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James Webb Space Telescope
James Webb Space Telescope model
Six out of 18 mirrors of the James Webb Space Telescope being subjected to temperature dipping test
Mission type Astronomy
Operator NASA / ESA / CSA / STScI

Mission duration 5 years (design)
10 years (goal)
Spacecraft properties
Manufacturer Northrop Grumman
Ball Aerospace
Launch mass 6,500 kg (14,300 lb)
Dimensions 20.197 m × 14.162 m (66.26 ft × 46.46 ft) (sunshield)
Power 2,000 watts
Start of mission
Launch date May 2020
Rocket Ariane 5
Launch site Kourou ELA-3
Contractor Arianespace
Orbital parameters
Reference system Sun–Earth L2
Regime Halo orbit
Periapsis 374,000 km (232,000 mi)
Apoapsis 1,500,000 km (930,000 mi)
Period 6 months
Epoch plan
Type Korsch telescope
Diameter 6.5 m (21 ft)
Focal length 131.4 m (431 ft)
Collecting area 25 m2 (270 sq ft)
Wavelengths from 0.6 µm (orange)
to 28.5 µm (mid-infrared)
JWST logo
James Webb Space Telescope insignia

The James Webb Space Telescope (JWST) is a space telescope developed in collaboration between NASA, the European Space Agency and the Canadian Space Agency. One particular goal involves observing some of the most distant events and objects in the universe, such as the formation of the first galaxies. These types of targets are beyond the reach of current ground and space-based instruments. Some other goals include understanding the formation of stars and planets, and direct imaging of exoplanets and novas.

It is a replacement for the Hubble Space Telescope which was launched in 1990. The telescope is named after James E. Webb, who was a director at NASA and created the Apollo program that put astronauts on the moon.

In March 2018, NASA delayed the JWST's launch an additional year after the telescope's sunshield ripped during a practice deployment and the sunshield's cables did not sufficiently tighten. The JWST is currently scheduled to launch in May 2020.

The telescope's delays and cost increases can be compared to the Hubble Space Telescope. The JWST has a history of major cost overruns and delays which have resulted from outside factors. By 2006, $1 billion had been spent on developing JWST, with the budget at about $4.5 billion at that time.


The telescope will orbit Earth in a very high orbit. It will have a main mirror that is 6.5 meter (21.3 feet) wide. This is 7 times larger than Hubble. It is so large it is made in 18 pieces that fold together after the launch, so that it can fit into a rocket. It will be looking mostly in the infrared but also some in the red part of the visible light (the pictures will be color coded so we can see them).

It will be able to see things that the Hubble Space Telescope cannot. Infrared vision can be used to see heat (like some kinds of night vision goggles). So the telescope itself must be kept as cool as possible. It is protected by a large sunshield, the size of a tennis court, to keep it cool and dark. It is also in a special orbit, beyond the moon, at Lagrange point 2. This keeps it in the Earth's shadow most of the time.

Launch and mission length

Launch is planned May 2020 on an Ariane 5 rocket. The observatory attaches to the Ariane 5 rocket via a launch vehicle adapter ring which could be used by a future spacecraft to grapple the observatory to attempt to fix deployment problems. However, the telescope itself is not serviceable, and astronauts would not be able to perform tasks such as swapping instruments, as with the Hubble Telescope. Its mission time is five years, with a goal of ten years.

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