23/09/2015 17:00 BST | Updated 23/09/2016 06:12 BST

British Astronaut Tim Peake: We Spend A Lot Of Time Fixing The Space Station Loo

In the weightlessness of space there is one piece of equipment you really do not want to malfunction.

British astronaut Tim Peake has spoken of the greatest challenge facing him when he blasts into Earth orbit in December - the International Space Station toilets.

He revealed that ensuring WC systems remain what the American space agency Nasa refers to as "nominal" will take up a large chunk of the mission.

Major Peake came clean about the problem as he was quizzed by children from a London primary school in a live link to Nasa's Johnson space centre in Houston, Texas.

One youngster named Eddie asked the question children want the answer to more than any other when it comes to human space flight. How do you go to the toilet?

Tim replied: "The most training we have is not how to use it but how to fix it.

"It's been up there for 15 years now.

"There's one in the Russian segment and one in the American segment.

"Thankfully they're pretty identical so they share common parts, but they do break quite a lot.

"So it might not seem like a very glamorous task for an astronaut but we do spend an awful lot of time fixing the loo.

"In terms of using it, it's really very straight forward.

"It just uses air suction and a big fan to keep everything going in the right direction."

He added: "I'm sure there's going to be a bit of a rush to the loo after six hours in the Soyuz spacecraft when we dock and get on board the space station."

Tim will embark for a six month stay on the space station on December 15.

During his mission he will perform more than 30 experiments for the European Space Agency (Esa) as well as participating in many others.

The children who spoke to him from Queen's Park Primary School in Westminster, London, belong to one of a number of school groups engaged in activities related to the mission.

The aim is to promote an interest in science and technology with experiments involving food, coding, plant growth and fitness.

Besides fixing the toilet, another major challenge for Major Peake has been learning to speak Russian, the astronaut revealed.

He added that he planned to borrow the guitar that made American astronaut Chris Hadfield a YouTube sensation when he performed David Bowie's Space Oddity from the ISS.

"Unfortunately I've not got the talent set that Chris Hadfield has so I will be picking up his guitar in space and playing it on the weekends but not to the same level," he said.

Tim, 42, a former Army helicopter pilot, was the first British citizen to be selected for astronaut training by ESA. 

He joined the space agency in September 2009 and completed his basic training in November 2010.

His forthcoming mission has been called Principia, after Sir Isaac Newton's historic text Naturalis Principia Mathematica, describing the principal laws of motion and gravity.

Travelling with him will be Nasa astronaut Tim Kopra and Russian cosmonaut Yuri Malenchenko.