February 18, 2021

— NASA now has six new wheels sitting on the surface of Mars, ready to begin the first dedicated search for signs of life to return to Earth.

The space agency's Perseverance rover touched down on the Red Planet on Thursday (Feb. 18), landing in Jezero Crater, the site of a 3.5-billion-year-old river basin located in the Martian northern hemisphere. Confirmation of the safe landing came at 3:55 p.m. EST (2055 GMT), after the roughly 11 minutes needed for the rover's signal to reach Earth.

"Touchdown confirmed! Perseverance is safely on the surface of Mars ready to begin seeking the signs of past life," declared Swati Mohan, an entry, descent and landing (EDL) engineer at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, from where the Perseverance mission is being managed.

The announcement was quickly followed by the transmission of Perseverance's first images, showing the landscape in front of and behind the rover.

Perseverance lands on Mars. Click to enlarge video in a new, pop-up window. (NASA)

The primary goal for the Mars 2020 Perseverance rover is to collect documented rock and soil samples that may contain the signs of, or characteristics capable of supporting, ancient microbial life for a future mission to collect and then return to Earth. The rover is also carrying several technologies to support future expeditions to Mars, including an experiment to produce oxygen from the carbon dioxide atmosphere and a helicopter named "Ingenuity" that will attempt the first powered, controlled flight on another planet.

Perseverance is NASA's fifth rover and ninth spacecraft to land on Mars, including the Curiosity rover, which in January marked its 3,000th day exploring Gale Crater, and the InSight probe, which touched down in 2018.

"Perseverance builds on the long history of systematic, science-driven exploration of Mars that has been enabled by ever better technologies and systems," Thomas Zurbuchen, NASA's associate administrator for science, said in a press briefing previewing the landing on Tuesday. "Right now, InSight is taking measurements of Mars-quakes, Curiosity is focused on the geological and the chemical evolution of Gale Crater and two orbiters are out there, new in the last couple of weeks, joining other orbiters from NASA and other agencies in learning more about this planet."

"Our journey [at Mars] has been from following the water through seeing whether this planet was habitable to finding complex chemicals. Now we're at the advent of an entirely new phase, returning samples, an aspirational goal that has been with the science community for decades," Zurbuchen said.

Seven minutes survived

Like Curiosity, which in August 2012 survived what the engineers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California dubbed the "seven minutes of terror," Perseverance followed a similar seven-minute approach down to the surface of Mars — only this time, it targeted a much more challenging landing site.

Perseverance's descent began with its aeroshell encountering Mars' atmosphere, shielding the rover from temperatures that built up to about 2,370 degrees Fahrenheit (1,300 degrees Celsius). After entry was complete, a 70.5-foot (21.5-m) parachute deployed at a time that was based on the spacecraft's distance to the target in Jezero Crater.

"The biggest difference for Perseverance since the Curiosity mission is using what we call 'range trigger,'" Erisa Stilley, Perseverance's entry, descent and landing (EDL) systems engineer at JPL, told reporters. "This is a change in the way that we deploy our parachute. Curiosity deployed based on an estimated velocity. For Perseverance, we are using an estimated range that allows us to more precisely control the distance from the target."

The result was a smaller, more precise landing ellipse, or target landing area. The ellipse for Perseverance was 10 times smaller in area than Curiosity's and almost 300 times smaller than that of the first Mars rover, Sojourner, in 1997.

With the parachute deployed, the aeroshell separated and dropped away to reveal a radar and cameras for Perseverance's other new landing technology. Using terrain-relative navigation, the rover was able to determine its location and choose the best reachable place to land.

"The first thing we do is take images with a camera on board and compare those to a map on board, which allows Perseverance to reduce the error in where it thinks it is from kilometers to tens of meters," said Stilley. "It then uses a second on board map based on where we can currently divert to at that point in time and searches that area to find the safest place that it can fly to."

"That all happens in the 2.4 seconds it takes for Perseverance to send commands to separate from its back shell and start to free fall," she said.

Igniting eight retrorockets on its descent stage, Perseverance continued to slow its approach to the surface, decelerating from about 190 mph (306 kph) at 6,900 feet (2,100 m) to 1.7 mph (2.7 kph) by the time it was 66 feet (20 m) above the ground.

Finally, when the descent stage was 65 feet (20 m) over the landing area, it initiated the sky crane maneuver, lowering Perseverance 25 feet (7.6 m) by nylon cords until the rover touched down in Jezero Crater. The cords then severed, allowing the descent stage to fly a safe distance away before impacting Mars.

On the surface

Having made it through the 203-day, 293-million-mile (471-million-km) journey from Earth and the seven minutes to the surface, Perseverance will spend its first month on Mars undergoing system and engineering checks.

Although similar in configuration to Curiosity, Perseverance is slightly larger and is outfitted differently to achieve its search for life and sample collection mission.

"She looks a lot like Curiosity but she's packed with a whole bunch of new science instruments," said Adam Steltzner, Perseverance's chief engineer at JPL. "She's a little bigger than Curiosity; although she is a twin, she's a few inches longer, about 250 pounds [114 kg] heavier and she's a lot more capable."

In addition to having sturdier wheels and a different drill package, Perseverance will also use its new navigation technology to more quickly traverse Jezero Crater.

"Curiosity needs to either drive or think about driving, but not do both at the same time. We have used a piece of technology that we originally brought on for terrain-relative navigation, a special visual processor, to allow us to move Perseverance at three times the rate of Curiosity," said Steltzner.

During its first 30 Martian days (sols, each about 24 hours, 39 minutes, 35.244 seconds long), Perseverance is expected to take inspection images of its wheels, deploy its mast and high-gain antenna, photograph its landing site surroundings and the top of its instrument deck and perform a health check of its systems, all before performing a short drive test and extending its 7-foot (2.1-m) robotic arm.

Perseverance will then jettison the pan that protected its sampling system during landing, calibrate its camera systems and deploy the sample-tube-handling robotic arm inside its body.

Taking flight, collecting samples

Once Perseverance's systems are checked out, the rover will be commanded to find a flat area to act as a helipad for the Ingenuity helicopter. In the first month or so after landing, if all goes well, the rover will deploy Ingenuity in the center of this area and drive a safe distance away (about 330 feet, or 100 m).

The helicopter's team will then have up to 30 sols to perform a series of flight tests with Ingenuity, as Perseverance serves as a communications relay, weather station and photographer (and maybe cinematographer) for the demonstration.

"The first flight will ascend to about three meters in height and hover for about 20 seconds," said MiMi Aung, Ingenuity's project manager at JPL. "It will truly be a Wright brothers' moment, but on another planet."

From there, Perseverance will begin its surface operations phase, searching Jezero Crater for signs of ancient microbial life, characterizing the climate and geology of Mars, and collecting cached samples for a future return to Earth. In the process, Perseverance is expected to cover more ground than any previous Mars rover. Perseverance is designed to drive on average about 650 feet (200 m) per Martian day, which is nearly the current planetwide record drive distance in a day.

"We expect we might traverse up to 10 miles [16 km] in the prime mission, in two Earth years [or] one Mars year," said Ken Farley, Perseverance's project scientist at the California Institute of Technology (Caltech) in Pasadena, California. "And we expect that sometime in the summer, we will be ready to take our first sample."

Perseverance's drill is designed to cut intact rock cores that are about the size of a piece of chalk and then place them into pristine sample tubes, which will then either be stored aboard the rover until reaching an appropriate drop-off location or be delivered to a future lander as part of a planned Mars sample return campaign by NASA and the European Space Agency (ESA).

To identify what samples to collect, the rover will use its SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) spectrometer to detect organic matter and minerals and its PIXL (Planetary Instrument for X-ray Lithochemistry) spectrometer to map the composition of rocks and sediments. It will also use its laser-equipped SuperCam to vaporize rock and regolith, and RIMFAX (Radar Imager for Mars' Subsurface Experiment) to probe geological features underground.

"Perseverance is the first real astrobiology mission since Viking," said Lori Glaze, director for planetary sciences at NASA Headquarters in Washington, referring to the pair of probes that were the first to land on Mars 45 years ago. "Viking had an intent to look for life, but now that we've learned so much more — not just about Mars, but about how life forms and how it exists — we know the experiments that we designed were probably not quite the right way to go about that exercise."

"The new knowledge that we have gained over the last several decades has really helped us to design our first 'mobile astrobiologist,'" said Glaze.

In addition to its science mission, Perseverance also carries three fingernail-sized silicon chips etched with the names of the nearly 11 million people who signed up with NASA and the 155 finalist essays in the space agency's "Name the Rover" contest (Perseverance was named by Alex Mather, a secondary school student in Burke, Virginia). The rover also carries a plaque in tribute to the front line medical workers who faced the coronavirus pandemic while Perseverance was in the final stages of being prepared for its mission to Mars.