Which NASA astronaut posted the first unassisted off-Earth Twitter message?

NASA astronaut T. J. Creamer posted the first unassisted off-Earth Twitter message. He sent it from the International Space Station on January 22, 2010, using the station’s newly enabled web access.

Creamer’s message began, “Hello Twitterverse!” and announced that the station was now live-tweeting from space. The milestone mattered because earlier astronaut-related posts had not been sent directly by the astronaut. For example, Mike Massimino’s shuttle-era updates were emailed to mission control, where support staff uploaded them to Twitter.

The system Creamer used was called the Crew Support LAN. It provided access through the station’s communications links and a remotely operated ground computer, allowing crew members to interact with the web from orbit. That technical detail explains why “unassisted” is important: the tweet was entered by Creamer aboard the station rather than relayed as a prepared message for someone on Earth to post. Later astronauts, including Scott Kelly and Chris Hadfield, became much more prominent space users, but neither was first.