Hubble beams back spectacular photo to flaunt 30 years of cosmic trailblazing

Thirty years ago, the first major optical telescope was fired into space – and while it's easy enough to count the days since Hubble's historic lift-off aboard the US shuttle Discovery, it's a lot harder to count the stunning number of contributions it's made to science during that time.

Thirteen metres long and weighing more than 11 tonnes, Hubble is about the size of a bus, busily conducting its 97-minute planetary round trip at a cool speed of 28,000 kilometres an hour. 

It's higher than the International Space Station, with an altitude of 570 kilometres, positioning Hubble above the distortion of the atmosphere. Here it enjoys the clear, unobstructed view of the heavens that allows the telescope to beam back mind-bending images of the universe as far off as 13.4 billion light years away.

Indeed, with its three view-finders and powerful laser beam, Hubble can spot a one cent piece from a distance of 250 kilometres.

“Hubble is not attached to Earth, so it has the very long exposure times necessary to observe an object that is very dim,” French astronaut Jean-François Clervoy, who carried out repairs on Hubble in 1999, tells RFI.

“This is how Hubble is able to observe things deep in the universe … It sees in the visible spectrum while all the other space telescopes observe X-rays, gammas, infrared, and ultraviolet.”

Hubble's launch on 24 April 1990 marked the most significant advance in astronomy since Galileo's telescope four centuries earlier, fundamentally changing our understanding of the universe: everything from black holes, the expansion of the universe and the birth and death of a star.

An international collaboration between Nasa and the European Space Agency, Hubble has unravelled mysteries about the planets, the moon, the cosmos, discovering new galaxies within our own cosmic backyard and pinning down the age of the universe to within a few percent. 

It's collected some 1.4 million observations that astronomers have used to publish more than 16,000 critical scientific papers. 

Initially a monumental failure

Fruitful as it has been, though, Hubble got off to a rocky start. When the first images transmitted to Earth were a fuzzy blur, it became gut-wrenchingly clear the $1.5 billion observatory had vision problems that would need to be solved.

Hubble's primary mirror had a spherical aberration one-fiftieth thickness of a human hair that was affecting the clarity of its pictures.

French astrophysicist Fabienne Casoli, who recently became the first woman to take the helm of the Paris Observatory, a scientific powerhouse founded by Louis XIV, remembers discussing those blurred photos with colleagues early on in her career.

"The artefacts were of the kind usually found in observations of the sky by radio telescopes," explains Casoli, who was working in radio astronomy at that time. "We knew that the pictures could be corrected and treated to some extent with the algorithms used for radio telescopes – and this was indeed done before Hubble was repaired."

It was only after a successful repair mission to Hubble in 1993 that the telescope finally began beaming home the spectacular images for which it is now famous. Its largest photo to date encompasses a whopping 265,000 galaxies.

Named after the American astronomer Edwin Hubble, who discovered in the 1920s that the universe was expanding, the telescope was designed to be a 15-year project that could be serviced by astronauts in space, allowing for instruments to be replaced as technology improved.

It had many visitors between 1993 and 2009, with five missions keeping it up-to-date and running smoothly – including the one joined by Clervoy in December 1999. 

“When you approach the Hubble space telescope in orbit, the sun gives the solar panels a golden glow,” says Clervoy, recounting his most endearing memory of that space flight. “Hubble looked like a butterfly; it was beautiful.”

After the repair mission, the telescope control centre in Baltimore offered Clervoy and the three other astronauts who visited Hubble alongside him a poster of the first image taken after it was fixed. 

“The telescope had completely broken down, and this photo was proof of its revival…it was of the Eskimo nebula supernova explosion,” Clervoy says – the glowing remains of a dying star.

Anniversary celebrations subdued

To celebrate Hubble's 30 years of exploration, Nasa has planned many events that will unfortunately be feted without live audiences because of the coronavirus pandemic. The telescope itself delivered a stunning picture on its 30th birthday, which was released Friday at 1pm Paris time.

Meanwhile a podcast has been launched documenting its journey, while the space agency has created a search feature on its website that allows fans to look up photos taken by Hubble on their own birthdays. 

Hubble's impact on the public has been multiplied by the fact its observations are made available to researchers after just a few months, says Casoli – who points out that Hubble has not been the only telescopic game-changer.

"Most Hubble scientific breakthroughs have involved other telescopes, either ground-based or in space," she explains – naming in particular Chile's Atacama Large Millimetre Array radio telescope, the LIGO and Virgo observatories that detect gravitational waves and Nasa's Kepler mission that led to a breakthrough in the field of exoplanets.

Hubble successor preparing for launch

Nasa's next-generation space telescope, which will succeed Hubble when it launches from the French Guiana space centre sometime in 2021, is the much-awaited James Webb. Boasting the largest primary mirror of any space-based imaging system, the James Webb is also expected to revolutionise the field of astronomy.

The premier space telescope of the next decade will be fired off to a home about four times further away than the Moon, from where it will peer deeper into the universe than ever before.

For Clervoy, however, it's the humble Hubble that will always be credited with making astronomy popular to the masses as it fed the Earth with an endless stream of photographic gifts from beyond our skies.

“Hubble is a legendary instrument that revolutionised our knowledge of the universe,” he says. “As Galileo's telescope had a 'before and after', it's said there will also be a 'before and after' Hubble.”