Hubble issues 25th birthday image

The Hubble Space Telescope has celebrated its silver anniversary with a picture featuring a spectacular vista of young stars blazing through a dense cloud of gas and dust, the BBC reports. 

The "Westerlund 2" cluster of stars is located about 20,000 light-years away in the constellation Carina.
Hubble was launched on Space Shuttle Discovery on 24 April, 1990.

Engineers expect the observatory to keep operating for at least another five years.

"Even the most optimistic person to whom you could have spoken back in 1990 couldn't have predicted the degree to which Hubble would rewrite our astrophysics and planetary science textbooks," commented Nasa Administrator Charlie Bolden.

"A quarter of a century later, Hubble has fundamentally changed our understanding of our Universe and our place in it."

Famously, a flaw was found in the telescope's primary mirror soon after launch that blurred its images.

A smart fix was then installed by spacewalking astronauts in 1993 that allowed its instruments to correct for the aberration in the reflecting surface.

Four further servicing missions later, Hubble is in rude health and technically a far more capable observatory than when it was first put in orbit.

No more repair visits by astronauts are planned, but the latest assessment is that it will be with us for some time yet.

In the past, Hubble has suffered from degradation in its six gyroscopes - the spinning devices that allow it to point very precisely at objects on the sky.

However, the current batch has experienced just the one failure - in March, 2014.

"The instrumentation on Hubble has been getting better with time, in the sense that we've been able to calibrate it better and know more about how the observatory is working," said Ken Sembach, interim deputy director at the Space Telescope Science Institute in Baltimore.

"It's also worth noting that two of the instruments repaired on the last servicing mission - the Advanced Camera for Surveys, and the Space Telescope Imaging Spectrograph - are both working five years hereafter the servicing mission, which is longer than they worked originally with their original electronics.

"And so we have great hope that these two instruments, along with the two that were installed - the Cosmic Origins Spectrograph and the Wide Field Camera 3 - will continue to be operational for several more years."