Genesis of the James Webb Space Telescope Architecture: The Designers' Story

TL;DR

This paper details the design process, architectural considerations, and final implementation of the James Webb Space Telescope, highlighting the rationale, alternatives, and technological challenges involved in its development.

Contribution

It provides a comprehensive account of the design evolution, decision-making, and optimization processes leading to JWST's unique architecture and operational capabilities.

Findings

Multiple architectures considered before final design

Final design optimized for scientific performance and cooling

On-orbit performance aligns with design expectations

Abstract

The James Webb Space Telescope, launched in 2021, is an infrared observatory of novel design: deployable, with active optics, fully open to space for radiative cooling and orbiting the Lagrange point no. 2. This article explains the rationale leading to this specific design and describes the various other architectures that were considered along the way: from a monolithic 10-meter telescope in geosynchronous orbit to a 6-meter one in High Earth Orbit, then a 16-meter observatory on the Moon, a 4- or 6-meter one in an elliptical heliocentric orbit, and a segmented 8-meter one passively cooled to 50 K at L2, which was finally descoped to 6.6 meters. It also addresses the optimization for scientific performance, the challenge of dealing with such an ultra-low operating temperature, cost issues, supporting technology, modifications made during final design and, finally, how the architecture performs on orbit.