"Prior to landing safely, onboard sensors indicated the rotorcraft encountered roll and pitch excursions of more than 20 degrees, large control inputs, and spikes in power consumption," wrote Havard Grip, Ingenuity Mars helicopter chief pilot at NASA's Jet Propulsion Laboratory, in a blogpost.
"The resulting inconsistencies significantly degraded the information used to fly the helicopter, leading to estimates being constantly 'corrected' to account for phantom errors," Grip said.
The helicopter landed safely due to certain design features, Grip said.
The helicopter is designed to tolerate significant errors without becoming unstable, including errors in timing. Another design decision -- not using navigation camera images during the final phase of the descent to landing -- also played a role in helping Ingenuity land safely.
"Ingenuity ignored the camera images in the final moments of flight, stopped oscillating, leveled its attitude, and touched down at the speed as designed," Grip said.