Mars to Stay it is assumed the planet will be a magnet for settlers as wage costs will be high. Because of the labor shortage on Mars and its subsequent high pay-scale, Martian civilization and the value placed upon each individual's productivity is proposed as a future engine of both technological and social advancement. In the fifth chapter of "Mars Direct", Zubrin addresses the idea that radiation and zero-gravity are unduly hazardous. He claims cancer rates "do" increase for astronauts who have spent extensive time in space, but only marginally. Similarly, while zero-gravity presents challenges, near total recovery of musculature and immune system
Earthling English "yrþling", in the meaning "ploughman". The sense of "inhabitant of earth" is first attested in the 1590s. Its use in science fiction dates to 1949, in "Red Planet" by Robert A. Heinlein. The word "Human" has the same imposed meaning, since it originates from a PIE word "*ǵʰmṓ" "earthling" < "*dʰéǵʰōm" "earth". Compare Latin "homo" "human" and "humus" "earth, soil". Its modern use in science fiction literature contrasts "Earth" (the planet) with outer space or hypothetical other planets with sapient life. The term was often used in 1950s science fiction film and novels by aliens to express a disdainful