The Red Planet – Though man has yet to set foot on the surface of another planet, our fascination with learning about Mars is endless…
To date there have been 42 missions to Mars, with exactly half of them being complete failures. Other than the Earth it is the most studied planet in the solar system, and for centuries it has been at the heart of wild speculation and groundbreaking scientific discoveries.
Observations of Mars have not only revealed otherwise unknown secrets but also posed new and exciting questions, and it is for these reasons that it has become the most intriguing planetary body of our time.
Named after the Roman god of war. Mars has fascinated astronomers since Nicolaus Copernicus first realised Mars was another planet orbiting the Sun in 1543. Its notable features such as huge impact craters, gullies and dormant volcanoes suggest it was once more geologically active than it is now, leading scientists to speculate on whether it supported water and life in the past, or indeed if it still does today.
Astronomers in the 19th Century falsely believed they could see large oceans, and there were several reports of people receiving ‘communications’ from Martians in the form of bursts of light when they observed the planet through a telescope. Of course, we now have a better understanding of the planet, but we are still yet to unlock some of its most puzzling mysteries.
Mars sits 227 million km (141 million miles) from the Sun and takes 687 Earth days to orbit. As its orbital path is not in sync with Earth’s it goes through a 26-month cycle of being closest (known as opposition) and furthest (conjunction) from us, located at a distance of 56 million km (35 million miles) and 401 million km (249 million miles) respectively. This change in distance means spacecraft destined for Mars are sent in a launch window every 26 months, when Mars is closest to Earth. The next will be in November 2011, when NASA plans to launch its new Mars rover, Curiosity. The journey time is upwards of six months, so Mars will actually be closest on 3 March 2012.
Like all of the planets in our solar system, it is believed that Mars formed about 4.5 billion years ago inside a solar nebula, when dust particles clumped together to form the planet. At just under half the size of Earth Mars is actually quite a small planet, which is apparently due to the fact Jupiter formed first. The gravitational forces of Jupiter-a gas giant – consumed available material that would have otherwise contributed to Mars’s growth, while Jupiter’s gravity prevented another planet forming between Mars and Jupiter and instead left us with the asteroid belt. The northern hemisphere of Mars is significantly younger and lower in elevation than the southern hemisphere, which suggests that the planet was struck by a Pluto-sized object some time early in its lifetime.
Mars is often referred to as something of a dead planet. Indeed, its lack of folded mountains – like those we have here on Earth – shows that it has no currently active plate tectonics, meaning that carbon dioxide cannot be recycled into the atmosphere to create a greenhouse effect. For this reason Mars is unable to retain much heat, with a surface temperature as low as -133”C at the poles in the winter, rising to 27”C on the day side of the planet during the summer.
Despite this, the atmosphere of Mars offers conclusive evidence that it was once geographically active. The outer planets in the solar system have atmospheres composed of predominantly hydrogen and helium, but that of Mars contains 95.3% carbon dioxide, 2.7% nitrogen and 1.6% argon, with minimal traces of oxygen and water. This strongly suggests that volcanoes once erupted across its surface and spewed out carbon dioxide, further evidenced by giant mountains, such as Olympus Mons, which appear to be dormant volcanoes.
It might not be geologically active, but Mars does play host to some extreme weather conditions, most notably the appearance of dust devils. These tornadoes, ten times larger than anything similar on Earth, can be several miles high and hundreds of metres wide, creating miniature lightning bolts as the dust and sand within become electrically charged. The wind inside one of these, though, is almost unnoticeable, as the atmospheric pressure on Mars is so low. Interestingly, one of the reasons for the long survival rate of NASA’s Mars rovers is that these dust devils have been cleaning their solar panels, allowing them to absorb more sunlight.
Mars’s gravity is about 38% that of Earth, with Just 10% of the mass. The surface pressure is just over 100 times weaker than ours at sea level, meaning that a human standing on the surface would see their blood instantly boil. The red colour on Mars’s surface is the result of rusting, due to iron present in the rocks and soil reacting with oxygen to produce an iron oxide.
In 1877 the American astronomer Asaph Hall, urged on by his wife, discovered that Mars had two moons orbiting so close that they were within the glare of the planet. They were named Phobos and Deimos, after the attendants of Ares in the Iliad. Interestingly, the moons are not spherical like most other moons; they are almost potato-shaped and only about ten miles wide at their longest axis, indicating that they are the fragments of the collision of larger objects near Mars billions of years ago. Phobos orbits Mars more than three times a day, while Deimos takes 30 hours. Phobos is gradually moving closer to Mars and will crash into the planet within 50 million years, a blink of an eye in astronomical terms. The moons have both been touted as a possible base, from which humans could observe and travel to Mars.
Evidence of water
The cold temperature and low atmospheric pressure on Mars means that finding liquid water on its surface is highly improbable, as it would immediately freeze and then evaporate. While ice has been discovered at the poles, it is the search for liquid water that is the most important. Scientists have found life on Earth in many different environments, but none has been discovered in the absence of water. If there is liquid water on Mars, that means there could be life as well.
In 2008, NASA’s Phoenix Mars lander provided proof that there was water beneath the surface when it dug a trench and observed that some material subsequently disappeared, suggesting that underground water was being vaporized as it was exposed to the air. NASA’s Spirit rover gleaned one of the most conclusive pieces of evidence for water on Mars, after becoming stuck in soil in early 2009. Attempts to move the rover disturbed the ground and brought subsurface soil up to the surface, which suggested that water had moved downwards through the surface.
Why haven’t we set foot on Mars?
One of the problems with any manned mission to Mars is the region of space the crew must traverse. To get to Mars with current technology would take about six months, and a human spacecraft would also need enough fuel to take off and return to Earth. Another problem is the amount of solar radiation there would be subjected to. Outside Earth’s magnetosphere (and with Mars not having one), there is a high chance of potentially fatal damage caused by the Sun. There is the also the added mental strain of travelling such a long distance.
The Mars-500 mission at the Russian Academy of Sciences is currently performing an experiment where a crew of volunteers have been placed inside a mock-up potential Mars spacecraft for 640 days to simulate such a mission. All communications outside the enclosed environment have been given a 20-minute delay, similar to what humans would experience if they were to travel to Mars.
Currently, NASA and private enterprises are stepping up efforts to get humans to Mars by the 2030s. NASA’s space shuttle replacement, the Orion spacecraft, has provisionally been tasked with taking humans to Mars by 2035, while private companies such as Space X (with its Dragon capsule) also hope to eventually reach Mars at a similar time.