Chandra Uncovering the high-energy Universe

The world's most powerful X-ray telescope has been changing our understanding of space for a quarter of a century. Jane Green celebrates Chandra's achievements through some of its most spectacular images

- Jane Green

On 23 July 1999, Space Shuttle Columbia launched its heaviest-ever payload: the Chandra X-ray Observatory, a new flagship telescope for NASA. It is the world’s most powerful X-ray telescope, capable of detecting sources more than 20 times fainter than its predecessors and with a spatial resolution yet to be surpassed.

It immediately joined the ranks of NASA's Great Observatories; while Chandra had X-rays covered, the Compton Gamma Ray Observatory observed gamma rays, the Spitzer Space Telescope took infrared, and visible light fell under the remit of the still-operational Hubble Space Telescope. Over 25 years later, Chandra remains on its highly elliptical path around our planet, orbiting every 64 hours at an altitude a third of the way to our Moon, and returning extraordinary images.

Since high-energy X-rays cannot be observed by Earth-based telescopes and they reveal extremely hot objects and hugely energetic physical processes, Chandra has captured previously unseen phenomena. Neutron stars, supernovae shockwaves, elusive dark energy and the mysteries lurking in the hot gas surrounding our Galaxy's supermassive black hole: all have been brought into focus by Chandra’s super-sharp views and ultrasmooth mirrors.

Yet the entire project has recently come under threat of budget cuts so severe they would bring a premature end to Chandra's operation. Despite an outcry from the astronomy community, Chandra's future is uncertain. Although its two-year Legacy Program is ongoing, it now competes with newer projects demanding larger slices of a limited budgetary pie.

While Chandra continues, for now, to reveal secrets of the high-energy Universe, NASA marked its 25 years by releasing 25 stunning images. Here we've put together a selection of nine of the best wonders captured by Chandra over the last quarter of a century...

Centaurus A