There’s something about Mars

An artist's representation of the solar system. The planets are shown closer together than they really are so that they can be seen better. Pluto is no longer classified as a planet.

Ever since telescopic observations began about four centuries ago with the Italian astronomer Galileo Galilei, Mars has fascinated humankind and become an object of intense study and exploration. The United States is the world leader in the study of Mars, having done fly-bys and sent orbiters and rovers to examine it. Russia and Japan have sent orbiters to study the planet but their record of success is not enthusing.

Why does Mars hold such an allure for humankind? An important reason is that there are several similarities between Mars and the earth: their solid surface, their seasons, the duration of their day, the tilt of their axes from the vertical, their polar ice caps, the number of days they take to go round the sun, etc. Besides, water exists on Mars. Its discovery has fuelled the search for possible microbial life on the planet. In addition, it is the second closest planet to earth after Venus. While the nearest distance between Mars and the earth is 55 million kilometres, they are 400 million km apart at the farthest.

There are eight large planets in the solar system—the earth, Mars, Mercury, Venus, Jupiter, Saturn, Uranus and Neptune—of which only Mars has striking similarities to the earth. Pluto is no longer classified as a planet and is now called a dwarf planet. Mercury has no atmosphere. Its daytime temperature can soar to 425 °Celsius and the night-time temperature can drop to minus 180 °C. Venus is about the same size as the earth but its surface temperature can be more than 450 °C. Its atmosphere is also daunting, with a pressure that is 90 times that on the earth and consisting mostly of carbon dioxide.

Jupiter, Uranus, Neptune and Saturn are “gas giants” and have no solid surface. Man cannot walk on their surface. Man cannot land there. Mars has solid surface. Its terrain looks somewhat similar to the earth’s. If one were to stand on the surface of Mars and look around, one might feel as if one were standing in a desert. Mars is, in fact, a cold desert. Its temperature is a little lower than that in Antarctica, that is, it is colder. While a day on earth is 24 hours, it is 24 hours and 39 minutes on Mars. A day on Mercury is equivalent to 59 earth days and one day on Venus equals 243 earth days. Jupiter, Saturn, Uranus and Neptune spin fast on their axes and their days last less than 24 hours. For instance, the time taken by Jupiter and Saturn to rotate on their axes is about 10 hours, and Uranus and Neptune take about 16 hours to 18 hours.

Mars has a very thin atmosphere and its atmospheric pressure is 1 per cent of the earth’s. The earth takes 365 days to go round the sun. Mars takes 687 days, almost twice the time taken by the earth. While the earth’s axis is tilted at 23° from the vertical, Mars’ tilts about 25°. Mars has seasons, but they are twice as long as those on the earth. More than anything else, water exists on the surface of Mars. An analysis of fine Martian soil samples, scooped up from the planet’s surface by the U.S. rover Curiosity, has revealed that 2 per cent of the soil is water by weight. A special edition of the journal Science , published on September 26, 2013, with five papers on the rover’s analyses, announced these results. “The major gases released were water—about 2 per cent weight of the sample—and carbon dioxide, oxygen and sulphur dioxide,” said Laurie Leshin of the Mars Science Laboratory (MSL) of NASA, who was the lead author of the paper published by her team ( The Hindu , September 27, 2013). Liquid water has not been found on Mars.

Red dot in the sky For ages, humankind has observed Mars as a red dot in the sky, moving slowly against the backdrop of “fixed” stars. When telescopic observation began, astronomers could see the surface of Mars but not in detail. As more powerful telescopes were built, the red planet’s solid surface and its polar ice caps could be seen. This led people to believe that life could exist on Mars. Astronomers also saw that dark areas appeared and disappeared seasonally. This led them to believe that the dark areas were vegetation. Giovanni Schiaparelli (1835-1910), an Italian astronomer, claimed in 1877 that he saw a “network of fine straight lines” on the surface of Mars and called them canali . The word in Italian means channels, but was translated into English as canal, which implies a man-made structure. This led to speculation that intelligent beings who could build canals lived on Mars. In the 1890s, Percival Lowell, an American astronomer who had set up a private observatory in Flagstaff, Arizona, also claimed that he saw the same “canals” that Schiaparelli had observed. This fuelled further speculation about an advanced civilisation on Mars.

In 1898, the English writer H.G. Wells wrote a novel called The War of the Worlds , a fictional account of the invasion of the earth by Martians. In 1938, this novel was dramatised on radio by the American actor Orson Welles with such verisimilitude that it unleashed a scare among thousands of Americans that invading Martians had landed in New Jersey! In 1996, when an analysis was made of a piece of a meteorite that was originally found in 1984 at a place called Alan Hills in Antarctica, it came to light that it was from Mars and it could be the fallout of an impact on the planet. When scientists examined this rock, named ALH 84001, they believed it contained microbial life. This led to a buzz in the scientific community. However, to this day, no microbial life has been found on Mars.

Since water was found on Mars, the strategy has been “follow the water”, for scientists believe that searching for water on the red planet is an indirect way of searching for microbial life on it.

T.S. Subramanian