain. Past rovers could do this to some degree, but not if these obstacles were clustered near each other. They also couldn't react as far in advance, resulting in the vehicles driving slower while approaching sand pits, rocks, and ledges. In contrast, ENav's algorithm evaluates each rover wheel independently against the elevation of terrain, trade-offs between different routes, and "keep-in" or "keep-out" areas marked by human operators for the path ahead.
"More than 90% of Perseverance's journey has relied on autonomous driving, making it possible to quickly collect a diverse range of samples," said JPL autonomy researcher Hiro Ono, a paper lead author. "As humans go to the Moon and even Mars in the future, long-range autonomous driving will become more critical to exploring these worlds."
New science
A paper published Wednesday in Science details what Perseverance discovered in the "Margin Unit," a geologic area at the margin, or inner edge, of Jezero Crater. The rover collected three samples from that region. Scientists think these samples may be particularly useful for showing how ancient rocks from Mars' deep interior interacted with water and the atmosphere, helping create conditions supportive for life.
From September 2023 to November 2024, Perseverance ascended 1,312 feet (400 meters) of the Margin Unit, studying rocks along the way - especially those containing the mineral olivine. Scientists use minerals as timekeepers because crystals within them can record details about the precise moment and conditions in which they formed.
Jezero Crater and the surrounding area holds large reserves of olivine, which forms at high temperatures, typically deep within a planet, and offers a snapshot of what was going on in the planet's interior. Scientists think the Margin Unit's olivine was made in an intrusion, a process where magma pushes into underground layers and cools into igneous rock. In this case, erosion later exposed that rock to the surface, where it could interact with water from the crater's ancient lake and carbon dioxide, which was abundant in the planet's early atmosphere.
Those interactions form new minerals called carbonates, which can preserve signs of past life, along with clues as to how Mars' atmosphere changed over time.
"This combination of olivine and carbonate was a major factor in the choice to land at Jezero Crater," said the new paper's lead author, Perseverance science team member Ken Williford of Blue Marble Space Institute of Science in Seattle. "These minerals are powerful recorders of planetary evolution and the potential for life."
Together, the olivine and carbonates record the interplay between rock, water, and atmosphere inside the crater, including how each changed over time. The Margin Unit's olivine appeared to have been altered by water at the base of the unit, where it would have been submerged. But the higher Perseverance went, the more the olivine bore textures associated with magma chambers, like crystallization, and fewer signs of water alteration.
As Perseverance leaves the Margin Unit behind for Lac de Charmes, the team will have the chance to collect new olivine-rich samples and compare the differences between the two areas.
More about Perseverance
Managed for NASA by Caltech, NASA's Jet Propulsion Laboratory in Southern California built and manages operations of the Perseverance rover on behalf of the agency's Science Mission Directorate as part of NASA's Mars Exploration Program portfolio.
