50 Fun Facts About Hubble Space Telescope

In which year was the Hubble Space Telescope launched?

Hubble was launched on 24 April 1990, seven years after the 1983 date first planned, following programme delays and the grounding of the shuttle fleet after the 1986 Challenger disaster.

Which Space Shuttle carried Hubble into orbit on mission STS-31?

Discovery lifted off from Kennedy Space Center on 24 April and released Hubble the next day at about 600 km, the highest shuttle orbit up to then; the flight had been delayed by the 1986 Challenger grounding.

What is the diameter of Hubble's primary mirror?

The primary mirror is 2.4 metres across, reduced from the 3-metre design of the 1970s to cut costs; the blank is ultra-low-expansion glass with a lightweight honeycomb core.

What flaw did Hubble turn out to have when it reached orbit?

Its mirror had been ground to a bad shape: the edge was too flat by about 2.2 micrometres, producing spherical aberration that smeared starlight into fuzzy haloes when the first images arrived in May, weeks after launch.

Which company built Hubble's flawed optical telescope assembly?

Perkin-Elmer won the optical telescope assembly contract in 1977 and figured the primary mirror at its Danbury, Connecticut plant; NASA had required it to subcontract a back-up mirror to Kodak, which was never flown.

What did the Allen Commission find had caused the mirror flaw?

Two conventional null correctors used earlier had actually flagged the problem, but were dismissed as less accurate.

Which 1993 shuttle mission installed corrective optics that fixed Hubble's vision?

STS-61 saw Endeavour's crew make five spacewalks in December 1993, replacing the original camera and inserting corrective optics, along with new solar arrays and gyroscopes.

What was the name of the corrective optics package installed on the first servicing mission?

COSTAR, the Corrective Optics Space Telescope Axial Replacement, deployed small mirrors to correct the light reaching the remaining instruments; it displaced the High Speed Photometer and was removed in 2009 once every instrument carried its own correction.

How many Space Shuttle servicing missions visited Hubble?

Hubble received 5 shuttle servicing missions, SM1 in 1993, SM2 in 1997, SM3A in 1999, SM3B in 2002 and SM4 in 2009, each delivering new instruments, gyroscopes or solar arrays.

The final servicing mission was cancelled on safety grounds after which event, then reinstated?

The 2003 Columbia disaster led administrator Sean O'Keefe to cancel the mission in January 2004 as too risky; his successor Michael Griffin reinstated it in October 2006, with a second shuttle on standby for rescue.

Which shuttle flew the last Hubble servicing mission in May 2009?

Atlantis flew STS-125 in May 2009, the final servicing mission, whose five spacewalks installed Wide Field Camera 3 and the Cosmic Origins Spectrograph and repaired two older instruments.

Which astronaut led the spacewalks on the first Hubble servicing mission?

Story Musgrave, a physician who served as payload commander, led the spacewalk team on the December 1993 flight, going outside with Jeffrey Hoffman while Tom Akers and Kathryn Thornton took the alternate days.

Which astronomer-astronaut serviced Hubble on STS-103 and STS-109, doing five spacewalks in total across the two?

John Grunsfeld, an astrophysicist, flew on STS-103 in 1999 and STS-109 in 2002 and returned on the final servicing mission in 2009; he was NASA's associate administrator for science from 2012 to 2016.

Edwin Hubble was born in 1889 in which US state?

Missouri was his birthplace: Edwin Hubble was born in Marshfield on 20 November 1889 and moved with his family to Wheaton, Illinois, in 1900, where he starred in high-school athletics before entering the University of Chicago.

At which observatory did Edwin Hubble make his famous discoveries after Hale hired him?

Mount Wilson, above Pasadena, had the 100-inch Hooker telescope, then the world's largest, with which Hubble found Cepheid variables in the Andromeda and Triangulum nebulae in 1923-24 and showed they were separate galaxies.

What did Edwin Hubble study at Oxford as a Rhodes Scholar, keeping a promise to his dying father?

Law was his Oxford subject: Hubble read jurisprudence at Queen's College from 1910 to 1913 to satisfy his father, then after the elder Hubble's death in 1913 returned to astronomy as a graduate student at Yerkes Observatory.

Why was Edwin Hubble never awarded a Nobel?

The physics prize did not then cover astronomy, so Hubble spent his final years lobbying for astronomers to be treated as physicists; he died of a stroke in September 1953 with no award made.

Whose 1946 paper 'Astronomical advantages of an extraterrestrial observatory' begins Hubble's history?

Lyman Spitzer, a Princeton astrophysicist, wrote the 1946 RAND report arguing that a telescope above the atmosphere would escape the blurring astronomers call 'seeing'; he then lobbied for the project for decades.

Which NASA astronomer is known as the 'Mother of Hubble'?

Nancy Grace Roman, NASA's first chief of astronomy, spent the 1960s and 1970s building scientific and congressional support for a large space telescope; the Roman Space Telescope was named for her in 2020.

Which German rocketry pioneer's 1923 book first mentioned launching a telescope into orbit?

Hermann Oberth's 'Die Rakete zu den Planetenräumen' ('The Rocket into Planetary Space'), published in 1923, suggested that a telescope in orbit could escape atmospheric distortion; his pupil Wernher von Braun later led NASA's Saturn V programme.

Which international partner supplied Hubble's solar arrays and an instrument in return for observing time?

The European Space Agency contributed the Faint Object Camera and the original solar arrays, and in return European astronomers were guaranteed at least 15% of Hubble's observing time.

What was the observatory provisionally called before it was named after Edwin Hubble in 1983?

The Large Space Telescope, or LST, was the working name in NASA's 1968 plans, which called for a 3-metre mirror and a launch in 1979; the observatory was renamed for Edwin Hubble in 1983.

Which Baltimore-based body selects Hubble's targets and processes its data?

The Space Telescope Science Institute, set up in 1981 on the Johns Hopkins University campus in Baltimore, runs the observing programme and archives the data, while Goddard Space Flight Center in Maryland flies the spacecraft.

Which of these was NOT one of NASA's four Great Observatories alongside Hubble?

Kepler, launched in 2009 to hunt exoplanets by watching for transits, was not part of the programme; the Great Observatories were Hubble, Compton for gamma rays, Chandra for X-rays and Spitzer for the infrared.

The Hubble Deep Field of 1995 imaged a tiny patch of which constellation?

Ursa Major was chosen because the field near the Big Dipper's handle is far from the Galactic plane, nearly empty of bright stars and visible to Hubble continuously; 342 exposures were taken over ten days in December 1995.

Roughly how many objects, almost all galaxies, appear in the original Hubble Deep Field?

About 3,000 objects, nearly all galaxies, were counted in the image, with only a handful of foreground Milky Way stars in the field; some galaxies appear as they were more than 10 billion years ago.

Which institute director used his own discretionary time to create the 1995 Hubble Deep Field?

Robert Williams, director of the institute from 1993 to 1998, committed his director's discretionary time to the project despite colleagues' warnings that the field might show nothing; the image became one of astronomy's most famous.

The 2004 Hubble Ultra-Deep Field, with about 10,000 galaxies, lies in which southern constellation?

Fornax, a faint southern constellation bordered by Eridanus, holds the Ultra-Deep Field, a patch imaged for about a million seconds of exposure between September 2003 and January 2004.

The famous 'Pillars of Creation' photograph shows columns of gas and dust in which star-forming region?

The Eagle Nebula, Messier 16 in the constellation Serpens about 7,000 light-years away, contains the pillars, photographed on 1 April 1995 by Jeff Hester and Paul Scowen; light from nearby young stars is slowly eroding them.

Which comet's 1994 collision with Jupiter was 'fortuitously timed' for the newly repaired Hubble?

Shoemaker–Levy 9, torn into more than 20 fragments, struck the planet between 16 and 22 July 1994, seven months after the first servicing mission restored the optics; the impact scars were more prominent than the Great Red Spot.

Hubble observations of distant supernovae helped show that the universe's expansion is doing what?

Accelerating: in 1998 the two supernova teams found that distant Type Ia supernovae were fainter than expected, meaning the expansion had sped up; Perlmutter, Schmidt and Riess shared the 2011 Nobel Prize in Physics for it.

One of the telescope's three original 'key projects' was to pin down which quantity to within 10%?

The Hubble constant, the present expansion rate of the universe in kilometres per second per megaparsec, was the target of the Key Project led by Wendy Freedman, which reported a value of about 72 in 2001.

Astronomers using Hubble discovered Styx, a tiny fifth moon of which body?

Pluto's fifth known moon, Styx, was spotted in Hubble images in June 2012 during a search for hazards ahead of the New Horizons flyby; Kerberos had been found the year before.

Which observatory, launched 25 December 2021, is Hubble's infrared-to-visible successor?

James Webb, launched from Kourou on an Ariane 5 on 25 December 2021, carries a 6.5-metre segmented mirror and observes mainly in the infrared from the L2 point 1.5 million km from Earth.

Hubble's optical design, with two hyperbolic mirrors, is which type of reflector?

Ritchey–Chrétien Cassegrain optics use hyperbolic primary and secondary mirrors to remove coma and give sharp images across a wide field; the hyperbolic figures are harder to make and test than the parabola of a classical Cassegrain.

Hubble's mirror had to be polished to an accuracy of about how much?

10 nanometres is about 1/65 of the wavelength of red light; Corning made the blank from ultra-low-expansion glass and the grinding and polishing ran from 1979 to 1981.

Which company's mirror, built during the Hubble programme, later went into the Magdalena Ridge telescope?

Itek and Kodak had bid jointly for the optics contract, proposing to check each other's work; the Itek mirror produced in that effort was later installed in the telescope at Magdalena Ridge Observatory in New Mexico.

In 1974, what happened to Hubble's funding in Congress?

It was deleted entirely by the House appropriations subcommittee in 1974; astronomers mounted a nationwide lobbying campaign and the Senate restored half the requested sum, with the project slimmed down to cut costs.

What did NASA official Noel Hinners do to Hubble's 1977 budget request as a deliberate political ploy?

Zeroed it out to galvanise astronomers: Noel Hinners, NASA's space-science chief, left the telescope out of the budget so that the astronomical community would feel the threat and lobby Congress, which it did, and funding began in 1977.

Which NASA centre was responsible for designing and building the telescope itself?

Marshall Space Flight Center in Huntsville, Alabama, was given charge of designing and building the telescope in 1972, with Goddard Space Flight Center handling the science instruments and ground control.

Which instrument, installed in 1993 to replace the original WF/PC, was itself replaced in 2009?

Wide Field and Planetary Camera 2, built at the Jet Propulsion Laboratory with its own correction for the mirror's aberration, took the Pillars of Creation and Deep Field images before Wide Field Camera 3 replaced it in 2009.

Which two atmosphere-absorbed spectral bands did Spitzer argue a space telescope could uniquely observe?

Hubble's mirrors are kept at a warm 15°C, which limits its infrared performance.

Which Hubble instrument, installed in 2002, took the Ultra-Deep Field?

Advanced Camera for Surveys, installed by the STS-109 crew in March 2002, took the Ultra-Deep Field between September 2003 and January 2004; its electronics failed in 2007 and were repaired on the final servicing mission in 2009.

On launch day in 1990, why did McCandless and Sullivan prepare for an emergency spacewalk?

Ground controllers eventually got the array deployed by command and the spacewalk was not needed.

Which 2013-16 programme paired deep images of lensing galaxy clusters with parallel blank fields?

Frontier Fields, a director's discretionary programme run from 2013 to 2016, imaged massive clusters such as Abell 2744, whose gravity magnified galaxies far behind them, with a blank parallel field observed beside each cluster.

How many gyroscopes does Hubble's pointing control system carry?

6 gyroscopes, mounted in pairs, sense how fast the telescope is turning while reaction wheels do the actual pointing; the full set was replaced on the servicing missions of 1999 and 2009.

Which planet can Hubble never observe because of its roughly 50-degree solar avoidance angle?

Mercury never strays more than about 28 degrees from the Sun, well inside Hubble's solar avoidance zone, so it is permanently off limits; the telescope also keeps its optics turned away from the bright Earth limb.

At roughly what altitude does Hubble orbit the Earth?

540 km is roughly the altitude in the 2010s, down from about 610 km at release as drag from the thin upper atmosphere slowly lowers the orbit; the inclination is 28.5 degrees and each circuit takes about 95 minutes.

Which company was commissioned to build and integrate the spacecraft that houses the telescope?

Lockheed Missiles and Space Company in Sunnyvale, California, built the support systems module and integrated the telescope; its graphite-epoxy structure was kept in a nitrogen purge before launch so absorbed water would not outgas as ice onto the optics.

How many of Hubble's gyroscopes had failed when Servicing Mission 3A was split off in 1999?

Three gyroscopes had failed by early 1999, prompting NASA to bring forward part of the planned mission; a fourth failed in November, putting Hubble into safe mode until the STS-103 crew fitted a full new set that December.