NASA astronaut Scott Kelly retiring

HOUSTON (KTRK) -- With his feet firmly back on Earth, NASA astronaut Scott Kelly is calling it a career.

NASA announced Kelly is retiring from the agency, effective April 1. He'll continue to participate in ongoing research related to the one-year mission in space from which he just returned.

Kelly holds the American record for most time spent in space.

Shortly after his retirement was announced, Kelly posted this letter to his Facebook page.

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