The launch of SpaceX's Dragon cargo ship to the International Space Station on Monday has been cancelled.
NASA tweeted that the cancellation is due to a helium leak in the Falcon 9 rocket's first stage.
The next launch opportunity is Friday at 3:35 p.m. ET.
The Dragon spacecraft would have carried more than 4,000 pounds of supplies and equipment to the station and marked the first attempt to return the rocket's first stage with four landing legs to Earth as part of an experimental reusable rocket program.
