NASA's newest Mars rover won't just explore the Red Planet; it will, the space agency hopes, help a little bit of Mars make it to Earth a decade or so from now.
Known as Perseverance, the rover will hunt for signs of habitable environments on Mars while searching for signs of past microbial life. The robotic traveler will also cache a series of samples that can be returned to Earth by a future campaign.
Perseverance is the centerpiece of NASA's $2.7 billion Mars 2020 mission, which blasted off from Cape Canaveral, Florida, on July 30, 2020, at a time when Earth and Mars were positioned to require the least amount of power for interplanetary travel. It landed precisely and gently on the surface of Mars via sky crane on Feb. 18, 2021, with an initial mission duration of at least one Martian year, or 687 Earth-days.
The car-sized rover is about 10 feet long (not including its robotic arm), 9 feet wide, and 7 feet tall (about 3 meters long, 2.7 m wide, and 2.2 m tall). At 2,314 lbs. (1,050 kilograms), Perseverance weighs less than a compact car.
Mixing old and new
If photos and sketches of the Perseverance rover look familiar, that's because the robotic explorer is largely based off its predecessor, the Mars Science Laboratory (MSL) Curiosity rover. Roughly 85% of the new rover's mass is based on this "heritage hardware."
"The fact that so much of the hardware has already been designed — or even already exists — is a major advantage for this mission," Jim Watzin, director of NASA's Mars Exploration Program, said in a statement. "It saves us money, time and most of all, reduces risk."
Like Curiosity, Perseverance has a rectangular body, six wheels, an arm and hand, cameras and instruments, and a drill for sampling rocks. But the new rover has different goals that require a suite of cutting-edge instruments. Using an X-ray spectrometer and an ultraviolet laser, Perseverance will seek out biosignatures from the past on a microbial scale. A ground-penetrating radar will be the first rover instrument to look under the surface of Mars, mapping layers of rock, water and ice up to 33 feet (10 m) deep.
"Our next instruments will build on the success of MSL, which was a proving ground for new technology," said George Tahu, NASA's Perseverance program executive. "These will gather science data in ways that weren't possible before."
These upgrades kicked in before the rover ever touched the surface of Mars. NASA's Jet Propulsion Laboratory, which is developing and managing the mission for the space agency, also developed a new landing technology called terrain-relative navigation. As the mission hardware approached the Martian surface, it used a computer to compare the landscape with pre-loaded terrain maps, guiding the descending mission to a safe landing site and making corrections on the way down.
Read more about the technology needed to land Perseverance safely on Mars.
A related feature, known as a range trigger, used location and velocity to determine when to open the spacecraft's parachute, narrowing the landing ellipse by more than half.
"Terrain-relative navigation enables us to go to sites that were ruled too risky for Curiosity to explore," said JPL's Al Chen, the Perseverance entry, descent and landing lead. "The ranger trigger lets us land closer to areas of scientific interest, shaving miles — potentially as much as a year — off a rover's journey."
Cameras on the spacecraft filmed the final journey, capturing the heat shield falling away, the opening of the parachute and the sky crane's deployment above the Red Planet for the first time.
"It is quite a ride," Ian Clark of JPL, the test's technical lead, said in a statement. "The imagery of our first parachute inflation is almost as breathtaking to behold as it is scientifically significant. For the first time, we get to see what it would look like to be in a spacecraft hurtling towards the Red Planet, unfurling its parachute."
Perseverance boasts nearly five times as many cameras as the first Mars rover, Sojourner, which carried only five. NASA's twin rovers Spirit and Opportunity were designed with 10 cameras apiece. Curiosity has 17.
The new rover carries 23 cameras. Some will provide more color and 3D imaging than on Curiosity, according to Jim Bell of Arizona State University, the principal investigator for Perseverance's Mastcam-Z. "Z" stands for "zoom," one of the improvements on Curiosity's high-definition Mastcam.
The engineering cameras for planning drives and avoiding hazards on Spirit, Opportunity and Curiosity all captured 1-megapixel images in black and white. Perseverance's engineering cameras will acquire high-resolution, 20-megapixel color images. Their wider field of view means that, instead of spending time taking multiple images to be stitched together on the ground, the new cameras can capture the same view in a single snapshot. The cameras can also reduce motion blur, so they can snap images while the rover is traveling.
But more detailed images mean more data to beam through space.
"The limiting factor in most imaging systems is the telecommunications link," Maki said. "Cameras are capable of acquiring much more data than can be sent back to Earth."
Smarter rover cameras are helping to reduce the load. On Spirit and Opportunity, compression was done on the onboard computer. Perseverance, like Curiosity, will have its compression performed by electronics built into the camera.
Data will be beamed back to Earth through spacecraft already orbiting Mars: NASA's Mars Reconnaissance Orbiter (MRO), MAVEN and the European Space Agency's ExoMars Trace Gas Orbiter. NASA's Mars Odyssey orbiter was the first orbiter to send rover data home from Spirit and Opportunity.
"We were expecting to do that mission on just tens of megabits each Mars day, or sol," Bell said. "When we got that first Odyssey overflight, and we had about 100 megabits per sol, we realized it was a whole new ballgame."
Perseverance also carries two microphones. One was designed to record sounds during entry, descent and landing. According to NASA it did not collect useable data during the descent, but did capture several seconds of rover sounds and gusts of wind on Feb. 20, 2021.
Read more about the first song to sample sounds from Mars.
The other microphone is built into the rover's rock-zapping SuperCom instrument.
"There's a lot of good science that can be done by having a microphone on Mars," Sylvestre Maurice, a planetary scientist at the Research Institute in Astrophysics and Planetology in France, told Space.com. He and his colleagues investigated the possibility of pairing a microphone with a laser that will be used to vaporize rocks on the Martian surface.
In addition to gathering science, a microphone will represent a public relations coup, Maurice said.
"It will be the first time we can listen to a sound on Mars," he said. (Two other NASA Red Planet missions have carried microphones — the Mars Polar Lander and the Phoenix lander. But the Mars Polar Lander crashed during its touchdown attempt, and NASA turned off Phoenix's mic due to technical issues before it could record any sounds on Mars.)
Dave Gruel, lead engineer for Mars 2020 Perseverance’s EDL camera and microphone subsystem at JPL, told NASA, “We know the public is fascinated with Mars exploration, so we added the EDL Cam microphone to the vehicle because we hoped it could enhance the experience, especially for visually-impaired space fans, and engage and inspire people around the world.”
Choosing a Parking Spot
In February 2017, a team of scientists narrowed the Mars 2020 landing-site candidates down to three finalists: Columbia Hills, Jezero Crater and Northeast Syrtis.
One of those site has been explored before. Starting in 2004, NASA's Spirit rover explored Gusev Crater and Columbia Hills, where the rover discovered evidence of past water, the only place it found water in the enormous crater. Later data analysis suggested that the crater may have once hosted a shallow lake.
The 28-mile-wide (45 km) Jezero Crater is an ancient lakebed where microbial life could have developed, NASA officials said in a statement. Jezero's river delta structure suggests that water filled and drained from the site at least twice, and MRO has identified minerals that have been chemically altered by water.
An ancient volcano in Northeast Syrtis could have led to hot springs and melting ice, creating the ideal conditions for past microbial life. The edge of the Syrtis Major volcanoes exposes 4-billion-year-old bedrock, as well as many minerals altered by the encounter during the Red Planet's early history.
In November 2018, NASA announced the final selection: Perseverance will explore Jezero Crater.
"The landing site in Jezero Crater offers geologically rich terrain, with landforms reaching as far back as 3.6 billion years old, that could potentially answer important questions in planetary evolution and astrobiology," Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, said in a statement at the time.
"Getting samples from this unique area will revolutionize how we think about Mars and its ability to harbor life," he added.
Bringing samples home
Unlike previous rovers, Perseverance will prepare samples to return to Earth. The rover will try to drill at least 20 rock cores, and possibly more than 30 or 40. Samples will be secured in sample tubes and deposited at select locations for return to Earthby a future sample-retrieval campaign involving NASA and the European Space Agency. The earliest the samples could get here is 2031, NASA officials have said.
"The Mars 2020 rover is the first step in a potential multi-mission campaign to return carefully selected and sealed samples of Martian rocks and soil to Earth," Geoffrey Yoder, then-acting associate administrator of NASA's Science Mission Directorate in Washington, D.C., said in a 2016 statement. "This mission marks a significant milestone in NASA's Journey to Mars — to determine whether life has ever existed on Mars, and to advance our goal of sending humans to the Red Planet."
Assuming the samples make it to Earth, scientists will be able to use powerful instruments to provide a more in-depth examination than can be carried out by the car-sized rover on Mars.
That being said, Perseverance will perform some impressive science work on the Red Planet, if all goes according to plan. For example, the rover's Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) laser instrument will be the first instrument on Mars to use Ramen and fluorescence spectroscopies, techniques familiar to forensics experts. When an ultraviolet light shines over certain carbon-based chemicals, they glow much like material beneath a black light. The glow can help scientists to detect chemicals that form in the presence of life. SHERLOC will photograph the rocks it studies, then maps the chemicals it detects across the images.
"This kind of science requires texture and organic chemicals — two things that our target meteorite will provide," Rohit Bhartia of JPL, SHERLOC's deputy principal investigator, said in a statement.
That target is a Martian meteorite known as Sayh al Uhaymir 008 (SaU008), which Perseverance is carrying to help calibrate SHERLOC. Previous rovers have included calibration targets, but none of them have ever relied on Martian meteorites. (A meteorite has, however, ridden to Mars aboard the Mars Global Surveyor, which continues to orbit Mars now that its mission has ended.)
Mars helicopter and other futuristic exploration tech
The Mars 2020 mission will also demonstrate a variety of technologies that could advance future Red Planet exploration efforts.
For instance, a tiny, solar-powered helicopter named Ingenuity is flying to Mars attached to Perseverance's belly and will attempt to become the first rotorcraft ever to fly on a world beyond Earth.
Successful test flights by the 4-lb. (1.8 kilograms) chopper could pave the way for extensive aerial exploration of the Red Planet down the road. Future Mars helicopters could help scout out promising terrain for rover investigations and/or gather a variety of data themselves, NASA officials have said.
Perseverance also carries an instrument called MOXIE, which is short for "Mars Oxgyen ISRU Experiment." (ISRU is short for "in situ resource utilization.") MOXIE is designed to generate oxygen from the thin, carbon dioxide-dominated Martian atmosphere. This technology, once scaled up, could help humanity get a foothold on the Red Planet, NASA officials have said.
What's in a name?
Like NASA's previous Mars rovers, Perseverance was named by a schoolkid. In March 2020, the agency announced that Virginian Alex Mather, then a seventh-grader, had won the competition to hang a name on the Mars 2020 rover.
During the announcement ceremony, Mather read the essay he submitted as part of his contest entry. It ends like this:
"We are a species of explorers, and we will meet many setbacks on the way to Mars. However, we can persevere. We — not as a nation but as humans — will not give up. The human race will always persevere into the future."
Ingenuity was named by a student as well — Alabama high schooler Vaneeza Rupani, who submitted the moniker as a potential name for the Mars 2020 rover. It didn't win that contest, obviously, but then-NASA Administrator Jim Bridenstine liked "Ingenuity" so much that he picked it as the helicopter's name.
"It took a lot of hard and ingenious work to get the helicopter ready and then placed on the rover, and there's a lot more going to be required," Bridenstine said in a statement in April 2020, when the helicopter's new name was announced. "I was happy we had another great name from the naming contest finalists from which I was able to select something so representative of this exciting part of our next mission to Mars."
This article was updated on Jan. 21, 2021 by Space.com Senior Space Writer Mike Wall, and again on Feb. 23, 2021 by Space.com Reference Editor Vicky Stein.