"We have to appreciate that we can see bits of the universe from our ground telescopes, but Hubble was several dimensions larger and more accurate," Vernikos said.

The telescope has solar panels on the sides that convert the sun's energy into 2,800 watts of electricity, some of which is stored to be used when the Hubble is in the shadows.

Problems overcome

The telescope has long been plagued by problems, but repairs have improved the quality of images it can capture, with detailed images of the surface on planet Mars taken in 1997.

"The human factor has been a great part of the Hubble story - it was a failure at first and we had five servicing missions since its inception twenty years since it was launched," Vernikos said.

Hubble has found ancient galaxies that formed well before scientists believed it was possible for them to exist. It has also looked deep into the unknown, capturing stunning images of stellar nurseries - like the Carina Nebula 7,500 light years away.

It also provided evidence of an anti-gravity force known as "dark energy" that is inflating all of space at a constantly increasing pace.

While Nasa is going through a shake up under Barack Obama, the US president, more telescopes are being planned to eventually replace the Hubble.