50 Fun Facts About Hubble Space Telescope

In which year was the Hubble Space Telescope launched?

It went up on Space Shuttle Discovery on 24 April, seven years later than originally intended.

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

The mission had to wait for shuttle flights to resume after the 1986 Challenger disaster.

What is the diameter of Hubble's primary mirror?

The 3-metre design was shrunk to save money; the mirror was polished to an accuracy of 10 nanometres.

What flaw did Hubble turn out to have when it reached orbit in 1990?

The spherical aberration was traced to a mis-assembled testing device called a null corrector at Perkin-Elmer.

Which company built Hubble's flawed optical telescope assembly?

NASA had made it subcontract a back-up mirror to Kodak, which was never launched and now sits in the National Air and Space Museum.

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?

Endeavour's crew, led on the spacewalks by Story Musgrave, worked over ten days in December.

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

It was not a science instrument, but it took up one of the four axial instrument bays; it is now in the Smithsonian.

How many Space Shuttle servicing missions visited Hubble?

Hubble is the only telescope ever designed to be maintained by astronauts in space, and every main instrument has been replaced.

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

NASA administrator Michael Griffin overturned the cancellation, and Atlantis flew the mission in May 2009.

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

It installed Wide Field Camera 3, which replaced the camera that had itself replaced the original in 1993.

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

NASA paired him with six other experienced astronauts, including two from the Intelsat rescue mission STS-49.

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

He later became NASA's associate administrator for science.

Hubble is named after Edwin Hubble, who confirmed which finding in 1929?

Georges Lemaître had proposed it two years earlier; the telescope was named in 1983.

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

There he found Cepheid variables in the Andromeda and Triangulum nebulae, proving they were separate galaxies.

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

He also led the University of Chicago basketball team to a Big Ten title in 1907.

Why was Edwin Hubble never awarded a Nobel?

A model of the telescope now stands in his home town of Marshfield, Missouri.

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

He argued a space telescope would beat atmospheric 'seeing' and could observe ultraviolet and infrared light; the infrared Great Observatory was later named for him.

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

She lobbied Congress through the 1970s and set up the program's steering committee; a successor telescope now bears her name.

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

Die Rakete zu den Planetenräumen came out two decades before Spitzer's paper.

Which international partner gave Hubble funding, solar cells and an instrument for observing time?

European astronomers were guaranteed at least 15% of the telescope's time.

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

The 1968 plan called for a 3-metre mirror and a 1979 launch.

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

Goddard flies the spacecraft; STScI sits on the Johns Hopkins campus.

Hubble is one of NASA's four Great Observatories. Which of these is NOT one of the others?

Compton covered gamma rays, Chandra X-rays and Spitzer the infrared; all four launched between 1990 and 2003.

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

342 exposures over ten days revealed some 3,000 galaxies in a patch the size of a tennis ball at 100 metres.

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

Only a handful of foreground Milky Way stars fall within it.

Which Space Telescope Science Institute director used his own discretionary time to create the 1995 Deep Field?

Colleagues warned it might show nothing; it became one of the most famous images in astronomy.

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

It caught light from galaxies as they were 400 to 800 million years after the Big Bang.

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

Taken on 1 April 1995 by Jeff Hester and Paul Scowen, the pillars are being eroded by light from newly formed stars.

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

The impacts came just months after the first servicing mission restored the optics.

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

Three members of the two supernova teams later won Nobel Prizes for the discovery of what is now called dark energy.

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

It measures how fast the universe expands, and the telescope's namesake first estimated it in 1929.

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

Hubble has also studied the dwarf planets Eris and Sedna in the outer Solar System.

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

NASA's next flagship, the Nancy Grace Roman Space Telescope, was slated to follow it with a launch target of 2026.

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

The design gives good images over a wide field but the mirrors are notoriously hard to make and test.

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

That is roughly 1/65 of the wavelength of red light; the blank was made by Corning from ultra-low-expansion glass.

Which company built the rival to Kodak's back-up mirror, now in the Magdalena Ridge telescope?

Kodak and Itek had bid jointly to double-check each other's work, which would almost certainly have caught the flaw.

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

A nationwide lobbying campaign by astronomers eventually won back half the budget, and the mirror shrank from 3 m to 2.4 m.

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

He gambled that a zero would 'marshal the troops', and it worked.

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

Goddard got the instruments and ground control; Lockheed built the spacecraft that houses the telescope.

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

It was retired in 2009 when Wide Field Camera 3 went in, and is now on display in the Smithsonian.

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.

What is Hubble's remaining lifetime predicted to be, as of its 30th anniversary in 2020?

It has already outlived several of its planned successors' schedules.

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 2012 programme used galaxy-cluster gravitational lensing to find the faintest distant galaxies?

It built on the Deep Field tradition; CLASH separately mapped dark matter and dark energy in massive clusters.

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

Reaction wheels and magnetic torquers do the actual turning; gyro failures have repeatedly forced NASA to change how the telescope points.

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

Keeping sunlight off the optical assembly also means the telescope steers clear of the bright Earth and Moon.

At roughly what altitude does Hubble orbit the Earth?

Its inclination is 28.5 degrees, and drag from the thin upper atmosphere means its position weeks ahead cannot be predicted precisely.

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

A nitrogen purge was performed before launch because the graphite truss might otherwise have released water vapor as ice onto the instruments.

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

A fourth failed weeks before launch, halting science entirely; the December 1999 flight replaced all six.