Hubble Space Telescope History, Discoveries, & Facts

 Hubble Space Telescope

Seen in orbit from the departing Space Shuttle Atlantis in 2009, flying Servicing Mission 4 (STS-125), the fifth and final Hubble mission.

Names

HST, Hubble

Mission type

Astronomy

Operator

STScI

COSPAR ID

1990-037B

SATCAT no.

20580

Mission duration

31 years, 8 months, 14 days (ongoing)

Spacecraft properties

Manufacturer

Lockheed Martin (spacecraft)

Perkin-Elmer (optics)

Launch mass

11,110 kg (24,490 lb)

Dimensions

13.2 m × 4.2 m (43 ft × 14 ft)

Power

2,800 watts

Start of mission

Launch date

24 April 1990, 12:33:51 UTC

Rocket

Space Shuttle Discovery (STS-31)

Launch site

Kennedy, LC-39B

Contractor

Rockwell International

Deployment date

25 April 1990

Entered service

20 May 1990

End of mission

Decay date

2030–2040 (estimated)

Orbital parameters

Reference system

Geocentric orbit

Regime

Low Earth orbit

Perigee altitude

537.0 km (333.7 mi)

Apogee altitude

540.9 km (336.1 mi)

Inclination

28.47°

Period

95.42 minutes

Main telescope

Type

Ritchey–Chrétien reflector

Diameter

2.4 m (7 ft 10 in)

Focal length

57.6 m (189 ft)

Focal ratio

f/24

Collecting area

4.525 m2 (48.71 sq ft)

Wavelengths

Near-infrared, visible light, ultraviolet

Instruments

NICMOS: Near Infrared Camera and Multi-Object Spectrometer

ACS: Advanced Camera for Surveys

WFC3: Wide Field Camera 3

COS:  Cosmic Origins Spectrograph

STIS: Space Telescope Imaging Spectrograph

FGS:  Fine Guidance Sensor

Hubble Space Telescope (HST), the first sophisticated optical observatory placed into orbit around Earth. Earth’s atmosphere obscures ground-based astronomers’ view of celestial objects by absorbing or distorting light rays from them. A telescope stationed in outer space is entirely above the atmosphere, however, and receives images of much greater brightness, clarity, and detail than do ground-based telescopes with comparable optics.

Hubble Space Telescope in the cargo bay of the orbiting space shuttle Discovery (STS-82) after its servicing by astronauts and prior to its release, February 1997.

After the U.S. Congress had authorized its construction in 1977, the Hubble Space Telescope (HST) was built under the supervision of the National Aeronautics and Space Administration (NASA) of the United States and was named after Edwin Hubble, the foremost American astronomer of the 20th century. The HST was placed into orbit about 600 km (370 miles) above Earth by the crew of the space shuttle Discovery on April 25, 1990.

Cutaway of the NASA Hubble Space Telescope, revealing the Optical Telescope Assembly, the heart of the spacecraft, built by Hughes Danbury Optical Systems, Inc

The HST is a large reflecting telescope whose mirror optics gather light from celestial objects and direct it into two cameras and two spectrographs (which separate radiation into a spectrum and record the spectrum). The HST has a 2.4-metre (94-inch) primary mirror, a smaller secondary mirror, and various recording instruments that can detect visible, ultraviolet, and infrared light. The most important of these instruments, the wide-field planetary camera, can take either wide-field or high-resolution images of the planets and of galactic and extragalactic objects. This camera is designed to achieve image resolutions 10 times greater than that of even the largest Earth-based telescope. A faint-object camera can detect an object 50 times fainter than anything observable by any ground-based telescope; a faint-object spectrograph gathers data on the object’s chemical composition. A high-resolution spectrograph receives distant objects’ ultraviolet light that cannot reach Earth because of atmospheric absorption.

Image of MyCn18, a young planetary nebula located about 8,000 light-years away, taken with the Wide Field and Planetary Camera 2 aboard NASA's Hubble Space Telescope

About one month after launch, it became apparent that the HST’s large primary mirror had been ground to the wrong shape owing to faulty testing procedures by the mirror’s manufacturer. The resulting optical defect, spherical aberration, caused the mirror to produce fuzzy rather than sharp images. The HST also developed problems with its gyroscopes and with its solar-power arrays. On December 2–13, 1993, a mission of the NASA space shuttle Endeavour sought to correct the telescope’s optical system and other problems. In five space walks, the shuttle astronauts replaced the HST’s wide-field planetary camera and installed a new device containing 10 tiny mirrors to correct the light paths from the primary mirror to the other three scientific instruments. The mission proved an unqualified success, and the HST soon began operating at its full potential, returning spectacular photographs of various cosmic phenomena.

Three subsequent space shuttle missions in 1997, 1999, and 2002 repaired the HST’s gyroscopes and added new instruments including a near-infrared spectrometer and a wide-field camera. The final space shuttle mission to service the HST, intended to install a new camera and an ultraviolet spectrograph, was launched in 2009. The HST is scheduled to remain operational through at least 2021, after which it is expected to be replaced by the James Webb Space Telescope, equipped with a mirror seven times larger than that of the HST.

Astronauts John Grunsfeld and Richard Linnehan near the Hubble Space Telescope, temporarily hosted in the space shuttle Columbia's cargo bay, March 8, 2002.

The HST’s discoveries have revolutionized astronomy. Observations of Cepheid variables in nearby galaxies allowed the first accurate determination of Hubble’s constant, which is the rate of the universe’s expansion. The HST photographed young stars with disks that will eventually become planetary systems. The Hubble Deep Field, a photograph of about 1,500 galaxies, revealed galactic evolution over nearly the entire history of the universe. Within the solar system, the HST was also used to discover Hydra and Nix, two moons of the dwarf planet Pluto.