Weather postpones SpaceX Dragon launch

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WASHINGTON — Stormy weather postponed the scheduled June 1 launch of a SpaceX Falcon 9 carrying a Dragon spacecraft, setting up a busy period of activity on the International Space Station in the coming days.

The Falcon 9 was scheduled to launch at 5:55 p.m. Eastern June 1 from Launch Complex 39A at the Kennedy Space Center. A lightning strike within 18 kilometers of the launch pad about 25 minutes before the scheduled launch violated a rule that prohibits launches within 30 minutes of lightning strikes that close to the pad. With an instantaneous launch window, controllers scrubbed the launch.

The launch is rescheduled for June 3 at 5:07 p.m. Eastern. Earlier forecasts predicted a 60 percent chance of acceptable weather, slightly worse than the forecast for the June 1 launch attempt.

The Dragon, flying a mission designated SpX-11 by NASA, is carrying more than 2,700 kilograms of cargo for the ISS. More than 2,000 kilograms of that is scientific hardware, including experiments to be conducted inside the station as well as astrophysics, earth science and space technology experiments to be mounted on the station’s exterior.

Should the Dragon launch June 3, it will arrive at the station on the morning of June 5. That arrival will come after two spacecraft currently at the station depart.

The Soyuz MS-03 spacecraft, carrying Russian cosmonaut Oleg Novitskiy and French astronaut Thomas Pesquet, will undock from the station at 6:50 a.m. Eastern June 2. The spacecraft will land in Kazakhstan at 10:10 a.m. Eastern, ending a 196-day mission for the two.

They launched with American astronaut Peggy Whitson, who was originally scheduled to return on the same spacecraft. However, NASA announced April 5 that she will remain on the station until September, ensuring that the station’s crew size remains no fewer than three people.

NASA also announced June 1 that, with the delay of the Dragon launch by at least two days, it has moved up the unberthing of the Cygnus OA-7 spacecraft that has been attached to the station since mid-April. Release of the Cygnus by the station’s robotic arm is scheduled for June 4 at 9:10 a.m. Eastern, around the time the Dragon would have arrived had it launched on schedule.

The Cygnus was originally scheduled to remain at the station for about three months. The agency didn’t disclose why the spacecraft’s departure was taking place earlier. Cygnus will remain in orbit for a week after departure, releasing a set of cubesats and performing a fire experiment inside the spacecraft, before reentering June 11.