The Expedition 39 crew welcomed nearly 2.5 tons of supplies and scientific payloads to the International Space Station with the arrival of the third SpaceX Dragon commercial cargo spacecraft Sunday, April 20.

With Dragon securely in the grasp of Canadarm2, the robotics officer at Mission Control remotely operated the arm to install the capsule to its port on the Earth-facing side of the Harmony module. Once Dragon was in place, Flight Engineer Rick Mastracchio monitored the Common Berthing Mechanism operations for first and second stage capture of the cargo ship, assuring that the vehicle was securely attached to the station with a hard mate. Second stage capture was completed at 10:06 a.m. EDT as the station flew 260 miles (420 kilometers) above Brazil.

Dragon was grappled at 7:14 a.m. as it flew within about 32 feet (10 meters) of the complex by Commander Koichi Wakata, with assistance from Mastracchio, as he controlled the 57-foot (17m) Canadarm2 from a robotics workstation inside the station’s cupola. Flight Engineer Steve Swanson joined his crewmates in the seven-windowed cupola to assist with the capture and help coordinate the activities. At the time of capture, the orbital laboratory was flying around 260 miles (420km) over Egypt, west of the Nile River.

Afterward, Wakata sent down his kudos to SpaceX and the ground teams as he remarked, "Congratulations to the entire ops team for the successful launch, rendezvous, and capture operation. The vehicle, the spacecraft was very solid and very stable. And the Canadarm2 was really solid, and it made it easier for us to capture."

The crew spent much of the remainder of their workday pressurizing the vestibule between Dragon and the station and setting up power and data cables to prepare for the opening of Dragon’s hatch today, April 21.

Filled with nearly 5,000 pounds (2,300 kilograms) of crew supplies and cargo to support more than 150 scientific investigations planned for Expeditions 39 and 40, Dragon is scheduled to spend four weeks attached to the station. The crew will reload the space freighter with about 3,600 pounds (1,600kg) of experiment samples and hardware for return to Earth.

After Dragon’s mission at the station is completed, Mission Control Houston will remotely unberth Dragon from Harmony and maneuver it to the release point with Canadarm2. The station crew then will release Dragon for its parachute-assisted splashdown and recovery in the Pacific Ocean.

Dragon launched atop a Falcon 9 rocket at 3:25 p.m. Friday, April 18, from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida. The SpaceX-3 mission is the company's third cargo delivery flight to the station through a $1.6 billion NASA Commercial Resupply Services contract.