Fifty years ago this week, Space Mountain opened in Magic Kingdom at Walt Disney World. The original Space Mountain, which opened at Walt Disney World in 1975, was the first fully-enclosed, dark roller coaster and the first to be controlled by a computer.

When the ride opened on Jan. 15, 1975, an Apollo moonwalker was its first passenger, NASA's insignia was on display and Space Mountain was dedicated to opening the new frontier.

A cultural touchstone, the dark ride opened to the public on Jan. 15, 1975, three years and three months after the Magic Kingdom’s debut.

Space Mountain is one of the most recognizable theme park attractions around the world, but here’s what you may not know about the beloved ride.

• Jan. 15, 1975: Space Mountain opened at a cost of $15 million, the Sentinel reported, “an amount more than the whole cost of Disneyland, built in 1955.” Astronauts Scott Carpenter, James Irwin and Gordon Cooper posed with Mickey Mouse, who is decked out in a spacesuit.

Space Mountain, at Walt Disney World! Celebrate the magic of milestones at Walt Disney World this year and reminisce about your own Disney childhood milestones.

Space Mountain at Walt Disney World's Magic Kingdom celebrated it's 50th Anniversary, and to celebrate the occasion, Disney bathed it in gold

Walt Disney wanted to build Space Mountain at Disneyland a decade before the indoor roller coaster forever altered the skyline of the Magic Kingdom a few years after the debut of the Florida theme park.