X-37B Mysteries Continue: The launch of the fourth X-37B mission has not resolved some of the biggest mysteries that surround this flight, and the X-37B program in general. X-37B is a robot mini-shuttle launched by the US Air Force on semi-secret missions that last for months or well over a year.
It was a surprise to be openly informed of two payloads on this latest launch. The X-37B is testing an electric Hall Effect thruster in its small payload bay, which will be used on future US Air Force satellites. It is also carrying small material samples for NASA, which are being tested for their exposure to outer space. The Air Force has never discussed the payloads carried on previous missions, and we are still no closer to finding out.
Curiously, we do not know which X-37B is being used on this flight. We were openly told about the particular model in the past. So why not now? For the record, two X-37B spaceplanes have flown before. One made the first and third flights.
