This is a cutaway diagram of the Hubble Space Telescope, with components labeled. The forward shell houses the telescope’s optical assembly. In the middle of the telescope are the reaction wheels and the bays that house the observatory's control electronics. The aft shroud houses the scientific instruments, gyroscopes, and star trackers. The instruments are located in containers that make them easy to remove and replace.
INSTRUMENTS:
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:
Primary mirror
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.
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.
Aperture door
Hubble’s aperture door can close, if necessary, to prevent light from the Sun from entering and potentially damaging the telescope or its instruments.
Communication antennas
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.
Solar panels
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.
Support systems
Essential support systems such as computers, batteries, gyroscopes, reaction wheels, and electronics are contained in these areas.
SPACECRAFT SYSTEMS:
Communications antennas
Hubble performs in response to detailed instructions from people on the ground. The antennas allow technicians to communicate with the telescope, telling it what to do and when to do it. Four antennas receive and send information to a set of satellites, which in turn communicate with Earth.
Solar arrays
Hubble is powered by sunlight. Each wing-like array has solar cells that convert the Sun’s energy into electricity. Some of that electricity runs the telescope, some is stored in onboard batteries for the periods when Hubble is in Earth’s shadow.
Computers and automation
Several computers and microprocessors reside in Hubble’s body and in each science instrument. There are two main computers. One talks to the instruments, sends commands and other information, and transmits data; the other handles pointing control, gyroscopes and other system-wide functions.
Thermal protection
Hubble has blanket of multilayered insulation, which protects the telescope from temperature extremes.
Pointing system
Hubble uses a combination of gyroscopes, reaction wheels and Fine Guidance Sensors to orient itself.
