The Indian Space Research Organization achieved something remarkable this week when it successfully landed its Vikram lander on the surface of the moon.
Today it published an incredible video of the Pragyan rover wheeling down a ramp on to the lunar surface and taking its first moonwalk.
How long it will live for, however, is the subject of speculation.
The uncrewed Chandrayaan-3 mission become the first to land close to the moon’s south pole, though precisely where it landed has huge consequences for how long the solar-powered mission might last.
First To South Pole?
“Vikram touched down at a latitude of 69.4º south, placing it near the southern polar region,” said Tom Kerss, astronomer and author of the new Observing Our Solar System: A Beginner’s Guide, in an email. So calling Chandrayaan-3 the first mission to the lunar south pole is a bit of a stretch.
One reason why the mountainous region around the south pole is so attractive to space agencies is because it has craters permanently in sunlight. For landers and rovers like Vikram and Pragyan that means a constant supply of solar power is possible.
However, Vikram and Pragyan haven’t landed close enough to the south pole for that to be a possibility. “It will still experience a typical lunar day-night period of just over 14 Earth days each,” said Kerss. During one orbit of Earth—which takes just under a month—any specific location on the lunar surface gets about two weeks of daylight and two weeks of darkness.
In effect, a day on the moon lasts two weeks and so does a night.
Astonishing Cold
“Vikram and Pragyan will face a challenge familiar to all previous lunar landers—the astonishing cold of the lunar night,” said Kerss. Both are solar powered and can draw energy from the sun during the first 14 Earth days of the mission, but after that it will gets very dicey. “When the lunar night sets in the batteries will drain and the onboard electronics will be subject to low temperatures around -328ºF (-200ºC),” said Kerss.
Will Vikram and Pragyan survive the long lunar night? Probably not. Knowing that, ISRO has planned the surface mission to last just a single lunar day (14 Earth days), so we can look forward to regular updates—and perhaps more videos from the lunar surface—for the next 10 days or so.
“Surviving 14 Earth days of cold darkness and waking up again is a big ask for any lander or rover, but perhaps we’ll be pleasantly surprised,” said Kerss. After all, in 2014 the Chinese Yutu rover unexpectedly woke up after its first lunar night and “phoned home” to mission control in China. “The fact that Yutu could still operate was a testament to its engineering—I would imagine the scientists at ISRO are hopeful for a similar outcome,” said Kerss.
Wishing you clear skies and wide eyes.