(Sen) - SpaceX's Dragon came a step closer to berthing with the International Space Station yesterday as two other commercial companies celebrated advances in their own high-flying ambitions.

The unmanned Dragon, on its second test flight, reached the orbiting outpost and flew less than 2,500 metres (8,000 ft) beneath it, performing a number of tests to show that it is working flawlessly.

Dragon showed its Absolute Global Positioning System (GPS) is in good working order. It also demonstrated free drift, floating freely in orbit as it will when grappled by the space station’s robotic arm. 

And early today, SpaceX announced that NASA had given the go-ahead for the ship to close in so that astronauts aboard the ISS can perform that manoeuvre to bring it in to mate with the station. Yesterday they took a snap of Dragon with its distinctive solar panels extended.

Dragon photographed from the ISS yesterday. Credit: NASA

Assuming berthing happens, the crew of six astronauts aboard the space station will begin to open Dragon’s hatch on Saturday morning, an operation that will take around two hours. Then they will enter Dragon for the first time and be able to unload supplies.

Meanwhile, two other companies were celebrating milestones in their own separate efforts to build spacecraft to carry passengers to the final frontier. Aerospace giant Boeing - a direct rival to SpaceX - announced the successful development of software that will operate its Crew Space Transportation (CST) vehicle intended to ferry NASA astronauts to and from the ISS.

And XCOR Aerospace, based in Mojave, California, said it had achieved a key technical milestone in developing its Lynx suborbital rocket plane that will carry tourists and science experiments, including micro satellites, to the edge of the atmosphere.

While not as spectacular as SpaceX's demonstration, they reported that engineers have successfully and repeatedly used piston pump hardware to deliver liquid oxygen at flow rates required to supply the Lynx's four main engines.

Andrew Nelson, XCOR Chief Operating Officer, said: "Our customers recognise in our technology the ability to contain the costs of developing, extending and maintaining a propulsion system over several decades."

The Lynx will be a piloted, two-seat, fully reusable vehicle that takes off and lands from a runway. XCOR has partnered with the Planetary Science Institute, based in Tucsn, Arizona, to adapt the Lynx to flying an observatory called Atsa on some missions.

Atsa's specially designed telescope will allow astronomers to make observations above the atmosphere at low cost and while under direct control of humans.

Lynx is also being backed by Dutch airline KLM which wants to include the suborbital trips in their frequent flyer program and future holiday packages, flying from a new spaceport on the Caribbean island of Curacao.