Authors:

Exploring Mars is a far different venture from Apollo expeditions to the moon; it necessitates leaving our home planet on lengthy missions with a constrained return capability.

Buzz Aldrin, Leonard David (2013). “Mission to Mars: My Vision for Space Exploration”, p.166, National Geographic Books
Exploring Mars is a far different venture from Apollo expeditions to the moon; it necessitates leaving our home planet on lengthy missions with a constrained return capability.