Mikhail Metzel / Pool / EPA

Russian space agency rescue team members carry U.S. astronaut Donald Pettit shortly after the landing of the Russian Soyuz TMA-03M space capsule at the southeast of the Kazakh town of Dzhezkazgan, Kazakhstan, July 1.

Sergey Remezov / AFP - Getty Images

The Soyuz TMA-03M capsule, carrying International Space Station (ISS) crew members lands.

In a blog post describing his final day in space, Pettit reflected on the impact of his months-long mission, and encouraged humanity to keep pushing the boundaries of space exploration.

"On Earth, the frontiers opened slowly," Pettit wrote. "The technology of sailing was known and advanced for over a thousand years before the Earth was circumnavigated. Such bold acts require the technology, the will, and the audacity to explore. Sometimes you have one, but not the others. I only hope that my small efforts here, perhaps adding one grain of sand to the beach of knowledge, will help enable a generation of people in the future to call space 'home.'" [Landing Photos: Soyuz Capsule Returns 3 Astronauts Home]

-- Reported by Denise Chow, space.com

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