Telescope passes critical test in preparation for launch

The James Webb Space Telescope (JWST), NASA's next-generation successor to the Hubble, has passed a crucial milestone towards its 2013 launch with the help of National Instruments' LabVIEW FPGA.

An important element of the JWST is the Near Infrared Spectrograph, which is equipped with more than 250,000 microshutters designed to observe thousands of distant galaxies to better understand the origins of the universe.

These microshutters are microelectromechanical system devices that physically open and close for light exposure, similar to shutters on a camera.

Engineers at the NASA Goddard Space Flight Center have tested the microshutters using LabVIEW FPGA to control the shutters in a test chamber.

"LabVIEW FPGA and R Series intelligent DAQ saved hundreds of man-hours and thousands of dollars," said David Rapchun, lead testing engineer at Global Science and Technology/NASA Goddard Space Flight Center.

"The decision to go with commercial off-the-shelf hardware instead of a custom solution provided a more cost-effective method, and the control algorithm can be easily modified to improve testing, explore shutter issues and otherwise further the development of the microshutters."

NASA selected Mink Hollow Systems, a National Instruments Alliance Partner, to develop the FPGA software required for a test application capable of not only actuating each of the nearly 62,000 microshutters that are tested at a time but also providing design feedback and estimating the life of each unit.

For this, the LabVIEW graphical development environment was selected to develop the test software required to give engineers the ability to customise shutter actuation tests while monitoring and controlling the test environment. To control the opening and closing of the shutters, engineers use FPGA to design a custom control algorithm that could manage the synchronisation required for opening and closing the shutters 240 times per minute.

NASA engineers pulled the shutters open by sweeping a magnet, controlled with motion controllers, across the array of shutters. They controlled the individual shutters within each array through National Instruments PXI-7811R and PXI-7813R intelligent data acquisition (DAQ) modules.

By using magnets to open and close the shutters, which reduced the impact of a shutter on a light baffle, the engineers significantly extended the life of the shutters.