Had there been astronauts aboard the SpaceX rocket that exploded on Thursday, they would have been just fine, says CEO Elon Musk.

That's because the Dragon space capsule, which SpaceX plans to use for manned flights as soon as next year, has eight escape rockets built into its walls designed to lift astronauts out of harm's way if the Falcon rocket below it is destroyed.

The escape rocket system, which is designed to fire only in case of an emergency, was successfully tested it in May of last year. The Dragon capsule shot into the air, away from the launch pad, and splashed down in the ocean about a mile off shore during the test.

"Dragon would have been fine" Musk said on Twitter.

But this week the Falcon 9 rocket was launching a satellite into orbit, instead of sending astronauts into space in the Dragon space capsule. And a according to a video from USLaunchReport.com, the Amos-6 satellite that was on top the Falcon 9 rocket fell to the ground until about 9 seconds after the first fireball engulfed the Falcon.

That would have been enough time for the Dragon's escape rockets to lift the capsule to safety. The rockets can launch the capsule 100 meters away from the rocket in just two seconds, and a half-kilometer away within five seconds.

SpaceX declined to comment on its practice of running engine tests with a satellite already attached, CNN reports.