NASA’s Perseverance rover successfully touched down on Mars at 3:55 p.m. Eastern Time, making it the fifth NASA rover to reach Martian soil.
The landing was the most challenging and technically complex ever attempted on Mars, which has claimed the robotic lives of roughly half the crafts seeking its surface. Now that the rover has safely landed, it begins its nuclear-powered mission to search the Red Planet for signs of ancient life, drop off a fledgling helicopter named Ingenuity to see if it can fly on Mars and conduct experiments that could pave the way for human exploration.
All Mars landings are hard, but Perseverance’s bid for the rust-colored soil was made especially difficult by its targeted location, a depression called the Jezero Crater. By NASA’s reckoning, the crater was once a river delta, making it an attractive spot to search for signs of water and traces of bygone life. But that also means it’s strewn with boulders, dunes and other hazards for the 2,260-pound Perseverance.
This dangerous landing required unprecedented precision. Perseverance’s targeted landing zone is just shy of 20 square miles, almost ten-times smaller than that of NASA’s last rover, Curiosity, which landed in 2012.
To stick this treacherous landing, Perseverance’s navigation computers needed to execute a carefully choreographed series of maneuvers. The craft began its descent as a $2.4 billion bullet ripping through Mars’ atmosphere at 12,100 miles per hour. Drag at that speed quickly translated to intense heat, so Perseverance’s capsule needed a heat shield capable of withstanding temperatures of 2,370 degrees, according to a statement.
When “Percy” slowed down to a still-supersonic 1,000 miles per hour, its computer deployed a massive, 70.5-foot-wide parachute and then ditched its heat shield after pulling a head-snapping 9 G’s-worth of deceleration. With the heat shield out of the way, cameras and radar assessed the Martian surface using a system NASA calls Terrain Relative Navigation (TRN). The system essentially compares what Perseverance is seeing to preloaded maps of Mars, reports Jatan Mehta for Scientific American.
Using TRN, the craft picked the precise altitude to detach the parachute, sending Perseverance hurtling towards Mars at around 200 miles per hour in a rocket-powered metal frame. Firing the rockets rapidly eliminated the remaining speed and steered the rover towards its landing zone where it was finally lowered to the ground from a hover via a “sky crane” similar to the one used to land Curiosity. The entire landing happened in the space of what NASA’s team refers to as “seven minutes of terror.”
The seven-minute landing sequence is terrifying not just because of everything that can go wrong, but because of the unnerving radio silence while it’s all happening. Signals take just over 11 minutes to get from Mars to Earth, meaning Perseverance had to land itself. By the time the control room got word that the rover had begun its descent, the mission had actually been over for several minutes.
With its six wheels firmly on Martial soil, Perseverance’s daredevil landing will pay off with a much reduced need to motor across the surface to points of scientific interest.
The car-sized rover’s first few days or weeks in the Jezero crater will mostly involve taking pictures, making sure everything is working as it should and loading new software for the rest of its mission, reports Max G. Levy for Wired. Perseverance’s plutonium power-source could keep it going for about three years, but its planned mission lasts a bit less than two years.
During this relatively low-key period, Perseverance will be a kind of chaperone for the four-pound Ingenuity helicopter as it attempts what would be the first ever flight in another planet’s atmosphere.
Once the scientific mission gets under way, Perseverance will drive around filling 38 sample tubes with rock, soil and air, reports Leonard David for Scientific American. If all goes well, those samples will fall back to Earth in 2031 as part of the ambitious Mars Sample Return operation.
Perseverance will also be testing an instrument called MOXIE aimed at making oxygen out of Mars’ abundant carbon dioxide, which, if successful, would be a huge step toward making human-piloted missions possible.
Percy is the last of three spacecraft to reach Mars this month. NASA joins the United Arab Emirates’ Hope space probe and China’s Tianwen-1, which aims to land its own rover after spending time in orbit. All three missions launched last July to take advantage of a particularly close pass between Earth and its neighbor in the solar system.