It’s time to land a car on Mars. After 6 months of flight, 8 years of planning, and decades of scientific desire, NASA is set to put the Perseverance rover on the surface of the Red Planet. If success comes tomorrow, it will mark the first chapter of an audacious scientific campaign to drill and collect samples—and bring them back to Earth. But before the mudstone can be drilled, and before an onboard helicopter can fly, the $2.7 billion rover must first safely land at Jezero crater, which billions of years ago contained a lake and a river delta—auspicious places to look for life.
There’s little to do but wait. On Friday, engineers from NASA’s Jet Propulsion Laboratory (JPL) sent a simple command to the rover: “Do EDL.” That began the process of entry, descent, and landing, sending the rover, encased in a protective heat shield and backshell, barreling toward the planet. The landing sequence will mirror that of the Curiosity rover, a near-clone that landed in 2012. “We are headed exactly where we want,” says Jennifer Trosper, the mission’s deputy project manager at JPL. “The spacecraft is focused. The team is focused. And we are all ready to go.”
Tomorrow, at 3:27 p.m. EST, the rover will separate from the cruise stage that ferried it to Mars, dropping tungsten weights to angle its entry into the thin martian atmosphere at hypersonic speeds. (Events will be received on Earth on an 11-minute, 22-second radio delay, with NASA streaming a live feed from JPL’s control room.) At 3:38 p.m., the heat shield will hit temperatures of 1300°C, hot enough to melt iron. Whereas Curiosity deployed its parachute once it hit a set speed, Perseverance will wait until it gets within range of the landing site. It’s a trivial change in-flight software—one line of code—that engineers expect will make its arrival 10 times more precise than Curiosity’s.
Twenty seconds after the parachute deploys, the heat shield will eject, allowing a radar and cameras arrayed on the rover’s belly to look for hazards in the terrain below. The rover will orient itself by comparing what it sees to stored high-resolution maps created by Mars orbiters. After identifying a safe haven among the crater’s cliffs, sand dunes, and boulders, the rover and its sky crane—a sort of rocket-propelled hovercraft—will detach from the parachute.
A minute later—about 3:55 p.m. for those watching from Earth—the sky crane, now falling at only 2.7 kilometers per hour and 20 meters above ground, will lower the rover to the surface, unspooling it with nylon cords. After the rover deploys its six cleated aluminum wheels, explosively powered blades will sever the cords, sending the sky crane to fly and crash a safe distance away, says Erisa Stilley, an EDL engineer at JPL. “And now we’re on the surface of Mars,” she says. “We have a brand new baby spacecraft in its new environment ready to start rolling around.”
If the rover lands where engineers want it to, it will find itself staring at a 70-meter cliff of mudstone, the edge of Jezero’s fossilized delta. Within minutes, the rover should peer through clear dust covers on its hazard cameras to spy the ground in front and behind it. Microphones and commercial video cameras attached to the spacecraft should capture, for the first time, the sights and sounds of landing, though that material won’t be available for several days. And something else will be listening: NASA’s InSight spacecraft, thousands of kilometers away, will use its sensitive seismometer to record the impact of Perseverance’s tungsten weights on the surface.
After a safe landing, the rover will begin a campaign to drill more than 30 rock and soil samples and cache them in pristine tubes to be picked up by a subsequent mission. Some 3.8 billion years ago, a thicker and warmer martian atmosphere allowed water to flow on the surface: One river penetrated Jezero crater and filled it nearly to the rim. It would have been a lovely place for any microbial life to evolve, analogous to some lakes on Earth today. But Perseverance, though armed with an array of scientific instruments, is unlikely to spy signs of past life on its own. Rather, these samples will be returned to Earth for analysis, allowing researchers to probe the geological and climatic history of Mars, and why life did, or didn’t, evolve in these conditions.
NASA and the European Space Agency have already approved the two multibillion-dollar missions needed to collect these samples, which could launch in 2026 or 2028. Those rocks wouldn’t be delivered to Earth until the early 2030s—students who are teens today could investigate these samples for their future dissertations. It’s “the planetary science endeavor of our generation,” says Bobby Braun, JPL’s director of Solar System exploration. “If we work together over a timescale of decades, it’s just within our reach.”
But first, the rover must land.