Celebrating 35 years of the Hubble Space Telescope
- 22nd Apr 2025
- Author: Emma Mosley
24 April 1990 might have seemed like any other ordinary Tuesday here in the UK. Madonna’s ‘Vogue’ was number one in the charts and we were enjoying 17oC weather here in Leicester, with just a few clouds.
Meanwhile, over in Florida the Space Shuttle Discovery launched with a space telescope onboard that would go on to change our understanding of the Universe. It was the first space-based observatory, and remains one of the most famous and recognisable across the globe. It is of course, the Hubble Space Telescope!
It was first pitched as an idea in the mid-1940s and finally received the go ahead by the US Congress in 1977. Named after the famous American astronomer Edwin Hubble, Hubble was designed and built by NASA in collaboration with the European Space Agency (ESA) as its flagship ‘Great Observatory’. It did cost NASA over $16 billion (2021 figures with inflation taken into account) to develop and build Hubble. That's not including launch costs! Its aim was to make high resolution observations of planets, stars and galaxies, that were not able to be taken from the ground due to our atmosphere interfering with the light.
Let’s look at the journey Hubble has taken over the past 35 years.
Hubble almost didn't happen!
By 1985, Hubble had been built and was ready to launch. But in January 1986 the Challenger disaster happened and Hubble’s launch was put on hold until NASA had the Space Shuttle fleet cleared to fly again. While waiting, they upgraded the design and parts onboard keeping Hubble up to date in technology. Though there were probably a few rounds of Super Mario Bros on the Nintendo being played to fill the time! The Space Shuttles were cleared to fly again in 1988 and a launch opportunity for Hubble appeared in 1990. The rest they say is history, or was it?...
Two months after Hubble’s launch, NASA announced that the telescope was flawed and producing blurry images. After investigating, they discovered that the primary mirror was ground too flat by a margin smaller than the width of a human hair. This was enough for the light to not be focused enough to give pinpoint clear images. This is called spherical aberration and for some, this was enough for the mission to be game over! Luckily Hubble had been designed to be serviceable in space by astronauts, as part of extending the life expectancy of the mission.
Room Service?
The race was on to fix Hubble! The blurry images taken by Hubble were still useful to scientists but there was a fall in confidence by everyone as to whether Hubble could live up to expectations. Was an attempt to fix it going to work?
NASA worked to find a solution to this issue and their solution was to fit Hubble with ‘glasses’. Insert your ‘they should’ve gone to Specsavers’ jokes here.
Launching on the Space Shuttle Endeavour, STS-61 Servicing Mission 1 arrived at Hubble in December 1993. Hubble was docked into the loading bay for 10 days of maintenance and upgrades.
As the end of the year approached and Jurassic Park was making a record-setting box office weekend, the astronauts, on a remote 'island' of their own, completed five spacewalks to repair and upgrade the telescope. These totalled 35 hours and 28 minutes to fully service Hubble and included Jeff Hoffman, who later opened the National Space Centre in June 2001.
To fix the spherical aberration problem with the mirror, they installed the Corrective Optics Space Telescope Axial Replacement or COSTAR for short. It contained five pairs of corrective mirrors to refocus the light for the onboard instruments.
This ended up being a complete success with Hubble finally able to give clear images which far exceeded expectations! Over the years there have been five servicing missions in total with the last being in 2009 just before the Space Shuttles were decommissioned.
Hubble has had various upgrades and new instruments installed enabling the telescope to keep going past the planned 15 year lifespan.
How does Hubble 'see'?
Hubble has cameras and spectrometers onboard to look at the universe around us. These collect light from the Infrared (IR), Visible and Ultraviolet (UV) parts of the Electromagnetic Spectrum. Our atmosphere absorbs the IR and UV light meaning we can’t see objects in these wavelengths from the ground.
As the light enters Hubble it is reflected by both the mirrors and into the instruments to produce an image. In 2009 COSTAR, Hubble's ‘glasses’, was removed as the new cameras were adapted to compensate for the spherical aberration.
The two cameras currently on Hubble are the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3). They both have CCD sensors, like the ones you’d find in some older digital cameras. The images produced by these cameras are not the ones you see being released to the public.
Instead, the images are a monochromatic view based on the intensity of light at the wavelength being measured. Scientists have to combine the images from these different wavelengths to get the images we see today. As Hubble also sees in IR and UV which we can’t see, the images need colours put into them during image processing. So rather than paint by numbers, its paint by wavelength with the resulting images being breathtakingly stunning!
The spectrometers onboard split the light up and record how much of each wavelength was present in the light from an object. Each element has a unique fingerprint as to the wavelengths of light it emits and absorbs. By looking at the resulting spectrograph, we can determine the elements found in planets, nebulae and galaxies!
The data from Hubble can be combined with data from other space telescopes like Spitzer and the James Webb Space Telescope. All of this data provides a lot of information for scientists to help them understand the nature of nebulae, galaxies and our universe.
What has Hubble ever done for us?
Well, Hubble has achieved many firsts:
- First confirmation that supermassive black holes exist
- First exoplanet exosphere detected and elements determined
- First to detect water vapour plumes off of Europa
- First precision measurement of the expansion rate of the universe
- First confirmation that the Andromeda galaxy will collide with our Milky Way galaxy
- And lots more!
As well as these firsts, over 21,000 peer reviewed science papers have been created using Hubble data. This research has been a truly global effort with 39 different countries being granted time to observe. Hubble has completed over 1.6 million observations with the furthest viewed object being 13.4 billion lightyears away. All the data that Hubble has collected over the years is about 430 Terabytes. That's enough data to cover the monthly internet usage (including browsing, checking email, and watching a few videos daily) of an average household of four people for 35 years!
As there have been so many observations, you can also see what observations Hubble made on your birthday here. More discoveries are still being made as our ability to process the data improves and we catch up analysing all the observations made.
After all these achievements over the last 35 years, Hubble has only really explored about 0.1% of the night sky. It is thought Hubble will last until the late 2020s to early 2030s in its current condition. But if we can go and service Hubble again, we could be here in another 35 years time celebrating again!
Hubble has pushed the boundaries of our understanding of the universe around us and who knows what it may find out in the future!
Happy 35th Birthday Hubble!
Image Credits:
Banner - Hubble Space Telescope in space - ESA/NASA
Image 1a - Hubble being built at Lockheed Missile and Space Company - NASA
Image 1b - Hubble's primary mirror being polished - NASA
Image 1c - Hubble being launched onboard the Space Shuttle Discovery - NASA
Image 1d - Image of Supernova 1987A which was the image released with the first scientific results from the mission - NASA, ESA and STScl
Image 2a - Astronauts from Servicing mission 1 installing COSTAR - NASA
Image 2b - Astronauts from Servicing mission 1 working on Hubble - NASA
Image 2c - Hubble Space Telescope docked onto the Space Shuttle Endeavour - NASA
Image 3a - Infographic showing the EM spectrum and instruments - NASA
Image 3b - Layout of Hubble's instruments - NASA's Goddard Space Flight Center
Image 3c - Comparison of the Sombrero Galaxy taken by Hubble and JWST - NASA, ESA, CSA, STScI, Hubble Heritage Project (STScI, AURA)
Image 4a - Ultra Deep Field image taken by Hubble - NASA, ESA, S. Beckwith (STScl) and the HUDF Team
Image 4b - Pillars of Creation from the Eagle Nebula - NASA, ESA/Hubble and Hubble Heritage Team
Image 4c - New image of a Cosmic pillar within the Eagle Nebula released by ESA as part of the 35th Anniversary of Hubble - ESa/Hubble & NASA, K. Noll
