Arecibo Observatory collapse video captured by drone

'I was screaming,' one eyewitness said

Video has emerged of the collapse of the world-famous Arecibo Observatory in Puerto Rico.

The 305-metre telescope was decommissioned in November after an engineering assessment concluded that damage to the structure could not be repaired without risk to construction workers.

It fell apart this week before it could be dismantled, resulting in the 900-ton receiver platform and Gregorian dome – the structure that sat above the dish –  to tumble more than 400 feet onto the telescope below.

Areas of the observatory that were affected by the uncontrolled collapse had already been evacuated.

Witnesses to the incident described a large crash.

“It sounded like a rumble. I knew exactly what it was,” Jonathan Friedman, a worker at the facility, told the Associated Press.

“I was screaming. Personally, I was out of control… I don’t have words to express it. It’s a very deep, terrible feeling.”

The observatory had until recently been the largest radio telescope in the world, serving as a world-class research and astronomy hub for 57 years.

It was fundamental in the discovery of gravitational waves, as well as asteroids and other celestial objects in the galaxy.

The Arecibo Observatory before the collapse (H. Schweiker/WIYN and NOAO/AURA/NSF.)

It is also famous for its portrayal in fictional works over the decades, most notably in the James Bond film Goldeneye.

It is not yet clear what will happen to the site, with scientists working there originally lobbying for it to be repaired when it was first damaged.

Building a new observatory of a similar size would cost $350 million.