Definitely the space shuttle! The versatile workhorse that helped build the ISS, launch and repair Hubble and added 100's of names to the list of people who have visited space. Seeing the Atlantis exhibit at the cape was profound.
Hi Tariq! With all the problems posed by micro-G, how likely is it that the first earth-mars manned mission architectures will incorporate artificial gravity? Why haven't we seen more progress in this area?