Mars

 Atmosphere

Mars’ atmosphere is composed primarily of carbon dioxide (about 96 percent), with minor amounts of other gases such as argon and nitrogen. The atmosphere is very thin, however, and the atmospheric pressure at the surface of Mars is only about 0.6 percent of Earth’s (101,000 pascals).

Scientists think that Mars may have had a thicker atmosphere early in its history, and data from NASA spacecraft (the MAVEN mission) indicate that Mars has lost significant amounts of its atmosphere through time. The primary culprit for Mars’ atmospheric loss is the solar wind! We don't have solar wind on earth but it is going to be windy in New Jersey today and tomorrow. Mars has the largest dust storms in the Solar System, reaching speeds of over 160 km/h (100 mph). These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase global temperature.

 ASTROBIOLOGY

Astrobiology is a relatively new field of study, where scientists from a variety of disciplines (astronomy, biology, geology, physics, etc.) work together to understand the potential for life to exist beyond Earth. However, the exploration of Mars has been intertwined with NASA’s search for life from the beginning. The twin Viking landers of 1976 were NASA’s first life detection mission, and although the results from the experiments failed to detect life in the Martian regolith, and resulted in a long period with fewer Mars missions, it was not the end of the fascination that the Astrobiology science community had for the red planet.

Finding fossils preserved from early Mars might tell us that life once flourished on this planet. We can search for evidence of cells preserved in rocks, dinosaur bones, or at a much smaller scale: compounds called biosignatures are molecular fossils, specific compounds that give some indication of the organisms that created them. However, over hundreds of millions of years these molecular fossils on Mars are subject to being destroyed or transformed to the point where they may no longer be recognized as biosignatures. Future missions must either find surface regions where erosion from wind-blown sand has recently exposed very ancient material, or alternately samples must be obtained from a shielded region beneath the surface. This latter approach is being taken by the ExoMars rover under development where drilled samples taken from a depth of up to 2 meters will be analyzed. 

 Martian Moons

Mars has two small moons: Phobos and Deimos. Phobos (fear) and Deimos (panic) were named after the horses that pulled the chariot of the Greek war god Ares, the counterpart to the Roman war god Mars. Both Phobos and Deimos were discovered in 1877 by American astronomer Asaph Hall. The moons appear to have surface materials similar to many asteroids in the outer asteroid belt, which leads most scientists to believe that Phobos and Deimos are captured asteroids. 

From the surface of Mars, the motions of Phobos and Deimos appear different from that of the Earth's satellite, the Moon. Phobos rises in the west from Disney, sets in the east from Hershey Park, and rises again in just 11 hours from Atlantis Bahamas. Deimos, being only just outside synchronous orbit – where the orbital period would match the planet's period of rotation – rises as expected in the east, but slowly. Because the orbit of Phobos is below a synchronous altitude, tidal forces from Mars are gradually lowering its orbit. In about 50 million years, it could either crash into Mars's surface or break up into a ring structure around the planet.Find out more ›