If you took your laptop computer into space it might work for a few minutes. But then it would lock up, or would not operate correctly, or output nonsense rather than pictures and video and clear audio. On Earth, this is not a problem because you could just restart it or bring it back and trade it in. However, if your computer was running a satellite, it would be a major problem. In space, a satellite’s computer can not be readily maintained, worked on, or replaced.

Radiation is damaging to microelectronics, and there is radiation in space. This radiation occurs naturally from a variety of sources, such as the sun and cosmic rays. Radiation can come in the form of high energy photons (such as X-rays), or high energy massive particles such as protons, electrons, and alpha particles. Most of this radiation is deflected by the Earth’s magnetic field and often trapped in the Van Allen radiation belts or mitigated by the Earth’s atmosphere, and therefore never reaches the surface. However, it has a major effect on satellites in space. problem space

Radiation in space can cause several types of problems in electronics. The problems fall into two broad categories: total ionizing dose (TID) effects and single event effects (SEE).

Total ionizing dose effects are caused by cumulative exposure to ionizing radiation over time. It was a significant problem during the 1970s and 1980s, but as microelectronic processes have advanced, TID plays an increasingly less important role. TID causes problems primarily by charge building up on the isolating layers that separate transistors on a microchip. However, as circuits have shrunk in recent years, so has the thickness of these insulating layers, which allows much less chance for charge buildup. Most microelectronics produced today can handle TID levels far beyond what is encountered during a satellite mission.

Single event effects, on the other hand, have become more problematic as circuits have become smaller and more complicated. SEEs are caused when an energetic particle strikes a semiconductor and produces unintended electrical currents within the circuit. If these currents occur at critical locations on the circuit, several effects can occur, ranging from single event upsets (SEU) to single event functional interrupts (SEFI) to single event latchup (SEL). Each of these can severely limit the functionality of a satellite computer in space.

Single event upsets cause bit errors, which results in an error in the output or operation of the device. For example, an SEU could result in corrupted data transmitted by a satellite’s electronics. An occasional SEU, such as one per year, is not too troublesome. However, many commercial microelectronics would suffer far SEU rates much greater than that in the space radiation environment. If the SEU rate is too high, the microelectronics are rendered useless. SEUs are a temporary error and not permanently damaging to the circuit.