First Steps To Mars

The landing site is unknown. The rockets are still on the drawing board. Some of the astronauts haven't been born yet. Never mind all that. NASA's journey to Mars has already begun.

The first steps are being taken onboard the International Space Station (ISS). "Astronauts are stationed on the ISS for six months at a time," says Dr. Clarence Sams, lead scientist for the ISS Medical Project at NASA's Johnson Space Center.