"How do you go to the toilet in space?" was one of the questions that pupils of a north London school asked of Nasa astronaut Greg Chamitoff.

And they expected an honest answer, as Chamitoff spoke to them via a live teleconference link from the International Space Station as it passed over Honolulu, Hawaii.

All 180 pupils in years five and six of the Michael Sobell Sinai school in Kenton got a space lesson with a difference thanks to a family connection: Chamitoff is the cousin of two pupils, Jessica and Amelia Diamond.

Jessica asked what the food was like and Amelia wanted to know what things he missed on a six-month mission in orbit.

As well as asking about the practical difficulties of coping with everyday functions like eating, sleeping and going to the toilet in the weightless environment of a space station they also be asked about the scientific aims of the mission.

Daniel Niessen wanted to know how close the space station is to other planets and if they are recognisable. Sammy Jacobs asked: "Could you describe what earth looks like when you are in space and can you identify the countries, weather conditions and seas."

Carla Raphael wondered if he noticed light, dark, day and night and temperature in space. She also wanted to know how astronauts observe their religion in space. And Jamiee Miller simply wanted to know "what do you do for fun".

Chamitoff has worked for the Johnson Space Centre since 1995 developing software to monitor, control and predict spacecraft manoeuvrability and operations. He was selected by Nasa as an astronaut in 1998 and qualified for space flights as a mission specialist in 2000.