Overview
The James Webb Space Telescope (JWST) is a joint NASA/ESA/CSA infrared space observatory launched on 25 December 2021 aboard an Ariane 5 rocket. It orbits the Sun-Earth L2 Lagrange point, approximately 1.5 million km from Earth, where it can keep its sunshield permanently oriented between itself and the Sun/Earth/Moon, maintaining the extreme cold required for infrared observations.
Key Facts
| Launch | 25 December 2021 (Ariane 5 ECA) |
| Location | Sun-Earth L2 Lagrange point (~1.5 million km from Earth) |
| Primary Mirror | 6.5 m diameter (18 gold-coated beryllium segments) |
| Sunshield | 22 m × 12 m (tennis court-sized) |
| Operating Temperature | ~40 K (–233°C) on the cold side |
| Instruments | NIRCam, NIRSpec, MIRI, FGS/NIRISS |
| Wavelength Range | 0.6–28.5 μm (near- to mid-infrared) |
| Design Life | 5–10 years (fuel budget supports 20+ years) |
| Cost | ~$10 billion USD |
Key Discoveries
JWST has already transformed astronomy: imaging the earliest galaxies formed after the Big Bang (some from over 13 billion years ago), analysing the atmospheres of exoplanets for signs of habitability, providing unprecedented views of star-forming regions, and studying the compositions of objects in our own Solar System. Its infrared capability reveals phenomena invisible to Hubble.