After scrubbing the International Space Station cargo delivery mission and fly-back booster attempt earlier this week, SpaceX has now confirmed that it will try again on Friday, April 18 at 3:25 pm ET. A live webcast will begin at 2:45 at www.spacex.com/webcast.
If all goes well, the Dragon cargo ship launched on Friday will reach the space station on Sunday, April 20, to be captured by the station’s robotic arm at 7:14 am ET.
The launch originally planned for Monday was scrubbed due to a helium leak in the rocket. From an email I received from SpaceX this morning:
A launch on Friday results in a rendezvous with the space station on Sunday, April 20 and a grapple at 7:14 a.m ET.
During Monday’s launch attempt, preflight checks detected that a helium valve in the stage separation pneumatic system was not holding the right pressure. This meant that the stage separation pistons would be reliant on a backup check valve.
No issue was detected with the backup valve and a flight would likely have been successful, but SpaceX policy is not to launch with any known anomalies. We have brought the vehicle back to horizontal and are replacing the faulty valve, as well as inspecting the whole system for anything that may have contributed to the valve not working as designed.