An astronaut living in orbit has delivered the International Space Station's first address to the deaf community.

NASA astronaut Tracy Caldwell Dyson recorded a six-minute video for deaf children to give them a glimpse of what life as an astronaut is like. While American Sign Language (ASL) is the fourth most commonly used language in the United States, it had never before been used on the space station, NASA said in a statement.

In the video, Caldwell Dyson also discussed what inspired her, as a hearing person, to learn sign language.

"Long time ago, when I was a young university student, I met a girl who's deaf; she's same as me, a sprinter on the track team," Caldwell Dyson said in ASL, according to a NASA translation. "So she taught me how to sign."

A ponytail bounced gently above Caldwell Dyson's head as she gestured to the camera. [Video of the space station sign language message.]

Later on in college, she studied sign language along with her science coursework. Eventually, the two subjects connected when Caldwell Dyson encountered a deaf student while teaching chemistry in graduate school. The young student struggled to keep up with the material because she couldn?t watch the teacher, read and watch the interpreter at the same time.

"It was a difficult and strange way to learn," Caldwell Dyson said in a separate NASA interview, "but it was all she had and it opened my eyes to the challenges deaf students in hearing universities face every day ? challenges that hearing people take for granted." 

The experience had a deep and lasting impact on Caldwell Dyson. It also taught her new words in sign language, such as for the signs for "chemistry" and "electrons."  

"One thing I have learned is that deaf people can do anything," Caldwell Dyson said. "The only thing they can't do is hear. Maybe someday you can fly into space and live on the ISS."

Caldwell Dyson was inspired to film the video to encourage deaf students to pursue science ? and possibility even aim to be a part of NASA.

"Ultimately, this isn't really about me learning or knowing ASL," Caldwell Dyson said. "This story should be an avenue for deaf students ? from children in kindergarten to college undergraduates to doctoral candidates ? to see themselves belonging to this amazing thing called NASA and participating in scientific research and space exploration."

The video was sent to many schools, NASA spokesperson Kelly Humphries told SPACE.com.  

Caldwell is the first astronaut use sign language on the space station, but not the first person ever to use sign language in space. Nearly two decades before her message from the space station, another NASA astronaut used American Sign Language, or ASL, to send a greeting to hearing-impaired students encouraging them to consider a career in the space program.

In January 1992, pilot Bill Readdy signed from onboard space shuttle Discovery during the STS-42 mission. He was inspired by the work performed by his crewmates and himself to analyze the effects of microgravity on the human vestibular system ? how we hear and maintain balance.

"Today in our mission we are studying how gravity effects human life," Readdy signed at the time. "Although you only see astronauts here in the space shuttle there are many thousands of engineers and scientists that made the original engineering, mission planning and, of course, the science that is so very vital to this mission. There is room for anyone to participate in the space program and to make a real contribution to the future health of mankind."

Readdy's sign language message can be viewed here: http://www.collectspace.com/asl_readdy

SPACE.com contributor Robert Pearlman, editor of collectSPACE.com, contributed to this report from Houston.