The United States may be retiring the last of its famous space shuttles in the coming months, but that does not mean that made-in-the-USA winged craft will be absent from the skies above.
You may not have known it, but there is already such a thing orbiting the earth.
To the untrained eye, it looks a lot like the Atlantis or the Discovery, but its name isn't quite so evocative: this particular craft is called the X-37B. Unlike its forebears, its purpose is secretive and militaristic - so much so that it may be the first time America has put anything in space with an orbit that is officially secret.
There are other differences between it and the shuttles we know so well. The former is far smaller, for example, with a wing-span of just 4.6m and a length of 8.38m. The shuttles are 37m long with 24m wingspans. The new space explorer, moreover, is robotic with no humans on board.
No one is calling it a drone. But the connotations of clandestine warfare might not be entirely inappropriate. While every shuttle launch is attended by banks of cameras and spectators at Cape Canaveral in Florida, the launch, also from Canaveral, of this new craft one month ago was shrouded in a cloak of secrecy. Although the project began as part of Nasa, it was taken over by the Pentagon four years ago.
Some of that cloak is now being punctured, however, thanks to amateur skygazers in countries as far apart as Canada and South Africa. They think they have seen the craft, also known as Orbital Test Vehicle 1 (OTV-1), in recent days. Seemingly, it is flying 410km up and circles the planet once every 90 minutes on a course that takes it south of New York City and, more importantly, directly over war zones like Iraq and Afghanistan.
One of the amateur sky-watchers is Kevin Fetter, a contributor to a satellite-tracker website called heavens-above.com. He was the first to capture the OTV-1 crossing his telescope's viewfinder a few days ago. Eventually, following tidbits of information - including an anonymous email - about the OTV-1's probable orbit, he and fellow amateur enthusiasts were able to establish that it was the satellite in question.
Despite all the secrecy, the US military has insisted that the craft is non-aggressive. The OTV-1 has "no offensive capabilities", a US Air Force official told the New York Times. But no one is willing to say more about what the OTV-1 is doing up there or how long its flight will last. It could, we are told, be nine months before instructions are sent from a command base in Colorado to the space craft to land itself at Vandenberg Air Force Base in California.
"I don't think this has anything to do with weapons," Brian Weedon, a former Air Force orbital analyst, told space.com. "But because of the classification, and the refusal to talk, the door opens to all that. From a US perspective, that's counterproductive."
He speculates that the Pentagon hopes to use the space craft in the longer term for orbital surveillance and reconnaissance better to support commanders in the battlefield.
Alternatively, if it could be fitted with a grabbing arm, the vehicle might be able to pluck satellites out of the sky and put them into an orbit more suited to the needs of the military.
The spacecraft was launched atop an Atlas 5 rocket from a Canaveral pad on April 22. It can remain powered up for months at a time thanks to solar panels. It was built by Boeing and a second is on order.