Twenty-four hours after an aborted rendezvous attempt, SpaceX’s CRS-10 Dragon capsule was captured by the International Space Station’s robotic arm. This second approach to the outpost went by the book. The capture took place at 5:44 a.m. EST (10:44 GMT) Feb. 23, 2017, while the orbiting laboratory was flying 250 miles (402 kilometers) over the west coast of Australia. At the controls of the robotic Canadarm2 were Expedition 50 Commander Shane Kimbrough and Flight Engineer Thomas Pesquet.
Ground teams then took over for the next couple hours to maneuver the capsule to just below the Harmony module in order to berth the spacecraft with the station. Final bolting between Dragon and the station took place at 8:12 a.m. EST (13:12 GMT), about three days after launching from Kennedy Space Center’s Launch Complex 39A.
The crew will unload the nearly 5,500 pounds (2,500 kilograms) of supplies and experiments onboard the capsule.
Dragon’s first attempt at rendezvousing with the outpost was called off at 3:25 a.m. EST (08:25 GMT) Feb. 22 while the spacecraft was just 3,900 feet (1,200 meters) below the station. The capsule’s onboard computer triggered the abort when it saw an incorrect value in the spacecraft’s Relative GPS hardware. The hardware allows the computer to plan burns as it decreases its distance to the ISS.
For the second attempt, however, things went smoothly. Just after 4 a.m. EST (09:00 GMT), Dragon was on final approach having left a 1,150-foot (350-meter) hold point. During this hold, it maneuvered itself to align its grapple fixture with the station’s robotic arm.
The next hold point was at 820 feet (250 meters). Dragon and the station then established a two-way UHF link with each other.
At about 4:30 a.m. EST (09:30 GMT), Dragon made its move toward a 98-foot (30-meter) hold point. Taking about 30 minutes to reach, the vehicle used its laser navigation sensors and thermal imagers to verify its distance to the $100 billion-outpost.
Once at the 98-foot (30-meter) hold point, teams in Houston and in Hawthorne, California, verified all was go for final approach to the 33-foot (10-meter) mark for capture. Movement toward that position began at about 5:18 a.m. EST (10:18 GMT).
Kimbrough and Pesquet monitored the rendezvous from the station’s Cupola window. Inside there is a panel that allows the crew to manually call a hold, abort, or retreat if needed.
At 5:37 a.m. EST (10:37 GMT), Dragon was in position beneath the outpost for capture by the 58-foot (18-meter) long Canadarm2. Pesquet controlled the arm to capture Dragon a few minutes later.
Thursday's rendezvous and berthing was the 10th time a Dragon had visited the outpost. It is the 89th automated supply ship to reach the complex and 178th overall mission to the ISS.
Dragon will spend about a month attached to the space station. Sometime in late-March, hatches will be closed and the spacecraft unberthed. The crew will release the cargo ship and it will pull away to a safe distance to perform a de-orbit burn. The capsule will re-enter Earth’s atmosphere to splash down in the Pacific Ocean just off the coast of Baja California.
Written by: Derek Richardson
Original source: spaceflightinsider.com