About two hours after sunrise on Tuesday, SpaceX was about to blast off from Vandenberg Air Force Base to deliver a Soyuz capsule packed with a NASA astronaut and two new space station crew members to orbit. But at least four people were on board for the ride — due to the severe thunderstorms that hit southern California on Sunday.
SpaceX’s launch of a Dragon capsule is fraught with weather concerns.
If all goes according to plan, the rocket will launch into space at 8:12 a.m. PST and the Soyuz will deploy two of its solar arrays a minute later. But it will be able to carry only one crew member — space station commander Shane Kimbrough of NASA — as the other two seats remain unfilled.
Shane Kimbrough will conduct live coverage of the launch on Tuesday.
“We want the sun so bad,” Mr. Kimbrough, who is scheduled to launch at 7:21 a.m. PST, said in a Twitter video last week. “We really don’t want any cloud cover.”
Mr. Kimbrough and crew mates Ricky Arnold and Anne McClain of NASA have been training for the mission for months. On Monday, they went through a “trip-card course” from VR goggles on to prepare for the launch, Mr. Kimbrough said in another video.
NASA’s Arlene Krieger said in an interview last week that NASA space station managers were concerned that their astronauts would be subjected to solar radiation — which can damage the eyes, skin and other parts of the body — during the docking. “So it’s not yet time to have a full day of orientation for the flight, but you can start a progression to that over the next few days,” she said.
Officials at NASA were going to debate whether to postpone the launch until Wednesday.
Jeffrey Niebur, spokesman for SpaceX, said the weather at Vandenberg had improved by Monday night. “The actual possibility of a launch on Tuesday afternoon is 50-50,” he said. “We’re anticipating we’ll be trying for launch again on Wednesday.”
To make room for the two additional astronauts — Peggy Whitson of NASA and Oleg Artemyev of Roscosmos, the Russian space agency — the Soyuz is adding a mass of up to 500 pounds, Mr. Niebur said.
Despite a number of recent delays, the SpaceX launches have been a productive part of the program, Mr. Niebur said. “They’ve really made some positive advancements over the last two years,” he said.
The launch is the first of two scheduled next month, also involving SpaceX. On May 11, the company is scheduled to launch another SpaceX capsule, carrying Japanese astronaut Norishige Kanai and two crew members.