Just a couple of weeks after the Ingenuity helicopter celebrated a year of flying on Mars, things got quiet.
For the first time, the Ingenuity team on Earth lost contact with Ingenuity on sols 427 and 428, or Martian days that correspond with May 3 and May 4. The little chopper’s engineers spent a week investigating what might have caused the communication blackout.
The team discovered that loss of contact occurred because Ingenuity experienced insufficient battery charge as night fell. This reduced voltage reset the mission clock, causing the helicopter’s system to be out of sync with its companion, the Perseverance rover. While Ingenuity has returned to relaying messages reliably to Earth through the rover, the team expects this issue could happen again.
That’s because it’s early winter on Mars. Winter on the red planet will last until September or October. During Martian winter, dust gets lofted into the atmosphere and obscures the light necessary to charge Ingenuity’s solar panels.
So far, Ingenuity has logged 4.2 miles (6.8 kilometers) across 28 different flights.
The helicopter remains healthy and has resumed operations, albeit a bit modified, and the team remains optimistic that Ingenuity will soon go for its 29th flight. But there is no mistaking that Ingenuity is on borrowed time.
“Challenges like these are to be expected: After hundreds of sols and dozens of flights beyond the five flights originally planned, the solar-powered helicopter is in uncharted terrain,” Teddy Tzanetos, Ingenuity team lead at NASA’s Jet Propulsion Laboratory in Pasadena, California, wrote in an update.
“We are now operating far outside our original design limits. Historically, Mars is very challenging for spacecraft (particularly solar-powered spacecraft). Each sol could be Ingenuity’s last.”
MARTIAN WINTER IS COMING
With winter on Mars, Ingenuity will experience more dust in the air and dropping temperatures — both of which could wreak havoc on the chopper’s ability to stay powered, warm and operational.
As a result, Ingenuity will no longer be able to maintain its battery and electronics at a programmed temperature threshold of minus 13 degrees Fahrenheit (minus 25 degrees Celsius) using heaters.
Instead, the aerial vehicle will experience overnight temperatures of minus 112 degrees Fahrenheit (minus 80 degrees Celsius), which could pose a risk to any electronic components. So far, these are holding steady and haven’t sustained damage during the frigid nights.
Each morning as the helicopter warms up and recharges, the blackout from the previous night will misalign the mission clock.
Perseverance has to be a little more creative now when communicating with Ingenuity. Basically, the rover has to allow for the helicopter “sleeping in” and waking up at the wrong time because of its clock issue. Using its onboard Helicopter Base Station, Perseverance is able to chat with Ingenuity each day and reprogram the chopper’s mission clock for that day.
The Ingenuity team can’t predict how Ingenuity’s electronics core module components will perform throughout winter, but “cold-soaking electronics is believed to have caused the end of the Opportunity and Spirit Mars rover missions,” Tzanetos wrote in the update.
Currently, Ingenuity reaches sunset on Mars with about a 68% state of charge for its battery. The chopper needs at least 70% to keep its heaters, clock and core electronics powered overnight, JPL engineers estimated.
“Our 2% (state-of-charge) deficit is expected to grow to a 7% deficit once we reach winter solstice (Sol 500 in July), at which point conditions will start to improve,” Tzanetos wrote.
PREPARING FOR THE FUTURE
Retrieving data from Ingenuity, including its flight performance logs and color images from the previous eight flights, has become the top priority. Next, the mission team will determine if the helicopter is ready for another flight and have the chopper perform a high-speed spin of its rotors.
If Ingenuity is able to do a short flight to the southwest, the little copter will be in a good position to communicate with the Perseverance rover as it studies and collects samples from an ancient river delta.
The flight software team is also working on upgrades for Ingenuity’s advanced navigation capabilities to help it fly over the river delta and continue operating as an aerial scout for the rover.
“The Perseverance and Ingenuity operations teams have done an extraordinary job in reestablishing reliable communications with Ingenuity,” Tzanetos wrote.