Last Updated Apr 14, 2014 4:30 PM EDT
Launch of a SpaceX Falcon 9 rocket carrying a Dragon cargo capsule bound for the International Space Station was scrubbed Monday afternoon because of an apparent first stage helium leak. A new launch date has not been announced, but the flight is off until Friday at the earliest, officials say.
The Falcon 9 version 1.1 rocket was on track for liftoff from launch complex 40 at the Cape Canaveral Air Force Station at 4:58 p.m., roughly the moment Earth's rotation would have carried the pad into the plane of the station's orbit.
But engineers preparing the rocket for liftoff discovered ran into what NASA described as a helium leak in the plumbing of the rocket's first stage, an issue that could not be resolved in time for launch. SpaceX launch director Ricky Lim ordered a scrub at 3:39 p.m.
"As folks heard on the anomaly net, we have encountered an issue that will result in our scrubbing today's 4/14 launch attempt," he said. "The team here will start to safe the vehicle, offload propellants and then working on the details of the next few days forward. So for now, launch is scrubbed. Propellants offload will be commencing here shortly."
Based on the space station's orbit and the requirements of the Dragon rendezvous sequence, the next launch opportunity is Friday at 3:25 p.m., setting up a berthing at the International Space Station early Sunday.
The unpiloted Dragon spacecraft is loaded with nearly 5,000 pounds of equipment and supplies, including a new spacesuit, spare parts for suits already aboard the station, food and clothing, an experimental laser communications system, high-definition video cameras and equipment to grow salad-type crops in weightlessness in research that also will augment the crew's menu.
Whenever it arrives, Expedition 39 commander Koichi Wakata and Rick Mastracchio, operating the station's robot arm and berthing system, will be standing by to lock onto a grapple fixture to pull the spacecraft in for attachment to the Earth-facing port of the forward Harmony module.
The launching was approved by NASA's Mission Management Team Sunday after engineers showed the failure of an external computer aboard the space station Friday posed no increased risk for normal lab operations.
The computer, which serves as a backup for commanding solar array motion, a robot arm transporter and other critical systems, will be replaced during a contingency spacewalk next week. In the meantime, modified procedures have been developed to keep the station operating normally even if another failure occurs.
Mike Suffredini, the space station program manager, said Sunday a launch delay would not have any major impact on NASA's plans to operate the station "as is" until the contingency spacewalk can be carried out.
Getting the Dragon spacecraft safely into orbit is the primary objective of SpaceX's third commercial resupply mission, or CRS-3. But the company also plans to used the launch as an incremental step in an ongoing series of tests aimed at learning how to recover, and eventually reuse, Falcon rocket stages.
With the Dragon capsule and the Falcon's second stage safely on their way, the discarded first stage is programmed to attempt what amounts to a "soft landing" in the Atlantic Ocean east of Cape Canaveral, firing its engines for a controlled descent and deploying four 25-foot-long landing legs just before ocean impact. Recovery crews aboard a nearby ship will be on station to monitor the descent and possibly recover hardware.
Earlier experiments with controlled stage re-entries have been problematic, and Hans Koenigsmann, vice president of mission assurance at SpaceX, is not overly optimistic this time around, putting the odds of controlling the descent all the way to the ocean at just 40 percent at best.
But if SpaceX engineers eventually perfect a recovery system, future rocket stages could be guided to nearby landing sites for refurbishment and reuse, dramatically lowering costs compared to traditional throw-away boosters.
"I must point out that the entire recovery of the first stage is completely experimental, it has nothing to do with the primary mission," said Koenigsmann, adding that SpaceX is "really low-balling the probability of success here because this is a really difficult maneuver."
Koenigsmann stressed that the test was designed to have no impact on Dragon's flight to the space station.
The pressurized section of the Dragon capsule, the cabin accessible to the station crew, is packed with 1,576 pounds of research equipment, 1,049 pounds of food and other crew supplies, 271 pounds of spacesuit tools and parts and 449 pounds of space station hardware.
The equipment includes a fresh spacesuit, a set of legs for the station's humanoid robot, Robonaut 2, and the Vegetable Production System, or VEGGIE, the crew will use to grow food and carry out research.
"Based on anecdotal evidence, crews report that having plants around was very comforting and helped them feel less out of touch with Earth," Gloria Massa, a project scientist at the Kennedy Space Center, said in a NASA description. "You could also think of plants as pets. The crew just likes to nurture them."
The Dragon spacecraft also features and unpressurized "trunk" section that can be accessed by the station's robot arm. The trunk is being utilized for the first time in the CRS-3 mission to carry up components that will be mounted on the station's exterior.
One trunk-mounted payload is NASA's Optical Payload for Lasercomm Science, or OPALS, which will be mounted on the station's solar power truss. The OPALS hardware will test high-speed laser data transmission to and from a California ground station in a demonstration that could pave the way to improved communications with future spacecraft.
Compared to traditional radio communications, the laser technology represents an increase in speed reminiscent of what home computer users experienced upgrading from dial-up modems to DSL or cable for high-speed internet access.
"Future operational laser communication systems will have the ability to transmit more data from spacecraft down to the ground than they currently do, mitigating a significant bottleneck for scientific investigations and commercial ventures," said Michael Kokorowski, the OPALS project manager at the Jet Propulsion Laboratory.
Another trunk-mounted payload includes four high-definition cameras that will be mounted on the station's exterior as part of the High Definition Earth Viewing, or HDEV, project. The cameras will be used to downlink live, streaming video of Earth while engineers monitor the effects of the space environment on the camera hardware.
Because of the space station computer failure Friday, however, the crew will not move the lab's robot arm to begin extracting the trunk-mounted payloads until after a replacement is installed. As of this writing, engineers at the Johnson Space Center are targeting April 22 for a planned 2.5-hour spacewalk by astronauts Steven Swanson and Rick Mastracchio.
The crew spent part of the day Monday replacing components in spacesuit 3005, which Swanson will wear, to minimize any chance of a water backup like one that flooded a European astronaut's helmet during a spacewalk last year.
The Dragon capsule will remain attached to the space station until around May 8 when it will be unberthed for re-entry and splashdown off the coast of California. The Dragon is the only cargo ship currently servicing the station that is capable of bringing components, experiment samples and other materials back to Earth for post-flight analysis.
This time around, the spacecraft will be packed with some 1,600 pounds of experiment samples and other station components.
This will be the third commercial resupply mission carried out by SpaceX under a $1.6 billion contract with NASA that calls for 12 missions through 2016 to deliver some 44,000 pounds of supplies and equipment.
Another company, Orbital Sciences Corp., holds a $1.9 billion contract covering eight cargo delivery missions using its Antares rockets and Cygnus supply ships. Both contracts were awarded after the decision to retire NASA's shuttle fleet.