When Neil Armstrong landed on the moon 50 years ago this week, he was talking to Houston, but his words were sent to Greenbelt first.

During the Apollo 11 mission, the Goddard Space Flight Center was the main control center for sending and receiving messages and information between the spacecraft and mission control in Houston, as highlighted recently by Maryland Milestones.

Here’s how the Washington Post described it at the time:

“About two seconds after Apollo 11 emerged from behind the moon on its crucial first lunar orbit Saturday, a green light flowed on a computer control in NASA’s Goddard Space Flight Center in Greenbelt. The Goddard computer began talking to its mate in Houston, passing on to Mission Control the message that the maneuver had gone well… Shortly afterward came a sign that Mission Control’s computer had digested and processed the data flowing out of Goddard. Another green light blinked on the computer console. ‘A command,’ said Stetler. A message from Houston, advising Apollo 11 of necessary course corrections, had just passed through the Goddard computer. In about 1.9 seconds, the message was to be transmitted to Andover, Maine, across the Atlantic to Madrid, and finally to the spacecraft circling the moon. In a few minutes, Apollo was about to circle behind the moon for the second time. In a room full of beeps and bleeps, engineers in headsets sat listening. ‘There it goes,’ one said. ‘It just went behind the moon.’ ‘Just went,’ somebody else said, taking off his headset.”

A NASA spokesman at the time said that Goddard was the heart of the mission, and that they could not afford to have anything go wrong in Greenbelt.

To commemorate the moon landing, the Goddard visitors center at 9432 Greenbelt Road will hold a model rocket building contest from noon to 4 p.m. on Saturday. While you’re there, be sure to check out the mock-up of the Apollo capsule used for training in its outdoor Rocket Garden.