LONDON (AFP) - British singer Sarah Brightman said Tuesday she was planning a duet when she becomes the first soprano to board the International Space Station later this year after paying a US$52-million (S$72.07 million) ticket.

The singer, who has been learning Russian and survival skills for her trip, said that she was working with ex-husband Andrew Lloyd Webber on the song to be performed with a singer on Earth.

"We're working on the music at the moment," she said at a press conference in a hotel in central London.

"It's finding a song that suits the idea of space and something that is incredibly simple," said the singer, who scored a British top 10 hit with I Lost My Heart To A Starship Trooper in 1978.

She admitted that her space flight - the first "space tourist" trip since 2009 - seemed "unrealistic and crazy", but said that watching the first Moon landing in 1969 when she was nine years old had been "a pivotal moment" in her life.

The soprano, known for her starring roles in West End musicals composed by Lloyd Webber, is due to spend 10 days in space in September after paying a reported US$52 million to become the eighth space tourist in a flight arranged by US firm Space Adventures.

In January she began training at the legendary Gagarin cosmonaut training centre in Star City outside Moscow.

In pictures of the survival course released by the training centre, Brightman is shown in a snowy forest of fir trees, lashing tree trunks together to make a shelter while wearing waterproof jacket and trousers and a winter hat.

Brightman, 54, is in training with cosmonauts and astronauts from Nasa, the Russian space agency and the Japanese space agency, as well as with a Japanese businessman who will take over as her replacement on the space flight if she has to drop out.

On the survival course, Brightman has to spend 72 hours outside and construct a wigwam shelter using branches and a parachute, while knee-deep in snow.

The team members are issued with rations of dried prunes, powdered cottage cheese, biscuits, chocolate, as well as coffee, tea and sugar.

"Cosmonauts and astronauts have to battle freezing temperatures and the harsh conditions of our winter and keep up their morale for many hours," the training centre said.

The aim of the course is to teach survival skills in case the astronauts drift off course when they fall to Earth in their landing capsule and are forced to seek shelter in rough terrain.

The astronauts' Soyuz landing capsule is equipped with medicines and food as well as ultra-warm winter outfits including socks made of animal fur.