James Webb Space Telescope (JWST)
Jerry Jones, PMP, SAFe POPM
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December 25th 2021 the James Webb Space Telescope (JWST) was finally able to launch.?It went active about 5 months later representing several phenomenal engineering success stories for NASA and Northrop Grumman. #jameswebbspacetelescope #nasa #engineering
When is the last time you had a conversation about absolute zero (0 degrees Kelvin (K), -459.7 degrees F) or photons, related sizes to human hairs??NASA said let’s make a telescope that is 7x size of the Hubble, and let’s send it 2500x further into deep space.?While we’re at it, the payload compartment is limited so let’s make it foldable and expect it to operate perfectly the first time.?Once the JWST launches, it cannot return, it cannot have a repair mission, like the Hubble needed.
The JWST was designed to see the light from the Big Bang, which was 18 billion years ago and the light has long since passed us so we have to look back but the light is now so old and so far away it is in the invisible infrared wavelengths.?To see this light, the telescope has to be moved away from any sources of heat so it was sent one million miles away.?It was still subject to heat from the sun so a new technology had to be developed for the heat shield.?The mirror itself needed new technology to fit in the payload volume of the spacecraft, be light enough fuel could be carried for the million-mile trek and yet large enough to reflect a single photon of invisible light, in fact it would be seen as heat.?WOW!
The mirror, was actually 18 individual mirrors, made of Beryllium.?Mined in Utah, Beryllium has strength greater than steel and weight less than aluminum and holds its shape over significant temperature ranges, but it is not inherently reflective.?The processing of these mirrors required traveling 15,000 miles making 14 stops at 11 different places in 8 different states.?Companies such as Northrop Grumman, Brush Wellman, L3, Axxysys, Ball Aerospace and many others helped in different phases of this process.?Gold is highly reflective so a very fine film of vaporized gold is applied to each mirror segment.
Approximately 250,000 Micro shutters were needed with a width 2-3 human hairs that open to “see” the light within their field of view.?Originally these were magnetically controlled.?During testing at temperature, these magnetic properties were no longer present so they are now electrically controlled.?Some great detail on the shutters can be found at the mirror link below.?
Space is typically about -370 degrees F (49.8 degrees Kelvin) but the JWST will be operated at 7 degrees kelvin-nearly absolute zero (0 K or -459.7 F).?Even at one-million miles away, the JWST still needed shielding from the sun, earth and moon to achieve this extra cooling.?Mechanical cooling can break down and is heavy so a heat shield was needed.?This heat shielding required developing another new technology.?Five layers of aluminum coated Kapton or doped-silicon, were used to channel heat out of each layer of the tennis court sized (40’ x 70’) heat shield.?To keep any damage, should it come in contact with a micro meteor or something of this nature, from propagating, a Thermal Spot Bond (TSB) was used which effectively melts certain areas of a layer together forming a rip-stop grid pattern.?
One would think this has been enough of an engineering challenge but the story continues.?Due to payload size, the mirrors and the heat shield have to be folded for launch and deploy without failure at the right time.?The process of unfolding these pieces is simulated in a video below.
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Testing was a critical phase of the build.?Tests, for instance, revealed the loss of magnetism on the shutters.?During vibration, some bolts came lose, but overall testing was very successful.?Another huge feat considering there is no facility large enough to test the entire telescope, at temperature and vibration so it was tested in pieces.
Shipping from Northrop Grumman to the launch site (5,800 miles) on the equator was the next major requirement and is detailed in a link below.?Much of the transit was done in secret, at night, to keep anyone, including pirates, from knowing what the cargo was and where it was at any particular moment.?
After multiple delays for budget, testing, COVID and weather, the JWST launched successfully on Christmas day 2021.?It deployed successfully in April 2022 and is now sending data-not photos back to earth for conversion into images.?While not at all involved in this process it is just so awesome and demonstrates what can be done to overcome obstacles.
JWST launch and unfolding simulation:?https://mashable.com/video/james-webb-space-telescope-launch-video