Robotic Space Missions Page

Space robots come in all shapes and sizes, and have a wide variety of functions. These include planetary flyby probes (e.g. Voyagers 1 and 2), orbiters (e.g. Galileo, Cassini), atmospheric probes (e.g. Huygens Titan probe), landers (e.g. Mars Pathfinder), rovers (e.g. Sojourner), robot arms (e.g. the Space Shuttle Remote Manipulator System), and robots currently under development for the International Space Station.

Nowadays, the word “robot” is often applied to any device that works automatically or by remote control, especially a machine (“automaton”) that can be programmed to perform tasks normally done by people. Early last century, “robot” usually meant a manlike mechanical device (“mechanical man” or “android”) capable of performing human tasks or behaving in a human manner. What all robots have in common is that they perform tasks that are too dull, dirty, delicate or dangerous for people.

Space probes hurtling through the solar system may not seem like robots, but they fully merit that name by performing programmed tasks over long periods without direct human supervision. Operating in the vacuum of space and withstanding exposure to radiation and extremes of temperature, they explore places not yet accessible to humans.

All space robots are basically quite similar, in that each has a controller, sensors, actuators, radio communications and a power supply. The sensors provide information about the robot and its environment. The controller processes the information from the sensors, along with instructions radioed from ground control, and sends appropriate command signals to the actuators. The actuators and drive convert the command signals into actions.

The long transmission times for radio waves over interplanetary distances preclude “real-time” remote control of distant space robots from Earth, so such robots must be capable of operating independently (autonomous control). This is particularly important for rovers, which are likely to encounter rocks, cliffs, craters and other hazards as they move around.

Many mobile robot (“mobot”) controllers use a layered system of control modules based on insect behaviour. In the development of the software, layers of behaviour generating modules are added one at a time, each of which connects sensing to action. The modules all run in parallel whenever triggered by the relevant sensors. To prevent conflicts arising between behaviours that could be triggered at the same time, the modules are organised into a “pecking order” (hierarchy). Higher-level behaviours have the power to temporarily suppress lower-level ones, but when the higher-level behaviours are no longer being triggered, the lower-level ones resume control.

ROBOT SPACE EXPLORERS