Hubble Space Telescope
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What is the Hubble Space Telescope?
The Hubble Space Telescope (HST) is the first sophisticated optical observatory to orbit Earth. It was placed into orbit by the space shuttle Discovery on April 25, 1990.
Free from Earth's atmosphere, the HST captures clearer and more detailed images than ground-based telescopes. This large reflecting telescope gathers light from celestial objects using its mirror optics and directs it to cameras and spectrographs.
The HST's discoveries have revolutionized astronomy. It has helped determine the age of the universe, played a key role in the discovery of dark energy, shown galaxies in early stages of growth, and found protoplanetary disks.
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Why was the Hubble Space Telescope put into space instead of being on Earth?
The Hubble Space Telescope (HST) is in orbit around Earth because Earth’s atmosphere obscures the view of celestial objects for ground-based astronomers by distorting light rays. A telescope in space receives images of greater brightness, clarity, and detail than ground-based telescopes because it is entirely above the atmosphere.
The HST is a large reflecting telescope with mirror optics that gather light from celestial objects and direct it into cameras and spectrographs. It can detect visible, ultraviolet, and infrared light. The HST's discoveries have revolutionized astronomy.
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When was the Hubble Space Telescope launched and by whom?
The Hubble Space Telescope (HST) was placed into orbit on April 25, 1990, by the crew of the space shuttle Discovery. Authorized by the U.S. Congress in 1977, it was built under the supervision of the National Aeronautics and Space Administration (NASA). Named after Edwin Hubble, a prominent American astronomer, the HST is a large reflecting telescope that gathers light from celestial objects using its mirror optics and directs it to cameras and spectrographs.
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What kinds of things has the Hubble Space Telescope helped astronomers discover?
The Hubble Space Telescope (HST) has revolutionized astronomy, making possible several important discoveries. It has allowed for the first accurate determination of Hubble's constant, which defines the rate at which the universe is expanding.
HST has sent back images of galaxies in early stages of development, helping scientists understand how galaxies form. It has also identified protoplanetary disks, which are clumps of dust and gas around young stars that are likely the birthplaces of planets, and it played a key role in the discovery of dark energy, a force that accelerates the expansion of the universe. Additionally, the HST found that gamma-ray bursts, incredibly powerful explosions of energy, occur in distant galaxies when massive stars collapse.
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How does the Hubble Space Telescope take and send pictures back to Earth?
The Hubble Space Telescope (HST) captures light from celestial objects using its mirror optics, then directs it into cameras and spectrographs that can detect visible, ultraviolet, and infrared light. The wide-field planetary camera can take either wide-field or high-resolution images of the planets and of galactic and extragalactic objects. According to NASA, the Hubble Space Telescope transmits about 120 gigabytes of science data every week.
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What are some challenges or problems the Hubble Space Telescope has faced during its mission?
The Hubble Space Telescope (HST) has faced several challenges during its mission. About a month after its launch in April 1990, it was discovered that the primary mirror had been ground to the wrong shape due to faulty testing, resulting in fuzzy images because of spherical aberration. The HST also experienced issues with its gyroscopes and solar-power arrays.
A servicing mission in 1993 by the space shuttle Endeavour corrected the optical system and other problems. Further missions in 1997, 1999, and 2002 repaired the gyroscopes and added new instruments. Another servicing mission was launched in 2009 to install a new camera and spectrograph.
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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.
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.
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.
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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. In 2021, the HST was joined in space by the James Webb Space Telescope, equipped with a mirror seven times larger than that of the HST.
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.