Locals in Lincolnshire reported seeing mysterious glowing orbs in the evening sky shortly before the giant structure was wrecked.
More mundane theories for the cause of the damage – from a block of frozen urine dropped by a passing plane, to simple mechanical failure – have been mooted, but none has yet proved conclusive.
“It sounds unbelievable but actually we don’t have any explanation at the moment,” said Dale Vince, founder of Ecotricity, the energy company which owns the wind farm at Conisholme near Louth.
At least half a dozen Lincolnshire residents reported seeing the orange-yellow spheres, which some witnesses claimed were trailing octopus-like “tentacles”.
Dorothy Willows, who lives a mile and a half from the farm, said she saw a “low-flying object skimming across the sky towards the turbines” on Sunday evening.
In the early hours of the following morning a 213 ft fibre glass turbine at the farm was left crippled, with locals reporting hearing a loud bang like thunder. One of the £1 million turbine’s 65 ft blades was ripped off clean off and thrown to the ground, while another was severely damaged.
Although no foreign debris was found at the site, rumours of a possible alien collision quickly spread among local residents. RAF Scampton, the nearby base that hosts the Red Arrows display team, said it had no planes flying that night.
Robert Palmer, chairman of East Lindsey District Council and one of those who claimed to have seen the lights, said that he was keeping an open mind.
“I would be very interested to find out what it was. If we are being looked at by other people, by other planets, it would be interesting to find out why they have chosen this part of the country,” he said.
But wind farm experts said the explanation was likely to be mechanical, not extra-terrestrial.
Fraser McLachlan of GCube, which insures more than 25,000 wind turbines, said it was extremely unlikely that any external object hit the turbine. He said there were five or six instances a year of blades separating of their own accord, usually due to construction faults.
“Water could have got into hairline cracks in the blade, weakening the structure when it turned into ice, or it’s possible that the blades were just poorly attached to the hub,” he said. “Sometimes machines just break.”
Dr Peter Schubel from the University of Nottingham, an expert in the design and manufacture of wind turbine blades, said that it could have been struck by ice thrown from a neighbouring turbine.
Professor Christopher French of Goldsmiths University in London, editor of The Skeptic magazine, which investigates paranormal claims, said that the lights in the sky could have been caused by aircraft, satellite debris or a meteorite.
“Any of these explanations, plus several others, appear to me to be much more plausible than the idea that technologically advanced aliens have travelled light years across space but then bumped into a wind turbine,” he said.
Mr Vince said that fragments for the blade had been sent for analysis by the manufacturers Enercon, and that they expected to have an explanation by next Wednesday, by when the damaged blade should have been repaired. “We are focusing on the rational, not the paranormal,” he added. Telegraph Media Group Limited