Active versus standby redundancy for improved cryocooler reliability in space
Long-life space cryocooler applications, such as NASA’s Atmospheric Infrared Sounder (AIRS) instrument, require that the cryocooler system possess a very high level of reliability. This need for high reliability not only demands that high reliability coolers be used, but often requires that some form of redundancy be incorporated. One common implementation is standby redundancy; however, active redundancy is another equally viable choice. Recently, experience with both types of redundancy has been gained with the AIRS instrument. The AIRS cryocoolers were initially designed and launched as standby redundant units; they were then switched over to active redundancy after six months of in-space operation.
Cryocooler Reliability and Redundancy Considerations for Long-Life Space Missions
One means of achieving high reliability with cryogenic payloads involving cryocoolers is to incorporate redundancy, either in the form of redundant coolers and/or redundant drive electronics. To access the redundant elements, electrical and/or heat switches must also be incorporated. Although the redundant elements protect against a possible failure, the increased system complexity and increased cryogenic load associated with the incorporation also have a negative effect on reliability that must be taken into account.
Occupational risks of (meth)acrylate compounds in embedding media for electron microscopy
(Meth)acrylates are the main constituents of embedding media widely used in electron microscopy research for low‐temperature embedding of biological tissue. (Meth)acrylates toxicology is still incompletely understood and therefore an estimation of health hazards involved in handling must be inaccurate. (Meth)acrylate monomers are known to be harmful to skin and other tissues and may sensitize workers. Since low‐temperature electron microscopy techniques have gained popularity in research laboratories, it is important to establish safety rules for handling the (meth)acrylate‐containing solutions.