SpaceX began the Pacific Ocean recovery of the company's third commercial re-supply mission to the International Space Station Sunday afternoon, capping a month-long round trip that featured the delivery of nearly 5,000 pounds of cargo and the return of more than 3,500 pounds of station hardware and scientific equipment, including perishable research samples.
Dragon splashed down under parachute 350 miles west of Baja, Calif., at 3:05 p.m., EDT.
"Dragon has successfully splashed down, and recovery operations are underway," NASA's Mission Control informed ISS commander Steve Swanson and his Russian crewmates, Alexander Skvortsov and Oleg Artemyev, moments after the capsule was sighted in Pacific waters.
"Wonderful, great news," replied Swanson.
The SpaceX Dragon capsule awaits release commands from U. S. astronaut Steve Swanson with assistance from cosmonaut Alexander Skvortsov. NASA TV
Personnel in NASA's Mission Control issued commands seven hours earlier that unberthed the 14 foot long commercial freighter from the station's U.S. segment Harmony module using Canada's 58-foot-long robot arm. More commands extended the robot arm for Dragon's release at 9:26 a.m.
Three separation burns within a dozen minutes pushed Dragon away from a NASA monitored ISS "keep out” zone, returning oversight of the supply mission to controllers at SpaceX's Hawthorne, Calif. control room who set up a 10 minute deorbit burn at 2:12 p.m.
"I'd like to thank everyone who worked this Dragon mission. It went very well. I appreciate that tremendously," radioed Swanson, who issued the release commands from the ISS Cupola observation deck.
Swanson took command of ISS Expedition 40 on May 13, with the departure of three U.S., Japanese and Russian crew members aboard the Soyuz TMA-11M crew transport.
The departure left the station temporarily staffed by three.
There were no outward signs of the terrestrial tensions between the U.S. and Russia over the annexation of Crimea as Skvortsov joined Swanson for the late stow of Dragon cargos returning to Earth as well as at the robot arm's Cupola control post for the capsule's release.
Dragon's return cargo of crew supplies, station hardware and spacewalk tools included 1,600 pounds of scientific gear, including a pair of low temperature Glacier freezers with medical specimens and preserved biological samples for a range of crew health, human and plant biology and biotechnology experiments.
One investigation, Antibiotic Effectiveness in Space, returned E. Coli samples as part of a continuing investigation into the aggressive responses of bacteria to weightlessness. Some strains thrive, resisting antibiotics
"We intend to further corroborate these early findings and conduct more in depth genetic assays of the returned samples to get a better understanding of what might be responsible for this outcome,'' said AES-1 principal investigator David Klaus, of BioServe Space Technologies at the University of Colorado in Boulder, in a NASA statement.
Patterns of gene expression from the studies may aid in the development of more effective antibiotics.
Researchers from the University of Florida flew similar investigations that cultivated antibiotic resistant versions of two common bacteria found on the skin and in the soil. The space-flown samples will be compared to ground controls for signs of mutations linked to weightlessness and new clues about the loss of effectiveness of antibiotics in space.
The capsule also delivered the T-Cell Activation in Aging investigation. The experiment looked for defects in the space activation of human T-cells, which are normally mobilized quickly by the body to fight terrestrial illnesses. Researchers are hopeful the work will improve the treatment of auto-immune diseases including arthritis, as well as slow the decline of the immune system among the aging.
The SpaceX-staffed recovery ship American Islander will head for Los Angeles to offload Dragon and begin the distribution of science experiments to researchers and station hardware in need of refurbishment. Most of the cargo will be transported to SpaceX facilities in Central Texas for processing.
Dragon's third mission under a $1.6 billion, 12-flight NASA contract signed in late 2008, lifted off from Cape Canaveral, Fla., on April 18. The station's since-departed commander, Koichi Wakata, of Japan, and NASA flight engineer Rick Mastracchio used the Canadian arm to capture and berth Dragon.
Orbital Sciences' second Cygnus resupply flight, the next scheduled ISS cargo delivery, is being readied for a June 10 lift off from Virginia's Mid-Atlantic Regional Spaceport. SpaceX is scheduled to launch its fourth Dragon cargo mission on Aug. 8.