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.

Space Mountain in Walt Disney World celebrates 50 years of operation. Initially opening on January 15, 1975, Space Mountain, an indoor steel rollercoaster themed to space travel, has been a staple of Tomorrowland, the area of the Magic Kingdom park where the ride resides.

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.

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

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.

As the demolition of the old Space Mountain and construction of the new one continue, work is now visible from inside Tokyo Disneyland. Space Mountain Demolition and Construction Tokyo Disneyland’s original Space Mountain — which opened with the park in 1983 — closed permanently in July of last year.

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.