---

Webb Telescope sunshield passes launch depressurization tests to verify flight design

October 11, 2010

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.

NASA/Goddard Space Flight Center

Related Webb Telescope Current Events and Webb Telescope News Articles

NASA Completes First Part of Webb Telescope's 'Eye Surgery' Operation
Much like the inside of an operating room, in the clean room at NASA's Goddard Space Flight Center in Greenbelt, Md., engineers worked meticulously to implant part of the eyes of the James Webb Space Telescope. They scrubbed up and suited up to perform one of the most delicate performances of their lives.

Practice Makes Perfect With Webb Telescope Mirror Placement
NASA engineers and scientists have been making practice runs to ensure the placement of primary mirror segments on the James Webb Space Telescope go perfectly when the flight equipment is ready.

Gravitational telescope creates space invader mirage
The NASA/ESA Hubble Space Telescope is one of the most powerful available to astronomers, but sometimes it too needs a helping hand. This comes in the form of Einstein's general theory of relativity, which makes galaxy clusters act as natural lenses, amplifying the light coming from very distant galaxies.

NASA'S Webb Telescope Team Completes Optical Milestone
Engineers working on NASA's James Webb Space Telescope met another milestone recently with they completed performance testing on the observatory's aft-optics subsystem at Ball Aerospace & Technologies Corp's facilities in Boulder, Colo. Ball is the principal subcontractor to Northrop Grumman for the optical technology and lightweight mirror system.

Hubble goes to the eXtreme to assemble the deepest ever view of the Universe
Like photographers assembling a portfolio of their best shots, astronomers have assembled a new, improved portrait of our deepest-ever view of the Universe. Called the eXtreme Deep Field, or XDF, the photo was assembled by combining ten years of NASA/ESA Hubble Space Telescope observations taken of a patch of sky within the original Hubble Ultra Deep Field. The XDF is a small fraction of the angular diameter of the full Moon.

First Two Webb Telescope Flight Mirrors Delivered to NASA
The first two of the 18 primary mirrors to fly aboard NASA's James Webb Space Telescope arrived at NASA's Goddard Space Flight Center in Greenbelt, Md.

Johns Hopkins astrophysicist spies ultra-distant galaxy amidst cosmic 'dark ages'
With the combined power of NASA's Spitzer and Hubble space telescopes as well as a cosmic magnification effect, a team of astronomers led by Wei Zheng of The Johns Hopkins University has spotted what could be the most distant galaxy ever detected.

Ultra-distant galaxy spied amidst cosmic 'Dark Ages'
With the combined power of NASA's Spitzer and Hubble Space Telescopes, as well as a cosmic magnification effect, a team of astronomers, including Carnegie's Daniel Kelson, have spotted what could be the most distant galaxy ever seen.

Hubble Discovers a Fifth Moon Orbiting Pluto
A team of astronomers using NASA's Hubble Space Telescope is reporting the discovery of another moon orbiting the icy dwarf planet Pluto.

Most Quasars Live on Snacks, Not Large Meals
Black holes in the early universe needed a few snacks rather than one giant meal to fuel their quasars and help them grow, a new study shows.

---

More Webb Telescope Current Events and Webb Telescope News Articles

---