SpaceX is shooting for another launch attempt on Friday to deliver supplies to the International Space Station.
NASA confirmed the launch date on Wednesday, two days after a last-minute rocket leak delayed the mission. Stormy weather, however, is forecast for Friday. Saturday is the backup launch date.
Mission Control has rescheduled urgent spacewalking repairs because of the new launch time.
Two US astronauts, Rick Mastracchio and Steven Swanson, had been aiming for a Tuesday spacewalk to replace a backup computer that failed late last week.
The prime computer has been working fine, but NASA wants to get a new backup installed outside the station as soon as possible. These computers control the pointing of the radiators and solar wings, among other things.
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The spacewalk will be either Easter Sunday or next Wednesday, depending on when - or if - the cargo ship flies.
The Dragon contains more than two tons of supplies, including material that would prove useful for the repair, but is not essential.
Former space station astronaut Christopher Cassidy, who's helping from Houston, said the spacewalk job should be "pretty straightforward" and involve the manual turning of just three bolts on the computer box.
"We anticipate it to go quickly, but as with anything in space ... you never know what's going to be thrown at you," said Cassidy, who served on the space station last year.
A bad valve resulted in Monday's helium leak in the unmanned Falcon rocket. The valve is in the system used to separate the rocket's first stage.
Although a backup valve was working properly and could have supported the flight, SpaceX followed its own policy of cancelling a launch in the event of equipment problems such as this.
