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Falcon 9 rocket stage lands back at Cape Canaveral.
After launch, SpaceX returned the tall portion of the Falcon 9 rocket to an upright landing at Cape Canaveral.
After a almost two-month delay, the rocket is set to blast off sometime during a two-hour launch window, which opens at 8 p.m.
SpaceX now has 21 successful first-stage touchdowns under its belt, nine of them at Landing Zone 1 and the other 12 on "autonomous spaceport droneships" stationed in the ocean.More news: Actor replaced in BBC drama after sexual assault claims
The actual payload of the Zuma mission is essentially unknown.
Among the few concrete details, however, is the launch's contractor, Northrop Grumman, who was selected by the US government to find a rocket for the launch, hence the use of Falcon 9.
"Northrop Grumman is proud to be a part of the Zuma launch". Satellite launches are typically scheduled months, if not years, in advance and the agencies responsible for classified payloads are usually identified. The satellite popped up on SpaceX's launch schedule last October, two weeks after the Federal Aviation Administration received an application for launch.
The first stage aced that landing, a little less than 8 minutes after taking off.
After a record 18 launches in 2017, this mission will be SpaceX's first flight of the new year.
The Falcon 9 lifted off at 8 p.m. EST (0100 GMT on January 9) from Cape Canaveral Air Force Station, on Florida's Space Coast.