Engineers use gold baffles to remove heat from Webb Space Telescope


Engineers at NASA have fitted gold baffles to reflect away excess heat generated by the James Webb Space Telescope’s scientific instruments and electronics.

The James Webb Space Telescope (JWST) is the planned successor to the Hubble Telescope and is one of NASA’s most complex and expensive projects.

The infrared telescope’s four science instruments are held within a support structure called the integrated science instrument module (ISIM), located behind the telescope’s primary mirror.

The ISIM and Webb’s optics form the science payload of the observatory. To keep heat away from the sensitive instruments, a majority of the electronics used to power and operate the instruments are housed in a compartment below the ISIM, where baffles direct the heat safely into space and away from any cold surfaces of the observatory.

The baffles act as mirrors to reflect the heat outward in a specific direction. This is the same technique used by Webb’s mirrors, but instead of reflecting heat into space, they will guide infrared light to the telescope’s scientific instruments.

Matthew Stephens, a mechanical systems engineer for Webb at NASA’s Goddard Space Flight Center said, “Gold has a very high reflectivity in the infrared spectrum range, so it is ideal for directing heat. This is the same reason all of the primary, secondary, and tertiary mirrors are gold-coated.”

Engineers have reinstalled the baffles, which had been previously removed and safely stored in a clean environment to protect them from any contamination during integration and testing of the science payload. The clear plastic sheets placed over the baffles will protect them from any contamination during the remaining integration and testing phases for the observatory.

The baffles had to be reinstalled before Webb’s science payload and its spacecraft element are integrated at Northrop Grumman Aerospace Systems in Redondo Beach, California, where both halves of the observatory currently reside. If the engineers waited until after integration, Webb’s tennis-court-sized sunshield will obstruct the ISIM electronics compartment and make reinstalling the baffles much more difficult.

The JWST was due to be launched in October 2018 on an Ariane 5 rocket, but was rescheduled in September last year by NASA to be launched between March and June 2019. Webb is an international project led by NASA with its partners, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

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Ben has worked as a journalist and editor, covering technology, engineering and industry for the last 20 years. Initially writing about subjects from nuclear submarines to autonomous cars to future design and manufacturing technologies, he was editor of a leading UK-based engineering magazine before becoming editor of Aerospace Testing in 2017.

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