The Moon mission, Chandrayaan-2, had been going well up until the lander was about 1.2 miles above the surface. It’s still not certain what caused the failure.

The discovery is a sad moment for India, which would have been just the fourth country to land a spacecraft on the Moon. However, it also underscores the challenges that remain for lunar missions half a century after Apollo 11. Simply put, landing on the Moon is hard — there are a lot of variables that have to fall into place, and India isn’t the only one to have run into trouble despite promising technology.