The technology used aboard most spacecraft always has to be very robust to survive the harsh environment beyond our atmosphere, but often the software and hardware used are rather basic and usually fairly old by the time a launch takes place.
Part of the reason why is that spacecraft take years to develop, but reliability is the biggest reason. If something goes bad on a spacecraft that can’t be fixed remotely, the mission is put into jeopardy.
Recently, ESA launched its Solar Orbiter mission, which is slated to travel 10 million kilometers closer to the Sun than Mercury, the innermost planet. Jacek Krywko at Ars Technica writes about what is required to keep the spacecraft from being cooked alive:
To withstand such temperatures, Solar Orbiter is going to rely on an intricately designed heat shield. This heat shield, however, will protect the spacecraft only when it is pointed directly at the Sun—there is no sufficient protection on the sides or in the back of the probe. So, accordingly, ESA developed a real-time operating system (RTOS) for Solar Orbiter that can act under very strict requirements. The maximum allowed off-pointing from the Sun is only 6.5 degrees. Any off-pointing exceeding 2.3 degrees is acceptable only for a very brief period of time. When something goes wrong and dangerous off-pointing is detected, Solar Orbiter is going to have only 50 seconds to react.
The whole article is fascinating, and well worth a read.