Richard A Lovett
In a staggering series of images that allow viewers to relive landing day from a new perspective, NASA’s Perseverance rover team has released a live-action video of its descent to Mars. The 3-minute, 25-second video stitches together thousands of images from six small cameras that watched the rover’s dramatic landing last week, from the moment its parachute deployed to its final touchdown.
Three of the cameras were perched on the descent vehicle’s back shell, looking upward at the parachute. Another was on the bottom of the descent stage looking down on the rover. Two more were on the rover, one looking up and one down.
In combination, they produced a dramatic movie of the descent – one that vividly recreates the emotion of the event. It’s a bit like watching an old-favourite film. You know the ending, but that doesn’t matter, because what you really enjoy is the ride.
“It gives me goosebumps every time I see it,” says Dave Gruel of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, the project’s assembly, test and launch operations manager.
The idea was the brainchild of JPL’s Matt Wallace, Perseverance’s deputy project manager. “My daughter is a gymnast,” he says. “At age 11, when the project was in formulation, she asked me for a sports camera.”
He got her one, and she wore it for a backflip.
Backflips aren’t anything Wallace has ever done (or plans to do), “[but] when she showed me the video,” he says, “I had a glimpse into what it would be like if I could do a backflip. That’s what led to the camera system.”
The whole thing, Gruel adds, was done with “off-the-shelf ruggedised cameras”. The only modifications were to add some glue to make sure vital components didn’t shake lose, and to swap out a few materials that under vacuum conditions might off-gas vapours that could deposit on the detectors, fogging their images. “Other than that, it’s commercial, off-the-shelf,” he says.
In addition to the simple joy of producing vivid images, the results are important for helping engineers understand how the descent proceeded, with an eye to doing even better, next time.
That’s why a full half of the cameras were directed at the most critical part of the landing, the parachute (a good decision, because one of the three failed to withstand the jolt of the chute’s deployment.)
This deployment happened very fast, says Al Chen, head of the entry, descent, and landing team. From the video, he says, “you get a sense of how violent that deployment and inflation are”.
Each step, however, was captured from two different angles by the surviving cameras, firing at 75 frames per second. “I’m sure we’ll be studying this video for many years, picking it apart frame by frame,” Chen says.
Other images caught the drop of the heat shield, allowing scientists to observe its aerodynamics as it fell, and to note that one of the springs that helped push it away from the spacecraft appears to have broken loose in the process. That wasn’t dangerous, Chen says, but it was unexpected, and wouldn’t have been known of without the camera.
Other images showed the final landing and the dust kicked up by the landing stage’s rockets, whose exhaust, unlike the giant plumes produced on takeoff from Earth, is otherwise invisible.
The descent videos, however, aren’t the rover’s only accomplishments, even though it’s only been on the ground a few days.
In addition to the low-resolution images it produced immediately after landing, it has now produced a much higher resolution panorama of its surroundings. “[It’s] an amazing scene,” says JPL imaging scientist Justin Maki. “This is Mars. We’re here.”
These images also show odd, “holey” rocks.
The holes in these rocks could come from a number of causes, but the most exciting would be bubbles left from the escape of volcanic gases. That would mean these rocks are volcanic in origin, making samples of them prime candidates for eventual return to Earth.
That’s because volcanic rocks are easy to date once they are in a lab, says Katie Stack Morgan, another JPL scientist.
At the moment, she says, dating of Mars outcrops is uncertain and somewhat relative, based on what is on top of what. Pinning down even one layer, she says, would be useful in finetuning our understanding of the planet’s history and evolution.
Meanwhile, the rover is preparing to rove. Instruments are being checked out, computer programs shifted to focus on driving, rather than landing, and the whole thing being checked for bugs.
To date, says JPL systems engineer Jessica Samuels, the rover has been given 5,000 commands and everything is performing nominally.
And, she says, “When I say nominal, I really mean fantastic.”
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