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  On Wednesday morning, the Falcon 9 rocket stands ready on the launch pad. [credit:
  Trevor Mahlmann for Ars ]

A twice-flown Dragon spacecraft is ready to be launched on Wednesday to the International Space Station. The mission, which will ferry nearly 2.6 tons of supplies to the orbiting laboratory for NASA, will remain in orbit for about a month before returning to Earth with more than 50 science experiments.

Liftoff is scheduled for 12:51pm ET (17:51 UTC) from Space Launch Complex-40 in Florida. Surface weather conditions are fine, but there are concerns about upper-level winds reaching as high as 120 knots later today. Before launch, meteorologists will release a weather balloon to determine whether upper atmospheric conditions are acceptable for the rocket to navigate through. A back-up launch opportunity is available at 12:29pm ET on Thursday.

New rocket

SpaceX has built a new Falcon 9 rocket for this mission—hence, no soot in the launch pad photos. However, it will be flying a different profile for this space station supply mission. Typically, the newest variant of the Falcon 9 rocket has enough lift capacity to loft the Dragon spacecraft into orbit before using its remaining fuel to steer it back to a landing site on the Florida coast.