On April 24 1990, the Hubble Space Telescope was launched into low Earth orbit on board the Space Shuttle Discovery, and deployed the next day. Named after Edwin Hubble, one of the great astronomers of the 20th century, this amazing instrument has offered us hugely important insights into our universe, not to mention some of the most iconic images of outer space ever captured. Even today, after 25 years, Hubble is one of the most famous and most important space telescopes out there. In order to celebrate this great milestone, here’s the story of the legendary telescope in five amazing facts about it.
First of all, the Hubble Space Telescope was a trailblazer. Famed astrophysicist Lyman Spitzer was one of the first to propose an astronomical observatory in space, far from our planet’s thick atmosphere, all the way back in 1946. Then, throughout the 1960s and 1970s he actively lobbied for the development of what would become the Hubble Space Telescope. After a series of delays due to various issues like funding difficulties and the Challenger disaster, Hubble was finally sent into orbit in 1990. Over the next thirteen years, it would be followed by three more powerful telescopes, part of NASA’s Great Observatories program: the Compton Gamma Ray Observatory (1991), the Chandra X-ray Observatory (1999), and the Spitzer Space Telescope (2003). Though all of them have provided scientists with valuable data regarding the Universe, none has even come close to the public profile of Hubble.
Soon after deployment however, a significant problem was discovered. Instead of the sharpest images of space ever taken, scientists were receiving low-quality, blurred photos. The error was eventually found to be a flaw in the 2.4-meter primary mirror, on the order of 2,200 nanometers (about a 50th of the thickness of a sheet of paper). Called a spherical aberration, the flaw meant that the light bouncing off the center of the mirror wouldn’t focus in the same place as the light reflected off the edge. Though the problem was well understood and could be corrected in “post-production,” it was a costly and time-consuming process. Which brings us to the second reason Hubble is awesome: it wears the most expensive pair of glasses of all time!
In December 1993, the first of five servicing missions was launched, which among others contained the Corrective Optics Space Telescope Axial Replacement, or COSTAR. This massive device was about the size of a phone booth and contained a series of mirrors designed to correct the aberration. The cost of the mission was a hefty $500 million, or about a third of the cost of the entire telescope at launch – but it was a complete success and Hubble finally started sending images of the quality scientist had expected all along.
Soon afterwards, scientists got busy using their new toy. The impact of Hubble on the scientific community is difficult to overstate. In its first decade in orbit, 8% of citations to the top-cited astronomy papers were based on Hubble data. Well into the first decade of the 21st century, Hubble Space Telescope papers were being cited tens of thousands of times per year, making it one of the most important scientific instruments in the world.
And it’s not like the data is about some very narrow aspects of astronomy, only professionals would be interested in. Data from Hubble has been used for a whole host of highly significant discoveries, related to everything from the birth of stars and planets, to the evolution of galaxies, measurements of exoplanets and gamma-ray bursts, and observations of gigantic black holes which we now know lurk within the centers of most galaxies. Not only that, but Hubble’s observations of Cepheid variable stars and distant supernovas have provided important insights regarding the rate of expansion of the Universe. The data gathered from the telescope, alongside other ground-based instruments, have led astronomers to believe the expansion of the Universe is accelerating (instead of slowing down, as previously thought). This remarkable finding has actually earned a group of scientists the 2011 Nobel Prize in Physics, and has led others to suggest the existence of dark energy to explain it.
But Hubble wasn’t just a highly advanced plaything for professional astronomers. For one thing, at least in the first few years, amateur astronomers could apply for usage of its instruments. But a lot more significantly, NASA soon started taking incredibly beautiful pictures of the Universe, and releasing them to the public. For the first time, perhaps, since the moon landing, the general public could also fully appreciate the work that was being carried out by astronomers. And this is the final point I would like to make about the Hubble Space Telescope: more than any other scientific instrument, it has shown us how awesome the Universe really is. Images like the iconic Pillars of Creation or the Hubble Deep Field are not only relevant to the trained eye of the astronomer, but are also, well, beautiful – more akin to works of art than the cold, dry results of science. No other telescope, not the Large Hadron Collider, nor the International Space Station have managed to captivate the imagination of the public quite like Hubble, and the glimpses it has offered us into the workings of our spectacular Universe.
The Hubble Space Telescope has long outlasted its initial service duration estimates. Over the years, five service missions have been deployed to correct flaws and upgrade instruments, so even after a quarter of a century Hubble is still going strong – in fact, it’s more powerful than ever, and is expected to be fully operational at least until 2020. Here’s hoping it’s going to be a long and productive journey!