50 Fun Facts About Hubble Space Telescope

Hubble lifted off in April 1990 from which US state?

Florida's Kennedy Space Center sent Hubble up aboard a shuttle on 24 April 1990, seven years later than once planned, after budget trouble and the grounding of the whole fleet in 1986.

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

Discovery got Hubble up at the second attempt: a countdown two weeks earlier had been halted just four minutes before liftoff by a faulty valve.

What is the diameter of Hubble's primary mirror?

2.4 metres is modest for a great telescope: the mirror was shrunk from a planned 3 metres to save money in the 1970s, and Hubble's sharp sight comes from sitting above the air, not from its size.

What flaw did Hubble have when it reached orbit?

Its mirror had been ground to a bad shape: the edge was too flat by about 2.2 micrometres, enough to smear starlight into fuzzy haloes instead of sharp points.

Which company built Hubble's flawed optical telescope assembly?

Perkin-Elmer shaped the mirror with new computer-controlled polishers, so NASA made it order a back-up from Kodak in case the new method failed; the spare never flew.

What did investigators find had caused Hubble's mirror flaw?

A wrongly assembled test device was to blame: one lens in the instrument used to check the mirror sat 1.3 mm out of place, and it was found still set that way nine years later.

In the 1991 comedy The Naked Gun 2½, a picture of Hubble hangs on a wall among images of what?

Famous disasters share the wall: the film hung the newly launched Hubble beside the Titanic and the Hindenburg, a jab at its blurry first pictures that the 1993 repair turned around.

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

COSTAR, the Corrective Optics Space Telescope Axial Replacement, swung small mirrors into the light path; it was taken out in 2009, once every newer instrument carried its own correction.

Hubble is about the size of what?

A large school bus is NASA's comparison: Hubble is about 13 metres long and weighs more than 11 tonnes, sized to ride into orbit inside a space shuttle's cargo bay.

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

The 2003 Columbia disaster led NASA chief Sean O'Keefe to cancel the visit as too risky; a robot repair was studied and judged not feasible before his successor Michael Griffin sent astronauts back.

Why did a second shuttle stand ready on the pad during Hubble's last servicing mission in 2009?

To rescue the crew: from Hubble's orbit the astronauts could not reach the space station for shelter if their ship was damaged, so Endeavour stood by to fetch all seven.

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

Story Musgrave, a physician turned astronaut, led the two alternating pairs of spacewalkers who went outside on five days in December 1993, then a record for one shuttle flight.

Which astronomer-astronaut flew to Hubble on three servicing missions, the last in 2009?

John Grunsfeld repaired Hubble in 1999, 2002 and 2009, then returned to NASA in 2012 to run its whole science programme, the telescope he had mended included.

In the 1920s Edwin Hubble proved that the Andromeda 'nebula' was really what?

A galaxy beyond our own: Hubble picked out pulsing stars in Andromeda whose faintness put it far outside the Milky Way, ending the belief that our galaxy was the whole universe.

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, and with it Hubble could pick out single stars in the faint, fuzzy patches then called nebulae.

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

Law was his Oxford subject, taken up to meet his father's expectations; after his father died in 1913 Hubble dropped it and went back to astronomy, earning a doctorate at Chicago.

Why was Edwin Hubble never awarded a Nobel?

The physics prize did not then cover astronomy: Hubble lobbied for years to have astronomers counted as physicists, and he died in 1953 without the prize.

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

Lyman Spitzer argued in 1946 that a telescope above the atmosphere would escape its blurring, then lobbied for almost 30 years until the project was funded.

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

Nancy Grace Roman, NASA's first chief of astronomy, spent the 1960s and 1970s winning over astronomers and Congress to a telescope in orbit; a newer NASA observatory now carries her name.

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

Hermann Oberth's 'The Rocket into Planetary Space' began as a doctoral thesis his university rejected, so he helped pay to have it printed as a book.

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

The European Space Agency built one of the first cameras and the solar arrays; those first arrays flexed each time Hubble crossed from sunlight into shadow, shaking the telescope, and were swapped out in 1993.

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

The Large Space Telescope was the working name in NASA's 1968 plans, which pencilled in a launch for 1979; funding fights and a grounded shuttle fleet pushed the real one back eleven years.

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

The Space Telescope Science Institute, on the Johns Hopkins campus, referees a fierce contest for Hubble's time: about 150 scientists from around the world rank the rival proposals.

Which X-ray telescope, launched in 1999, was one of NASA's four Great Observatories alongside Hubble?

Chandra took the X-ray slot: each Great Observatory watched a different kind of light, and pointing two or more at one object showed far more than any single view.

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

Ursa Major was chosen because the spot lies far from the Milky Way's crowded plane and never slips behind the Earth as Hubble orbits, so the telescope could stare at it for ten days running.

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

3,000 or so turned up in a spot the team had picked because it looked almost empty from the ground; the faintest are galaxies seen as they were when the universe was young.

The patch of sky in the 1995 Hubble Deep Field is about as wide as what held at arm's length?

A pinhead at arm's length would cover it, yet institute director Robert Williams spent ten days of his own telescope time on that spot, and it proved to be crowded with galaxies.

The 2004 Hubble Ultra-Deep Field lies in which southern constellation?

Fornax holds the Ultra-Deep Field, where a million-second exposure caught about 10,000 galaxies, the faintest of them shining within a billion years of the Big Bang.

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

The Eagle Nebula holds the pillars, which Jeff Hester and Paul Scowen photographed in 1995; fierce light from young stars nearby is slowly wearing the columns away.

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

Shoemaker–Levy 9, already torn into 21 pieces, hit the planet over six days in July 1994, months after Hubble's repair; the dark scars it left were easier to see than the Great Red Spot.

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

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

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

The Hubble constant, the rate at which the universe expands, was measured to within 10%, which helped pin down the universe's age far more precisely than before, at a little under 14 billion years.

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 circles the Sun 1.5 million km from Earth, far beyond the reach of any repair crew, so unlike Hubble it had to unfold and work first time.

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, about 1/65 of the wavelength of red light, was the target because Hubble also observes ultraviolet light, whose shorter waves demand a smoother mirror than ground telescopes need.

Hubble's never-flown back-up mirror, made by Kodak, now belongs to which museum?

The National Air and Space Museum holds the spare, which Kodak finished and tested but which never got its reflective coating, so its honeycomb-like core shows through the glass.

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

It was deleted entirely by Congress in 1974 amid spending cuts; astronomers answered with a nationwide lobbying campaign, and the Senate restored half the sum for a slimmed-down telescope.

Which astronaut piloted the shuttle that launched Hubble and later ran NASA as its administrator?

Charles Bolden flew as pilot on the 1990 launch, then as NASA's chief from 2009 to 2017 oversaw the retirement of the shuttle fleet, the only craft that had ever serviced Hubble.

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

Marshall Space Flight Center in Huntsville, the home of the Saturn V Moon rocket, managed the building of the telescope, while Goddard in Maryland took charge of its instruments and still controls it.

Which Hubble instrument, fitted in 1993, took the Pillars of Creation and the first Deep Field?

Wide Field and Planetary Camera 2 gave its famous pictures their odd stair-step outline: one of its four detectors zoomed in on a smaller patch of sky, leaving a blank corner.

How do Hubble's cameras actually record the images that are released in vivid colour?

In shades of grey: each exposure is taken through a filter that passes one band of light, and the colour is built up afterwards by tinting and stacking several of those frames.

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

Advanced Camera for Surveys took the Ultra-Deep Field soon after it was fitted in 2002; an electrical fault knocked it out in 2007, and spacewalking astronauts repaired it in orbit two years later.

During Hubble's release in 1990, why did two astronauts suit up for an emergency spacewalk?

A solar array would not unreel at first, so two of the crew suited up to go out and free it; ground controllers then got it open by command and the spacewalk was never needed.

Hubble's Frontier Fields programme used giant clusters of galaxies as what?

Natural magnifying lenses: the gravity of a massive cluster bends and brightens the light of galaxies far behind it, revealing objects too faint for Hubble to see unaided.

What turns Hubble toward a new target?

Reaction wheels turn Hubble by recoil: spin one up one way and the telescope swings the other, at about the pace of a clock's minute hand.

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.

Which kind of orbit does Hubble follow?

Low Earth orbit keeps Hubble only a few hundred kilometres up, close enough for shuttle crews to visit; thin air there slowly drags it down, so those crews also nudged it back up.

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

Lockheed assembled the whole observatory in its clean room, fitting the telescope inside the spacecraft shell, where it then sat for years waiting for the grounded shuttles to fly again.

A 1999 Hubble repair flight was rushed forward after too many of which parts had failed?

Gyroscopes tell Hubble which way it is turning, and it then needed three of its six to do science; when a fourth failed in late 1999 the telescope sat idle until astronauts fitted a new set.