The NASA Ingenity helicopter encountered some problems during its sixth flight on Mars, which took place on Thursday (27), but managed to safely land about 5 meters from where it was supposed to land.
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According to NASA, the problem occurred shortly after the spacecraft finished its first stage of flight, according to telemetry. Creativity rose to 10 meters in height and traveled 150 meters in a straight line to the southwest, at a speed of 15 km / h. From that point, it should move another 15 meters south, take pictures to the west, then another 50 meters in the previous direction and land.
However, after the first 150 meters, the helicopter began to adjust its speed without needing and swinging in the air back and forth. This continued for the rest of the trip. According to NASA, before landing, the sensors indicated large differences in the trajectory and peak power consumption.
To clarify what happened, the agency told how the helicopter measures its position with respect to the ground. Using inertial measurement equipment, it is able to measure the acceleration and rotational speed of fans. As the data accumulates, it is possible to estimate the vehicle’s location, speed, and altitude, and the onboard computer can set the controls using these estimates around 500 times per second.
To prevent any measurement errors from accumulating, the vehicle corrects its position with a navigation camera, which takes 30 pictures per second of Martian soil and sends it to the navigation system.
This is where the algorithm comes into play, as it checks timestamps for each image, to determine where the helicopter is in the home at the time of flight and then predict where it will go, based on color differences and terrain bumps, such as small rocks and sand banks.
These predictions made by the algorithm are then compared to the following images. To determine the position of the car, is it correct or needs to be corrected. However, it is possible to correct altitude, velocity, and position.
What happened in flight was a failure in the sequence of images taken by the navigation camera, about 54 seconds after takeoff. The failure caused the system to lose one image, but with all the timestamps of the following images appearing incorrectly, causing Ingenuity to count a different location than it was during the entire flight and attempting to make adjustments that weren’t necessary to correct errors that were not there.
Even with this bug, the spacecraft managed to land only 5 meters from the specified location, and safely. This happened because, in building Ingenuity, engineers expanded the flight safety margin and chose to stop using images from the navigation camera during landing, which is the most critical part of the process.
According to NASA, “Flight 5 ended with Ingenuity landing safely on the ground because a number of systems responded to the requirements to keep the helicopter on track and make it alive. We now know about this vulnerability and will be able to fix it.”