China’s rover on Mars has not woken up after months of hibernating, the scientists operating it finally explained on Tuesday.

Zhurong, as the solar-powered rover is known, was in a scheduled sleep during the red planet’s winter. And though it was named after an ancient Chinese god of fire, it seems remarkably… docile, right now.

So what’s stopping it from waking up? Dust, apparently, as this stops it turning sunlight into electricity.

Chief designer of the Mars exploration programme, Zhang Rongqiao, explained: “Based on our analysis, the most likely possibility is that an unpredictable accumulation of dust from Mars led to a decrease in its ability to produce electricity, such that it’s insufficient for it to wake up.”

If the dust levels exceed more than 40% that the Chinese engineers had prepared for, it would become inactive “forever”. No amount of solar activity could help it, Zhang told Chinese state broadcasters.

He did not explain how much dust is already on it.

The rover successfully landed back in May 2021, meaning China was only the second country after the US to succeed to landing a probe like this on Mars.

The landing was seen as a sign that Beijing was really starting to establish itself in space exploration.

When the rover first touched down, it explored Mars for about a year in Earth days (358 days in Martian time) and covered 1.2 miles, even though it was only meant to look around for three Martian months.

It was then put to sleep in May 2022, and was meant to autonomously wake up December 2022 during the planet’s northern spring equinox.

Five months later, it’s looking like the rover has decided it would rather stay sleeping. And who can blame it?