Webb Telescope Sunshield Passes Launch Depressurization Tests to
NASA's James Webb Space Telescope continues to make significant
progress, successfully completing a series of sunshield vent tests that
validate the telescope's sunshield design.
"While adequate venting is a design consideration for all spaceflight
hardware, this was a particularly unique challenge for the sunshield
given the large volume of trapped air in the membrane system at
launch," said Keith Parrish, Webb telescope sunshield manager at NASA's
Goddard Space Flight Center in Greenbelt, Md. "From the beginning of
its development venting features have been a critical part of the
overall sunshield design. Since we cannot vent test the actual flight
article these test have shown the design works and the sunshield will
vent safely on its way to orbit."
The sunshield on the Webb telescope will block the heat of the Sun and
Earth from reaching the cold section of the Observatory. That's a
critical function because the telescope and instruments must be cooled
below 50 Kelvin (~-369.7 Fahrenheit) to allow them to see faint
infrared emissions from astronomical objects. The sunshield consists of
five layers of Kapton ®E with aluminum and doped-silicon coatings
to reflect the sun's heat back into space.
Using flight-like sunshield membranes, the tests are designed to mimic
the rapid change in air pressure the folded sunshield will experience
the first minutes of launch. Several different folding configurations
each underwent a series of 90-second depressurization tests and proved
that the stowed sunshield will retain its shape during launch and allow
trapped air to escape safely, both critical to sunshield deployment and
performance.
Northrop Grumman Corporation is leading Webb's design and development
effort for NASA's Goddard Space Flight Center in Greenbelt, Md. The
first tests were conducted the last week of August in vacuum chambers
at Northrop Grumman Aerospace Systems' Redondo Beach facility. Another
series of complementary tests were completed in October where air was
injected into the stowed sunshield test article, and that provided more
detailed data used in evaluating analytical models.
"This is another significant risk reduction activity that continues to
move sunshield development forward," said Scott Willoughby, Webb
Telescope program manager for Northrop Grumman Aerospace Systems. "We
have demonstrated the effectiveness of our sunshield vent design."
Three critical full-scale sections of the sunshield were tested: the
section on top of the spacecraft around the tower that supports the
telescope; the vertical pallet structure that contains the folded
sunshield membranes, and the intervening four-bar linkage area that is
folded in an inverted V-shape. The flow paths are complex and the
sunshield material, a tough plastic film, Kapton ®E, is only one to
two thousandths of an inch thick and covers a surface area the size of
a tennis court.
The James Webb Space Telescope is the world's next-generation space
observatory and successor to the Hubble Space Telescope. The most
powerful space telescope ever built, Webb will observe the most distant
objects in the universe, provide images of the very first galaxies ever
formed and see unexplored planets around distant stars.
The Webb Telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.
For more information on the James Webb Space Telescope, visit:
