Hubble had five scientific instruments at launch. They were the Wide Field and Planetary Camera, Faint Object Camera, Faint Object Spectrograph, Goddard High Resolution Spectrograph, and High Speed Photometer. Together, they allowed the new observatory to image and analyze astronomical objects across ultraviolet, visible, and near-infrared wavelengths.
These instruments were designed for different jobs. Cameras recorded images, spectrographs separated light into its component wavelengths to reveal chemical and physical information, and the photometer measured brightness. Hubble also carried Fine Guidance Sensors for extremely precise pointing; these are often mentioned alongside the science equipment, but they were primarily navigation and aiming systems rather than part of the five original scientific instruments.
The launch-era list is also different from Hubble’s later instrument lineup. Servicing missions replaced the original devices with more capable instruments such as the Wide Field Camera 3, Advanced Camera for Surveys, and Cosmic Origins Spectrograph. In 1993, corrective hardware was added after the mirror problem was discovered, and several original instruments were eventually removed. Thus, five describes Hubble’s initial scientific payload, not every instrument it has ever carried.