SpaceX scrubbed its May 19 attempt to launch the Falcon 9 rocket/Dragon capsule on the first commercial U.S. resupply mission to the International Space Station after a last-moment engine shutdown.

Another attempt to launch the near two week test mission from the Cape Canaveral Air Force Station, Fla., could occur no sooner than May  22 at 3:44 a.m., EDT, according to NASA spokesman George Diller. More trouble-shooting was anticipated.

The difficulties detected by the Falcon 9 flight control computer were described as a high chamber pressure in the No. 5 first stage engine. The first stage is comprised on nine SpaceX developed Merlin liquid oxygen/kerosene engines.

The launch of the two stage Falcon 9 from Launch Complex 40 had been scheduled for 4:55 a.m., EDT.

The engine start sequence, which commenced three seconds before lift offt, was underway when the flight computer initiated the shutdown.

Favorable weather is forecast for a May 22 launch. A desire to preserve as much of Dragon’s fuel for on orbit maneuvers as possible, restricts future launch opportunities to every third day. After May 29, the high temperatures from an increasing solar beta angle on the space station’s orbital plane would restrict additional launch attempts until after mid-June.