CAPE CANAVERAL, Fla. (AP) — SpaceX's big new rocket blasted off Tuesday on its first test flight, carrying a red sports car aiming for an endless road trip past Mars.

The Falcon Heavy rose from the same launch pad used by NASA nearly 50 years ago to send men to the moon. With liftoff, the Heavy became the most powerful rocket in use today, doubling the liftoff punch of its closest competitor.

The three boosters and 27 engines roared to life at Kennedy Space Center, as thousands watched from surrounding beaches, bridges and roads, jamming the highways in scenes unmatched since NASA's last space...