25 YEARS OF THE HUBBLE SPACE TELESCOPE
The Hubble Space Telescope has completed 25 years of astronomical observation since its launch on 24 April 1990.
Nasa Administrator Charlie Bolden said 'A quarter of a century later, Hubble has fundamentally changed our understanding of our Universe and our place in it'.
An early problem was a flaw found in the telescope's primary mirror that blurred its images A smart fix was installed by spacewalking astronauts in 1993 that allowed its instruments to correct for the aberration in the reflecting surface.
Engineers expect the observatory to keep operating for at least another five years. Its successor , the much bigger James Webb Space Telescope, is due for launch in 2018.
The scientific contribution of Hubble is enormous. Before Hubble, astronomers did not know whether the Universe was 10 billion or 20 billion years old. Hubble's study of pulsating stars narrowed the uncertainty. The age of the Universe is now known to be 13.8 billion years. Hubble also played a part in revealing the expansion of the Universe, and provided definitive evidence for the existence of super-massive black holes at the centre of galaxies, among many other discoveries.
Comment: The images received from Hubble have been truly breathtaking, and often stunningly beautiful. Hubble in many ways has revolutionised astronomy and cosmology.