After weeks of delays, NASA is finally poised for the launch of a historic flight Wednesday to send a crew of four astronauts on a trailblazing nine-day trip around the moon and back.

The launch window opens at 6:24 p.m. Wednesday for the mission sending humans back to the moon for the first time in more than 50 years.

After weeks of delays, NASA is just hours away from the launch of its historic lunar flyby.