The American space agency NASA says it has found the likely cause of a crash that grounded its Mars helicopter Ingenuity.

The finding comes after NASA said it had carried out the "first aircraft accident investigation on another world."

Ingenuity arrived on Mars along with NASA's Perseverance explorer, or rover, in February 2021. The experimental helicopter took its last flight, number 72, in January. That flight ended in a hard landing on the Martian surface.

In April 2021, Ingenuity became the first aircraft to complete a powered, controlled flight on another planet. The aircraft was built to test take-off, short flight and landing operations. The flights on Mars aimed to support NASA's efforts to build new aircraft that can fly in the atmospheres of other planets.

Engineers from NASA's Jet Propulsion Laboratory in California fully investigated Ingenuity's last flight on Mars. They found the cause of the crash was linked to the helicopter's navigation system. That camera-based system was not able to collect dependable data on elements of the Martian surface to support a safe landing.

A detailed, final report on the accident is to be issued in the coming weeks. But the engineers have already described their main findings in a statement published online.

They said the helicopter's last flight saw the aircraft climb to about 12 meters, where it stayed, or hovered, while capturing images of the Martian surface. Data records show Ingenuity began its planned descent after about 19 seconds. By 32 seconds, the helicopter was back on the surface and was no longer sending communication signals.

The next day, Ingenuity team members reestablished communications and received images from its last flight. The images showed the aircraft suffered severe damage to its rotor blades.

NASA explained that Ingenuity's navigation system plays an important part in collecting data about the surface to ensure the aircraft can complete a smooth landing. The helicopter uses a camera that points downward, capturing information about what is below the craft.

In past flights, the engineers said the camera was able to find smooth, suitable landing possibilities. But NASA said during the final flight, the helicopter was traveling in an area with very few surface features for the camera to capture. This meant the aircraft's navigation system could not find enough of these features to choose a good landing spot.

At the time, Ingenuity was operating together with NASA's Perseverance rover in an area of Mars known as Jezero Crater.

The images recovered from Ingenuity suggested the navigation system's inability to pick up surface features made the helicopter descend too fast. The hard landing on a sand hill is believed to have caused the helicopter to turn over and roll.

The engineers said images showed that all four of Ingenuity's rotor blades broke at their weakest point. The damaged blades also caused the aircraft to shake. Events related to the crash led to increased power demand, which resulted in the loss of communications.

Although the crash ended Ingenuity's flight operations, NASA said it is still able to provide and send back weather information and other kinds of data. The space agency says this information could be helpful in designing future aircraft or other explorers to be sent to Mars.

Teddy Tzanetos is Ingenuity's project manager. He said in a statement one major thing the team learned was that future aircraft designed for space travel do not necessarily need to be large flying machines. Tzanetos added that Ingenuity's longevity suggests that "not everything needs to be bigger, heavier, and radiation-hardened" to work in the Martian environment.

With this in mind, NASA engineers have been testing smaller, lighter flying vehicles, with limited electronics, in order to produce future helicopters that can make a large number of smaller exploration trips.

Tzanetos shared details about one aircraft NASA is currently developing. It is called the Mars Chopper rotorcraft. Tzanetos said Chopper is about 20 times heavier than Ingenuity. Developers say it would be built to carry several kilograms of science equipment, while self-exploring distant areas of Mars. Chopper would also have a much longer travel ability, flying up to 3 kilometers in a day. Ingenuity's longest flight was 704 meters.

Tzanetos said that overall, "Ingenuity has given us the confidence and data to envision the future of flight at Mars."

I'm Bryan Lynn.