has a scale height of approximately 11 km, 60% greater than that on Earth. The climate is of considerable relevance to the question of whether life is or ever has been present on the planet.

Mars has been studied by Earth-based instruments since the 17th century, but it is only since the exploration of Mars began in the mid-1960s that close-range observation has been possible. Flyby and orbital spacecraft have provided data from above, while landers and