Mars: the only other “habitable” planet
(in contrast with other competitors; e.g. Moon, Europa, Titan)
•Size and distance from the Sun:
•Size: diameter 6787 km (53% of Earth)
•Surface gravity : almost 40% of Earth
•Only planet in the habitable zone besides Earth that is potentially habitable for humans
•Venus: too hot
•Europa, Titan: too far, cold
•Moon: long day, too small
•Jupiter: too big, no surface
Why Mars colonization first ?