The Virgin Galactic people have been talking about turning down a million-dollar offer to allow a zero-gravity porn film to be made on their space craft. Then I'm told that a young South Korean astronaut named Yi So-Yeon has been going around describing herself as "crazy, sexy and cool". There even seems to be a spring in the step – well, the slow roll – of Brigitte, a working prototype of the Rover vehicle which, all being well, will trundle over Mars in 2015.

Brigitte is named after Bardot but looks like WALL-E. She's designed to be able to cope with the rocky surface of the Red Planet; in the SECC, however, she rumples up the carpet something shocking.

All the exhibitors are keen to get rid of their freebies so they don't have to cart them home. Space geeks must have sweet teeth, judging by the goodies on offer at the stalls. Clyde Space is dishing out sherbet flying saucers. Commercial Space Technologies has a big tin of Quality Street. SpaceTech is handing around Chupa Chups. The Swiss Air Force, meanwhile, fly in the face of national stereotypes – instead of chocolate, it offers mints.

John Harlow, president of the British Interplanetary Association (BIA), which organises these events, is wandering around in dress tartan, silver buttons outgleamed by his grin. He's delighted to have attracted a record 2,100 delegates. The BIA was founded in 1933 to promote space exploration. It was a visionary organisation, says Harlow. "In 1933 the UK had just introduced the first speed limit – 30 miles an hour, 44 feet per second – yet these guys were thinking in terms of getting off the planet at tens of thousands of feet per second. It was an enormous leap of the imagination."

Harlow is an expert on propulsion. At college, he and his pals would stage competitions, firing rockets the size of Coke cans a mile into the air. He may have been responsible for a good number of UFO sightings in the Newport Pagnell area.

He despairs at the lack of state funding for space exploration, and the way that expensive events on Earth keep man out of the heavens. "If the Americans hadn't had Vietnam," he says, "we might have been having this conversation on the moon."

He is 61. I ask what development he'd most like to see in his lifetime. "Back to the moon," he says. "I'd love to mine Helium 3 from the surface." This amazing substance can be scooped up in moon dust and used to power nuclear fusion reactors. "If you had a litre bottle you could run the whole world for a year. Fusion energy is incredible. But a fusion weapon this big" – he spreads his hands two feet – "would take out more than Glasgow." Swings and roundabouts, then.

Harlow has to go, so I visit the Clyde Space stand. Based in Maryhill, they make power systems for satellites. Andrew Strain points out a wee circuit-covered box, about the size of a Rubik's cube. "That's the entire satellite," he says. "It always surprises people. They think it's a scale model."

Clyde Space shares a stand with STAR-Dundee, a Scottish company that has developed a computer network for use on board space craft. It will be part of the James Webb space telescope, successor to Hubble, when it launches in 2013. "It has a 6.5-metre diameter mirror and a sun-shield the size of a tennis court," says Dr Steve Parkes. "It can look such a long distance into space that you are effectively looking back in time. They are trying to look right back at the origins of the universe."

Head spinning, I leave the hall and bump into June Scobee Roberts. She is a small, blonde woman of 66 who has come here from Chattanooga, Tennessee. Her late husband was Dick Scobee, commander of the Space Shuttle Challenger which broke apart shortly after launch in January 1986 with the loss of all seven crew.

The Challenger mission had been intended as the first stage of the Teacher In Space Project; Christa McAuliffe, a teacher from New Hampshire, was on board, and it was intended that she would inspire children to study maths and science. The families of the crew members decided to continue that part of the mission by founding a network of Challenger Centres in which school pupils can experience space simulations.

"I put aside my personal grief," Scobee Roberts says. "I moved from concerns for me and my children to a more global outlook. The world knew how the crew died. I wanted the world to know how they lived and for what they were willing to risk their lives. Every day, dozens of times, my children saw on television their father's Challenger explode. It was traumatic for all of us. But if we could see their mission continued then that gave us all hope."

Asked how her late husband felt about his work, her eyes light up. "His first flight into space was 41C, an important mission to repair a satellite," she recalls. "President Reagan went on television to congratulate the crew but forgot to mention Dick's name. When he returned from space he was so excited to tell me what it was like. We had married as young teenagers and this was a dream come true." Back home, Scobee kept dropping things, expecting them to float. "I asked, didn't it upset him that the President forgot his name? He said: 'Oh no, June, what was important was the mission. We got the job done.'"

Her own mission has been to ensure his legacy through her Challenger project; she says seeing the joy on the faces of children is a better memorial than any statue.

And has it been consoling personally to work on this? "Oh yes," she smiles. "It has made all the difference in my life."