(PhysOrg.com) -- The first astronaut to tweet from space has passed another social media milestone. NASA's Mike Massimino, known as @Astro_Mike on Twitter, now shares his daily experiences with more than a million followers on the micro-blogging service.

Massimino flew in May aboard the final mission to service the Hubble Space Telescope. He began a Twitter account about a month before his launch, provided updates throughout his time in orbit and continues to tweet about his post-flight experiences and the life and work of an astronaut.

"I am thrilled that so many people have been following and responding with such wonderful comments," Massimino said. "I tweet because I feel very lucky to have, what in my opinion, is the best job in the world. I've learned that there are so many people around the world who really love the space program and have a heartfelt interest in space travel -- just like me."

Massimino can be followed at: www.twitter.com/Astro_Mike

Since Massimino's flight, many other astronauts have begun to share insights of their experiences on Twitter. They offer varied perspectives of both training on Earth and flying in space. Among the NASA astronauts now active on Twitter:

-- Jeff Williams, space station Expedition 21 flight engineer and future station commander who arrived at the station early Friday. He will provide updates, including video and still imagery, about his six-month stay in orbit. He can be followed at: www.twitter.com/Astro_Jeff

-- Expedition 21 Flight Engineer Nicole Stott, also aboard the station, is providing insights of her time in space. She can be followed at: www.twitter.com/Astro_Nicole

-- Astronauts and twins Mark and Scott Kelly, slated to command the space shuttle and the , respectively, next year, are sharing their unique perspectives with the Twitter community -- and with each other -- as they train at locations around the world.

Mark Kelly can be followed at: www.twitter.com/shuttlecdrkelly

Scott Kelly can be followed at: www.twitter.com/stationcdrkelly

-- Astronaut Jose Hernandez began NASA's first bilingual Twitter account in July about his preparation for last month's STS-128 shuttle mission. He tweets about his post-flight activities in English and Spanish. He can be followed at: www.twitter.com/astro_jose

More astronauts flying in space and training on Earth are expected to begin tweeting about their experiences in the near future. All NASA astronauts on Twitter can be followed at: .com/NASA_" target="_blank">www..com/NASA_

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