Watch Live: Perseverance Rover’s Landing on Mars Updates

NASA’s latest robotic explorer will reach Mars on Thursday afternoon, the third spacecraft to arrive at the planet this month after visitors from the United Arab Emirates and China. The Perseverance rover is headed to Jezero Crater, a place that planetary scientists think could be an ideal place to find preserved signs of life from several billion years ago, if life ever did arise on Mars.

But first, NASA’s mission has to land in one piece.

Touchdown is expected around 3:55 p.m. Eastern time. NASA Television will begin broadcasting coverage from the mission’s control room at the Jet Propulsion Laboratory in California at 2:15 p.m. Or you can watch it in the embedded video player above.

Shortly before 2:30 p.m., NASA set the rover to operate on its own as it prepares for landing. During the descent, the spacecraft will send updates on how it is doing. Because its main antenna will not be pointing at Earth, its direct communications will just be a series of simple tones.

“We can use those tones to tell us different things, like the heat shield has come off or something like that,” Allen Chen, the lead engineer for the landing part of the mission, said during a news conference on Wednesday.

It is possible that Perseverance will send back some photographs from the surface through NASA’s Mars Reconnaissance Orbiter, but they could take hours to arrive. “If we get that, that’s golden,” said Jennifer Trosper, a deputy project manager for the mission.

In a nutshell, Perseverance will have to decelerate from more than 12,000 miles per hour to a full stop during what NASA calls “seven minutes of terror,” for the period of time from the rover’s entry into the atmosphere until its landing. There is no chance for a do-over. The path of Perseverance will intersect with the surface of Mars. The only question is whether the rover will end up in one piece, ready to begin its mission, or smashed into many pieces.

The thin atmosphere of Mars adds several levels of difficulty. A spacecraft needs a heat shield, because friction from the air molecules heats its bottom side to thousands of degrees. But there is not enough friction to slow it down for a gentle landing with just parachutes.

The spacecraft will have to handle the landing operation all by itself. It takes 11 minutes for a radio signal to travel from Mars to Earth. That means if anything were to go wrong, it would already be too late by the time people in NASA’s mission operations center got word.

“It all has to happen autonomously,” said Matt Wallace, a deputy project manager. “Perseverance really has to fight her way down to the surface on her own. It’s something like a controlled disassembly of the spacecraft.”

First, a capsule-shaped container holding the rover separates from the part of the spacecraft called the cruise stage. That section held systems that were needed for the 300 million-mile journey from Earth to Mars but would be of no use for getting through the Martian atmosphere.

About 80 seconds after entering the atmosphere, the spacecraft experiences peak temperatures, with the heat shield on the bottom of the capsule reaching 2,370 degrees Fahrenheit. Inside the capsule, it’s a lot less toasty — about room temperature. As the air becomes denser, the spacecraft continues to slow.

Small thrusters on the top of the capsule fire to tweak the angle and direction of its descent and keep it on course toward its landing site.

At an altitude of about seven miles, four minutes after entry into the atmosphere, the capsule is traveling at a speed under 1,000 miles per hour. It then deploys a huge parachute, more than 70 feet in diameter.

The spacecraft now drops the heat shield, allowing cameras and other instruments to take note of the terrain below to determine its position.

Even with the huge parachute, the spacecraft is still falling at about 200 miles per hour.

The next crucial step is called the sky crane maneuver. The top of the capsule, called the backshell, is let go and is carried away by the parachute. There are two pieces of the spacecraft left. The top is the descent stage — in essence a rocket-powered jetpack carrying the rover beneath it. The engines of the descent stage fire, first steering to avoid a collision with the backshell and the parachute. Then the engines slow the descent to less than two miles per hour.

About 66 feet above the surface, the rover is then lowered on cables. The descent stage continues downward until the wheels of the rover hit the ground. Then the cables are cut, and the descent stage flies away to crash at a safe distance from the rover.

It has worked once already. The Curiosity rover, which is currently on Mars, successfully used the same landing system in 2012. But spacecraft are complicated systems, and one success does not guarantee a second success.

Perseverance has stronger parachutes and a more precise navigation system. NASA engineers say they have tried to take every step to improve the chances that everything will work, but they do not know if they have figured out every contingency.

“We’ve never really come up with a good way of calculating the probability of success,” said Mr. Wallace, the deputy project manager.

Over the decades, NASA has succeeded in eight of nine landing attempts on Mars. The only failure was the Mars Polar Lander in 1999. (Two basketball-size probes carried by that mission that were released during descent and designed to survive impact also did not work.)

Steve Jurczyk, the acting NASA administrator, acknowledged in an interview, “I will be extremely nervous.”

Over the past 20 years, NASA has gradually asked more complex questions about Mars. First, the mantra was “Follow the water,” as that is where there once may have been life. With giant canyons, winding river channels and signs of dried-up lakes, it has been clear that in the past, water has flowed on Mars even though the planet is cold and dry today.

Perseverance’s destination is Jezero Crater. The rover will explore the delta of a river that once flowed into a lake that filled the crater. The piles of sediments are a promising place where the fossil chemical signatures of ancient Martian microbes might still be preserved today.

The rover is largely the same design as the Curiosity rover, which is now studying the Gale Crater. But it is carrying a different set of instruments, including sophisticated cameras, lasers that can analyze the chemical makeup of rocks and ground-penetrating radar. Tests of these tools on Earth demonstrated the possibilities of finding preserved signs of past life.

The mission will also collect a series of rock and dirt samples to be picked up by a future mission to Mars and eventually brought back to Earth.

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NASA’s new rover is carrying a four-pound helicopter called Ingenuity that will attempt something that has never been done before: the first controlled flight on another world in our solar system.

Flying on Mars is not a trivial endeavor. There is not much air there to push against to generate lift. At the surface of Mars, the atmosphere is just 1/100th as dense as Earth’s. The lesser gravity — one-third of what you feel here — helps with getting airborne. But taking off from the surface of Mars is the equivalent of flying through air as thin as what would be found at an altitude of 100,000 feet on Earth. No terrestrial helicopter has ever flown that high, and that’s more than twice the altitude that jetliners typically fly at.

NASA’s engineers used a series of materials and computer technology advancements to overcome a number of these challenges. About two months after landing, Perseverance will drop off the helicopter from its belly, and Ingenuity will attempt a series of about five test flights of increasing duration.

If the tests succeed, it could pave the way for future, larger Marscopters. Having the option of using robotic fliers could greatly expand a space agency’s ability to study the Martian landscape in more detail, just as the transition from stationary landers to rovers did in earlier decades.

Send a robotic spacecraft to Mars, grab some rocks and dirt and bring those back to Earth.

How hard could that be?

It’s more like an interplanetary circus act than you might imagine, but NASA and the European Space Agency think that now is the time they can finally pull off this complex choreography, tossing the rocks from one spacecraft to another before the samples finally land on Earth in 2031.

One of the key tasks of Perseverance is to drill up to 39 rock cores. Each sample of rock and dirt, weighing about half an ounce, will be sealed in an ultraclean cigar-size metal tube, and Perseverance is to drop each tube back on the surface.

Under current plans, the samples will wait in the cold as the rover continues its studies of Jezero crater.

Two spacecraft are to blast off to Mars in 2026 as part of a mission to bring the rocks back.

One will be a NASA-built lander that will be the heaviest vehicle ever put on the surface of Mars. It will be carrying a rover, built by the Europeans, to pick up the rock samples, and a small rocket that will launch the rocks to orbit around Mars. It will arrive in August 2028, and the rover will make a dash to collect at least some of the rock samples and bring them back and transfer them to the lander for launch off Mars.

Waiting above Mars for the sample container, about the size of a soccer ball, will be the Earth Return Orbiter, built by the European Space Agency. Assuming it captures the container successfully, the orbiter would then depart Mars. As it approached Earth, it would eject the samples, which will land in the Utah desert.

The mission is expected to cost several billion dollars, but this is a long-sought goal of Mars scientists, to closely study rocks and see if they discern whether life once existed on Mars.

“To really get into some of the really intriguing questions at a detail level means we need to parse the evidence down on the molecular level and try to tease the information out of very, very old material,” James Watzin, the director of the Mars exploration program at NASA, said in an interview in 2020. “And that requires a whole suite of instrumentation that was clearly too large to shrink and send to another planet.”

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Whether or not Perseverance sticks its landing on Thursday, it won’t be the only spacecraft to attempt to touch down on Mars in one piece this year.

China was the second country to arrive at Mars this month, pulling into orbit on Feb. 10 with its Tianwen-1 spacecraft. China’s lunar exploration program has accomplished a great deal in the past decade, and Tianwen’s travel is the country’s first successful journey to another planet in our solar system.

Video released by China’s space agency last week showed the red planet as Tianwen-1 began its orbit. In washed-out colors, cameras on the spacecraft captured Martian haze and some of the planet’s surface features as the probe raced past.

China has now adjusted Tianwen-1’s orbit to pass over the planet’s poles, similar to the orbits used by some NASA and European spacecraft for scientific observations of the surface. It will begin preparations for releasing a lander and robotic rover that will head to the surface. China has stated that this landing attempt will occur in May or June. Its destination is Utopia Planitia, a large impact basin on the red planet’s surface. Once it lands successfully — if it does — China’s space agency plans to announce the rover’s name.

NASA’s rover is the third spacecraft to arrive at the red planet this month. Two more robotic probes, built by the United Arab Emirates and China, went into orbit last month. All three spacecraft launched in July 2020, aiming to take advantage of the period every two years when the journey between Earth and Mars is shorter than usual.

The first new visitor to Mars was Hope, a robotic probe from the United Arab Emirates sent on a path toward Mars last summer by a Japanese rocket. The spacecraft was built at the University of Colorado’s Laboratory for Atmospheric and Space Physics, with Emirati engineers and scientists working closely alongside American counterparts.

Until last year, the United Arab Emirates’ small space program had only built Earth observation satellites and had sent one astronaut for a brief stay aboard the International Space Station. Its Mars orbiter expanded the program’s ambition, with a long-term goal of inspiring more Emiratis to pursue careers in science and technology.

But the Hope spacecraft will also aid planetary scientists on Earth. During its mission of at least two years, it will collect data on how dust storms and other weather conditions near the surface affect the speed at which Martian air leaks into outer space. This could help further understanding of how Mars, a world that had running water on its surface in the early days of the solar system, turned into the cold and seemingly lifeless world that it is today.

The spacecraft pulled into orbit on Feb. 9. On Sunday, the Emirates released a direct image of Mars captured by Hope, made at a distance of about 15,000 miles on Feb. 10. Half of the rust-colored world emerges from shadow, revealing some of the giant Martian volcanoes, including Olympus Mons, the largest volcano in the solar system, as well as an icy region at its northern pole.