NASA officials released never-before-seen views of a spacecraft landing on another planet Monday, showcasing multi-angle replays recorded by ruggedized high-definition cameras mounted on the Perseverance rover last week when it safely touched down on Mars.
The mission’s entry, descent, and landing cameras recorded video as Perseverance made its way to a landing site in Jezero Crater, a location that was home to a lake of liquid water more than three billion years ago. The imagery brought to life the rover’s high-stakes landing maneuvers, showing the mission’s supersonic parachute blowing open in an instant, followed by separation of the craft’s heat shield, and a final descent powered by eight throttleable rocket engines
Finally, the descent stage rocket pack lowered the one-ton rover to the Martian surface on three nylon bridles. The rocket engines slowed the descent to a crawl in the final seconds before touchdown, whipping up a cloud of dust before the descent stage cut the cords to the rover and flew a safe distance away to impact the Red Planet.
Matt Wallace, deputy project manager on the Perseverance mission, said ground teams at JPL were “like kids in a candy store” as images from the entry, descent, and landing, or EDL, cameras streamed back to Earth via an interplanetary radio link over the last few days.
In all, Perseverance’s EDL cameras collected more than 23,000 images — totaling more than 30 gigabytes — for engineers to string together into high-definition video clips, according to Dave Gruel, the mission’s EDL camera lead at JPL.
“I don’t know about you, but it is unlikely at this point in my career that I will pilot a spacecraft down to the surface of Mars, but when you see this imagery, I think you will feel like you are getting a a glimpse of what it would be like to land successfully in Jezero Crater with Perseverance,” Wallace said.
Perseverance’s landing system, called the “sky crane” by NASA engineers, had the same design that the Curiosity rover used to successfully reach Mars in August 2012. But until now, the system’s designers at NASA’s Jet Propulsion Laboratory in California had never seen the sky crane at work.
That’s because engineers can’t put the rover landing system through an end-to-end test on Earth. The Martian atmosphere is less than 1 percent the density of Earth’s, and the gravity on Mars is 38 percent that of Earth, meaning NASA could not test the full landing sequence in a Mars-like environment.
Curiosity carried a downward-facing camera that recorded the rover’s descent into Gale Crater, showing the heat shield separation and features on the Martian surface growing larger in the moments before touchdown. But the 2012 landing lacked the resolution and the multitude of views on Perseverance.
“This is the first time we’ve been able to see ourselves, see our spacecraft, land on another planet,” Wallace said.
“Being able to see this system operate like this in high-definition, landing at Jezero, it doesn’t get too much better than that,” Wallace said.
Engineers noticed only a few minor surprises in the video, according to Al Chen, Perseverance’s entry, descent, and landing phase lead.
The parachute lid on top of the spacecraft’s backshell appeared to come off in multiple chunks, rather than in a single piece. One of the chunks appeared to be a radome antenna used to communicate with the spacecraft on the cruise to Mars. Engineers knew that might happen, Chen said.
One of the springs used to push the heat shield off the rover during descent appeared to come loose in flight, Chen said. But the other separation springs worked as expected, and the spacecraft was not endangered, he said.
The spacecraft’s 70.5-foot-wide (21.5-meter) supersonic parachute billowed open in less than a second on the command the rover’s guidance computer, which timed the chute deployment when Perseverance was at predetermined location relative to its landing site. The parachute deployment trigger was a new feature on Perseverance, allowing the mission to target a more precise landing zone than previous Mars probes.
The violent chute deployment shook the spacecraft in the EDL camera views.
“The parachute is packed so densely that the pack is basically the same density as oak, and it’s about 150 pounds,” Chen said. “It gets launched out of the spacecraft with a mortar, which basically a cannon with a muzzle velocity of about 100 mph.”
The shock of the mortar firing knocked one of the mission’s three parachute-pointing EDL cameras offline. The craft’s other five cameras — two pointing at the parachute, one on the descent stage looking down, and two on the rover — all functioned as designed.
“The entry, descent, and landing system behaved as expected, and it did what it had to do,” Chen said. “A big shout out to the terrain relative navigation system, which put us down in the safest spot that was available to us.”
After “textbook” deployment and inflation, the parachute slowed the spacecraft from a velocity nearly twice the speed of sound, setting up for release of the 14.8-foot-diameter (4.5-meter) heat shield, revealing the Martian landscape to a landing radar and cameras to help steer Perseverance toward a safe landing site.
The terrain relative navigation capability used on Perseverance used images from on-board cameras to find a flat, rock-free zone for landing.
The final phase of the landing sequence used eight hydrazine-fueled rocket jets to put the brakes on the rover’s descent. The rocket pack and rover separated from the top part of the spacecraft’s aeroshell, leaving the parachute behind, and ignited the eight thrusters at an altitude of about 1.3 miles, or 2 kilometers.
The descent smoothed out during the final seconds before landing.
Finally, as the descent stage neared the Martian surface, the rover lowered on three nylon cords and configured its six-wheel suspension for contact. The rover fired a pyrotechnic blade to sever the bridles and an electrical umbilical as soon as it sensed it was on the ground, allowing the descent stage to rapidly ascend and divert away from Perseverance.
The video shows a cloud of dust kicked up by the landing engines, which produced clear exhaust not visible in the rover’s upward-facing camera view. Hints of a pink glow from the super-hot engines are seen near the thrust chambers, Chen said.
In the end, the rover’s terrain relative navigation system succeeded in choosing a safe landing site, and Perseverance set down just 16 feet, or 5 meters, from the location the spacecraft autonomous selected, according to Chen.
“As a fresh-faced kid when the sky crane was invented, I was in that room, and it’s amazing to see it finally in action,” Chen said. “Even though we knew it worked once, we didn’t know for sure it was going to work again. And for it to work again, for us to see it, is incredible.”
“The video of Perseverance’s descent and landing, and the amazing panorama, and the first wide landscape shot of Jezero Crater seen with the human eye, and the first Martian sounds are the closest you can get to landing on Mars without putting on a pressure suit,” said Thomas Zurbuchen, associate administrator of NASA’s science mission directorate.
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