But more than 120 Martian days past that experiment window, Ingenuity is still flying and doing things no one ever expected. The helicopter, which took its first flight on April 19, is breaking its own records for distance and speed (SN: 4/19/21). It’s helping the Perseverance rover explore near an ancient river delta that may hold signs of past Martian life (SN: 2/17/21). And Ingenuity is coping with changing seasons and navigating over rough terrain, two things that the flier wasn’t designed to do. “It’s gotten into a good groove,” says Ingenuity’s original chief engineer, NASA’s Jet Propulsion Lab in Pasadena, Calif. “It’s in its element and having fun.”
Ingenuity is flying farther, faster and higher than it did in its first few flights. The helicopter has lifted itself a maximum of 12 meters above the Martian surface, zipped along at up to five meters per second (about half as fast as record-setting sprinter Florence Griffith-Joyner) and covered 625 meters (about a third the length of the Kentucky Derby) in a single flight. These extremes give engineers valuable information about the limits of flying on Mars. “We are still trying to learn lessons,” says JPL robotics engineer and a team leader for the Ingenuity mission. “Flight after flight, we’re learning the boundaries of performance.” Early on, Ingenuity tested its limits in a way that the flight team really didn’t plan for. During its sixth flight on May 22, the helicopter’s navigation system suffered a glitch that made it roll and sway alarmingly. The helicopter’s navigation software keeps track of the craft’s position by taking an image, reading the time stamp and predicting what the camera should see next based on landmarks from previous photos that Ingenuity took. If the next image doesn’t match that prediction, the software corrects the helicopter’s position and velocity to match up better. Less than a minute into the May 22 flight, a single image got lost on its way from Ingenuity’s cameras to its onboard computer. That meant that the time stamps on all subsequent images were a little off. In trying to correct what it perceived as errors, Ingenuity “went on a wild joyride,” chief engineer says. Luckily, the helicopter touched down safely within five meters of its intended landing spot. The anomaly was a blessing in disguise, chief engineer says. It put the helicopter through extremes of movement — “how aggressively you can move the joystick, if you will” — that the engineers would not have asked it to do on purpose, and did perfectly fine, he says. “It’s a serendipitous thing that we got that flight experience under our belt,” the chief engineer says. “We have much more confidence in the vehicle.”
Originally, the helicopter team wanted to push the vehicle until it broke. But now the researchers are flying more cautiously and less often. That’s because the helicopter is currently supporting the Perseverance rover in doing science (SN: 4/30/21). “We’re no longer in the Month of Ingenuity,” the robotic engineer says. “We’re a small part of a much larger team.” The helicopter has already proven its worth by telling the rover about the locations. Scientists thought those ridges could record some of the deepest water environments in the lake that filled the crater long ago. In 3-D images from the helicopter, it turned out that those ridges did not show the layers that would have indicated that the rocks formed in deep water. The rover team decided to move on, saving Perseverance a long, arduous and potentially dangerous drive. “They didn’t have to send the rover all the way to this particular target, and then realize, hey, this may not be the highest priority thing,” the chief engineer says. Scouting for the rover has also taken Ingenuity over terrain that the helicopter wasn’t designed to understand. Ingenuity’s navigation software was programmed to assume that the ground beneath it is always flat because that was the type of terrain selected for that experimental first month of flight demonstrations. “It was a perfectly reasonable simplification for a technology demonstration,” the chief engineer says. “But it was baked in. And now you’re stuck with a system with a flat ground assumption.” When the helicopter is flying over a sloped surface, some features seem to move faster in its view than they would if the ground were flat, giving the helicopter a false sense of its motion. “The onboard navigation has no way of explaining it, except for thinking maybe I’m turning or spinning a bit,” the chief engineer says. The helicopter ends up veering to the side. The team has come up with some works, such as choosing large enough landing zones that a precision landing isn’t necessary and slowing down when flying over rough terrain.
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