No service calls, ever
Every course in this track has dealt with an environment that punishes mistakes, but space punishes them differently. A surgical robot that fails can be paused and attended to by a room full of trained staff. An agricultural robot that breaks down can be trailered back to a shop. Even an underwater vehicle, operating far from easy reach, can usually be recovered, hauled onto a deck, and repaired. A spacecraft or planetary rover, once deployed, is for most missions permanently beyond physical intervention. There is no crew to swap a part, no dock to return to, no hand that can reach in and reseat a connector. Whatever hardware and software leave the ground is, in almost every practical sense, all that will ever exist for that mission. This single fact reshapes everything else in the field: design, testing, redundancy, and autonomy all exist in service of the reality that failure is frequently permanent and unrecoverable.
Layered on top of that is an environment actively hostile to the machine itself. Temperatures swing by hundreds of degrees between direct sunlight and shadow, sometimes within the same orbit or the same day on a planetary surface, stressing materials and electronics with constant expansion and contraction. Ionizing radiation, unfiltered by any atmosphere, steadily degrades electronics and can flip individual bits in memory or corrupt a running process outright. The vacuum of space removes two things engineers on Earth take for granted: air to carry away waste heat through convection, and air to provide aerodynamic control surfaces like fins or parachutes for most of a mission's duration. Every one of these conditions is chronic, not occasional, and a robot built for space has to survive all of them simultaneously for years without a single maintenance visit.