A FIRST LOOK AT THE MARTIAN ENVIRONMENT
Mars is half the size of Earth but has roughly the same land area. Early science fiction portrayed Mars as totally alien and unfamiliar, but some aspects of the Martian surface would seem surprisingly recognizable to a human visitor. The Martian day is a bit longer than 24 hours--almost the same as Earth's. The sun rises in the east and sets in the west. The land is a cold but beautiful desert of sand, gravel, rocks, lava, dunes, and strata. Seasonss of spring, summer, fall, and winter follow each other as on Earth, except that they add up to a year that is about twice as long as that on Earth, consisting on 669 Martian days.
WHAT TO WEAR: A LOOK AT MARTIAN WEATHER
On Mars, typical daily air temperatures range from about -87 degrees C (-125 degrees F) at night to a "balmy" -25 degrees C (-13 degrees F) in the afternoon. The soil and rocks absorb sunlight and become much warmer than the air; summer afternoon soil temperatures can rise to 10 degrees C (50 degrees F) or higher. However, soils in the morning and evening, as well as soils just below the surface, are usually much colder, with temperatures of -70 degrees C (-94 degrees F).
The atmosphere of Mars is very thin, almost pure carbon dioxide, with an air pressure typically just less than 1 percent of that on Earth's surface. This is still much less than the pressure of the thin air at 35,000 feet, where commercial jets cruise; it is more similar to the pressure encountered by a high-flying spy jet, 110,000 feet above Earth.
To wander among the dusty hills of Mars, you'd need a space suit similar to that worn by Apollo astronauts on the Moon. Because the soil and rocks of Mars can be much colder than those on the daylit Moon, on which Apollo astronauts landed, Martian visitors would need boots and gloves that are especially insulated.
A particular hazard facing the space-suited explorer is dust. Apollo astronauts had problems with the fine lunar dust; on Mars, this could be worse because occasional strong winds can blow the dust into suit joints, oxygen regulators, and vehicle parts. Local dust storms may strongly reduce visibility and cause blinding "brownout" conditionslike arctic whiteouts, during which visibility drops to a yard or two, destroying all sense of direction.
