Mars: A reassessment of its interest to biology

摘要: Of all the planets in solar system, Mars is certainly one that has inspired most speculation concerning extraterrestrial life. Observers had long ago noticed exhibits changes its polar caps and alterations surface coloration parallel seasonal on Earth. The fascination with possibility of life continued into spacecraft era was directly expressed Viking Missions. These highly successful missions search for as their principal goals. A review Missions experiments presented. Results these investigations are summarized. While returned a negative answer to question Mars, they also showed many years very different place enjoyed conditions may have been conducive origin - since become extinct. Evidence existence water past Techniques used study early Earth, which be similar studies described.