On April 24th, 1990, the Space Shuttle Discovery thundered into a spring Florida sky on one of the most important missions of the entire space shuttle programme: the launch of the Hubble Space Telescope (HST), one of the four great orbital observatories placed in orbit in the closing years of the 20th century.
At the time of its launch, the telescope probably didn’t surface to any great degree in the broader public consciousness, although in the 30 years it has been in operation it has become if not a household name, then certainly one most people will recognise, even when abbreviated down to just “Hubble”.
As I noted when marking 25 years of HST operations, Hubble’s roots go well back in history – to 1946, in fact; while the whole idea of putting a telescope above the distorting effects of the Earth’s atmosphere can be traced back as far as the early 1920s. A joint NASA / European Space Agency operation, HST faced many challenges along the road to commencing operations: it’s low Earth orbit – vital for it to be within reach of servicing astronauts – meant it had to face bot extremes of temperature as it orbited the Earth, passing in and out of sunlight, and it would also have to contend with a slow but inexorable atmospheric draft, so would have to be periodically boosted in its altitude.
However, these issues paled into insignificance after HST was launched, when the commissioning process revealed something was badly wrong with the telescope’s optics, resulting in badly blurred images being returned to Earth. The problem was traced back to an error in the production of the 2.4m primary mirror – one side of which has been ground an etra 2.2 nanometres (a nanometre being one billionth of a metre) compared to the other, leaving it “out of shape”. Small as the error was, it was enough to prevent Hubble focusing correctly, leading to the blurred images – and the entire programme being seen as a huge white elephant around the world, despite HST completing some excellent science between 1990 and 1993.
Again, as I reported five years ago, the optical error lead to a “Hubble rescue mission” in 1993, when the crew of the space shuttle Endeavour arrived to give HST corrective optics called COSTAR and an updated imaging system, the Wide Field and Planetary Camera (WF/PC). Together these effectively gave HST a corrective set of glasses that overcame the flaw in the primary mirror. In doing so, they assured Hubble’s place in history, as they allowed the telescope to exceed all expectations in its imaging capabilities, turning into into perhaps the most successful astronomical / science instrument of modern times.
When launched, HST could see both in the visible light and in the ultraviolet (the region in which it saw outstanding results even before the operation to correct its “eyesight”). In 1997, during another servicing mission which saw the Discovery return to the telescope it had launched and deployed, HST was given a set of infra-red eyes as well. These allowed it to see farther into space (and thus further back in time) than we’d been able to do previously, and they allowed Hubble to peer into the the dusty regions of the galaxy where stars are born, opening their secrets.
Together, Hubble’s various eyes and its science instruments – and the men and women supporting HST operations here on Earth – have given us the ability to look back towards the very faintest – and earliest – light in the cosmos, study star clusters, look for planetary systems around other stars, increase our understanding of our own galaxy, look upon and study our galactic neighbours, help to verify Einstein’s theories of the universe, and do so much more.
Before Hubble, we knew essentially nothing about galaxies in the first half of the life of the universe. That’s the first 7 billion years of the universe’s 13.8-billion-year life. Now Hubble, through remarkable surveys like HXDF [Hubble Extreme Deep Field] capability, has probed into the era of the first galaxies. Through this type of work, Hubble has discovered galaxies like GN-z11, the most distant discovered by Hubble. Just 400 million years after the Big Bang, Hubble is looking back through 97% of all time to see it, far outstripping what can be done with the biggest telescopes on the ground.
– Garth Illingworth, HST project scientist
Hubble is a truly unique platform in this regard. Despite issues over the years such as with its various flywheels (the gyroscopes designed to hold it in place whilst it is capturing images), it can remain rock-steady for extended periods with no more than 0.007 arcseconds of deviation. To put this into context, that’s the equivalent to someone standing at the top of The Shard in London and keeping the beam of a laser pointer focused on a penny taped to the side of the Eiffel Tower in Paris, for 24 hours without wavering.
HST’s science mission is so broad, it occupies the working days of literally thousands of people around the globe. Dedicated teams manage the programme for both NASA and ESA, with the Space Telescope Science Institute (STScI) located at the Johns Hopkins University Homewood Campus in Baltimore being the primary operations centre, supported by the European Space Astronomy Centre (ESAC), Spain, both of which will manage operations with the James Web Space Telescope when it is launched. Beyond these teams, scientists and astronomers around the globe can request time using HST and its instruments for their projects and observations, all of which makes the telescope one of the most used globally.
Many of those currently working with Hubble share a unique link to it: they have either grown up with it as a part of their lives, learning about it at school and through astronomy and science lessons, or they been with Hubble since its launch, and have lived their entire careers with it.
Hubble has changed the landscape of astronomy and astrophysics,. It has far exceeded its early goals — no other science facility has ever made such a range of fundamental discoveries. It’s been a privilege to be associated with this effort that has become embedded in the culture of our time.
– Colin Norman, HST manger and senior manager, STScI (1990-2020)
Continue reading “Space Sunday 30 years with HST; planets in lockstep”
