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On-orbit Protection Systems |
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Many payloads have sensitive instrumentation,
such as optics, CCDs, that are vulnerable to contamination effects
and all exposed systems are at threat from micrometeoroid and debris
impacts. Optical systems, in particular, degrade greatly due to contamination
being deposited as particles and thin film. Obscuration leads to data
loss, rendering the system useless.
Utilising on-orbit contamination monitors, active protection systems can protect payloads from the effects of contamination and particulate impact. It has been well documented that debris clouds exist in LEO, with flux rate orders of magnitude higher than the general background rate. These have been most recently measured by T & M Engineering's ICA payload on Mir. A contamination monitor can continuously monitor the environment and be set to activate a protection system when a certain flux/deposition rate is reached, indicating a period of high activity from particle or contaminates, that could damage the payload. The protection system employed consists of simple baffles and covers activated via flight proven hot oil paraffin (HOP) actuators. This simple system allows for a low cost, highly reliable, highly cyclic, protection system. The covers can be re-opened either using the contamination monitor detecting a lower flux rate/level, and/or command from the ground. T & M Engineering also provides the electronic systems to allow ground control of such devices such allowing the covers to be commanded to close and open when periods of high activity are expected. Such circumstances may arise from docking operations, venting, thrusting, and meteor storms. |