NASA's helicopter on Mars, Ingenuity, was only supposed to fly five times, yet it has completed 12 flights and isn't ready to retire.

Given its unexpected success, the U.S. space agency has extended Ingenuity's mission indefinitely.

The tiny helicopter has become the regular travel companion of the rover Perseverance, whose core mission is to seek signs of ancient life on Mars.

"Everything is working so well," said Josh Ravich, the head of Ingenuity's mechanical engineering team. "We're doing better on the surface than we had expected."

On April 19, Ingenuity carried out its maiden flight, making history as the first motorized craft to fly on another planet.

Exceeding all expectations, it has gone on to fly 11 more times.

"We've actually been able to handle winds greater than we had expected," Ravich told AFP.

"I think by flight three we had actually accomplished all of our engineering goals ... (and) got all the information we had hoped to get," said Ravich, who works for NASA's famed Jet Propulsion Laboratory, which developed the helicopter.

Since then, Ingenuity has flown as high as 12 meters, and its last flight lasted two minutes and 49 seconds. In all, it has covered a distance of about 2.6 kilometers.

In May, Ingenuity flew its first one-way mission, landing outside the relatively flat "airfield" that had been carefully selected as its initial home. 

But not all has gone smoothly. Its sixth flight brought some excitement.

After being knocked dangerously off-balance by a malfunction affecting the photos taken in flight to help it stabilize, the tiny craft was able to recover. It landed, safe and sound, and the problem was resolved.

Ingenuity is now being sent out to scout the way for Perseverance, using its high-resolution color camera.

The purpose is twofold: to chart a path for the rover that is safe, but also which is of scientific interest, notably in geological terms.

What explains its longevity?

"The environment has been very cooperative so far: the temperatures, the wind, the sun, the dust in the air... It's still very cold, but it could have been a lot worse," said Ravich.

In theory, the helicopter should be able to keep operating for some time. But the approaching Martian winter will be challenging.

NASA engineers, now armed with the data from Ingenuity's flights, are already working on its next-generation successors.

"Something in the 20 to 30 kilograms (range) maybe, able to carry science payloads," said Ravich.

Those future payloads might just include the rock samples collected by Perseverance.

NASA is planning to retrieve those samples during a future mission – sometime in the 2030s.