Hubble

The Hubble Space Telescope (HST) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. Although not the first space telescope, Hubble is one of the largest and most versatile, and is well known as both a vital research tool and a public relations boon for astronomy. The HST is named after the astronomer Edwin Hubble, and is one of NASA's Great Observatories, along with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and the Spitzer Space Telescope.[6]
Hubble Space Telescope
The Hubble Space Telescope in orbit
The Hubble Space Telescope as seen from the departing Space Shuttle Atlantis, flying Servicing Mission 4 (STS-125), the sixth and final Hubble mission
Mission typeAstronomy
OperatorNASA · ESA · STScI
COSPAR ID1990-037B
SATCAT no.20580
Websitenasa.gov/hubble
hubblesite.org
spacetelescope.org
Mission durationElapsed: 27 years, 1 month, 16 days
Spacecraft properties
ManufacturerLockheed (spacecraft)
Perkin-Elmer (optics)
Launch mass11,110 kg (24,490 lb)[1]
Dimensions13.2 × 4.2 m (43.3 × 13.8 ft)[1]
Power2,800 watts
Start of mission
Launch dateApril 24, 1990, 12:33:51 UTC[2]
RocketSpace Shuttle Discovery (STS-31)
Launch siteKennedy LC-39B
Deployment dateApril 25, 1990[1]
Entered serviceMay 20, 1990[1]
End of mission
Decay dateestimated 2030–2040[3]
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Semi-major axis6,919 km (4,299 mi)
Eccentricity0.000283
Perigee539 km (335 mi)
Apogee543 km (337 mi)
Inclination28.47°
Period95.47 minutes
RAAN342.12°
Argument of perigee159.60°
Mean anomaly334.64°
Mean motion15.08 rev/day
Velocity7.59 km/s (4.72 mi/s)
EpochSeptember 21, 2016, 13:51:39 UTC[4]
Revolution no.24,968
Main telescope
TypeRitchey–Chrétien reflector
Diameter2.4 m (7.9 ft)
Focal length57.6 m (189 ft)
Focal ratiof/24
Collecting area4.5 m2 (48 sq ft)[5]
WavelengthsNear-infrared, visible light, ultraviolet
With a 2.4-meter (7.9 ft) mirror, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared spectra. Hubble's orbit outside the distortion of Earth's atmosphere allows it to take extremely high-resolution images, with substantially lower background light than ground-based telescopes. Hubble has recorded some of the most detailed visible light images ever, allowing a deep view into space and time. Many Hubble observations have led to breakthroughs in astrophysics, such as accurately determining the rate of expansion of the universe.
The HST was built by the United States space agency NASA, with contributions from the European Space Agency. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center controls the spacecraft.[7]
Space telescopes were proposed as early as 1923. Hubble was funded in the 1970s, with a proposed launch in 1983, but the project was beset by technical delays, budget problems, and the Challenger disaster (1986). When finally launched in 1990, Hubble's main mirror was found to have been ground incorrectly, compromising the telescope's capabilities. The optics were corrected to their intended quality by a servicing mission in 1993.
Hubble is the only telescope designed to be serviced in space by astronauts. After launch by Space Shuttle Discovery in 1990, five subsequent Space Shuttle missions repaired, upgraded, and replaced systems on the telescope, including all five of the main instruments. The fifth mission was canceled on safety grounds following the Columbia disaster (2003). However, after spirited public discussion, NASA administrator Mike Griffin approved the fifth servicing mission, completed in 2009. The telescope is operating as of 2017, and could last until 2030–2040.[3]Its scientific successor, the James Webb Space Telescope (JWST), is scheduled for launch in 2018.

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