James Webb Space Telescope

Article

January 24, 2022

The James Webb Space Telescope (JWST; originally the Next Generation Space Telescope, NGST) is a telescope developed by NASA, the European Space Agency and the Canadian Space Agency to replace the obsolete Hubble Telescope in the future. , presented in September 1989. Development began in 1996 with a planned budget of $ 500 million and, after many changes and delays, culminated in the launch of the telescope into space on December 25, 2021 and a budget of nearly $ 10 billion. The telescope is named after James E. Webb, director of NASA from 1961 to 1968, at the height of the space race. This is the first major space mission, not named after a prominent scientist, but formally an official. Currently, the telescope is moving along the expected trajectory and all systems are working as expected.

Main tasks

The main objectives of the mission are to know the evolution of the first galaxies and stars after the Big Bang (the most distant objects), a better understanding of the formation of star systems and the search for life outside the solar system.

Technical description

Unlike its predecessor, which captures the universe in the visible light, the new telescope will operate in the infrared range (light wavelength 0.6 to 28 μm), which is more convenient for tracking very distant objects with large redshifts and objects with low surface temperature. . It will be located in the L2 center of the Earth-Sun system, ie about 1.5 million km from the Earth, on the opposite side from the Sun. Service flights with the current conventional manned means to this telescope are therefore practically excluded. It should operate for five years, with ten years of fuel reserves. The telescope consists of 4 main units.

Shielding

In order for the telescope to observe the universe in the infrared range, its temperature must be kept below 50 K (-223 ° C). Each body emits radiation corresponding to its temperature, and if the components of the telescope were heated to a higher temperature than the mentioned 50 K, its own radiation would interfere with the observation and practically blind the telescope. Shielding against the sun's rays is solved by a protective shield, which consists of a special foil made of kapton plated on both sides with aluminum. The foil is stretched in the frame in five parallel layers. Each layer is about as thin as human hair. In addition, the first two layers, exposed to sunlight, are coated with a silicone-based material that radiates trapped heat back into space. The sunshine is in its fully developed state, approx. 14.16 m × 21.20 m. Due to shielding, the telescope's field of view is limited to 40% of the sky. Thanks to its movement around the L2 point, the telescope is able to see the entire universe once every 6 months.

Optics

The collecting mirror consists of 18 hexagonal segments of gilded beryllium (each weighing 20 kg) with a total area of ​​25 m², its diameter is 6.5 m. The movement of individual segments and thus the curvature of the mirror can be regulated from the Earth.

Scientific facilities

The telescope carries four main scientific devices and a guidance camera. These devices are mounted on a modular platform made of a graphite-epoxy composite material that provides the electricity, computing resources, cooling, and stability needed for scientific equipment to function properly.

Supporting structure

It carries a number of computing, communication, propulsion and strength parts, as well as components providing power supply.

History

Progress

The first concept of the new telescope was presented

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