SpaceX’s Polaris Dawn mission, a groundbreaking journey into Earth’s Van Allen radiation belts with a four-person civilian crew aiming to conduct the first commercial spacewalk, successfully launched at 5:23 a.m. ET.

SpaceX livestreamed the event, with ground controllers offering encouragement to the crew, including the first SpaceX employees to go to space.

The mission, delayed by weather, requires careful timing for the crew’s five-day return, as the spacewalk will deplete oxygen supplies, limiting life support to five or six days in space, CNN has reported.

Written by B.C. Begley