US Space Agency NASA’s Ingenuity helicopter experienced some problems during its sixth flight on Mars this Thursday (27), but managed to land safely about 5 meters from the location where it should have landed.
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According to NASA, according to telemetry, the problem occurred shortly after the vehicle completed the first phase of flight. Ingenuity increased to 10 meters in height and moved 150 meters in a straight line to the southwest at a speed of 15 km / h. From that point, he should move another 15 meters to the south, drawing westward, then 50 meters backward and to the ground in the previous direction.
However, after the first 150 meters, the helicopter began to adjust its speed without need and started swinging back and forth in the air. This continued for the rest of the flight. According to NASA, prior to landing, the sensor indicated major changes in passage and peaks in energy consumption.
To explain what happened, the agency explained how the helicopter measures its position in relation to the ground. By using inertia measuring devices, it is capable of measuring the acceleration and speed of rotation of the propeller. As data accumulate, it is possible to estimate the position, speed, and altitude of the vehicle, and the internal computer is able to adjust the controls approximately 500 times per second using these estimates.
To prevent any measurement errors from accumulating, the vehicle corrects its position using a navigation camera, which takes 30 pictures per second of Mars soil and sends them to the navigation system.
This is where an algorithm comes into play, examining the timestamp of each image, to determine where the helicopter was at home at the time of flight, and then to predict where it would go, by color variation and terrain. At the base of the bumps, such as small rocks and sand banks.
These predictions made by the algorithm are compared with the following images. To determine where the vehicle is, is it correct or needs to be improved. From this it is possible to fix the height, speed and position.
What happened on the flight was a failure in the sequence of images taken by the navigation camera, about 54 seconds after takeoff. The system lost a single photo due to the failure, but with it all the timestamps of the following photos incorrectly left, causing Ingenuity to compute a different position from where she was during the entire flight and try to make adjustments. Which were not necessary. To correct mistakes that did not exist.
Despite this error, the vehicle was only 5 meters from the designated location and was able to land safely. This happened because, in the creation of Ingenuity, engineers widened the flight safety margin and chose to stop using images from the navigation camera during landing, which was the most important part of the operation.
For NASA, “Flight 5 ended with Ingenuity safely landing on the ground as many systems responded to the requirements to keep the helicopter on track and keep it alive, now we are aware of this vulnerability and we Will be able to fix it “.