Of all the planets in the solar system, Mars seems to have captured our imaginations more than any other. From the martian attack in H.G. Wells’ The War of the Worlds to Arnold Schwarzenegger’s character in Total Recall on a secret mission to the red planet, Mars has endured speculation that it is home to extra-terrestrials or might someday be habitable for humans.
The fourth planet from the sun is about half the size of Earth, and its rocky terrain encompasses some extreme heights and depths. Valles Marineris is a valley canyon ten times longer and three times deeper than the Earth’s Grand Canyon, believed to have been caused by tectonic forces when the planet was geologically active. Olympus Mons, on the other hand, is a volcano in the planet’s western hemisphere twice as tall as Mount Everest.
The atmosphere on Mars is cold and dry with “air” that is about 95% carbon dioxide. Though water might have covered entire regions of Mars in the past, the surface of the planet was most likely formed by lava flows that cooled into a mantle and crust surrounding a molten iron core, similar to the way the other terrestrial planets evolved.
A light dusting of iron oxide on the surface of Mars causes the planet to appear fiery red in contrast to the bright white stars in it’s pathway on the ecliptic
Similarities between Mars and the Earth could mean that life forms existed at some point in the planet’s history and that humans could journey to Mars and one day even colonize the planet. Mars and the Earth are both rotating on their axis at a 23-25 degree angle, resulting in observable seasonal changes in the northern and southern hemispheres. From Earth, the polar ice caps in the north and south can be seen receding and then reappearing as Mars makes its yearly orbit of the sun in 687 “earth” days.
Though a year is twice as long on Mars compared to earth, a day differs by only 40 minutes. As a result, there are times when the orbit of Mars seems to loop backward in the night sky before continuing on it’s trajectory across the ecliptic. This retrograde movement was seen long ago by Egyptian astronomers, as well as by Galileo in the seventeenth century.
Mars is named after the Roman god of war, and its two moons, Phobos and Deimos, were the sons of Mars who accompanied him into battle.
The two moons of Mars are irregularly shaped and thought to be large meteorites that locked into its gravitational field during the solar system’s phase of planet formation.
Phobos is the larger of the two and is only about 5,500 km away from Mars, orbiting the planet three times within one day. Deimos is farther away, and at 6.2 kilometers wide is about half the size of Phobos and orbits Mars once a day.
Mars: Past, Present, and … Future?
Prior to the years of space exploration, astronomers could only theorize about various canals and changing patterns of light and dark patches on the face of Mars. They believed that darker regions were either bodies of water or expanses of vegetation that responded to changes in seasonal temperatures. Forty years later, we have detailed maps of the landscape and a better understanding of the weather conditions that cause dust storms to sweep across the planet.
The Mars Exploration Rovers, Spirit, and Opportunity, have provided scientists with invaluable evidence about the geological history of Mars. After landing on opposite sides of the planet in 2004, Spirit was active until 2010 and Opportunity is still working, analyzing samples of rock and soil that has confirmed the theory that water once flowed on Mars. The Curiosity rover arrived in 2012 and is continuing the search for fossils or microbial life in the soil, and studying the weather conditions.
NASA’s ambitious plan to build a human settlement on Mars is on schedule for the year 2030. Visit nasa.gov for the latest news about the upcoming tests and experiments involving the new technologies needed to send humans into deep space.