After years of training and in some cases as little as days in space, astronauts need to decide what to do next with their lives. Many will get a second chance to go to space, with all the training that that new mission will entail. But eventually, you?ve done your last space flight. Being an astronaut is, still, a very high profile position. Do you use that position as a platform to champion a cause or to move yourself into a longer-term career?

I want to look at some of the astronauts who have decided to champion causes, and what they?ve done.

Buzz Aldrin
One of the most famous astronauts (Aldrin was the second man to walk on the Moon, right behind his commander and shipmate Neil Armstrong), Aldrin has resurfaced in the past few years, working hard to promote one cause, ?Get Your Ass to Mars!?

Buzz Aldrin is a firm believer that humanity needs a second village to live in, and Mars is it. He?s guest editor of a special ?Welcome to Mars? edition of National Geographic Kids. He?s doing a speaking tour around the world (The closest he comes to me is Sydney, Australia in November).

Bernard Harris
The first black man to walk untethered in outer space, Dr. Harris has gone on to create and manage a foundation geared toward promoting STEM career paths to underprivileged students as well as giving them financial literacy. (Disclaimer, I met Dr. Harris while working at African Leadership Academy in Johannesburg, South Africa. He visited as part of the ?Dream Tour? in 2011 to promote STEM to young African students).

Sally Ride
Sally Ride wasn?t just the first American woman in space, she was, at 32, the youngest astronaut ever and may have been the first LBGT person to travel in space (we don?t know if there were any before her). Sally created a small publishing empire, Sally Ride Science. The books that she created promoted a love for science and all STEM fields, and were mostly geared towards middle-school students, but especially girls, who are under-represented in STEM.