By Jonathan Amos
Science correspondent, BBC News
It is the picture that proves the UK's astronaut candidate Tim Peake has made a giant leap forward in his training.
The Briton is seen floating free in the cabin of a jet plane as it flies a series of parabolic loops to simulate the weightlessness experienced in orbit.
Major Tim is the first UK citizen to be admitted into the European Space Agency's (Esa) Astronaut Corps.
His training will get him ready to fly to the International Space Station.
"We had a number of very important tasks to do, but at each stage there was also a lot of laughter because it was so much fun," Major Tim told BBC News.
The former British Army helicopter pilot took the parabolic flight with Esa's other astronaut rookies - Samantha Cristoforetti, Alexander Gerst, Andreas Mogensen, Luca Parmitano, Thomas Pesquet - who all joined the agency in September last year.
Although the group have practised spacewalking in a giant water pool at their training centre in Cologne, Germany, this was their first microgravity, or "zero-g", flight in an aeroplane.
The outing was made on a specially prepared Airbus A300 which operates from Bordeaux airport, France.
The jet makes a series of steep climbs and when the pilot throttles back, anything not strapped down in the cabin begins to float free. Each parabola gives about 20 seconds of weightlessness.
L-R: Andreas Mogensen, Samantha Cristoforetti, Timothy Peake, Alexander Gerst, Thomas Pesquet and Luca Parmitano
"You teach the astronauts how to move in microgravity," explained Dr Gail Iles, an Esa instructor on the flight. "For example, when you throw a container in these conditions, you will move backwards because you have an opposite reaction. They learn how to deal with that."
The rookies tried out the whole-body actions they would need to make to manoeuvre themselves from module to module inside the space station. They also tested a new treadmill for the orbiting platform.
"That was a novel experience because it was on its side and your running position actually faced the roof of the aircraft," explained Major Tim.
"Initially, it felt a bit bizarre in normal flight and as you were doing the pull-ups; but once you were in zero-g and you started running, everything was completely normal."
Esa's rookie astronauts hang from the ceiling of the jet
Five of the six astronauts are pilots by trade, a number of them with extensive experience in fighter jets. But Major Tim said that experience had little bearing on the sensation he felt on the microgravity jet.
"It's genuinely a unique sensation; you don't get that in any aircraft where you are strapped in. And in fact, we all had the opportunity to go up to the cockpit where you are strapped in, and that was completely benign compared to being in the back of the aircraft. It doesn't compare at all to the manoeuvres in fighters or helicopters."
The next three Esa astronauts to go into orbit are all from the old guard - Italians Roberto Vittori and Paolo Nespoli, and Dutchman Andre Kuipers.
Esa is keen to get one of its rookies into space as soon as possible, but the first opportunity will not come before 2013 or 2014.
With the Americans set to retire their space shuttles at the end of this year, the only way to get to the space station will be on a Russian Soyuz vehicle. Its smaller size will restrict the number of flight opportunities for all the world's astronauts.
The US hopes eventually to introduce commercial systems to taxi astronauts to and from the station. These new rockets and capsules should be in operation within a few years.