On March 5th, three months after the first U.S. Air Force X-37B UOV (unmanned orbital vehicle) returned from seven months in orbit, the second one was put into orbit. The second vehicle will stay up for at least nine months. The air force also revealed that enhancements had been made to the automatic landing software, that would be tested when this vehicle returned and landed.
The X-37B is a remotely controlled mini-Space Shuttle. The space vehicle, according to amateur astronomers (who like to watch spy satellites as well), appeared to be going through some tests on the first flight. The X-37B is believed to have a payload of about 227-300 kg (500-660 pounds), and is capable of staying in orbit for nine months or more. The payload bay is 2.1x1.4 meters (7x4 feet). As the first one returned to earth, it landed by itself (after being ordered to use a specific landing area.) The X-37B weighs five tons, is nine meters (29 feet) long and has a wingspan of 4 meters (14 feet). The Space Shuttle is 56 meters long, weighs 2,000 tons and has a payload of 24 tons.
The X-37B is a classified project, so not many additional details are available. It's been in development for over a decade, but work was slowed down for a while because of lack of money. When the first one returned, the air force mentioned that the second X-37B was going to be launched in 2011. No one expected the launch this quickly. Apparently the long mission of the first one was very successful in confirming the soundness of the design.
What makes the X-37B so useful is that it is very maneuverable, contains some internal sensors (as well as communications gear), and can carry mini-satellites, or additional sensors, in the payload bay. Using a remotely controlled arm, the X-37B could refuel or repair other satellites. But X-37B is a classified project, with little confirmed information about its payloads or missions (other than testing the system on its first mission). Future missions will involve intelligence work, and perhaps servicing existing spy satellites (which use up their fuel to change their orbits.) The X-37B is believed capable of serving as a platform for attacks on enemy satellites in wartime.
Perhaps equally important, the X-37B proved elusive to amateur astronomers. Little is publicly known about what the first X-37B was doing up there. This indicated the air force had managed to evade the scrutiny of amateur "satellite spotters" who have proven very skilled at spotting even the most secret orbital objects. This has been annoying to those who put "classified" satellites into orbit. The international collection of amateur sky watchers have proved remarkably adept at spotting orbital objects in the past, including classified ones like the X-37B. But not this time. The air force said the first flight was simply to test the aircraft, but would not say what, if anything, was in the cargo bay. No details on what the testing consisted of. The amateur orbital observer community has concluded that one thing the X-37B tested was how well it could constantly switch positions, and stay hidden. In that respect, the X-37B was a resounding success. That's because these amateur observers are generally very good at tracking what's up there.
For example, in one notable incident two years ago, when a U.S. spy satellite fell out of orbit (apparently because of a failure in its maneuvering system), the amateur astronomers were able to track it. If this had not been an American reconnaissance satellite, there would have been no media attention to this, because 4-5 satellites a month fall back to earth. Since most of the planet is ocean, or otherwise uninhabited (humans like to cluster together), the satellites tend to come down as a few fragments, rarely is anyone, or anything manmade, hit.
Before the Internet became widely used a decade ago, you heard very little about all these injured or worn out space satellites raining down on the planet. But with the Internet, the many thousands of amateur astronomers could connect and compare notes. It was like assembling a huge jigsaw puzzle. Many sightings now formed a pattern, and a worldwide network of observers made visible the movements of hundreds of space satellites. These objects were always visible at night, sometimes to the naked eye, but unless you knew something about orbits and such, they could be difficult to keep track of. These days, a lot of the activity is posted and discussed at http://www.satobs.org/. But the X-37B has proved elusive, and became a frustrating challenge to the amateur sky watchers. This is pleasing to American air force officials, who designed the X-37B to be elusive to terrestrial observation.