Officials said the trio has plenty of supplies, and can last until October. A Russian rocket is set to launch Friday.
American officials had been hoping the success of SpaceX _ including 18 straight successful launches _ would mean less reliance on Russia as relations have soured to their worst stage since the Cold War.
The SpaceX Falcon 9 exploded 139 seconds into the flight. Musk Tweeted: “There was an overpressure event in the upper-state liquid oxygen tank. Data suggests counterintuitive cause. That’s all we can say with confidence right now. Will have more to say following a fault three analysis.”
Debris tumbled into the Atlantic off Cape Canaveral.
Bill Gerstenmaier, Nasa's associate administrator for human exploration and operations,
called it a blow to the space program.
"Through these failures and events we can learn more, and come back stronger," he said. "It's not easy living on the frontier of space."
The crew, one American and two Russians, was not considered in any danger. Scott Kelly, representing the U.S. was to spend a year in space to compare his experiences with his twin brother on Earth.
Now the space program must conduct a rapid review of all rockets, as well as decide whether to go ahead with plans to send three more astronauts.
"Once we identify the issues we will submit that documentation to the FAA and it will be considered prior to the next flight," said SpaceX president Gwynne Shotwell.
"I don't have a timeline for that right now. It certainly isn't going to be a year - (more likely) a month or so."