Hubble Space Telescope

The Hubble Space Telescope has been observing the Universe for over quarter of a century.

Hubble, one of the most famous and awe-inspiring pieces of technology ever created, was launched on 25 April 1990, hitching a ride with the Space Shuttle Discovery STS-31, and has been continuously observing the night sky ever since.

From its position in low-Earth orbit, floating some 547km (340 miles) above Earth, the Hubble telescope can see things in the Universe that we could previously only dream of.

Observations have been carried out across all wavelengths of light, from ultraviolet to infrared, which have given astronomers an unprecedented window on the Universe.

Much has been learned over the lifetime of Hubble’s mission, from the causes of gamma-ray bursts to how planetary collisions work, the expansion of the Universe and hidden dark matter. To this day, it still inspires us with its breath-taking images.

The telescope was named after the visionary US astronomer Edwin Hubble, whose observations in the 1920s pointed to our expanding Universe being filled with distant galaxies, but things did not get off to the best of starts.

The first images returned by the Hubble Space Telescope were blurry and featured stars surrounded by fuzzy halos. A microscopic flaw in Hubble’s 2.4-metre primary mirror caused by testing equipment during manufacture meant the telescope could not focus properly.

Although much of Hubble was replaceable, the primary mirror was not. However, engineers realised they could use their second-generation camera, the Wide Field and Planetary Camera 2 (WFPC2), and a number of other corrective instruments to bring the telescope back into focus.

On 2 December 1993, the Space Shuttle Endeavour launched the first Hubble Space Telescope servicing mission, and over the course of 11 days and five spacewalks, the new instrumentation was installed. The mission was a success, and from that moment on the world has been in awe of the beautiful photos being returned by Hubble.

A total of four servicing missions has doubled the effective lifespan of the Hubble Space Telescope, an in its lifetime has taken more than 1.4 million observations, with data that has been used in more than 16,000 studies. How long it remains gazing deep into our Universe depends on the skill and ingenuity of the engineers and scientists currently working on the telescope, but with no more servicing missions planned, Hubble’s twilight years are ahead of it.

However, a report from September 2018 predicts Hubble re-entry no earlier than 2027, so there is still plenty more science to send back.

The next great space telescope on the horizon and successor to Hubble is the James Webb Telescope, planned for launch in 2021, which with its 6.5-metre lens will be able to search deeper in the Universe than any telescope before it.