Robert "Bobby" Lee Satcher, Jr. ’86, PhD ’93 is a physician, chemical engineer, and NASA astronaut. At 38 years old he was one of 11 candidates chosen from a field of more than 4,000 applicants. The 2004 astronaut cohort was the first new class formed since the Columbia Challenger space shuttle accident in which Satcher's fellow MIT alum and inspiration, Ronald E. McNair PhD '76, lost his life.

Satcher flew on STS-129 Atlantis (November 16-29, 2009), becoming the first orthopedic surgeon to travel into space. Satcher was tweeter-on-board for the mission. His tweets from space are documented under two Twitter accounts: Astro_Bones focuses on the overall mission, and ZeroG_MD recounts medical updates. For additional images of the STS-129 Atlantis Mission, visit NASA .