Measurement system verifies spec of space sunshield
Engineers at Vesper have developed a non-contact system to verify the dimensional specifications of the five layered sunshield for NASA’s James Webb Space Telescope (JWST). The sunshield will allow the telescope to cool down to a temperature below 50 Kelvin by passively radiating its heat into space.
Awarded a contract in 2010, Vesper is performing shape and dimensional validation of the large membranes used in the sunshield that were fabricated by ManTech International Corporation (Huntsville, AL, USA) for Webb design and engineering contractor Northrop Grumman (Falls Church, VA, USA).
The five Webb sunshield layers, each the size of a tennis court, are made of specialized Kapton material, a very thin plastic with a reflective metallic coating. Once they are tensioned, the membranes are not flat, so their 3-D shape has to be measured carefully. The relative separations and alignments of each of the five membrane layers are a critical factor in achieving the desired cryogenic operating temperature of JWST's telescope and instruments.
According to Vesper CEO Eric Lundberg, it is particularly challenging to measure the mirrored surface of the sunshields with a non-contact system. To take the measurements, Vesper used a modified Metricvision/Metris MV260 non-contact laser radar optical measurement system and a custom mirror array.
Along with the ManTech engineering team, Vesper's team will use ther equipment to measure all five of the membranes to ensure that the sunshield system will perform as designed in orbit.
After all five layers of the full-size sunshield templates are completed and tested in Huntsville, they will be sent to Northrop Grumman Aerospace Systems (Redondo Beach, CA, USA) for final assembly and additional testing.
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-- Dave Wilson, Senior Editor, Vision Systems Design