Dragon rendezvous aborted, next attempt in 24 hours
SpaceX’s CRS-10 Dragon capsule will try again tomorrow as its planned Wednesday, Feb. 22, 2017, rendezvous and berthing attempt with the International Space Station was called off. An onboard computer triggered the abort when it saw an incorrect value in the data about the location of the outpost.
The abort occurred at 3:25 a.m. EST (08:25 GMT) while the spacecraft was 3,900 feet (1,200 meters) below the ISS. The space station’s Expedition 50 crew was expecting to capture Dragon with the robotic Canadarm2 just hours later.
According to NASA, the spacecraft automatically reset for another attempt in 24 hours and there are no issues with the cargo capsule. Should everything go as planned on Thursday, the crew should capture Dragon at around 6 a.m. EST (11:00 GMT).
Dragon launched atop a Falcon 9 at 9:39 a.m. EST (14:39 GMT) Feb. 19, 2017, from Kennedy Space Center’s Launch Complex 39A. It has on board some 5,500 pounds (2,500 kilograms) of supplies, commodities, and experiments.
Once in orbit, Dragon’s Draco thrusters began altering its orbit to begin catching up with the orbiting laboratory. According to SpaceFlight101, around 1:15 a.m. EST (06:15 GMT), the capsule moved into the space station’s 17-miles (28-kilometer) communications zone to establish a space-to-space data link between the two vehicles.
A couple hours later, the computers detected an incorrect value in the spacecraft’s Relative GPS hardware. This allows the computer to plan its burns to decrease its distance to the space station. As the computer was no longer sure where it was, it aborted for the day.
Engineers at SpaceX’s Hawthorne, California, headquarters immediately began troubleshooting the issue. The capsule is currently setting itself up for another approach attempt in 24 hours.
Dragon approaches, like all cargo ship rendezvous, are automated. The crew, however, does have some manual abort, retreat, and hold commands they can activate, should they see an issue the computers do not.
This was the first unplanned abort by a Dragon capsule since starting cargo deliveries in 2012. The demonstration 2012 Dragon C2+ mission demonstrated its ability to abort during its first approach.
When CRS-10 finally gets close enough to the outpost, Expedition 50 Flight Engineer Thomas Pesquet will helm the controls of the station’s robotic arm to “grab” the spacecraft. Ground controllers will then command the arm to maneuver the capsule below the Harmony module for berthing. Once attached and leak checks are performed, the hatches will be opened to allow for cargo to be unloaded.
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.