Late last week, NASA’s Ingenuity helicopter managed to reestablish its connection with the Perseverance rover following a brief communications disruption. The space agency says the looming winter is likely responsible and is making adjustments as a result.
On Thursday, Ingenuity — mercifully — sent a signal to Perseverance after the intrepid helicopter missed a scheduled communications session. It marked the first time since the pair landed together on Mars in February 2021 that Ingenuity has missed an appointment, according to NASA.
The team behind the mission believes that Ingenuity had entered into a low-power state to conserve energy, and it did so in response to the charge of its six lithium-ion batteries dropping below a critical threshold. This was likely due to the approaching winter, when more dust appears in the Martian atmosphere and the temperatures get colder. The dust blocks the amount of sunlight that reaches the helicopter’s solar array, which charges its batteries.
The Perseverance rover is on a mission to find evidence of ancient microbial life on Mars, while the rover’s much smaller companion, Ingenuity, became the first powered aircraft to lift off from the surface of another planet on April 19, 2021. The two robots share a communication line, with Perseverance relaying Ingenuity’s messages to Earth. Ingenuity uses small antennas to communicate with Perseverance, exchanging data that is then routed to the rover’s main computer and transferred to Earth through NASA’s Deep Space Network (a global array of radio antennas).
Ingenuity has an alarm that wakes the helicopter for its scheduled communication sessions with Perseverance. But on May 3, Ingenuity was a no-show for the scheduled daily data exchange after its field-programmable gate array lost power overnight, causing a reset of the helicopter’s onboard clock (the gate array manages Ingenuity’s operational state, switching its electronic systems on and off to conserve power). The Sun’s rays recharged Ingenuity’s batteries the following morning, but the helicopter’s clock was now out of sync with Perseverance’s clock. By the time Ingenuity was able to send out a signal, the rover was no longer listening.
Two days later, mission control set out to fix the pair’s communication issue by programming the rover to spend nearly the entirety of its 429th sol (a Martian day, which lasts slightly longer than a day on Earth) listening for the helicopter’s signal. Ingenuity’s call finally came in on May 5 at 11:45 a.m. local Mars time. Although brief, Ingenuity’s call reassured the team at NASA’s Jet Propulsion Laboratory that the helicopter’s battery was healthy and that the solar array was recharging its batteries.
Ingenuity wasn’t exactly built to withstand the harsh Martian winter nights, as the rotorcraft was designed to last only 30 sols on Mars. But the 19-inch tall (48 cm), 1.8 kg helicopter has gone far beyond its test flights, recently receiving an extension on its mission to assist Perseverance as it explores the Martian terrain. Ingenuity will now fly above the Martian surface, advising Perseverance’s controllers on the most ideal routes.
“We have always known that Martian winter and dust storm season would present new challenges for Ingenuity, specifically colder sols, an increase in atmospheric dust, and more frequent dust storms,” Teddy Tzanetos, Ingenuity team lead at JPL, said in a statement. “Every flight and every mile of distance flown beyond our original 30-sol mission has pushed the spacecraft to its limits each and every sol on Mars.”
For now, the team has put together a plan to help the tiny helicopter survive the looming winter. The newly issued commands “lower the point at which the helicopter energizes its heaters from when the battery falls below minus 15 degrees Celsius to minus 40 degrees Celsius,” according to NASA, which added that the “helicopter then shuts down quickly, rather than consuming the battery charge with the heaters.” This should allow Ingenuity to accumulate battery charge during the day, which it can then use to survive the bitterly cold nights.
“Our top priority is to maintain communications with Ingenuity in the next few sols, but even then, we know that there will be significant challenges ahead,” Tzanetos said. “We are hopeful that we can accumulate battery charge in order to return to nominal operations and continue our mission into the weeks ahead.”
Even with the dropped call, Ingenuity still remains the little copter that could, surpassing expectations with a total of 28 flights logged on Mars. Hard to believe now, but the original plan was to have Ingenuity perform just five flights on the Red Planet.