SpaceX was gearing up to launch TRACERS, NASA’s latest mission to study solar wind and how it impacts Earth, with liftoff set to occur at SLC-4E at Vandenberg, with the booster also targeting a return to launch site landing at the launch site. On Tuesday, all appeared to be going well in the final seconds of the countdown. As per usual, the Launch Director can normally be heard on the communication loop at T-45 seconds saying “Go for launch”. This time, however, we heard the “Hold Hold Hold” call. This call tells all operators in mission control that the count is being paused, and in the case of Falcon 9, they can no longer launch that day, resulting in a scrub. It was quickly noted on the official stream that the reason for the Hold was “FAA airspace concerns”, which is not totally uncommon, as the Range can go red when a vehicle, such as a boat or plane, enters the downrange exclusion zone. Notably, this time, this was not the reason. The FAA confirmed that the airspace concerns were not any specific aircraft, but rather the Air Traffic Control Center monitoring those aircraft. An ARTCC isn’t like a control tower at an airport; it’s what is called a Center, which is responsible for a huge area of airspace, called a Flight Information Region (or FIR). See Also