Super-tough sunshield to protect NASA telescope from space hazards

Washington, Nov 13 : Engineers at Northrop Grumman Corporation in the US have created a sunshield for NASA's James Webb Space Telescope that can withstand the severe cold and heat of space, a barrage of radiation and high-speed impacts from small space debris.

Any satellite that flies in the depths of space has to be able to withstand the rigors of space, including the icy cold or the intense heat and radiation of a solar flare. imilarly, the James Webb Space Telescope needs a sunshield to block heat from the sun so its cameras and instruments can operate properly a million miles from the Earth, when it launches in 2013.

Temperatures in space can range from a super-hot 400 K (260 F) to a frigid 30 K (-406 F).

In addition, the Webb telescope's sunshield will be bombarded with tiny meteorites and radiation in space, so it has to be tough.

It has to stand up against those things, as well as tension and aging under the extreme space environments.

Blocking light and heat from the sun will keep the observatory operating at cryogenic (cold) temperatures, enabling its infrared sensors to see distant galaxies, early stars, and planetary systems.

That's important because infrared sensors actually measure the heat given off from far away galaxies and stars. Shaded and protected from the Sun, the Sunshield allows the telescope to cool down to a nice and chilly 40 K (-387 F).

Any warmer than that and the heat given off from the telescope would corrupt the data.

According to Martin Mohan, Program Manager for the Webb Telescope at Northrop Grumman, Redondo Beach, California, "Previous to this crucial technology, materials with thermal properties that reflect the sun without being heated did not exist."

The super-tough sunshields are made from a polymer-based polyimide film, DuPont Kapton E.

What's most impressive about their strength is that each Sunshield "membrane" layer is about as thick as a human hair (one to two-thousandths of an inch thick).

The semi-conductive silicon coating is very good at reflecting the sun's energy while the nice and shiny aluminum layers are chosen to reflect out to space any of the sun's heat that does get by the first two layers.

These coatings and sunshield geometry work together to reduce the 250,000 watts of the sun's energy that hits the first sun facing layer to less than 1 watt by the time it works its way to the fifth and last layer.

ANI