There’s a lot of secret spacecraft in the sky this month. Last week, China launched its experimental robotic space plane, Shenlong, for the third time, and next week SpaceX plans to launch the US Air Force’s little-discussed X-37B. And, of course, there is Santa’s sleigh, which has a unique and unexplained reindeer propulsion system. Here’s what we know about these mysterious spacecraft.
X-37B
The size of a small bus, the US military’s X-37B has been used to bring mysterious payloads into space and conduct long-lasting experiments (its last flight lasted more than two years) since its debut in 2010. The government has been tight-lipped about what the Boeing-built spacecraft does exactly, but said in a press statement that the shuttle’s upcoming flight, scheduled for launch on Dec. 28, will be used to test “new orbital regimes” and for “experimenting with future space…
