NASA's Mars Helicopter Had an Unscheduled Landing, But Flew Again

The Ingenuity helicopter continues to explore the landscape around Jezero Crater on Mars, now more than 800 days into its original 30-day demonstration mission. Recently, Ingenuity completed its 54th flight on the Red Planet. However, things haven’t gone exactly to plan the past several weeks.

On its 53^rd fight on July 22, 2023, the helicopter cut the flight short after one of its warnings was triggered, implementing the “LAND_NOW” protocol. Ingenuity should have flown for 136 seconds but was only in the air for 74 seconds before performing an emergency landing.

The good news is that the emergency landing procedure worked as it should, and Ingenuity has ‘lived’ to fly another day.

“Since the very first flight we have included a program called ‘LAND_NOW’ that was designed to put the helicopter on the surface as soon as possible if any one of a few dozen off-nominal scenarios was encountered,” said Teddy Tzanetos, team lead emeritus for Ingenuity at NASA’s Jet Propulsion Laboratory in Southern California, in a press release. “During Flight 53, we encountered one of these, and the helicopter worked as planned and executed an immediate landing.”

While Ingenuity’s team back on Earth is still working to determine exactly why the emergency landing happened, for the 54th flight on August 3, the helicopter was instructed to make a short hop to see if the problem persisted. The team is still analyzing the data, but the 25-second up-and-down hop hopefully provided information that could help determine why flight 53 ended early.

Flight 53 was a complicated flight. The plan was for Ingenuity to collect imagery of a rocky outcrop to scout ahead for the Perseverance Mars rover science team. The complex flight profile included flying north 666 feet (203 meters) at an altitude of 16 feet (5 meters) and a speed of 5.6 mph (2.5 meters per second), then descending vertically to 8 feet (2.5 meters), where it would hover and obtain imagery of the outcrop. Ingenuity would then climb straight up to 33 feet (10 meters) to allow its hazard divert system to initiate before descending vertically to touch down.

Instead, the helicopter executed the first half of its autonomous journey, flying north at an altitude of 16 feet (5 meters) for 466 feet (142 meters). Then the flight-contingency program was triggered, and Ingenuity automatically landed after 74 seconds.

Based on the data so far, Ingenuity team is fairly confident that the early landing was triggered when image frames from the helicopter’s navigation camera didn’t sync up as expected with data from the rotorcraft’s inertial measurement unit. This glitch in the image pipeline threw the timing sequence off and confused the craft about its location. The IMU measures Ingenuity’s acceleration and rotational rates – data that makes it possible to estimate where the helicopter is, how fast it is moving, and how it is oriented in space.

This glitch happened before. Back on May 22, 2021, multiple image frames were dropped, resulting in excessive pitching and rolling near the end of Flight 6. After that flight, the team updated the flight software to help mitigate the impact of dropped images. The fix worked well for the subsequent 46 flights. However, on Flight 53 the quantity of dropped navigation images exceeded what the software patch allows.

“While we hoped to never trigger a LAND_NOW, this flight is a valuable case study that will benefit future aircraft operating on other worlds,” said Tzanetos. “The team is working to better understand what occurred in Flight 53, and with Flight 54’s success we’re confident that our baby is ready to keep soaring ahead on Mars.”

Keep tabs on Ingenuity at the Mars Helicopter blog.