James Webb Space Telescope: A Cryogenic Approach

Abstract

James Web Space Telescope (JWST) is a milestone to space exploration. JWST is concerned to observe the universe in infrared spectrum, provide unprecedented insight into the early universe, study formation of galaxies and birth of stars, give significant understanding of planetary system and discover signs of life on other planets. To sustain the hostile environment of space, cryogenic cooling system is used to keep telescope operational even at extremely low temperature just above absolute zero. Three-stage Pulse Tube precooler and a single Joule-Thomson cryocooler is used to generate cooling effect for effecting cooling of instruments and detectors. These instruments and detectors are responsible for providing data of astronomical phenomena and capturing high quality pictures of the planet, galaxies, stars, black holes and other astronomical objects.

Introduction

The James Webb Space Telescope (JWST) is a joint mission by NASA, the Canadian Space Agency, and the European Space Agency, designed to observe the universe in the infrared spectrum. Launched on December 25, 2021, JWST aims to study the early universe, star birth, galaxy formation, planetary systems, and potential extraterrestrial life. It is equipped with advanced scientific instruments and a sophisticated cryogenic cooling system to keep its detectors at extremely low temperatures, minimizing interference from the telescope's own infrared radiation.

JWST features a large 6.5-meter primary mirror made of 18 hexagonal segments, making it much more powerful than the Hubble Space Telescope. Its design includes two operational sides: a hot side facing the sun, protected by a multi-layer Kapton sunshield to block heat and radiation, and a cold side where sensitive instruments operate at cryogenic temperatures maintained by a pulse-tube and Joule-Thomson cryocooler system.

The telescope is positioned at the second Lagrange point (L2), about 1.5 million kilometers from Earth, where gravitational forces from the Earth and Sun balance, providing a stable, interference-free environment for observations.

Extensive thermal vacuum tests have validated JWST’s thermal design, ensuring its instruments remain functional in the harsh conditions of space. The cryocooler system employs advanced vibration control and monitoring to prevent image distortion and is remotely managed via telemetry from ground control.

JWST's advanced design and instruments enable it to capture detailed infrared data, promising transformative insights into the cosmos.

Conclusion

The cryogenic approach utilized by the James Webb Space Telescope (JWST) is a crucial aspect of its mission to capture unprecedented views of the cosmos. By utilizing cryogenic cooling systems, the telescope can operate at extremely low temperatures, minimizing interference from thermal emissions and enabling the detection of faint infrared signals from distant objects. The development, design, and testing of the cryogenic system and its components were integral to ensuring the success of the JWST mission. JWST represents a significant breakthrough in space exploration and holds great promise for providing transformative insights into the origins and evolution of the universe.

References

[1] Online Document James Webb Space Telescope (JWST): The First Light Machine, NASA Technical Report, Retrieved 04 February 2024 [2] R. Franck, A. Gurule, Drew Brown, P. Brinckerhoff, Thomas McCallan and Michael Renbarger, “High Performance Cryogenic Radiators for James Webb Space Telescope”, 46th International Conference on Environmental Systems ICES-2016-141, 10-14 July 2016, Vienna, Austria, July 2016 [3] Online Document Webb Innovation NASA Cryocooler, Retrieved 04 April 2024 [4] D. Harvey, T. Flowers, N. Liu, K. Moore, D. Tran, P. Valenzuela, B. Franklin and D. Michaels, “James Webb Space Telescope Mid Infra-Red Instrument Cryocooler Electronics”, Cryocooler 19, International Cryocooler Conference, Inc., Boulder CO, 2016 [5] M. Menzel, M. Davis, K. Parrish, J. Lawrence, A. Stewart, J. Cooper, S. Irish, G. Mosier, M. Levine and J. Pitman “The Design, Verification, and Performance of the James Web Space Telescope”, Publications of the Astronomical Society of the Pacific, 135:058002 (42pp), 2023, https://doi.org/10.1088/1538-3873/acbb9f

Copyright

Copyright © 2025 Arjun Gautam. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.