An automated control system for the microshutter assembly (MSA) portion of the JWST MSS (James Webb Space Telescope Micro shutters Subsystem) was developed. This is a cryogenic device that operates at 35 K. Cooling down and warming back up is a critical activity since the arrays are very fragile. This process used to be manual. After seeing the difficulties of operating in this mode with the engineering test unit (ETU), a decision was made to develop a LabVIEW-based control system to monitor temperature sensors, and control the heater, cryocooler, and vacuum pumps. This system fully automated the process for warm-up and cool-down, and reduced the overall time it took in the process. A text message alert system was included so that members of a call tree were alerted if there were any violations of set constraints.

This innovation is comprised of the LabVIEW-based system, Lakeshore Cryotronics temperature monitors, pressure sensor, pump speed sensors, and a cryogenic quartz crystal microbalance (CQCM). The LabVIEW control software is set with a desired temperature and a delta to maintain between temperature points, while monitoring pressure, pump speeds, etc. A series of configurable alerts is set, and any violation is sent via text message to personnel on a call tree. Utilizing a virtual private network (VPN) connection and a control list, certain team members can monitor and control the software remotely.

This work was done by Dion Smallwood of Goddard Space Flight Center. GSC-16401-1

NASA Tech Briefs Magazine

This article first appeared in the September, 2015 issue of NASA Tech Briefs Magazine.

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