SpaceX is attempting to launch a new, heavier rocket on Tuesday, with takeoff now scheduled for 3:45 pm ET. You can watch the attempt here.
Why it matters: The Falcon Heavy is designed to carry larger payloads, opening the door to more kinds of missions. "It's either going to be an exciting success or an exciting failure — one big boom," Elon Musk told reporters on Monday. Watch our preview video for more details.