It will be the greatest game of "capture the flag" ever played. When Nasa astronauts Doug Hurley and Bob Behnken set foot on the International Space Station they will collect a small US flag that has acquired mythical status in space lore. The 12 inch by 8 inch banner will be brought back to Earth and presented to SpaceX as the prize for being the first commercial company to launch humans into orbit, winning a decade-long race with rivals including Boeing. Hurley, 53 and Behnken,49, are due to blast off from Florida's Kennedy Space Center on Wednesday, watched by President Donald Trump. A SpaceX Falcon 9 rocket and Crew Dragon capsule will lift off from launchpad 39A, the same one from which Neil Armstrong, Buzz Aldrin and Michael Collins departed to the moon on Apollo 11. It will be the first time astronauts have been launched into orbit from US soil since the end of the space shuttle programme in 2011, and the first time by the private sector.