USSRC Hosts James Webb Space Telescope Chief Engineer

Dr. Jon Arenberg, Chief Engineer of Northrup Gruman’s James Webb Space Telescope, delivered presentations about the telescope’s design, building, and findings at the Space and Rocket Center’s planetarium on July 15 at 4 and 7 pm.

The James Webb Space Telescope sets itself apart from other Space Telescopes, such as the Hubble Space Telescope, in using infrared light to better observe the early Universe.  

“Web is designed to collect images and collect data from the first luminous objects in the history of the universe. Literally the universe’s baby pictures,” Arenberg said. 

He explained the JWST is such a large telescope because its diameter sets its ability to resolve objects. Without a high level of resolution, the telescope would not be able to differentiate between celestial objects that are close together. 

Second, its large mirror allows the telescope to collect more light. As a result, the JWST has unique capabilities like the ability to show clear definition between the rings of Saturn.

The telescope also features a plastic sunshield built in Alabama. The sunshield is integral to the telescope’s design because the telescope must stay as cold as possible to be able to capture accurate images in infrared, Arenberg explained, comparing the concept to a photo of his cat, Orion, in infrared. 

“His body temperature is 38 or 39 degrees, a little warmer than human body temperature. But thankfully, the walls of my house are not that warm, but we get less than 20.” 

Because the walls were cool and Orion was warm, he could clearly be seen in the infrared photo. Had the walls been the same temperature as Orion, he would not have been visible. If the telescope itself were hot from the sun, it would obscure the differences between celestial bodies and their background.

Each layer of the sunshield is approximately 1/1000 of an inch thick, so they could not be walked on during the installation of the 2.5-by-2.5-meter shield. To combat the problem of attaching such a delicate material to a large surface, technicians practiced working while lifted on “diving boards” by sterile forklifts so they could work from just above the fragile plastic.

The telescope’s beryllium infrared imager, called a mirror, is 6.5 meters in diameter. This collecting area is roughly 7.3 times the size of that of the Hubble Telescope. The mirrors were designed to unfold after its launch, and the placement of each mirror had only a two-nanometer allotted margin of error. The size and shape of the mirrors were verified in Northern Alabama’s X-ray & Cryogenic Facility.

The telescope had a requirement to view a minimum of 35% of the sky; it exceeds that minimum at 39.25% visibility at all times. As the telescope orbits near the Earth’s second Lagrange point, it will eventually sweep the entire sky.

Additionally, there is a portion of sky that remains visible at every point, allowing for long-term measurements in that portion of the sky. That orbit, however, does not impede the telescope’s capacity to be pointed at any point in the sky in a given year. 

Arenberg praised the design of the Hubble Space Telescope, calling Hubble’s research in the early 20th Century “amazing.” He explained, however, that if the JWST had been designed in the same way as the Hubble Space Telescope, it would have been too heavy. Implementing a much larger mirror on a telescope of roughly the same size as the Hubble Telescope required a much greater focus on keeping weight down. The back plane stability test article was also tested at the XRCF.

The James Webb Space Telescope was launched on Christmas day of 2021. Since then, it has been orbiting near the second Lagrange point in order to more thoroughly map the Universe than other telescopes can. Arenberg called the project “an epic act of collective perseverance and genius.”

The event took place in the U.S. Space and Rocket Center’s INTUITIVE Planetarium and featured images gathered from the telescope as well as images taken throughout the building of the telescope. 

After his presentation, Arenberg took questions from the audience.  The presentation was hosted by the INTUITIVE Planetarium Director, David Weigel. Tickets were sold-out for both the 4 and 7 p.m. showings. Cocktails and concessions were available for purchase.

 The INTUITIVE Planetarium has daily shows about the James Webb Space Telescopes, updated each time new JWST images are released.