Seven months and 300 million miles from the spot at Cape Canaveral where it launched, NASA’s Perseverance rover is scheduled to land on Mars at 3:55 p.m. today to begin its search for signs of ancient life and test technology for future human missions to the Red Planet.
“For me, that’s what it’s all about. That question,” said Thomas Zurbuchen, NASA’s associate science mission directorate. “A question that for thousands of years philosophers have asked, scientists have asked … and that is, is there life out there?”
But those last few thousand miles will be the most difficult and dangerous of the mission, and there’s no guarantee the $2.7 billion spacecraft will make it down to its destination, the unexplored Jezero crater, in one piece.
Landing on Mars is so notoriously difficult, the United States remains the only country to ever touch down on the planet, eight times since Viking 1 and 2 launched in 1975. Around the same time Perseverance was launched aboard United Launch Alliance’s Altas V rocket, China and the United Arab Emirates also sent up spacecraft, which successfully entered Mars orbit earlier this month.
“This is one of the most difficult maneuvers that we do in the space business. Almost 50% of the spacecraft that have been sent to the surface of Mars have failed, so we know we have our work cut out for us to get down to the surface safely,” said Matt Wallace, deputy project manager at NASA’s Jet Propulsion Laboratory. “There’s no go-backs. There’s no re-tries.”
Once the rover, which is about the size of a car, reaches the edge of the Martian atmosphere, it’ll be going about 12,000 mph. It’ll separate from the cruise stage that flew it from Florida and needs to slow down to about 1,000 mph to deploy the 70-foot parachute it’s got packed away.
From there, Perseverance will use its “eyes” to find a safe spot to land, a capability that America’s previous rovers didn’t have that allows the probe to take pictures of the surface and match them up against an onboard map to avoid rocky areas.
After shedding more of its outer shell, the rover will engage its jetpack-like descent stage, which will use retrorockets to slow down Perseverance to just 2 mph and lower it to the surface on nylon tethers. All the while, NASA’s ground teams back on Earth won’t be able to communicate with the rover at all, during a period its scientists call the “seven minutes of terror.”
“That all has to happen in about seven minutes, and that all has to happen autonomously,” Wallace said. “Perseverance really has to fight her way down to the surface on her own.”
After Perseverance lands
After the landing is over, Perseverance’s years-long mission is just beginning.
First on the to-do list is taking its first pictures of the Martian surface from Jezero, a 28-mile-wide crater that scientists believe billions of years ago was a river delta. The hope is that Perseverance will snap better shots than the first taken in 1965 during the Mariner 4 fly-by.
It’ll also take audio recordings and sensor readings of the pressure, heat and wind. At this point, the spacecraft will have heated up to about 2,370 degrees. Fortunately, NASA timed the mission so the rover wouldn’t arrive during Martian winter, when dust storms dominate the planet.
Then, over the next month, the Perseverance team will remotely inspect the rover and upload software with the instructions for its search of previous life.
The spacecraft, which weighs about 2,300 pounds, will travel less than a mile a day looking for these “biosignatures,” and over the two years allowed for the search, it’ll explore about 10 miles. Perseverance will “sleep” at night to conserve power.
“What we’re looking for are really the patterns and textures where we have a hard time explaining how that could have formed without the influence of life,” Katie Stack Morgan, a deputy project scientist at JPL, said before the rover’s launch last July. “Our bar is high for the identification of a sign of life on another planet, as it should be, because we don’t want to make that discovery lightly. But at the same time … I think we also have to open our minds to the possibilities of what life would look like on another planet.”
Using the rover’s robotic arm, NASA will have about 30 to 40 tries to drill for possible biosignatures, which will be collected in titanium test tubes that NASA has called “one of the cleanest things that’s ever been built.” It was very important to ensure they weren’t contaminated on Earth and won’t be compromised on the way back.
NASA expects the rover to arrive at its first sample site, a flat part of the crater, by the summer. Once there it will perform the first test flight of a 4-pound helicopter that also hitched a ride to Mars. If it’s successful, the helicopter - named Ingenuity – could be used to explore more of the surface that the rover can’t reach.
The rover will also test a tool that can turn carbon dioxide into oxygen and swatches of spacesuit material to see how they hold up on Mars.
But unlike pre-pandemic missions, NASA’s teams of scientists, engineers and astrobiologists will be apart. They’ll also be on a topsy-turvy Martian-time sleep schedule, working mostly during the night.
“The science team is not going to be shoulder-to-shoulder doing this,” said Ken Farley, a Mars 2020 project scientist based at CalTech. “For the foreseeable future, we are going to be operating remotely, so literally the science mission is going to be executed from people’s living rooms and bedrooms all around the world.”
Getting the samples back to Earth
After the rover spends about two years (one Mars year) searching for and stowing samples, the next trick is getting those test tubes back to Earth. But it won’t be until 2031 that the samples arrive, following a complicated recovery joint mission with the European Space Agency. And even then, analyzing the samples won’t be quick work.
In 2026, NASA will launch a lander on a two-year journey back to Mars, packed inside it another rover to collect the test tubes and a small rocket to jettison them away from Mars in 2029. By that time, a European orbiter also will have made its way to the Red Planet, waiting for the small rocket to hand over the goods.
The samples will arrive in a thrice-sealed container in Utah.
David Parker, director for human and robotic exploration for ESA, said its portion of the return mission is about $1.8 billion and NASA’s $3 billion.
But even then, there is the great possibility the test tubes won’t contain signs of ancient life, that the samples were not more than pieces of the rocky Martian surface. In that case, Farley said, NASA would need to keep looking to answer that age-old question: are we alone?
“This will be the first time that we have peered in great detail into a past habitable environment, both with the tools on the rover and with the samples when they come back,” he said. “And we either will find life that is there and that will be a spectacular discovery, or … maybe we won’t.”
But maybe they will.