By Will Dunham
WASHINGTON, May 20 (Reuters) - For NASA's Perseverance Rover, life on Mars has been a marathon, not a sprint. For more than five years, the six-wheeled robotic explorer has been steadily traversing the Martian surface seeking signs of ancient life, studying its geology and climate, and collecting rock samples for possible return to Earth.
The rover has now traveled 26.09 miles (41.99 km), just shy of the official marathon distance of 26.22 miles (42.2 km), and, according to Perseverance
mission manager Robert Hogg, it will exceed that distance likely in the next month.
The car-sized rover landed on February 18, 2021, with a mission duration initially planned to last one Martian year, about 687 Earth days.
"The rover continues in good health with at least a decade left in its power source. The duration of the mission will depend on choices NASA makes," Ken Farley, Perseverance's deputy project scientist at Caltech, said in comments provided to Reuters by NASA.
Perseverance, toting a suite of scientific instruments, has operated in and around Jezero Crater, an area in the Martian northern hemisphere believed to have been flooded with water and home to an ancient lake basin. Among various water-related features, it exhibits an ancient fan-shaped sedimentary deposit where a river flowed into a lake more than three billion years ago.
Mars, now cold and desolate, long ago possessed a thicker atmosphere and warmer climate, allowing for liquid water on its surface. Scientists are eager to determine whether Mars ever harbored life. Water is considered a fundamental ingredient for life, making Jezero Crater - with its wet past - a prime place for the rover to study.
Perseverance's most important discovery was announced by NASA last year - a sample from inside the crater of reddish rock formed billions of years ago from sediment on the bottom of the lake that bore potential signs of ancient microbial life. Researchers said minerals detected by the rover could reflect ancient microbial activity but also could form through nonbiological processes.
"Further work evaluating whether these are truly evidence of Martian life requires analysis in terrestrial laboratories that contain the kinds of instrumentation necessary to make that determination," Farley said.
"Perseverance will continue to collect rock samples with the hope for return to Earth by a future robotic or crewed mission," Farley said.
It also has gathered evidence about organic molecules on Mars. In some other findings, Perseverance documented that the Martian atmosphere is electrically active, detecting electrical discharges often associated with whirlwinds called dust devils, and observed an aurora on Mars in visible light for the first time, with the sky glowing softly in green.
In its first years, Perseverance documented the life cycle of the lake that filled Jezero Crater about 3.7 billion years ago. The lake initially was shallow, depositing salt-rich sediments on the crater floor, then deepened to at least 30 feet (9 meters), and sandy sediments were deposited into the lake forming a delta, Farley said.
'THE ORIGIN OF LIFE'
The rover currently is operating just outside Jezero Crater, examining very ancient rocks - likely dating to more than four billion years ago. Mars, like Earth, formed roughly 4.5 billion years ago, so these rocks would date to early in its history.
"Importantly this time period, and this surface environment, are very likely similar to those on Earth when life originated. Because rocks of this era were completely destroyed on Earth, Mars offers a key analog environment in which to investigate pre-biotic chemistry and possibly the origin of life," Farley said.
NASA has a second rover operating on Mars, Curiosity, that landed in 2012 at a location called Gale Crater just south of the Martian equator, and has traveled 22.93 miles (36.91 km). The rover that logged the most mileage on the Martian surface was NASA's Opportunity, which drove 28.06 miles (45.16 km) during a mission lasting from 2004 to 2019.
Perseverance brought with it a small helicopter called Ingenuity that became the first aircraft to achieve powered and controlled flight on another planet, successfully flying in the extremely thin Martian atmosphere 72 times, covering 10.5 miles (17 km) and reaching altitudes up to about 79 feet (24 meters).
The different environments inside and outside Jezero Crater have made this region especially insightful about the Martian past.
"The fact that Perseverance could explore both a lake-river system and the early Martian crust, separated in time by perhaps half a billion years, means the Jezero site keeps on giving scientifically even after five years on the surface," Farley said.
(Reporting by Will Dunham; Editing by Daniel Wallis)
