Official blog of Nepal Astronomical Society (NASO) working in the field of astronomy & space science in Nepal
Tuesday, July 12, 2016
ASTRONOMY Missions To Mars!
Since time immemorial, Mars has always been gripping human imagination and attention with its blood-red hue and for playing fascinating role in mythology and for demonstrating the stunning success of landing objects on its sprawling dusty expanse, for investigating it meticulously and for searching alien life on it. In recent times, Mars has become the focus of much speculation and scientific study about possible colonisation. Its surface conditions and the likely presence of water make it arguably the most hospitable of the planets in the solar system, after earth. A trek to Mars would take six to seven months in space using the current chemical spacecraft propulsion methods.
The Martian day is counted to be pretty close in duration to that of earth. A solar day on Mars has been clocked to 24 hours 39 minutes 35.244 seconds. Mars’ area measuring 145 million square kilometer would be slightly less than the amount of 28 per cent of earth's surface. Mars has half the radius of earth (sparsely 6,300 kilometers) and only one-tenth the mass. This means it displays smaller volume and lower average density than our blue planet. Mars has alluring axial tilt of 25.19 degrees in contrast to earth's 23.44 degrees. Consequently, Mars has seasons much like on earth, though they would last nearly twice as long because the Martian year is about 1.88 earth years. The gravity of Mars is 38 per cent of earth. The density of its atmosphere has been merely six percent of earth’s value. Mars is conspicuously colder than earth, with a mean temperature swinging between minus 87 and minus 5 degrees Celsius.
Mars goes around the sun along the eccentric path from a distance of approximately 228 million kilometers. The solar energy entering its upper atmosphere per unit area (solar constant) is moderately 43.3 per cent of that reaching earth's atmosphere. The maximum solar irradiance on Mars suggests strongly 590 watt per square metre compared to basically one thousand watt per square metre on earth. Due to lack of a magnetosphere, in combination with surprisingly thin atmosphere, Mars receives bountiful ultraviolet radiation that poses serious threat to living entities on it. The Martian atmosphere comprises of circa 95 per cent carbon dioxide, three per cent nitrogen, two per cent argon and traces of other gases including oxygen totaling less than 0.4 per cent. Martian air points the partial pressure of carbon dioxide (CO2) to 0.71 kilo Pascal, compared to 0.031 kilo Pascal on earth. CO2 poisoning in humans is evident at scarcely 0.10 kilo Pascal. So, Martian air would be toxic to both plants and animals. Mars topology would not perhaps be hospitable to mankind or most known life forms due to greatly reduced air pressure and an atmosphere with exiguous oxygen and the paucity of liquid water, although big bulk of frozen water have been allegedly detected.
Our survival on Mars would require complex life-support measures, while living in artificial environments. Variety of equipment would be indispensable for directly providing basic need services to persons and to produce food, propellant, water, energy and breathable oxygen. Establishing power, communications, shelter, heating and manufacturing essential goods could begin with robotic systems, as prelude to crewed operations. Some nations and organisations have long-term intentions for sending people to Mars. The United States has delivered robotic missions presently exploring Mars with a sample-return planned for the future. In 2014, NASA magnificently launched and tested the Orion Multi-Purpose Crew Vehicle (MPCV), the first component of NASA's planned Mars mission programme scheduled for the 2030s. The European Space Agency (ESA) has divulged long-term plans of Exo-Mars to send astronauts to Mars. India had prosperously placed an unmanned Mars Orbiter Mission (Mangalyaan) satellite in Mars orbit in 2014. Russia and China with Japan have fruitful experience with manned space flights and have promising programs to Mars.
There would be challenges for manned missions to Mars. Health hazards from exposure to high energy cosmic rays and other ionizing radiation with negative effects of a prolonged low gravity environment on health along with the absence of community contact with earth have to be addressed. Social effects of pioneers living under crowded conditions for over one earth year in addition to inaccessibility of terrestrial medical facilities, equipment failure of propulsion or life-support systems demand reliable solutions. Forward contamination of chosen dwelling zones and back contamination of earth probably with Martian microbes should be strictly avoided. While sufficient fuel for round-trip could become critical concern, methane and oxygen could be generated utilising Martian water and atmospheric CO2 with mature technology. Estimated costs of carrying earthlings to Mars have ranged from whooping six to five hundred billion US Dollars.
In 2012 a nonprofit entrepreneur group Mars One based in the Netherlands had publicly announced the controversial concept for one-way journey to Mars for landing the first men and women on Mars and setting-up the first permanent colony there by 2027. Its original conception included the launching of a robotic Lander and orbiter by 2018 and 2020. Special base structures and exclusive four settlers would lift-off by 2023. Every two years, a new crew of four astronauts would arrive there. SpaceX Heavy rocket would transfer sophisticated hardware. The organisers would select the crew from aspiring applicants from worldwide public, who had paid some administrative fees to become the first residents of Mars with no plan of returning to earth. Partial funding options included ambitious reality television programme documenting the travel. The entire mission was to be filmed and broadcast back to earth as sensational media event from which the revenues would help to fund the programme. However, in April 2015, it was admitted that their proposed plan for flying earth citizens to Mars by 2027 was mostly fictitious.
Nicknamed after the Roman god of war the ruddy Mars would be the fourth planet from the sun. Its reddish appearance has been bestowed by the iron oxide prevalent on its surface with features reminiscent both of impact craters of the moon and the volcanoes, valleys, deserts, and polar ice caps of earth. Its two diminutive irregularly-shaped moons, Phobos and Deimos could be mysteriously captured asteroids. NASA’s Mariner-4 flew-by Mars marvelously in 1965. Mars rover Spirit had located chemical compounds containing water molecules in 2007. The Phoenix Lander had indicated water ice in shallow Martian soil in 2008. Seven spacecrafts with five in orbit (Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, MAVEN and Mars Orbiter Mission) and two on surface (Mars Exploration Rover Opportunity and the Mars Science Laboratory Curiosity) have been vigorously scrutinizing Mars. Availability of enormous slab of water ice beneath Mars had been confirmed lately. Assessing the past habitability potential of Mars and the possibility of extant life are being analyzed. Since Mars would seemingly hold the next best hope for the future of our existence, the preparation of missions to Mars for turning the dream of inhabiting Mars into reality has now compellingly commenced.