I'm fascinated by robotic spacecraft, so I'll take a stab at answering your question. <img src="/images/icons/wink.gif" /><br /><br />There are some things common to all spacecraft. (In fact, deep space probes are usually just more robust versions of the Earth-orbiting ones.) First off, in case you don't know, deep space probes are any that are targeted at someplace beyond the Earth-Moon system -- so, it's any probe that escapes Earth's gravity.<br /><br />Now, the basic components of an unmanned spacecraft will be these:<br /><br /><b>Power supply</b><br /><br />There are several ways to provide electrical power. Which you use will depend on how long it has to operate, what conditions it will operate in, where it will operate, and how much power it needs. If it only needs to run for a short time (like a short-lived probe), then batteries are fine. If it will be operating in the inner solar system, solar power is probably your best bet. In the outer solar system, radioisotope thermoelectric generators (RTGs) are probably the best bet. Nuclear reactors have been used on a few earth-orbiting spacecraft (and at least one Soviet one did crash in northern Canada!) but are not particularly popular; although no one was hurt in the Soviet accident, the political fallout remains.<br /><br /><b>Thermoregulation</b><br /><br />All spacecraft need to maintain a temperature between certain specified limits. This permits the equipment to operate properly. Just as your computer has a fan to dissipate excess heat, a spacecraft needs to get rid of extra heat generated by its electronics. You can't use a fan in space, since there's no air for it to blow around, so you need to conduct the heat away from the electronics and into a radiator to shed it into space. At the same time, you need to make sure your spacecraft doesn't bake in the sun. Painting it white or covering it in reflective Mylar are both popular techniques for this. You can also wrap the entire spacecraft in insulation <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>