The Polaris Dawn crew boarded a SpaceX Dragon capsule for a 5:23 a.m. liftoff Tuesday atop the Falcon 9. The orbital mission will last five days.

The first private spacewalk is set for Thursday by a group of astronauts who will leave a SpaceX capsule after a delay of a few hours, testing a new line of spacesuits in the company's riskiest mission yet.

The Polaris Dawn mission took off Tuesday morning. The civilian crew launched aboard a SpaceX capsule into Earth’s orbit to attempt an unprecedented spacewalk.