The guests nibbled on Red Planet tartlettes and chewed Beagle 2 brochettes. It took a Mars biologist to interpret the menu but thankfully there were plenty at this event.
By Helen Briggs
BBC News Online science reporter
With the steppe of Kazakhstan off limits for many, supporters of the Beagle 2 project gathered in London to watch a live transmission of the launch.
Lead scientist Professor Colin Pillinger sat on the front row next to the British science minister Lord Sainsbury for the final minutes of the countdown.
Colin Pillinger and Lord Sainsbury (right) watching the launch
They smiled broadly as the white-nosed rocket on the launchpad became a tiny dot in the night sky.
Before the launch, Colin Pillinger had briefed reporters about what to expect.
He had spoken about the first few nail-biting minutes of the flight and the crucial stages of separation, when bits of the rocket fall away from the space craft.
In the packed auditorium, we cheered when we learned that all was well so far, and the precious cargo of Mars Express and Beagle 2 was looping around the Earth on its way to Mars.
Lord Sainsbury stepped forward to deliver congratulations and a message of support from the Prime Minister. But it fell to Colin Pillinger to utter what was on the lips of many - let's go to the bar.
In the interval, we waited for final confirmation that the space craft was on its way. It was a chance for some of the key players in the Beagle project to reflect.
Ian Wright of the Open University in Milton Keynes said he hoped Beagle would inspire a new generation of British scientists and engineers.
"What we hope will come out of this is that it will reach out to young people and say this is an exciting business - don't ignore science as a possible career."
Mike Healy of the European space company Astrium sees Beagle as a good old British success story, born of commitment and ingenuity.
"The engineering and technology that has gone into this is really outstanding, he said. "This is the Formula One of the space business."
For Lord Sainsbury, the project is "brilliant science" and a "British story of success in engineering".
"It's a project which will capture anyone's imagination down the realm," he told BBC News Online. "And show them what a remarkable thing space exploration can be."
We were ushered back into the auditorium for the final link-up to Baikonur. Only then could everyone relax, with the news that the launch had been successful.
But as Colin Pillinger describes it - the launch is only the quarter final of the game. The semi-final will be the tricky descent to the surface of Mars. Only then can scientists enjoy the final - carrying out the science that Beagle was built to do.