SpaceX's Polaris Dawn to Attempt Historic Private Spacewalk

Mission aims to set altitude record and test new technologies for future deep space exploration.

Crew will travel 870 miles above Earth, the highest altitude since Apollo missions.
First-ever commercial spacewalk planned, with entire cabin depressurized.
Mission funded by billionaire Jared Isaacman, includes two SpaceX engineers.
Scientific experiments will study human health effects and test laser-based communications.
Mission delayed by 24 hours for additional preflight checkouts, now set to launch Aug. 27.