ar

Mars
By: Amanda Baker

The discovery of Mars is not credited to a single individual, but rather a multitude of astronomers and observers that range from the early Egyptians to the Babylonians, Greeks, and Danish. In the earliest days of Mars observation, all that was known about it was that it appeared to be a fiery red and followed a strange loop in the sky, unlike any other. “The Babylonians studied astronomy as early as 400 BC, and developed advanced methods for predicting astronomical events such as eclipses. They made careful observations for their calendars and religious reasons, but never attempted to explain the phenomena they witnessed. The Babylonians called Mars Nergal - the great hero, the king of conflicts. The Egyptians were the first to notice that the stars seem "fixed" and that the sun moves relative to the stars. They also noticed five bight objects in the sky (Mercury, Mars, Venus, Jupiter, and Saturn) that seemed to move in a similar manner. They called Mars Har Decher - the Red One. Greeks called the planet Ares after their god of war, while the Romans called it Mars. Its sign is thought to be the shield and sword of Mars” (NASA, 2015).
Mars is the fourth planet from the sun and referred to as the god of War. The planet probably got this name due to its red color; Mars is sometimes referred to as the Red Planet. Mars has been known since prehistoric times, and of course, it has been extensively studied with ground-based observatories. But even very large telescopes find Mars a difficult target, it's just too small. It is still a favorite of science fiction writers as the most favorable place in the Solar System (other than Earth!) for human habitation. “The first person to watch Mars with a telescope was Galileo Galilei, and in the century after him, astronomers discovered its polar ice caps. In the 19th and 20th centuries, researchers believed they saw a network of long, straight canals on Mars, hinting at civilization, although later, these often proved to be mistaken interpretations of dark regions they saw” (Choi, 2014).
The Robot spacecraft began observing Mars in the 1960s, with the “United States, launching Mariner 4 there in 1964 and Mariners 6 and 7 in 1969. They revealed Mars to be a barren world, without any signs of the life or civilizations people had imagined there. In 1971, Mariner 9 orbited Mars, mapping about 80 percent of the planet and discovering its volcanoes and canyons. NASA's Viking 1 lander touched down onto the surface of Mars in 1976, the first successful landing onto the Red Planet. It took the first close-up pictures of the Martian surface, but found no strong evidence for life” (Choi, 2014). The next two craft to successfully reach Mars were the Mars Pathfinder, a lander, and Mars Global Surveyor, an orbiter, both launched in 1996. A small robot on-board Pathfinder named Sojourner, the first wheeled rover to explore the surface of another planet ventured over the planet's surface analyzing rocks. In 2001, the United States launched the Mars Odyssey probe, which discovered a vast amount of water ice beneath the Martian surface, mostly in the upper three feet (one meter). It remains uncertain whether more water lies underneath, since the probe cannot see water any deeper.
In 2003, “the closest Mars had passed to Earth in nearly 60,000 years, NASA launched two rovers, nicknamed Spirit and Opportunity; which explored different regions of the Martian surface, and both found signs that water once flowed on the planet's surface” (Choi, 2014). In 2008, NASA sent another mission, Phoenix, to land in the northern plains of Mars and search for water, two orbiters, NASA's Mars Reconnaissance Orbiter and ESA's Mars Express; are keeping Mars Odyssey Company over the planet. In 2011, NASA's Mars Science Laboratory mission, with its rover named Mars Curiosity, began to investigate Martian rocks to determine the geologic processes that created them and find out more about the present and past the habitability of Mars. Among its findings is the first meteorite on the surface of the red planet. In September 2014, India’s Mars Orbiter Mission reached the red planet, making it the fourth nation to successfully enter orbit around Mars, after the US, Europe and Russia.
Mars is the second smallest planet in the solar system; only Mercury is smaller. Mars is about half (53 percent) the size of Earth, but because Mars is a desert planet, it has the same amount of dry land as Earth. Despite appearances, Mars is not a sphere, because the planet rotates on its axis (every 24.6 hours), it bulges at the equator (as do Earth and other planets). At its equator, “Mars has a diameter of 4,222 miles (6,794 km), but from pole to pole, the diameter is 4,196 miles (6,752 km). Mars’ radius is half of planet’s diameter. The circumference of Mars around the equator is about 13,300 miles (21,343 km), but from pole-to-pole Mars is only 13,200 miles (21,244 km) around. This shape is called an oblate spheroid. Mars' mass is 6.42 x 1023 kilograms, about 10 times less than Earth. This affects the force of gravity. Gravity on Mars is 38 percent of Earth's gravity, so a 100-pound person on Earth would weigh 38 pounds on Mars” (Choi, 2014).
Mars is home to both the highest mountain and the deepest, longest valley in the solar system. Olympus Mons is roughly 17 miles (27 kilometers) high, about three times as tall as Mount Everest. “It is also one of the largest volcanoes in the solar system. It is about 370 miles (600 kilometers) in diameter, wide enough to cover the entire state of New Mexico. Valles Marineris system of valleys named after the Mariner 9 probe that discovered it in 1971, can go as deep as 6 miles (10 kilometers) and runs east-west for roughly 2,500 miles (4,000 kilometers), about one-fifth of the distance around Mars and close to the width of Australia or the distance from Philadelphia to San Diego” (Choi, 2014). Mars is much colder than Earth, in large part due to its greater distance from the sun. The average temperature is about minus 80 degrees Fahrenheit (minus 60 degrees Celsius), although they can vary from minus 195 F (minus 125 C) near the poles during the winter to as much as 70 F (20 C) at midday near the equator.
The carbon-dioxide-rich atmosphere of Mars is also roughly 100 times less dense than Earth's on average, but it is nevertheless thick enough to support weather, clouds and winds. “The density of the atmosphere varies seasonally, as winter forces carbon dioxide to freeze out of the Martian air. NASA’s Mars Reconnaissance Orbiter found the first definitive detections of carbon-dioxide snow clouds, making Mars the only body in the solar system known to host the unusual winter weather” (Nine Planets, 2015). The red planet also causes water-ice snow to fall from the clouds. The dust storms of the Mars are the largest in the solar system, capable of blanketing the entire red planet and lasting for months.
There are a number of theories regarding the dust storms of Mars; one theory is to why dust storms can grow so big on Mars starts with airborne dust particles absorbing sunlight, warming the Martian atmosphere in their vicinity. Warm pockets of air flow toward colder regions, generating winds. Strong winds lift more dust off the ground, which in turn heats the atmosphere, raising more wind and kicking up more dust. “The escape velocity of Mars is 18,000 kilometers per hour (11,000 miles per hour), a good deal slower than the escape velocity of Earth, because gravity on Mars is weaker” (NASA, 2015). In the past, Mars-bound space probes have gone into Mars orbit by firing retrorockets to slow down. The surface of Mars consists mainly of a red soil whose composition is still being investigated by the NASA Opportunity rover. The soil analyzed so far includes glass particles and common volcanic minerals. “Because the atmosphere of Mars is very thin, its albedo, at 29 percent, is dominated by the relatively dark surface” (NASA, 2015).
The axis of Mars, like Earth's, is tilted with relation to the sun. This means that, like Earth, the amount of sunlight falling on certain parts of the planet can vary widely during the year, giving Mars seasons. “The seasons that Mars experiences are much more extreme than Earth's; because the red planet's elliptical, oval-shaped orbit around the sun is more elongated than that of any of the other major planets. When Mars is closest to the sun, its southern hemisphere is tilted toward the sun, giving it a short, very hot summer, while the northern hemisphere experiences a short, cold winter. When Mars is farthest from the sun, the northern hemisphere is tilted toward the sun, giving it a long, mild summer, while the southern hemisphere experiences a long, cold winter” (Nine Planets, 2015).
Mars has two small moons named Phobos and Deimos. And whereas the vast majority of moons in our Solar System are large enough to become round spheres similar to our own Moon, Phobos and Deimos are asteroid-sized and misshapen in appearance. The larger moon is Phobos, “whose name comes from the Greek word which means “fear” (i.e. phobia). Phobos measures just 22.7 km across and has an orbit that places it closer to Mars than Deimos. Compared to Earth’s own Moon, which orbits at a distance of 384,403 km away from our planet; Phobos orbits at an average distance of only 9,377 km above Mars” (NASA, 2015). This produces an orbit of short duration, revolving around the planet three times in a single day. For someone standing on the planet’s surface, Phobos could be seen crossing the sky in only 4 hours or so. Phobos is heavily cratered from eon’s worth of impacts from meteors with three large craters dominating the surface. The largest crater is the Stickney crater, and “it is 10 km in diameter, which is almost half of the average diameter of Phobos itself. The crater is so large that scientists believe the impact came close to breaking the moon apart. Parallel grooves and striations leading away from the crater indicate that fractures were likely formed as a result of the impact (NASA, 2015).
Mars’ second moon is Deimos, which takes its name from the Greek word for panic. It is even smaller, “measuring just 12.6 km across, and is also less irregular in shape. Its orbit places it much farther away from Mars, at a distance of 23,460 km, which means that Deimos takes 30.35 hours to complete an orbit around Mars” (NASA, 2015). Much like Phobos, its surface is pockmarked and cratered from numerous impacts. “The largest crater on Deimos is approximately 2.3 km in diameter (1/5 the size of the Stickney crater). Although both moons are heavily cratered, Deimos has a smoother appearance caused by the partial filling of some of its craters” (NASA, 2015). When impacted, dust and debris will leave the surface of the moon because it doesn’t have enough gravitational pull to retain the ejecta. However, the gravity of Mars will keep a ring of this debris around the planet in approximately the same region that the moon orbits. As the moon revolves, the debris is redeposited as a dusty layer on its surfaces.
Like Earth’s Moon, Phobos and Deimos always present the same face to their planet. Both are lumpy, heavily-cratered and covered in dust and loose rocks. They are among the darkest objects in the solar system. “The moons appear to be made of carbon-rich rock mixed with ice. Given their composition, size and shape, astronomers think that both of Mars’ moons were once asteroids that were captured in the distant past. Phobos and Deimos, both appear to be composed of C-type rock, similar to blackish carbonaceous chondrite asteroids. This family of asteroids is extremely old, dating back to the formation of the Solar System. Hence, it is likely that they were acquired by Mars very early in its history” (NASA, 2015). However, it appears that of these two satellites, Phobos won’t be orbiting the Red Planet for very much longer. Because it orbits Mars faster than the planet itself rotates, it is slowly spiraling inward. “As a result, scientists estimate that in the next 10-50 million years or so, it will get so low that the Martian gravity will tear Phobos into a pile of rocks. And then a few million years later, those rocks will crash down on the surface of Mars in a spectacular string of impacts” (NASA, 2015).
Many of us have wondered if there is life on mars, and there are creditable reasons why many scientists and researchers believe it is a possibility. Mars could have once harbored life. Some conjecture that life might still exist there even today. A number of researchers have even speculated that life on Earth may have seeded Mars, or that life on Mars seeded Earth. The most public scientific claim for life on Mars came in 1996, “Geologist David McKay at NASA's Johnson Space Center in Houston and his colleagues focused on rocks blasted off the surface of Mars by cosmic impacts that landed on Earth. Within they found complex organic molecules, grains of a mineral called magnetite that can form within some kinds of bacteria, and tiny structures that resembled fossilized microbes” (Choi, 2014). However, these claims have proven controversial, and there is no consensus as to whether they are signs of life. Mars may have possessed oceans, on its surface in the past, providing an environment for life to develop. Although the red planet is a cold desert today, researchers suggest that liquid water may be present underground, providing a potential refuge for any life that might still exist there. “The rover Curiosity has found evidence for a lake that could have once supported life on the red planet, after previously establishing that the planet had the key ingredients present for life to evolve” (Choi, 2014).
There have been many researches done in regards to why Mars has water in parts of its hemispheres, “Not only does Mars have the largest volcanoes and deepest canyons in the Solar System, it also shows evidence for the most catastrophic floods. Large channels carved by these floods drain into the northern plains, lending support for the existence of an ancient ocean over most of the northern hemisphere. Valley networks that crisscross the southern highlands were also probably formed by water. And many craters, especially at high latitudes, are surrounded by fluidised ejecta resembling the ring of splattered debris around a stone dropped in soft mud” (European Space Agency, 2015). This suggests that there was underground water or ice in early times, and possibly more recently. “If water was largely responsible for these features, however, it has long since disappeared: most of the evidence is more than 3800 million years old. When Mars was a mere infant (like Earth, the planet is 4500 million years old) much of its atmosphere and all of any surface water vanished. Today, atmospheric pressure at ground level is only about one hundredth that on Earth” (European Space Agency, 2015). So where did the atmospheric gases and water go and why, which are questions many are still trying to figure out today.
With the recent studies going on in regards to Mars we may have more answers sooner than expected, “In April 2013, the Astronaut Selection Program was launched at press conferences in New York and Shanghai. The selection program started with an online application and proceeded with video applications and personal interviews. The subsequent selection rounds will consist of group challenges and simulations” (Mars One, 2015). At the end of the selection program, six teams of four individuals will be selected for training. New astronaut selection programs will begin every year to replenish the training pool regularly. In addition, “during this time an analogue of the Mars habitat is to be constructed on Earth for technology testing and training purposes. Groups selected from the first batch of applicants will train together until the launch in 2026” (Mars One, 2015). The group's ability to deal with prolonged periods of time in a remote location is the most important part of their training. Thus, they will learn to repair components of the habitat and rover, train in medical procedures, and learn to grow their own food in the habitat. Every group spends several months of each training year in the analogue outpost to prepare for their mission to Mars. The first outpost simulation location, a Mars-like terrain that is relatively easy to reach, will be chosen. A second training outpost will be located in a more remote environment like the Arctic desert. In 2026 they will send the first crew up to mars and the second crew in 2028.
The mars one mission it is to establish a human settlement on Mars, “human settlement of Mars is the next giant leap for humankind. Exploring the solar system as a united humanity will bring us all closer together. Mars is the stepping stone of the human race on its voyage into the universe. Human settlement on Mars will aid our understanding of the origins of the solar system, the origins of life and our place in the universe. As with the Apollo Moon landings, a human mission to Mars will inspire generations to believe that all things are possible, anything can be achieved” (Mars One, 2015). I am excited for what’s to come, and what this may mean for us on earth.

References
Choi, C. Q. (2014, November 4). Mars Facts: Life, Water and Robots on the Red Planet. Retrieved from Space.com: http://www.space.com/47-mars-the-red-planet-fourth-planet-from-the-sun.html
European Space Agency. (2015). Mars Express. Retrieved from European Space Agency: http://www.esa.int/Our_Activities/Space_Science/Mars_Express
Mars One. (2015). About Mars One. Retrieved from Mars One: http://www.mars-one.com/
McMilllan, C. (2014). Astronomy Today (8th ed.). San Fransisco, CA: Pearson Education, Inc.
NASA. (2015, April 16). NASA's Curiosity Rover Making Tracks and Observations. Retrieved from NASA.gov: http://mars.nasa.gov/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1803
Nine Planets. (2015). Mars Facts. Retrieved from Nine Planets: http://nineplanets.org/mars.html