SpaceX plans to fire up the engines on its Falcon 9 rocket on Tuesday at 3:44 a.m. ET in a second attempt to conduct the first-ever cargo run to the International Space Station by a private company.
Saturday's first launch attempt at Cape Canaveral in Florida was aborted at the last second when the spacecraft's flight computer detected slightly high pressure in the engine 5 combustion chamber, according to SpaceX.
"During rigorous inspections of the engine, SpaceX engineers discovered a faulty check valve on the Merlin engine. The failed valve was replaced on Saturday and after thorough analysis the vehicle has been cleared for launch," the company said in a statement Monday.
The SpaceX Falcon 9 booster carrying a Dragon capsule laden with supplies for the ISS had actually started firing up at the three-second mark of the countdown, when the onboard computer automatically shut down the engines. Because SpaceX and NASA had only one shot at launch, the mission was scrubbed and pushed back to this week.
All appeared to be going well until the rocket engines cut off, leaving the spacecraft on the launch pad at Launch Complex 40 at the Cape Canaveral Air Force Station.
The Dragon's computer systems have checked out following a longer-than-expected software validation process that delayed the mission's earlier May 7 launch date. Other technical issues that have caused months of delays to the first commercial flight to the ISS were also resolved.
But SpaceX president Gwynne Shotwell told reporters before Saturday's aborted launch attempt that SpaceX has never managed a liftoff of a Falcon 9 on the very first try. In fact, SpaceX has only launched its current booster rocket once before, on a December 2010 test flight that carried a Dragon capsule into orbit and back again as part of NASA's Commercial Orbital Transportation Services (COTS) program.
SpaceX and NASA are calling the mission to the ISS a test flight as well. The goal of the mission is to ferry 1,150 pounds of cargo aboard the SpaceX Dragon for delivery to the ISS and then take on a 1,455-pound payload to bring back to Earth.
But first, SpaceX has to insert its Dragon spacecraft into orbit, which it will again attempt to do on Tuesday. Once in space, the capsule will take approximately 75 hours to reach the space station and, if it passes a system check, it will dock with the ISS and unload supplies for the astronauts aboard.
The SpaceX rocket is actually carrying some extra cargo of a sentimental nature. The ashes of 308 deceased people are contained in a special pod that's designed to separate from the Falcon 9 rocket nine minutes into its flight.
Included among those remains are the ashes of Canadian actor James Doohan, who played Chief Engineer Montgomery "Scotty" Scott in the original Star Trek television and film series. Doohan's family has been attempting to fulfill his wishes of having his ashes taken to space since his death in 2005. Two previous attempts to do so using portions of Doohan's ashes, including one by SpaceX in 2006, failed.
The special capsule, which families paid $3,000 apiece to have their loved ones' remains place aboard, is designed to orbit the Earth for a year before re-entering the atmosphere and burning up.
Earlier this month, an American astronaut and two Russian cosmonauts successfully departed from the Baikonur Cosmodrome in Kazakhstan for a two-day trip to the ISS, where they will remain for four months.
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