Wake-up call No. 1

Chandrayaan-3 made history with its soft landing near the lunar south pole on 23 August. At work since touchdown, its Pragyan rover found chemicals like sulphur and oxygen in lunar soil even as it recorded temperatures and much else over two weeks before it went to “sleep" as night descended. The hope was that the lander and rover would survive the deep chill and awaken from slumber on 22 September for the dawn of a new lunar day to power up its solar-energy devices that could then start beeping signals back to India again. As it turns out, we’ve had no sign of any such awakening. This is not a failure, as the odds of it were poor all along, and crucial experiments had already been done. In fact, squeezing second-day work out of the contraptions would have been a bonus, as a few further tests could’ve been carried out. Neither craft was designed to survive a mercury plunge below minus 200° Celsius. The Moon has too sparse an atmosphere to regulate the difference between night and day. Such moderation is unique to Planet Earth, although industrial exhaust is threatening this perfection by trapping heat. And this threat, global warming, is the wake-up call that matters most.