NASA has revealed a six-day stretch where it could not make contact with its Ingenuity Mars helicopter.
For a long time postchief engineer Travis Brown explained that after the copter’s 49th flight, radio contact was lost for six sols – just short of six days and six hours of terrestrial time.
At first, NASA’s Mars boffins weren’t too worried. The Perseverance Rover moved behind a rocky outcrop that created a “communication shadow.” Brown wrote that since Sol 685 the helicopter had “unfortunately drifted in and out of night-time survival mode” which made daily contact with the craft. So a day or two of no contact is not a concern.
But once Perseverance moved to another location and Ingenuity still couldn’t be found, Brown wrote “the situation began to create some anxiety.”
“The weak performance of the telecom was seen as a reasonable explanation, but there are reasons to doubt it,” he wrote. “In over 700 sols operating a helicopter on Mars, we have never once experienced a total radio blackout. Even in the worst communications environment, we have always seen some indication of activity.”
But the signal received that day, sol 761, was just a simple ACK (acknowledgement). The next day, the copter again acknowledged a command, but did little else.
Mission staff determined that the ridge separating Ingenuity and Perseverance was a challenge for the copter’s radio. It didn’t help that the Perseverance’s helicopter base station (HBS) antenna was mounted low to the right of the vehicle and was subject to occlusion effects.
As the NASA people learned that, Perseverance moved on to its next goal – but it created new problems.
“It was critical for the Ingenuity to stay ahead of the Endurance while moving through the narrow channels of the Jezero delta,” Brown wrote, since the rotorcraft’s job was to scout ahead for the wheeled rover. And NASA operates a no-fly zone around Perseverance.
As the rover moved, and the helicopter stopped, it became necessary to move Ingenuity.
“Relying on the helicopter’s onboard preflight checks to ensure vehicle safety and banking on solid communications from the rover’s close proximity, the team will uplink the flight plan,” Brown wrote.
Ingenuity did more than just ACK that upload. It swallowed and carried it out, resulting in its 50th flight and an altitude record of 18 meters.
“It is an understatement to say that the helicopter team was relieved to see successful flight telemetry on the Sol 763 downlink the next morning,” Brown wrote.
But he added that stressful days lie ahead.
“It now appears that the dust covering our solar panels will ensure that Ingenuity will likely remain in this transitional power state for some time,” he wrote. “This means that, much to his team’s chagrin, we’re not done playing this high-stakes game of hide-and-seek with the playful little helicopter.”
Ingenuity last flew on April 22, when it made a 188-meter hop at a height of 12 meters. The craft was designed to fly just five times, so far exceeded expectations. ®
