Here’s why Mars selfies are serious business
62 frames, 1 selfie
NASA’s Perseverance rover has been touring Mars since it touched down on the red planet’s surface back in February 2021. In early April, it claimed the attention of fans with its first selfie on the neighbor planet, posed with its companion spacecraft, the Ingenuity Mars Helicopter. But the action behind the image wasn’t as simple as saying “cheese.” The process involved a series of individual commands, which took about a week to execute. On June 25, 2021, NASA released the video above, showing the sequence in which its Perseverance rover took the 62 photos needed for the selfie.
Space scientists back on Earth stitched the images together to create the finished product.
Perseverance, nicknamed Percy, is equipped with a WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) camera, primarily designed for detailed rock shots. It’s not designed for wide-angle photos as portrayed in the historic selfie. To get that, the Jet Propulsion Laboratory (JPL) – which manages Percy operations for NASA by Caltech in Pasadena, California – orchestrated each of the 62 small photos individually.
Among other scientific instruments, the WATSON camera sits on a rotating turret at the end of Percy’s robotic arm. It can act like a selfie stick and stays focused on the rover when taking self-portraits, remaining just out of frame during the final product. NASA’s Curiosity rover, now in Gale Crater, has one, too. See a video here.
But Percy’s size difference poses a (literally) bigger mechanical challenge to imaging than Curiosity does. Curiosity’s turret measures 22 inches (59 cm) across, while Percy’s measures 30 inches (76 cm) across. Its sweeping bulk can be risky; NASA compares it to waving something the diameter of a bicycle wheel just centimeters in front of Perseverance’s mast.
To prevent a collision, JPL developers designed software that can predict when Percy’s arm might strike it by running a series of simulations. If a crash seems likely, engineers can adjust the arm’s trajectory and run simulations until the movement is deemed safe. Vandi Verma, Perseverance’s chief engineer, said that the final command sequence gets the arm “as close as we could get to the rover’s body without touching it.” Other simulations ensure Ingenuity is pictured in the background, also mentioned in the NASA video.
From Mars to Twitter
Photos taken by spacecraft on Mars could take anywhere from a half an hour to more than 12 hours to reach Earth. Once delivered, JPL members worked with Malin Space Science Systems (MSSS) in San Diego, California, to form a “camera crew” team of about a dozen people. Among them were rover drivers, operations and test engineers, and software developers who went to work as the frames came in.
First, they processed the photos and removed any blemishes, such as dust, settled on the camera’s light detector. Once touched up, the team organized the frames into a mosaic with their edges smoothed out using software. Finally, an engineer stitches and crops the collage to form the recognizable image that’s ultimately shared with the world.
Everybody on the project worked on Mars time with a calendar day that lasts 37 minutes longer than Earth’s. That schedule alone poses unique, sometimes comical challenges, like coming to work 40 minutes later every day or adjusting a wristwatch to turn more slowly.
So why all this labor and sacrifice for a selfie? NASA offers two reasons. One is for the essential purpose of visually checking up on the rover, assessing the wear on its physical features, plus its surroundings on Mars. Another is to potentially inspire the next generation of multi-planetary enthusiasts.
I got into this because I saw a picture from Sojourner, NASA’s first Mars rover … When we took that first selfie, we didn’t realize these would become so iconic and routine.
Design-wise, the Perseverance rover is very similar to the Curiosity rover, but is the largest, most advanced rover NASA has sent to another world. Its flashy new cameras provided the first detailed photos and video recordings of a landing on a neighboring world yet. And while Curiosity focuses on finding evidence of past habitability, which it has done, Perseverance will be looking for direct evidence of life itself in broken pieces of rock and dust. Spacecraft selfies are the beautiful – and useful – bonuses we’ll get until NASA sends spacecraft to collect those sealed samples in future missions.
Bottom line: In early April, NASA’s Perseverance Mars rover claimed the attention of fans with its first selfie on the red planet. A video released by NASA on June 25, 2021, shows the sequence in which the Perseverance rover took 62 photos with its camera before space engineers stitched them together into a single composite image.