The US space agency was unaware that the shuttle Endeavour’s final mission to the International Space Station was in conflict with the royal wedding, a Nasa chief said.

“The frank answer is no,” said Bill Gerstenmaier, Nasa associate administrator for space operations, when asked by a reporter if the nuptials of Prince William and Kate Middleton were a factor in the shuttle scheduling.

“I didn’t realise when the wedding was when we moved the launch date,” said Mr Gerstenmaier. The shuttle was initially set to launch on April 19 and was later postponed to April 29.

“We kind of set that date independently.”

Mr Gerstenmaier said he received a phone call from someone notifying him of the crossover after the fact, though he did not elaborate on who made that call.

“That was a consideration,” he allowed, but quickly pointed out that Nasa considers multiple technical, weather and international space agency constraints whenever it sets a launch time.

“I haven’t yet put on our manifest charts ‘wedding constraints’ so we did not factor that in,” he said.

Endeavour will be the second-to-last flight of the 30-year-old US shuttle program before it closes for good later this year following the final launch by Atlantis in June.