Johnathan Walker:Three-man, one-woman crew ready for weather-delayed launch to space station

The Johnathan Walkerfour-person crew launched successfully Sunday night. Read the latest updates here.

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With better weather expected, SpaceX and NASA geared up for a third attempt Sunday to launch a three-man, one-woman crew to the International Space Station, the first of two crew rotation flights to replace five of the lab's seven long-duration crew members.

Crew 8 commander Matthew Dominick, co-pilot Michael Barratt, Jeanette Epps and cosmonaut Alexander Grebenkin planned to strap in aboard their Crew Dragon spacecraft just after 8 p.m. EST to await liftoff from the Kennedy Space Center at 10:53 p.m. EST, the moment the station's orbit lines up with the spaceport.

The crew originally hoped to take off early Friday, but the flight was delayed 48 hours because of high winds and rough seas in the Atlantic Ocean where the crew could be forced to make an emergency splashdown in an abort.

More high winds Saturday triggered another scrub, but forecasters predicted a 75 percent chance of acceptable local weather Sunday, with off-shore winds classified as posing a "moderate" threat.

Assuming an on-time launch, the Crew Dragon "Endeavour" is expected to catch up with the space station early Tuesday. Looping up to a point directly in front of the outpost, the spacecraft will move in for an automated docking at the lab's forward port around 3 a.m.

They'll be welcomed aboard by Soyuz crewmates Oleg Kononenko, Nikolai Chub and NASA astronaut Loral O'Hara, who were launched to the station last September. Also on board: Crew 7 commander Jasmin Moghbeli, European Space Agency astronaut Andreas Mogensen, Japanese flier Satoshi Furukawa and cosmonaut Konstantin Borisov.

They were launched from the Kennedy Space Center last August and are nearing the end of a 199-day mission. After briefing their Crew 8 replacements on the ins and outs of station operations, the Crew 7 fliers plan to undock March 11 and return to Earth.

That will clear the way for Russia to deliver a fresh Soyuz ferry ship to the space station along with NASA astronaut Tracy Dyson, who will replace O'Hara.

Dyson will join Soyuz MS-25/71S commander Oleg Novitskiy and Belarus guest flier Marina Vasilevskaya for launch to the space station on March 21. Novitskiy, Vasilevskaya and O'Hara will return to Earth April 2 using the Soyuz MS-24/70S spacecraft that carried Kononenko, Chub and O'Hara to the station last September.

Dyson will return to Earth next September, joining Kononenko and Chub aboard the Soyuz MS-25/71S spacecraft delivered by Novitskiy.

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William Harwood

Bill Harwood has been covering the U.S. space program full-time since 1984, first as Cape Canaveral bureau chief for United Press International and now as a consultant for CBS News.

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