SpaceX has again delayed the launch of a rocket carrying four private astronauts to space, part of a ground breaking mission aimed at performing the world’s first commercial spacewalk.

Due to unfavorable weather forecast in the spacecraft’s splashdown areas off the coast of Florida, SpaceX is standing down from Falcon 9’s launch opportunities of Polaris Dawn on Aug. 28 and Aug. 29, the company said in on its website. SpaceX teams will continue to monitor weather for favorable launch and return conditions.

The signature moment of the mission was to be a spacewalk by billionaire Jared Isaacman and SpaceX engineer Sarah Gillis. 

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