What’s on Board
Hubble was designed to hold six science instruments, each observing the universe in a unique way. The telescope has cameras, which capture Hubble's famed images, and spectrographs, which break light into colors for analysis. The current suite of instruments is listed below.
Wide Field Camera 3
Wide Field Camera 3 (WFC3) expanded Hubble’s reach by giving the telescope greater access to ultraviolet, visible and infrared wavelengths of light. With its high resolution and wide field of view, WFC3 has become the telescope’s workhorse camera, responsible for many of Hubble’s spectacular pictures. It has imaged everything from nearby star formation to galaxies in the very distant universe.
Cosmic Origins Spectrograph
The Cosmic Origins Spectrograph (COS) breaks ultraviolet radiation into components that can be studied in detail. COS is best at studying points of light, like stars or quasars (distant galaxies emitting tremendous amounts of light from their central regions). It has been used to study galaxy evolution, the formation of planets and the rise of the elements needed for life.
Advanced Camera for Surveys
The Advanced Camera for Surveys (ACS) conducts surveys of the universe. It is responsible for many of Hubble’s most impressive visible-light images of deep space. With its wide field of view, sharp image quality, and high sensitivity, ACS helps map the distribution of dark matter, detects the most distant objects in the universe, searches for massive planets and studies the evolution of clusters of galaxies.
Space Telescope Imaging Spectrograph
The Space Telescope Imaging Spectrograph (STIS) combines a camera with a spectrograph, which provides a “fingerprint” of a celestial object’s temperature, chemical composition, density and motion. STIS also reveals changes in the evolving universe and leads the way in the field of high-contrast imaging. The versatile instrument is sensitive to a wide range of wavelengths of light, from ultraviolet through the optical and into the near-infrared. STIS studies black holes, monster stars, and the intergalactic medium, and analyzes the atmospheres of worlds around other stars.
Near Infrared Camera and Multi-Object Spectrometer
The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is sensitive to infrared light, which is perceived by humans as heat. Infrared light reveals details about distant galaxies, planets and solar systems and star formation that are not available in visible light. It observes objects hidden by interstellar dust, such as site of stellar formation. The instrument sports three cameras — each with different fields of view. NICMOS operated from 1997 to 1999, and from 2002 to 2008.
Fine Guidance Sensors
Hubble’s three Fine Guidance Sensors (FGS) — its targeting cameras — are devices that lock onto guide stars and keep Hubble pointed in the correct direction. Two of the sensors point the telescope at an astronomical target and then hold that target in a scientific instrument’s field of view. The third sensor is available to perform scientific observations, precisely measuring the distance between stars and their relative motions.
Additional Telescope Features
Hubble’s primary mirror is 7.8-feet (2.4-meters) in diameter. It is made of a special glass coated with aluminum and a compound that reflects ultraviolet light. It collects light from the telescope’s targets and reflects it to the secondary mirror.
Like the primary mirror, Hubble’s secondary mirror is made of special glass coated with aluminum and a compound to reﬂect ultraviolet light. It is 12 inches (30.5 centimeters) in diameter and reﬂects the light back through a hole in the primary mirror and into the instruments.
Hubble’s aperture door can close, if necessary, to prevent light from the Sun from entering and potentially damaging the telescope or its instruments.
Digital images and spectra stored in Hubble’s solid-state recorders are converted to radio waves and then beamed through one of the spacecraft’s high-gain antennas (HGAs) to a NASA communications satellite, which relays them to the ground. Because the HGAs would extend off the page above and below the spacecraft image, they are shown here pressed against the side of the telescope in their “berthed positions.” This is how they were configured at launch.
Hubble’s current set of rigid solar panels use gallium-arsenide photovoltaic cells that produce enough power for all the science instruments to operate simultaneously. The first and second sets were larger, flexible panels, but produced less power.
Essential support systems such as computers, batteries, gyroscopes, reaction wheels, and electronics are contained in these areas.