Shortly after 6 p.m. ET Wednesday, SpaceX will attempt to land its Falcon 9 rocket on a robotic floating platform in the Atlantic Ocean.
Twice this week, engineers have called off the launch of SpaceX's Falcon 9 rocket just minutes before lift-off due to technical issues and uncooperative weather. Today, Elon Musk's private spaceflight company will try again to send a scientific satellite into orbit and then land its rocket vertically on a barge in the Atlantic Ocean. (Scroll down for the live stream.)