Five decades ago today, NASA's Mission Control Center came online for the first time. Better known by its radio call sign "Houston" (for the city it calls home), it was designed from the start to put a man on the moon. One of the most advanced facilities on the planet when it opened in 1965, it cost more than $100 million—that's $750 million today.

The facility was designed to handle a huge variety of scenarios, some of them utterly unpredictable. As a press release at the time noted, designers refined the specifications as they went along. “They had to: they were dealing with undefined dimensions—literally out of this world and off on tangents not yet explored by man.”

"Houston" has evolved since 1965, of course, but photos from its early days and from 2015 prove the core concept was a good one. Today's computer screens are bigger and more colorful. A 1990s revamp did away with the mainframe computer-based system to a more modern setup, and now that Americans are living on the International Space Station, the room is staffed at all times, rather than for the occasional launch. The facility has expanded to include a training flight control room (for practice), a life sciences control room (for experiments), and an "Exploration Planning Operations Center" (to test new concepts).

The facility was seriously state-of-the-art, and a huge step up from NASA’s earlier control centers.

But it doesn't look all that different, and the basic function of the command center hasn't changed. Every American who's gone into space since 1965—from Ed White to Scott Kelly—has been carefully watched over by science whizzes manning these stations.

'A Multitude of Superlatives'

The day after it opened, the center handled Gemini 4, the mission during which astronaut Ed White completed the first American spacewalk, floating outside the spacecraft for 20 minutes. But even before that success, NASA knew it had created something special. A few months before Mission Control went operational, it invited journalists down for extensive tours and technical briefings on the facility, as well as a full-scale simulation of GT-3, the code name for the first manned Gemini mission.

The facility was seriously state-of-the-art, and a huge step up from NASA’s earlier control centers. Mainframes built by IBM provided the computing backbone for the MCC's operations, allowing NASA controllers to pull up thousands of graphs, tables and pictures in seconds, and overlay static images like maps with dynamic, computer-generated images like spacecraft flight paths.

More than 200 different types of telemetry data—on the condition of the astronauts, spacecraft and booster systems—will flow into the MCC during a mission.

As the press release noted, the center was "a multitude of superlatives," with 10,000 miles of wire, two million wire connections, 140 command consoles, 136 television cameras, and 384 television receivers. A 53-station pneumatic tube system, with two miles of tubing and electrically-manipulated switches and control valves, automatically guided messages to their final destination.

Screens totaling 10-feet tall and 60-feet wide adorned the back wall, while hundreds of television monitors filled the consoles. Controllers could record images of their computer displays at the push of a button, which were immediately printed out for the historical record—an early take on today's screenshot.

"More than 200 different types of telemetry data—on the condition of the astronauts, spacecraft and booster systems—will flow into the MCC during a mission,” said the press release. “The amount of spacecraft information, received in the MCC’s Telemetry Equipment Room in code, is equivalent to that which would be received by approximately 1,000 standard Teletype circuits.” Telemetry data would be stored in the spacecraft when it was out of range of one of NASA’s worldwide communication sites, with data periodically dumped to a receiving station when the spacecraft passed within range.

Much thought was put into how to display the massive amount of incoming information, so as not to overwhelm the human controllers. Computer-controlled warning lights in various colors (white for ready to operate; green for go and safely operating; yellow for warning, attention needed; and red for danger, abort, land or take other immediate action) reflected mission status changes within half a second.

Voice communication systems were extensive, allowing group conversations within the MCC as well as with remote stations and astronauts. Teletype equipment allowed written messages to be transferred as fast as 100 words per minute. There was enough communications equipment installed to provide telephone service to a city of 10,000.

Timing, crucial in spaceflight, was synchronized with the National Bureau of Standards' time station. A television camera constantly filmed the official clock for display on monitors through the facility.

The MCC building itself filled 245,000 square feet, with 113,000 of that in the windowless Mission Operations Wing. Each Mission Operations Control Room filled 7,800 square feet of space. It all came together in about 30 months, from the awarding of the prime contract to the first operational flight. More than one hundred different vendors supplied hundreds of chassis-level pieces of equipment to the center, with hundreds more built by Philco, the primary contractor, and NASA itself.

Located at the Johnson Space Center (renamed in 1973 from the Manned Spacecraft Center), the various Mission Operation Control Rooms oversaw every Apollo, Skylab and Space Shuttle flight, and now controllers watch over the International Space Station. The control rooms have been rebuilt numerous times over the years, but always with the same two overarching goals: Keeping astronauts safe and completing the mission.