Canadian astronaut Chris Hadfield has said his life in space had to be shared on social media, in his first public appearance since returning to Earth.
Cmdr Hadfield, 53, said his experiences in space were "too good" to keep to himself. He landed on Tuesday.
With nearly 1 million Twitter followers, Cmdr Hadfield said he was pleased with the interest in his work.
He had been on the International Space Station since December 2012 and in command of the vessel since March.
While in space, Cmdr Hadfield tweeted about his life at the space station, sharing striking images of the Earth from space.
"There is beautiful imagery, there's poetry in what is happening, there is purpose in what is happening," Cmdr Hadfield said of his work on the space station. "There is a beauty to it, there is hope in it and it's an international thing."
Sore and dizzy
His social media activities included singing a song with children around the world and filming a cover of David Bowie's hit Space Oddity.
But Cmdr Hadfield insisted his social media activities were secondary to his main functions at the space station.
He said life in space was extremely busy, with no spare time to be idle.
At his first news briefing in Houston, Texas, where the astronaut is undergoing rehabilitation, Cmdr Hadfield described the physical sensations of being in space and landing on Earth.
His first sensation of Earth was the smell of spring after landing in the Kazakh steppe on Tuesday, he said.
Emphasising the differences between life in space and "reality" on Earth, Cmdr Hadfield said he was "readapting to it physically and mentally".
Cmdr Hadfield added that upon his return to Earth he noticed the weight of his tongue and lips and was remembering how to speak under the force of gravity, while his neck and back felt sore from having to support his head again.
"It feels like I played a hard game of rugby yesterday or played full-contact hockey yesterday and I haven't played in a while," he said. "My body is just sore and I'm dizzy, but it's getting better measurably by the hour."