Racing through space at more than 12,000 mph, NASA’s Perseverance Mars rover reached Mars on Thursday and pulled off a thrilling seven-minute plunge through the atmosphere to land on the surface of the red planet to look for evidence of past microbial life in the remnants of an ancient lake.
“Touchdown confirmed! Perseverance is safely on the surface of Mars, ready to begin seeking the signs of past life!” Swati Mohan, a guidance, navigation and control officer monitoring telemetry at the Jet Propulsion Laboratory, called out as the rover touched down. Elated, if socially distanced, flight engineers burst into cheers and applause, anxiety giving way to relief in the joy of the moment.
The relief was understandable. Frequently described as “seven minutes of terror,” the rover’s descent was a nail-biting sequence of computer-orchestrated make-or-break events that had to work in near flawless fashion to get the 2,260-pound rover safely down on an ancient lakebed in Jezero Crater, avoiding dangerous cliffs, large boulders and sand dunes in the process.
And the $2.4 billion rover did just that.
“I almost feel like I’m in a dream,” said Jennifer Trosper, deputy project manager. “Our job is to think of all the bad things that can happen and try to avoid those, and when all good things happen, you feel like you’re dreaming. And I’m happy to feel like I’m dreaming!”
President Biden tweeted: “Congratulations to NASA and everyone whose hard work made Perseverance’s historic landing possible.”
The rover hit the top of the discernible Martian atmosphere at 3:48 p.m. EST and quickly decelerated in a blaze of atmospheric friction, its protective heat shield enduring temperatures as high as 2,700 degrees — hot enough to melt stainless steel — and a braking force of 10 times the force of gravity on Earth.
Slowing to just below 1,000 mph, it deployed a giant 70.5-foot-wide parachute in the supersonic slipstream and used an advanced guidance system to identify hazards and pick out a safe landing spot on the floor of Jezero Crater.
Then, less than a minute from touchdown, at an altitude of about 2.1 miles, Perseverance fell free of its parachute while still descending at about 200 mph. Seconds later, eight engines in a rocket-powered backpack fired up, slowing the craft to less than 2 mph by the time it reached an expected altitude of just 70 feet or so.
At that point, Perseverance was lowered toward the surface suspended by tethers while the jet pack continued the descent. At 3:55 p.m., the rover’s six wheels settled to the surface, the tethers were cut and the “sky crane” backpack flew off to crash a safe distance away.
“Hello, world,” Perseverance “tweeted” a few minutes after landing, posting the rover’s first image of its landing site. “My first look at my forever home.”
Earth dropped below the horizon as viewed from Jezero Crater about a minute before touchdown, cutting off direct-to-Earth X-band radio signals from Perseverance. But UHF signals confirming the landing were relayed to JPL by NASA’s Mars Reconnaissance Orbiter, which was passing overhead.
“Sky crane maneuver has started. about 20 meters above the surface,” Mohan reported as the rover’s descent neared its conclusion.
“We’re still getting signals from MRO,” an engineer reported
“Touchdown confirmed! ” Mohan called a moment later.
A few moments later, the first image from one of the rover’s hazard cameras came in, showing a relatively flat surface with no large boulders or other obstacles in view. “YES! Whoo Hoo!” an engineer exclaimed as the photo flashed up on control room displays.
The rover’s automated descent appeared to go flawlessly as its flight computer used multiple cameras, radar and other sensors to figure out exactly where it was in relation to the planned landing target. The rover then adjusted its course as required to avoid possible missions-ending hazards.
Perseverance had to pull off the landing on its own because radio signals, moving at 186,000 miles per second, needed more than 11 minutes to cross the 127-million-mile gulf between Earth and Mars. Flight engineers at JPL could only sit and wait, watching data trickle in 11 minutes after the fact.
And to their relief, seven months after launch from Cape Canaveral and an interplanetary cruise covering 293 million miles, NASA’s fifth Mars rover, the first designed specifically to look for signs of past life, was safely on the surface of the red planet.
Jezero Crater was targeted because it once held a 28-mile-wide body of water the size of Lake Tahoe. The ancient lake was fed by a river that cut through the rim of the crater, depositing sediments in a fan-like delta clearly visible from orbit. The rover landed about 1.2 miles to the southeast of the delta, near the center of its predicted 4.8-by-4.1 mile landing footprint.
“We think we’re facing southeast based on the shadows, about 140 degrees,” Trosper said. “The tilt is flat, it’s about 1.2 degrees. The the power system looks good … everything looks great.”
A robot geologist on Mars
Assuming no major problems develop, engineers plan to spend about 90 days checking out the rover’s complex instruments and systems.
During the first month, they also plan to deploy and test a small 4.5-pound, $80 million helicopter named Ingenuity that will attempt the first powered flight in the thin air of Mars, a “Wright brothers’ moment” on another world.
Another experiment will test the feasibility of extracting oxygen from the Martian atmosphere, technology that could someday help future astronauts produce their own air and rocket fuel.
But the primary goal of the mission is to look for signs of past biological activity.
Equipped with a robot arm, a core-sampling drill and a suite of sophisticated cameras, rock-vaporizing lasers and other instruments, Perseverance will study lakebed deposits, venture across the delta and eventually make its away up to the ancient lake’s shoreline, collecting promising samples along the way.
Selected rocks and soil will be placed in a complex internal carousel mechanism that will autonomously photograph, analyze and load them in lipstick-size airtight tubes. The rover will then deposit, or cache, the sealed samples on the surface of Mars to await pickup.
NASA and the European Space Agency plan to send another rover to Jezero later this decade to collect the samples, load them into a small rocket and blast them into Mars orbit where yet another spacecraft will snag them for the return flight to Earth.