“It’s hard enough to land on another planetary body when everything works perfectly,” said Mark Johnson, the lead for the Lockheed Martin team during the successful landing of NASA’s InSight spacecraft on Mars in November, “but to have done it in the presence of a major anomaly would have been astounding.”

Chandrayaan-2 — India’s second mission to the moon — consists of two parts: an orbiter that will conduct research in orbit for up to seven years, and a lander named Vikram (which also contained a rover, Pragyan). The lander and orbiter separated last week with the orbiter remaining in a circular orbit 60 miles above the moon, and the lander moving to a more elliptical path, coming within 20 miles of the surface.

During most phases of a mission, if something goes wrong with a spacecraft, it is programmed to enter “safe mode” — that is, to largely shut down to prevent bigger problems and await new instructions from Earth. That is not uncommon. But a spacecraft in a stable orbit or parked on another world’s surface is usually not in any imminent danger, giving engineers days or even weeks or months to fix the problem.

A problem during landing is more like jumping out of an airplane and discovering that something is wrong with the parachute. There is only a short amount of time, and the ground is not going to move out of the way.