The US Air Force’s X37-B space plane is back home after its fourth mission

The US Air Force’s secret robotic space plane is back on Earth after its longest mission yet. The X37-B embarked on its fourth trip to space in 2015 and landed earlier this morning at Orlando’s Kennedy Space Center.The landing marks the completion of the spacecraft’s fourth mission, OTV-4. This was the first time the spacecraft landed in Florida — it touched down at Vandenberg Air Force Base after each of its previous three missions — and woke up residents with a so