When Neil Armstrong took his first step onto the moon on July 20, 1969, Harry Lang had just graduated from college with a bachelor’s degree in physics. But as Americans across the country gathered around their television sets to witness this historic moment, Lang, who is deaf and thus could not hear the words that went with those famous images, was unable to follow along with what was happening. In the days before captions became available for television programs, there was little those who could not hear could do to participate in shared cultural experiences like that one.

“What I saw was great irony,” Lang tells TIME. “Our country’s scientists could send a spaceship to the moon and back, but we couldn’t put captions on television for millions of deaf people who were watching it!”

It wasn’t until March 16, 1980 — 40 years ago this Monday — that the network TV channels ABC, NBC and PBS debuted closed-captioned television shows, in which the show’s dialogue and soundtrack appeared as text on screen as the action proceeded. Starting with The ABC Sunday Night Movie, Disney’s Wonderful World and Masterpiece Theatre, a new world opened up. But getting there was a fight, and that battle still continues today.