Williams, 52, and Creamer, 50, told The Wall Street Journal in a satellite interview from the International Space Station astronauts use the social networking and microblogging service, even in their "advanced years," to ease the feeling of isolation, the newspaper reported Friday.
Williams and former crewmate Nicole Stott, 47, participated Oct. 21 in the first live "tweetup" from the space station with about 35 members of the public gathered at NASA headquarters in Washington.
The astronauts also said their age was not a disadvantage but rather translated into seasoning and experience that space agencies valued.
"Today's 50s is like yesterday's 40s or 30s," Creamer joked.
The astronauts also praised the aging space shuttle program, which was responsible for carrying many astronauts to the space station and whose fleet is to be retired from service this year after 134 launches.
Williams called the shuttle -- the first orbital spacecraft designed to be reused -- "a beautiful machine, a magnificent machine."
He said the six airworthy shuttle orbiters had fulfilled their mission.