Nasa's Mars helicopter Ingenuity 'went silent for six days'

Nasa's Mars helicopter, Ingenuity, went missing on Mars for six days in April but has since responded again, ensuring that the device is still active.

The mini helicopter, developed by the Jet Propulsion Lab at Nasa, previously failed to respond to the mission team for almost a week in early April, Ingenuity chief engineer Travis Brown wrote in an update on May 26.

At first, this did not raise any concerns.

According to Brown's update, since January, the mini chopper has been drifting in and out of nighttime survival mode (having enough power to escape overnight brownouts) as winter set in at Ingenuity's residence — the floor of Mars' Jezero Crater.

As a result, Ingenuity's daily waking time became unpredictable, making it more difficult to hail the chopper and schedule its activities, Space.com reported.

However, Ingenuity's Perseverance rover was unable to communicate with its helicopter due to a rocky outcrop, making the situation worrisome.

"In more than 700 sols operating the helicopter on Mars, not once have we ever experienced a total radio blackout. Even in the worst communications environments, we have always seen some indication of activity," he continued.

One sol, or Martian day, is slightly longer than an Earth day, lasting about 24 hours and 40 minutes.

April 5 marks the start of sol 755, or the Ingenuity blackout. On sol 761, it finally came to an end when the mission team noticed a signal during the anticipated waking window for the chopper.

"The team was relieved when they received a second signal at the same time on sol 762, which proved that the helicopter was indeed alive," Brown wrote.

The very next day, on sol 763, or April 13, Ingenuity completed its 50th flight on Mars. On that sortie, it ascended to an all-time high of 59 feet (18 metres), breaking all previous records.

"It would be an understatement to say that the helicopter team was relieved to see the successful flight telemetry in the sol 763 downlink the following morning," Brown wrote.

Ingenuity flew again on April 22 but has stayed ground-bound since then.

Although the Jezero Crater will soon experience another summer, it will not prove much helpful as Martian dust on Ingenuity's solar panels will keep the chopper in a transitional power state for a bit longer.

"This means that, much to the chagrin of her team, we are not yet done playing this high-stakes game of hide and seek with the playful little helicopter," Brown wrote.