Humankind has cast an eye toward another "giant leap" forward nearly half a century after the United States' Apollo 11 spacecraft delivered humans to the moon for the first time.

The U.S. National Aeronautics and Space Administration (NASA) is planning to put a manned spacecraft into orbit around Mars in the 2030s, before sending humans to explore the red planet.

Similar in size to Earth, and relatively close, Mars is widely considered as the most promising and realistic candidate planet for manned space exploration.