NASA’s Mars rover successfully touched down on the Red Planet February 18 afternoon.

The spacecraft, called Perseverance, traveled 293 million miles from its launchpad at Florida’s Cape Canaveral on July 30. Mask-donning mission leaders at NASA’s Jet Propulsion Laboratory burst into applause when, 203 days after takeoff, they received confirmation of the probe’s landing.

Now the real mission begins. Perseverance is set to spend at least one Martian year—equivalent to about two Earth years—collecting rocks, testing new technologies, and, most significantly, hunting for signatures of life on the neighboring world.

“We don’t know what these pristine samples from Mars will tell us,” said Thomas Zurbuchen, associate administrator for science at NASA, in a statement. “But what they could tell us is monumental—including that life might have once existed beyond Earth.”

I’m safe on Mars. Perseverance will get you anywhere.

#CountdownToMars

— NASA's Perseverance Mars Rover (@NASAPersevere) February 18, 2021

Perseverance will get you anywhere

Perseverance is the ninth spacecraft to land safely on Mars since the 1970s.

All successful Martian touchdowns—only about half the missions stuck their landing—belong to the U.S., though other countries made unlucky attempts. China could become the second country to triumph; its Tianwen-1 probe is en route to the Martian surface today. (Up for debate: In Dec. 1971, the USSR’s Mars 3 lander touched down and promptly disconnected, less than two minutes later, during its first radio transmission.)

Perseverance picks up where past missions left off. In 1971, the U.S.’s Mariner 9 orbiter spotted ancient riverbeds using satellite imagery. Most recently, NASA’s Curiosity rover in 2012 confirmed, through inspection of telltale, conglomerate rocks, the existence of running water in the desert planet’s past.

Satisfied that water flows once existed on Mars, scientists are now pursuing the next logical line of inquiry: Did the planet ever support life? It’s up to Perseverance to find out.

Looking for signs of life

To hunt for traces of organisms from the distant past, scientists chose to investigate a place on Mars where they believe water once flowed: Jezero Crater.

A meteorite impact formed the 28-mile-wide crater more than 3.5 billion years ago. At that time, the site, located near a river delta basin—a Martian version of something like the Mississippi River delta basin here on Earth—would have flooded with water. A lake about the size of California's Lake Tahoe resulted.

That since-dried-out lake bed could contain microbial fossils, scientists wager. So they’re setting Perseverance to task exploring the geology and shoreline sediments, looking for organic molecules and other so-called biosignatures. The rover will gather samples that could, at a later date, be returned to Earth, where more sophisticated equipment can then inspect it.

Getting warmed up

Before Perseverance can go exploring, it has to get warmed up.

Engineers have started checking the car-size rover’s operational systems, a process that could take a month. Following that, the rover is slated to test an unmanned helicopter, called Ingenuity, that will scout out the terrain and demonstrate a new form of transportation that could come in handy on future missions.

Altogether, these phases could take two months to complete. After that, the rover will get, well, roving. The lab-on-wheels is set to cross a 10-mile span from the crater’s floor up to its rim. Along the way, it will drill into rocks, place core samples in a few dozen tubes, and store the lot in a special cache for later retrieval.

The guts of the machine

Just a few years ago, landing in and navigating a site like Jezero Crater might have been too treacherous for scientists to attempt.

But Perseverance has benefited from recent technological advances, including self-driving software smarts that make navigation easier. There’s also more far-out technology, like the helicopter drone and a device on board that’s designed to act like a tree, taking in carbon dioxide and turning it into oxygen—useful for both propellant and, maybe one day, human respiration.

The rover is outfitted with two microphones, 23 cameras, and seven other sensors that will survey the ground, analyze soil, and scan for organic compounds. Perseverance will persevere through the frozen conditions of Mars, which can reach temperatures as low as minus 130 F, and power through generating electricity by the natural decay of a radioactive plutonium isotope.

The burden of proof

Already, the machine is beaming back images.

An open horizon, with so much to explore. Can’t wait to get going.

#CountdownToMars

— NASA's Perseverance Mars Rover (@NASAPersevere) February 19, 2021

Scientists have high hopes for the mission. Steve Jurczyk, NASA’s acting administrator, called the landing “one of those pivotal moments for NASA, the United States, and space exploration globally—when we know we are on the cusp of discovery and sharpening our pencils, so to speak, to rewrite the textbooks.”

But proving life existed on Mars is no easy feat. As Lori Glaze, director of NASA’s Planetary Science Division, noted in a statement, there’s an “enormous burden of proof” to overcome.

A definitive answer “may very well require the far more capable laboratories and instruments back here on Earth to tell us whether our samples carry evidence that Mars once harbored life,” she said.