The launch of SpaceX's first completely recycled spacecraft has been delayed until Wednesday.
The mission to restock the International Space Station will be carried out by the Falcon 9 rocket and the Dragon capsule, both of which have been used before.
Now targeting Dec. 13 for launch of CRS-13 from SLC-40 to allow for additional time for pre-launch ground systems checks.
— SpaceX (@SpaceX) December 12, 2017
According to SpaceX, the back-up launch date of Wednesday is being used instead of Tuesday's planned date so additional ground-system checks can be made.
The recycled rocket doesn't add any extra risk, accoridng to NASA's International Space Station manager, Kirk Shireman.
But the launch is "still a dangerous business", he said, and although the Falcon 9 has been extensively inspected by NASA's experts, there is never "zero risk" when it comes to rocket launches.
SpaceX said: "This mission marks the first time SpaceX is flying both a flight-proven Falcon 9 and a flight-proven Dragon spacecraft."
This is the thirteenth of up to 20 missions to the International Space Station that SpaceX is contracted to fly for NASA.
Its Dragon capsules are not currently able to deliver crew to the ISS and are only being used to deliver cargo at the moment, although SpaceX is developing a variant for crew transport.
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With this mission, SpaceX will deliver about 4,800 pounds of cargo and material to support science investigations aboard the space station.
"After about one month attached to the space station, Dragon will return with results of earlier experiments, splashing down in the Pacific Ocean off the coast of Baja California."