James Webb Space Telescope

The James Webb Space Telescope is the National Aeronautics and Space Administration’s (NASA’s) largest and most powerful space science telescope ever constructed. After launching on December 25, 2021, the observatory will proceed to an orbit about one million miles away from Earth and undergo six months of commissioning in space. Astronomers worldwide will then be able to conduct scientific observations to broaden our understanding of the Universe and beyond! Check out NASA’s official JWST blog for more information and resources!

James Webb Space Telescope Poster


  • 1996: The Space Telescope Science Institute (STScI) and NASA initiated The Next Generation Space Telescope to follow the Hubble Space Telescope and view the furthest reaches of the Universe.
  • 2002: The telescope was renamed to honor James E. Webb, the second Administrator of NASA.
  • 2004: Construction began on more extensive telescope parts, including the science instruments and segments of the primary mirror.
  • 2009: The Integrated Science Instrument Module (ISIM) structure, built to house the four science instruments, arrived at Goddard Space Flight Center for testing in a giant thermal vacuum chamber that replicates the extreme conditions of space.
  • 2011: The US government’s annual budget bill threatened the expensive telescope project, however, a compromise was ultimately reached with NASA. Later in the year, Webb’s mirrors were completed.
  • 2013: The two side wings of Webb’s backplane structure were completed. The final two science instruments and primary mirror segments were delivered for testing.
  • 2014: Manufacturing of the other spacecraft parts such as fuel tanks, gyroscopes, and solar panels began. Goddard crews successfully completed the first combined test of all four instruments.
Labeled spacecraft image showing major subsystems.
  • 2016: Construction of Optical Telescope Element (OTE) and cryogenic testing of the scientific instruments and mirrors were completed.
  • 2018: Launch was delayed twice to further test spacecraft instruments.
  • 2019: The Optical Telescope Element was successfully connected to the spacecraft, finally joining the two halves of The James Webb Space Telescope.
  • 2020: The telescope was fully folded for the first time. Final environmental testing proved it could withstand the shaking and jostling of the launch environment. However, the launch was once again postponed due to technical concerns and the COVID-19 pandemic.
  • 2021: Launch was postponed several times due to further equipment testing, concerns about the readiness of the Ariane 5 launch vehicle, and adverse weather at the launch site.
  • Dec. 25, 2021 (7:20 am EST): NASA’s James Webb Space Telescope was launched on an Ariane 5 rocket from Europe’s Spaceport in Kourou, French Guiana!
  • 29 Days on the Edge – YouTube
  • Dec. 25, 2021 (7:47am EST): Webb was released from the Ariane 5 launch vehicle.
  • Dec. 25, 2021 (7:53am EST): After shedding the fairing and booster rocket, the solar panel was deployed and started generating its own power. This was the first automatic deployment.
  • Dec. 26, 2021: The Gimbaled Antenna Assembly (GAA) that holds the high rate antenna was rotated to point back towards Earth. The antenna sends science data back to Earth and receives commands from NASA’s Deep Space Network. This was the last automatic deployment; all other deployments are controlled by commands from the ground.
  • Dec. 28. 2021: The Unitized Pallet Structure (UPS) that carries the five folded sunshield membranes was deployed. Before this, the spacecraft was maneuvered and heated to keep the UPS warm enough for deployment.
  • Dec. 29, 2021: The Deployable Tower Assembly (DTA) movement separated the spacecraft and telescope to allow better thermal isolation and room for the sunshield membranes to unfold.
  • Dec. 30, 2021: The Aft Momentum Flap was deployed. It is used to help offset some of the solar pressure on the large sunshield and minimize fuel usage. The sunshield which protected the sensitive membranes during ground and launch activities was also released, .
  • Dec. 31, 2021: The Sunshield Mid-Boom Deployment included the completion of the sunshield cover roll up and extension of the left/port and right/starboard mid-boom along with the side of the five sunshield membranes.
  • Jan. 4, 2022: All 5 layers of the sunshield were completely deployed and tensioned during a multi-step two-day process.
  • Jan. 5, 2022: Webb’s secondary mirror is at the end of the Secondary Mirror Support Structure (SMSS) and reflects the light from the primary mirror to the instruments in the UPS. During the deployment, the long booms swung the secondary mirror out in front of the primary mirror.
  • Jan. 6, 2022: The last of four launch locks that hold the Aft Deployed Instrument Radiator (ADIR) in its launch configuration was released. The first three launch locks were released just after launch to prevent any unwanted strain.
  • Jan. 7, 2022: During this two-day process, the left/port mirror and right/starboard wings were deployed into their operational positions. Each of the Primary Mirror Wings holds three of the total 18 mirror segments.
  • January 8, 2022: The James Webb Space Telescope was fully deployed! It will continue to travel to the second Lagrange point (L2) for another two weeks, at which point it will enter a large orbit around the L2 point. The following five months will be used to cool the telescope to operating temperature, fine-tune the mirror alignment, and calibrate the instruments.

Where Is Webb? NASA/Webb
Deployment Explorer Webb/NASA

About the Telescope

The OTE is the eye of the Observatory. It consists of mirrors and the backplane. The OTE gathers the light coming from space and provides it to the science instruments located in the ISIM. The backplane is like the “spine” of Webb. It supports the mirrors.

The ISIM contains Webb’s cameras and instruments. It integrates four major instruments and numerous subsystems into one payload:

Photograph of the telescope folded upright with the hexagonal mirrors and heat shields visible.

The sunshield separates the observatory into a warm Sun-facing side (spacecraft bus) and a cold anti-Sun side (OTE and ISIM). The sunshield keeps the heat of the Sun, Earth, and spacecraft bus electronics away from the OTE and ISIM so that these pieces of the Observatory can be kept very cold (The operating temperature has to be kept under 50 K or -370 degrees F).

The spacecraft bus provides the support functions for the operation of the Observatory. The bus houses the six major subsystems needed to operate the spacecraft: the Electrical Power Subsystem, the Attitude Control Subsystem, the Communication Subsystem, the Command and Data Handling Subsystem, the Propulsion Subsystem, and the Thermal Control Subsystem.

Check out some fun Webb activities!

Webb and Origami – Webb Telescope/NASA

Make Your Own Paper Model! Webb Telescope/NASA

NASA’s James Webb Space Telescope #UnfoldTheUniverse Art Challenge | NASA