The James Webb Space Telescope (JWST) is designed to observe primarily in the infrared portion of the electromagnetic spectrum, including the near-infrared and mid-infrared regions. However, it is not optimized to observe the long-wave infrared (LWIR) portion of the spectrum. There are several reasons for this limitation:
Design Constraints: The design of the JWST was based on specific scientific goals and technical constraints. To achieve its primary objectives, the telescope was optimized for observations in the near-infrared and mid-infrared ranges. The instruments and detectors aboard the JWST are not specifically designed to cover the LWIR wavelengths.
Thermal Management: Observing in the LWIR range requires very low instrument temperatures to minimize thermal noise and achieve high sensitivity. The JWST employs a complex cooling system to maintain its sensitive instruments at cryogenic temperatures. However, cooling the instruments to the levels required for LWIR observations would significantly increase the complexity, size, and cost of the mission.
Available Technology: Developing instruments capable of observing in the LWIR range with the required sensitivity and spatial resolution is a challenging task. While there are detectors available for LWIR observations, incorporating them into the JWST's existing instrument suite would require substantial changes and compromises to the overall design and scientific capabilities of the telescope.
Scientific Priorities: The JWST's scientific goals were formulated based on the most pressing questions in astrophysics that can be addressed with infrared observations. While LWIR observations could provide valuable insights into certain phenomena, the prioritization of other scientific objectives led to the decision not to include LWIR capabilities in the JWST.
Despite its inability to observe in the LWIR range, the JWST's capabilities in the near-infrared and mid-infrared will still revolutionize our understanding of the universe. It will enable detailed studies of exoplanets, star formation, the early universe, and many other astrophysical phenomena, expanding our knowledge and pushing the boundaries of infrared astronomy.