"It's great," says Naomi Pritzer, a Year 5 pupil from Broomfield primary school, Leicester, who has just completed a mission to find the comet Encke. "I liked being in space and having to get all the notes from life support, and medical, and people like that."
"You're doing lots of school work, but you don't feel bothered about it, because it's all so interesting and fun," says Naomi's classmate, Amy Watkins, 9, part of the same mission.
"It was an excellent morning," says their teacher, Jean Hall. "You can see how much they all enjoyed it."
The centre simulates a space mission and is designed to encourage children, aged nine to 16, to learn how science, maths and technology are applied in space. There are 40 Challenger centres - set up as memorials to the crew lost in the 1986 space shuttle disaster - in the US and Canada, but this is the first outside North America, using materials adapted for the national curriculum.
A class group will divide into two groups and work as astronauts and mission controllers, undertaking scientific, navigation and communications tasks. By following instructions - and with the help of flight directors - they complete a successful mission, coping with "surprises" along the way.
"What they're learning is to be excited about spce, if nothing else," says Joy Horton, who used to be a secondary school chemistry teacher but is now Commander Joy - US-trained and fully kitted out in a blue astronaut jump suit. "But they're also doing co-ordinates and averages, testing PH, using computers, acquiring listening skills, and learning to work in teams. There's a tremendous amount of learning involved."
The centre is part of the much bigger pound;50 million National Space Science Centre, half of the cost of which has been funded by the Millennium Commission. Next year the Challenger centre will move to the other side of the city to dock permanently with the national centre. Meanwhile, 12,500 children have been through the doors of its temporary home since it opened in September - some from as far afield as Cornwall. Staff also run an outreach programme, taking an inflatable planetarium to schools.
Before a visit, teachers undergo a day's training to be mission controllers, and pupils prepare by studying relevant subjects, filling out job applications for mission tasks, and designing space badges.
During a mission, it is almost impossible to speak to anyone taking part, as pupils become absorbed in running medical tests, sending messages, speaking through their headsets, and working remote-controlled robotic arms.
When lights flash to indicate an "emergency" they look genuinely worried. When a visitor leaves through the airlock, it's clear that some, at least, believe that person might be lost in space forever.