Massimino began using the microblogging Web site a few months ago, updating his followers on the day-to-day life of an astronaut and his training for the upcoming mission.
Massimino and the other six members of the space shuttle Atlantis' trip to service the Hubble Space Telescope launched Monday. His first Twitter message (called a "tweet") from space communicated his excitement about the launch — in under 140 characters (one of the site's constraints).
"Launch was awesome!!" Massimino tweeted Tuesday via his Twitter alter ego @Astro_Mike. "I am feeling great, working hard, & enjoying the magnificent views, the adventure of a lifetime has begun!"
Since then, he's sent a couple more messages through the social networking technology. Massimino transmits his messages to Mission Control on the ground, and NASA posts them to the Web at: http://twitter.com/astro_mike.
"Rendezvous and grapple were great, getting ready for our first spacewalk," Massimino tweeted Thursday.
Massimino is a veteran spacewalker making his second trek to Hubble. He took up Twitter at the suggestion of NASA's Public Affairs Office, as a way to give the public a peek at life as an astronaut.
"Being an astronaut's a cool job, we're very fortunate to have it and day-to-day we get to do some fun things," Massimino said before flight. But the busy schedule can make it hard to reach out to people, he said. "The opportunity to use Twitter has been great, because by definition it has to be short."
While he's doing his best to stay in touch from orbit, there are some times that Twitter will be technologically out of reach for Massimino.
"We do not have a text device certified for spacewalks, so during that period he'll be unavailable," said fellow astronaut Scott Altman, commander of Atlantis' STS-125 mission.
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