Mars

The days and seasons are comparable to those of Earth, because the rotation period as well as the tilt of the rotational axis relative to the ecliptic plane are similar. Mars is the site of Olympus Mons, the largest volcano and highest known mountain on any planet in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the Northern Hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped.

Mars has been explored by several uncrewed spacecraft. Mariner 4 was the first spacecraft to visit Mars; launched by NASA on 28 November 1964, it made its closest approach to the planet on 15 July 1965. Mariner 4 detected the weak Martian radiation belt, measured at about 0.1% that of Earth, and captured the first images of another planet from deep space. The latest spacecraft to successfully land on Mars are CNSA’s Tianwen-1 lander and Zhurong rover, landed on 14 May 2021. The Zhurong rover was successfully deployed on 22 May 2021, which makes China the second country to successfully deploy a rover on Mars, after the United States.

There are investigations assessing the past habitability of Mars, as well as the possibility of extant life. Astrobiology missions are planned, such as the European Space Agency’s Rosalind Franklin rover. Liquid water on the surface of Mars cannot exist due to low atmospheric pressure, which is less than 1% of the atmospheric pressure on Earth.Both of Mars’s polar ice caps appear to be made largely of water.