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HOW IT’S COATED
Paint it Black: Behind the James Webb Space Telescope’s Signature Colour Chelsea Gohd Space.com
NASA’s James Webb Space Telescope has to stay super cool to observe the cosmos. How does it beat the heat? Black paint.
A
s the agency explained in its new
and a cool side, which are separated by the
noted, adding that objects painted black are
YouTube series “Elements of Webb,”
spacecraft’s sunshield. The cool side is where
highly emissive (a measurement of how well
the James Webb Space Telescope’s
its highly sensitive scientific instruments
something radiates heat).
radiator is painted black to absorb heat.
reside, and sunshield blocks any heat from the
To ensure that the black paint used on Webb
Just like how black asphalt gets hot in the
sun from reaching those instruments.
did the best job possible at soaking up and
summertime, objects that are black are
The cool side “even has a radiator to keep it
radiating heat away from the telescope’s
generally hotter as they absorb all wavelengths
extra cool,” NASA multimedia specialist Sophia
instruments, NASA used a special ultra-black
of light and convert it into heat (comparatively
Roberts said in the video. That radiator and
paint made by Ball Aerospace called Ball
white objects reflect light and do not absorb
everything except Webb’s bright gold mirrors
Infrared Black (BIRB).
heat).
are black on that side, she explained.
Webb’s cold side is about minus 388 degrees
Webb engineers use this principle to keep the
Now, this black paint is important not only
Fahrenheit (minus 233 degrees Celsius). So,
telescope cool.
because black objects absorb heat well, but
why do Webb’s instruments need to be so
Webb essentially has two sides, a hot side
also because they emit heat well, Roberts
cold?
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N. 78 - NOVEMBER/DECEMBER 2022 - international PAINT&COATING magazine