By the end of this section, you will be able to: If you’ve ever gone on a hike, you have probably been eager to see what lies just around the next bend in the path. Researchers are no different, and astronomers and engineers are working on the technologies that will allow us to explore even more distant parts of the universe and to see them more clearly. The premier space facility planned for the next decade is the James Webb Space Telescope (Figure 6.27), which was launched on December 25, 2021. James Webb was one of the early administrators in NASA. As we write this (in December 2021), the telescope is on its way to a stable orbit point, some 1.5 million kilometers from Earth (where no astronauts can currently travel if the facility needs repair). During its 29-day journey, a number of activities must be successfully executed in order to prepare the JWST to make observations. A solar array will be deployed to provide energy, and a sunshield will be stretched out to protect the telescope from the intense heat of the Sun. The secondary and primary mirrors will then be unfolded. The primary mirror is 6 meters in diameter, made up, like the Keck telescopes, of 36 small hexagons.

The James Webb Space Telescope (JWST) observatory is the first segmented, deployed optical telescope with optical elements exposed to a space environment that will be thermally controlled to operate at cryogenic temperatures. A multilayered sunshield comprised of layers of polyimide film coated with alloyed silicon and multilayered aluminum based coatings has been developed to control the operating temperature of and minimize stray light seen by the Optical Telescope Element (OTE). The key requirements of the membrane material are to control thermal stability and steady-state thermal performance of the OTE, limit solar and infrared light transmission, meet ESD grounding requirements, have low contaminant levels, and to have highly durable, robust coatings. The testing that was done to evaluate the durability of the membrane material and to show that it will survive the fabrication, integration, test, and launch environments will be explored.

The James Webb Space Telescope (JWST) is an infrared space telescope designed to explore four major science themes: first light and reionization, the assembly of galaxies, the birth of stars and protoplanetary systems, and planetary systems and origins of life. JWST is a segmented architecture telescope with an aperture of 6.6 m. It will operate at cryogenic temperature (40 K), achieved via passive cooling, in an orbit about the Earth-Sun second Lagrange point (L2). Passive cooling is facilitated by means of a large sunshield that provides thermal isolation and protection from direct illumination from the Sun. The large size of the telescope and spacecraft systems require that they are stowed for launch in a configuration that fits the Ariane 5 fairing, and then deployed after launch. Routine wavefront sensing and control measurements are used to achieve phasing of the segmented primary mirror and initial alignment of the telescope. A suite of instruments will provide the capability to observe over a spectral range from 0.6- to 27-μm wavelengths with imaging and spectroscopic configurations. An overview is presented of the architecture and selected optical design features of JWST are described.

The James Webb Space Telescope (JWST) is NASA's next great astronomical mission. At the time of this paper, the mission has just passed its preliminary design review. This paper will visit three areas of significant maturation since the design was initially introduced. The three areas discussed are; addition of a heater to the fine steering mirror, spacecraft bus rearchiteture, and redesign of the sunshield core. Each of these design evolutions enables the mission through improved performance, reduced risk or complexity. These three design changes are examples of the efforts being exerted on the other aspects of the design that are not covered in this paper.

The James Webb Space Telescope (JWST) is a cryogenic, 6.5 meter diameter space telescope. JWST has a unique architecture, compared to previous space telescopes, that is driven by its science requirements, ia passively cooled cryogenic design, and the need to stow the observatory for launch. JWST's large, segmented mirror meets the requirement for high angular resolution in the infrared coupled with a significant increase in collecting area compared to the Spitzer and Hubble Space telescopes in order to detect the first galaxies. JWST's unique five-layer sunshield allows the telescope and instrument module to passively cool to cryogenic temperatures. JWST will be launched on an Ariane 5, and so both its telescope optics, and the sunshield have to be stowed in order to fit the Ariane 5 fairing. Following launch the sunshield and telescope optics must be deployed, and the primary mirror phased for science operations. In this presentation we will review the design of the observatory and highlight recent progress in the construction of the JWST observatory. In particular, we address recent progress with the telescope optics, sunshield and spacecraft. We will discuss predicted observatory performance in terms of the scientific goals of JWST and address key operational considerations that might bear upon frontier science observations.

Il seguente elaborato ha lo scopo di analizzare le proprietà chimico-fisiche dei materiali Multi-layer insulation (MLI) impiegati per il controllo termico in ambito aerospaziale, con un focus specifico sul sunshield del James Webb Space Telescope (JWST). Il sistema di protezione termica rappresenta un elemento di fondamentale importanza per il conseguimento della missione, dovendo garantire un gradiente termico estremo per permettere alla strumentazione di operare nell'infrarosso. Lo studio approfondisce le caratteristiche del Kapton, il polimero di base utilizzato per i cinque strati del sunshield, e l'efficacia dei rivestimenti in alluminio e silicio drogato applicati per ottimizzare l'emissività e la riflettività. Vengono inoltre esaminate le sfide ingegneristiche legate alla degradazione dei materiali nell'ambiente spaziale, soggette a radiazioni ultraviolette e cicli termici.

In the coming decades new space observatories are destined to revolutionize our understanding of the universe and our place within it. Of all the new space telescopes in the pipeline, it is arguably the eagerly anticipated James Webb Space Telescope that is exciting the astronomical community most (Fig. 11.1). The James Webb Space Telescope (JWST), previously known as Next Generation Space Telescope (NGST), is a space observatory currently under construction and scheduled to launch in October 2018. The JWST will offer unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared, and is a successor instrument to the Hubble Space Telescope and the Spitzer Space Telescope. The center piece of telescope houses a segmented 6.5-meter (21 feet) primary mirror and will be located near the Earth–Sun L2 point. A large sunshield will keep its mirror and four science instruments below 50 K (−220 °C; −370 °F).

This presentation outlines how we programmatically simulated the deployment of a cloth-like sunshield for NASA's James Webb Space Telescope