Amazing Space logoServicing Mission 4 > SM4 Glossary

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Charge-Coupled Device (CCD)

Electronic circuits composed of light-sensitive picture elements (pixels) that record light from celestial objects to make photographs. Pixels are tiny cells that, when placed together, produce a complete image. The same technology is used in digital cameras.


The visual perception of light that enables human eyes to differentiate between wavelengths of the visible spectrum. The longest wavelengths appear red and the shortest appear blue or violet.

Cosmic Origins Spectrograph (COS)

An instrument that detects ultraviolet light. COS will study the structure of the universe and how galaxies, stars and planets formed and evolved. A spectrograph works by breaking up light from an object into its individual wavelengths. Astronauts will install COS during SM4.

Electromagnetic Spectrum

The entire range of wavelengths of electromagnetic radiation, including radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.