Swarms of autonomous micro-robots would be sent to other planets to conduct missions. Total autonomy actually increases mission reliability. Out of control of ground based operators, the robots can use force control with tight sensing feedback loops. Force control is the key to reliable performance in the face of any uncertainty. By completely removing all ground based control of the rovers, their complexity goes down drastically as there is no need for much of the communications equipment, and no need for the ground support maintaining communications.
Simplicity increases reliability.
These gnat-sized robots developed out of experiments dealing with how intelligence systems organize themselves. Lots of robots with pint-sized brains could have the same intelligence as one big robot. You know, now I'm thinking about the human brain, and how if part of it gets damaged, sometimes new neural pathways develop, making new connections. In an always incipient cosmos, The way, when we climb a mountain, Vermont throws itself together.