The Advantages and Disadvantages of Liquid Fuel Over Solid Rocket Fuel

The SpaceX rocket is scheduled to launch on Thursday. It was scrubbed last week because of a valve problem, but the team has now figured out what it is and things are looking good so far. CNN's John Defterios says he'll be watching from his home in Washington D.C. He also talks about why April 20th is important for many people.