NASA's Mars helicopter almost crashed as it went off-course during a "stressful" sixth flight over the Red Planet.
Ingenuity started oscillating wildly after a glitch in its navigational camera started feeding it the wrong information mid-flight.
Scientists held their breath as the chopper's onboard safety systems were pushed to their limits to stop it from smashing into the ground.
They said the "outer reaches of the helicopter’s performance envelope" had been tested just a month after it made its historic first flight on Mars.
Ingenuity was 33ft up in the air when it started going up and down wildly as its systems continuously tried to recorrect its flight path while being fed wrong data from the camera.
Its state-of-the-art stability safeguards kicked in allowing the cosmic chopper to bring itself down safely around 16 feet of its intended landing spot last Saturday.
The US space agency's Jet Propulsion Laboratory revealed the anomaly had taken place on Thursday.
Havard Grip, the chief pilot for Ingenuity at JPL, said Ingenuity started "adjusting its velocity and tilting back and forth in an oscillating pattern" mid-flight.
He added the anomaly was caused by "glitch" about a minute into the flight in the delivery of images by Ingenuity's navigation camera.
NASA helicopter takes incredible colour pictures of Mars' surface on daring flight
He said: "This glitch caused a single image to be lost, but more importantly, it resulted in all later navigation images being delivered with inaccurate timestamps.
"From this point on, each time the navigation algorithm performed a correction based on a navigation image, it was operating on the basis of incorrect information about when the image was taken."
He estimated that the inconsistencies led the helicopter to a state of "being constantly 'corrected' to account for phantom errors," adding that "large oscillations ensued".
NASA's Mars helicopter flies across planet's surface for the first time
Grip credited the landing to Ingenuity's multiple subsystems that ensure stability for kicking in when needed.
He said: "In a very real sense, Ingenuity muscled through the situation, and while the flight uncovered a timing vulnerability that will now have to be addressed, it also confirmed the robustness of the system in multiple ways.
"While we did not intentionally plan such a stressful flight, NASA now has flight data probing the outer reaches of the helicopter’s performance envelope.
"That data will be carefully analyzed in the time ahead, expanding our reservoir of knowledge about flying helicopters on Mars."
The cosmic helicopter pays homage to the Wright brothers' first flight on Earth, carrying with it a small amount of material that covered one of the wings on the brothers' history-making aircraft, says NASA.
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