Mars is a fascinating planet that has captivated the imagination of humans for centuries. It is the fourth planet from the Sun and the second smallest in the solar system, after Mercury. Mars is often called the Red Planet because of its reddish color, which is caused by iron oxide in its surface rocks. Mars has two small, irregular moons named Phobos and Deimos, which orbit very close to the planet.
Mars is a rocky world with a thin atmosphere, composed mainly of carbon dioxide. The atmospheric pressure on Mars is less than 1% of that on Earth, which means that liquid water cannot exist on the surface for long. However, there is evidence that Mars once had a much thicker atmosphere and a warmer climate, billions of years ago, when it may have supported liquid water and possibly life.
One of the most striking features of Mars is its topography, which shows a huge contrast between the northern and southern hemispheres. The northern hemisphere is mostly flat and low-lying, while the southern hemisphere is rugged and high-elevation. The highest point on Mars is Olympus Mons, a giant volcano that rises about 22 km (14 miles) above the surrounding plains. It is the largest volcano in the solar system and one of the largest mountains in the solar system. The lowest point on Mars is Hellas Planitia, a vast impact basin that lies about 7 km (4 miles) below the average elevation. It is the largest impact crater in the solar system and one of the deepest.
Mars also has a system of canyons that dwarfs anything on Earth. The largest canyon on Mars is Valles Marineris, which stretches for about 4,000 km (2,500 miles) along the equator. It is up to 200 km (120 miles) wide and 7 km (4 miles) deep in some places. It is so large that it would span the United States from coast to coast if placed on Earth. Valles Marineris was formed by a combination of tectonic forces and erosion by water and wind.
Mars has seasons like Earth, but they are twice as long because Mars takes about 687 Earth days to orbit the Sun. The seasons are also more extreme because Mars has a more elliptical orbit than Earth, which means that it gets closer and farther from the Sun during its year. The seasons are also influenced by the tilt of Mars' axis, which is similar to Earth's at about 25 degrees. This causes polar ice caps to grow and shrink as the seasons change. The ice caps are made of frozen carbon dioxide (dry ice) and water ice.
Mars is one of the most explored planets in our solar system, thanks to dozens of spacecraft that have visited it since the 1960s. Some of these spacecraft have orbited Mars, some have landed on its surface, and some have roved across its terrain. The current active missions on Mars are NASA's Perseverance rover, which landed in February 2021 and carries a small helicopter named Ingenuity; NASA's InSight lander, which measures seismic activity and heat flow; NASA's Curiosity rover, which studies the geology and habitability of Gale Crater; NASA's MAVEN orbiter, which studies the upper atmosphere and its interaction with the solar wind; NASA's Odyssey orbiter, which maps the surface composition and radiation environment; NASA's Mars Reconnaissance Orbiter, which provides high-resolution images and data; ESA's Trace Gas Orbiter, which detects trace gases such as methane; ESA's Mars Express orbiter, which studies the atmosphere, surface, and subsurface; ISRO's Mangalyaan orbiter, which studies the atmosphere and surface features; CNSA's Tianwen-1 mission, which consists of an orbiter, a lander, and a rover; and UAE's Hope orbiter, which studies the climate and weather.
The main goals of Mars exploration are to understand its origin and evolution as a planet, to determine if it ever hosted life or could support life in the future, and to prepare for human exploration and settlement. Mars exploration also helps us learn more about our own planet and our place in the universe.
References
- Overview | Mars – NASA Solar System Exploration
- In Depth | Mars – NASA Solar System Exploration
- NASA Mars Exploration
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