Guest Post by Albert Ho, Asst Hon Secretary of TASOS (The Astronomical Society of Singapore)
Of all our sister planets in the solar system, none holds more intrigue and fascination than the little red planet called Mars. The main reason for this is many people wanted to believe that life has or had existed on Mars. The other possible reason could be that a manned landing on Mars is theoretically achievable within the next few decades. Although unmanned space exploration is cheaper and safer and is able to do more, they are unable to inspire and evoke the same human spirit for adventure and exploration as a manned mission. This article looks at our fascination with Mars based on these two perspectives – Perceived habitation (past or present) and prospective man landing on Mars.
Mars is one of the four major rocky planets in the solar system and is the 4th planet from the Sun. It is about half the size of the Earth, with an equatorial radius of about 3400 kilometres. It orbits the Sun in about 687 Earth days or two Earth years and its rotational period is only slightly longer than Earth’s at 24 hours 37 minutes. Hence, a Martian day is similar to an Earth day. Mars also has nearly the same inclination of its rotational axis as Earth – 25 degrees 12 minutes versus Earth’s 23 degrees and 26 minutes. Therefore, Mars also experienced similar seasonal changes as Earth. However, each season lasts twice as long because Mars’ orbit around the Sun is twice as long. Mars has 2 small moons, Deimos (Greek~’Terror’) and Phobos (Greek~’Fear’).
Mars is commonly known as the red planet due to its distinctive red colour even when viewed with the naked eye. The red colour is due to the abundance of iron oxide (rust) in the martian rocks and soil. Because of this colour, Mars is often associated with bloodshed and war (Roman God of War ~ Mars; Greek ~ Ares).
The idea that life on Mars was possible came about after early 17th century astronomers saw through their telescopes what they thought were clouds and other earthlike surface features on Mars, such as continents and polar ice caps. As clouds indicated the presence of an atmosphere and ice, the presence of water, many thought that Mars could be inhabited. Then, in 1877, Italian Astronomer Giovanni Schiaparelli (1835 – 1910) thought he saw lines running across Mars from darker areas which he perceived to be seas. He called the lines Canali (Italian~’Channels’ or ‘Gullies’). Unfortunately, when the term was translated into English, the word lines came out as canals. The word ‘canals’ connote artificial waterways built by intelligent beings and triggered off a flood of ideas from astronomers to authors which included H.G. Wells’ now-famous science fiction novel “War of the Worlds”. This existence of Martians (including bacteria) persisted to this day even though unmanned probes which landed on Mars saw no sign of life other than a dusty red surface covered with red rocks under a pink sky. This persistent belief appeared to be validated when the astronomical community announced in 1996 that what appears to be fossilized Martian bacteria had been found in an ancient meteorite from Mars. This was reinforced by recent studies of life on Earth under Mars-like conditions such as the permafrost, which showed that primitive life (bacteria) may be possible under Martian-like conditions.
Other than the man landing on the moon in 1969, the only other realistic target for the next man landing is the planet Mars. The only other planets that have a solid surface to land on are Mercury and Venus. However, their environment is extremely hostile to man and machine. Being nearer to the sun than Earth is, their surface temperatures are much too hot (typically more than 400°C). In addition, the atmospheric pressure on Venus is more than 90 times that on earth and the atmosphere is also highly corrosive (acidic). Any attempted man landing on Venus would be suicidal as the explorers and their spacecraft would be corroded, crushed and roasted!
The four outer gaseous giants – Jupiter, Saturn, Uranus and Neptune – are gaseous planets without an appreciable solid surface and not possible for any man landing. These make Mars the only candidate for a planetary landing. Mars is similar to Earth in many ways and the Martian environment is almost ‘friendly’ compared to the other planets in our solar system. The average distance between Mars and Earth is about 78 million kilometers and based on present day technology, a round trip manned expedition to Mars could last between almost 2 to 3 years. Although the accompanying technological, physiological and psychological challenges for a man landing on Mars are great for both man and machine, they are not insurmountable. Perhaps these are what make Mars very intriguing to us, both from searching for life beyond Earth and as the next manned expedition to any world beyond our own and the moon.