The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy.

The Webb was launched on 25 December 2021 on an Ariane 5 rocket from Kourou, French Guiana.

In January 2022 it arrived at its destination

A solar orbit near the Sun–Earth L2 Lagrange point, about 1.5 million kilometres from Earth.

The U.S. National Aeronautics and Space Administration (NASA) led Webb’s design and development and partnered with two main agencies: the European Space Agency (ESA) and the Canadian Space Agency (CSA).

Webb is designed primarily for near-infrared astronomy, but can also see orange and red visible light, as well as the mid-infrared region.It can detect objects up to 100 times fainter than Hubble can, and objects much earlier in
the history of the universe, back to redshift z≈20 (about 180 million years cosmic time after the Big Bang)

The mass of the James Webb Space Telescope is about half that of the Hubble Space Telescope.

Webb has a 6.5 m (21 ft)-diameter gold-coated beryllium primary mirror made up of 18 separate hexagonal mirrors, giving a total collecting area of 25.4 m2. The mirror has a gold coating to provide infrared reflectivity and this is covered by a thin layer of glass for durability

This is over six times larger than the collecting area of Hubble’s 2.4 m (7.9 ft) diameter mirror, which has a collecting area of 4.0 m2 (43 sq. ft).

To make observations in the infrared spectrum, Webb must be kept under 50 K (−223.2 °C; −369.7 °F); otherwise, infrared radiation from the telescope itself would overwhelm its instruments. Its large sunshield blocks light and heat from the Sun, Earth, and Moon, and its position near the Sun–Earth L2 keeps all three bodies on the same side of the spacecraft at all times. [31] Its halo orbit around the L2 point avoids the shadow of the Earth and Moon, maintaining a constant environment for the sunshield and solar arrays.

The five-layer sunshield, each layer as thin as a human hair, is made of Kapton E film, coated with aluminium on both sides and a layer of doped silicon on the Sun-facing side of the two hottest layers to reflect the Sun’s heat back into space.


Integrated Science Instrument Module (ISIM) is a component of the James Webb Space Telescope and holds the main science payload which includes four science instruments and the fine guidance sensor. It provides electrical power, computing resources, cooling capability as well as structural stability to the Webb telescope. It is made with bonded graphite-epoxy composite attached to the underside of Webb’s telescope structure.

ISIM contains these instruments:

• Near-Infrared Camera, or NIRCam
• Near-Infrared Spectrograph, or NIRSpec.
• Mid-Infrared Instrument, or MIRI
• Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph , or FGS/NIRISS