Chandrayaan-3 moon lander: Hopes fade for renewed contact with Indian spacecraft

The Indian Space Research Organisation (ISRO) is still attempting to re-establish communications with its Chandrayaan-3 mission’s moon lander and rover, but experts say hopes are fading as suspicions grow that the spacecraft have succumbed to brutally cold temperatures during the lunar night.

ISRO’s Vikram lander touched down on the surface on 23 August before releasing the Pragyan rover. Both craft successfully carried out their scientific experiments and transmitted data back to Earth, and the mission had already proven a great success.

But after the landing, senior engineers said they were confident that the craft would be able to survive the lunar night and carry out more work. Around two weeks after the mission began – one single period of lunar daylight – both devices went into “sleep mode” and prepared for conditions as low as -238°C that could destroy their electronic components.

Following a long wait, the lunar terminator – the line between night and day – crossed the Chandrayaan-3 landing site around 22 September, bathing the craft in sunlight and theoretically allowing them to use their solar panels to charge their batteries and boot up their onboard computers once again. But there have been no signs of life.

ISRO tweeted on 22 September that it had been attempting to establish contact with the craft without success. Since then, it has provided no further updates and ISRO’s press office didn’t respond to a request for comment. On 25 September, former ISRO chief A. S. Kiran Kumar told the BBC that the “chances of reawakening are dimming with each passing hour”.

David Cullen at Cranfield University, UK, says it shouldn’t be considered a failure if Vikram and Pragyan don’t wake up, as the Chandrayaan-3 mission was designed to achieve its objectives in a single lunar day.

He says that designing craft to survive the vast temperature swings between lunar night and day, which can cause batteries and electrical components to literally crack as they expand and contract, can involve measures like adding radiation sources to provide warmth – but these also add complexity, cost and weight. Often, it is more pragmatic to land a leaner, simpler craft that quickly carries out science before the brutally cold nighttime temperatures destroy it, he says.

“To make sure it can survive is an enormous engineering challenge,” says Cullen. “So quite a few missions will be designed with no serious expectation of surviving the lunar light. And then if, by some chance, you do survive the lunar night, it’s a nice added-on extra.”

“It would seem logical to assume that if it didn’t respond during its second lunar day, then, when it comes to the third lunar day, the chances of responding are significantly less,” he says.

Sarah Casewell at the University of Leicester, UK, says it is now unlikely that the craft will reawaken. “You maybe expect some little bit of delay because things don’t warm up as fast as you’d like or, you know, there’s awkward shadows. But by now, I think you would have expected everything to have warmed up, so it sounds as though the cold was maybe too much.”

But she says that the project should be considered a huge success. “They’ve done everything they set out to do,” says Casewell. “How inspirational is this for a nation that has a relatively young space programme? I think that is just phenomenal, that’s such an achievement.”