What level of qualification do you really need for space electronics?
June 02, 2015 | BY: Niall Heffernan
Space missions present extreme environments for electronic equipment, perhaps more than any other aerospace application. Aside from high levels of vibration, shock and vacuums, space electronics are subjected to increased levels of radiation. These can lead to single-event effects which can render equipment useless or unreliable. Preventing these effects from influencing electronics is known as ‘radiation hardening’ while mitigating against these effects can be achieved with ‘radiation tolerant’ electronics.
Preventing an effect from happening with development flight instrumentation and/or operational flight instrumentation seems like the ideal approach, but there is one big trade-off – cost. Increasing commercial pressures are putting focus on keeping costs to a minimum and radiation hardened electronics can form a significant chunk of the cost required for a space mission. Companies like SpaceX, Boeing and Virgin Galactic are taking the lead over government agencies in developing the next generation of space launchers and vehicles, and saving costs is critical in a commercial environment. However, there is no avoiding more expensive lower-risk equipment for mission critical systems which could endanger the lives of the crew or cause a mission failure if they malfunction.
There are other systems where lowering the level of space qualification is acceptable and the cost savings are significant enough to justify an increased risk of failure. This risk of failure must be kept below a certain level so there does need to be careful consideration given to each system, and the interaction between them. Using a COTS based smart backplane system, which mixes radiation tolerant and hardened components, is a good example as it provides high levels of reliability without being fully hardened. This will be at least half the cost of a fully radiation hardened alternative. An illustration of the practical outcome of this is one organization the author knows of that believes using this strategy would lead to having the budget to launch perhaps six space missions instead of five.
Systems with no specialized radiation tolerant design are also perfectly suitable for some applications (e.g. launcher data handling, short duration sub-orbital missions) and the savings are even more significant here as standard flight test hardware is already highly ruggedized and designed for low size, weight and power (SWaP) requirements. This approach of mixing qualification levels for space electronics has been fully proven. For example, Curtiss-Wright provides equipment based on the same core COTS space data handling systems has been used successfully in such a wide variety of space missions from test aircraft, to launchers, to reentry vehicles to the international space station.
You can learn more by reading an example of a launcher space data handling system application, how ‘space qualified COTS’ will be used on the international space station and how onboard data handling equipment was used on a successful re-entry vehicle case study.