|Can Life Exist in Moon and Mars?
The Moon is our satellite and Mars the first ‘outer planet’ from us, away from the Sun. It is natural for us to be curious to know if life exists there. By ‘life’ it is assumed living organisms as we have on our planet. Earth is a unique planet where physical conditions (ecosphere) had been and continues to be exactly as is required to create, nurture and evolve carbon based organic life. Basically, the following factors are necessary to create and sustain life on any planet.
1) Water in gaseous, liquid or solid state
2) Atmosphere of suitable composition
3) Optimum atmospheric pressure and gravity
4) Tolerable range of temperature
5) Co-ordination of internal rhythm with the external
Water: Water is an essential ingredient of any living organism. No cell can exist and perform its functions in the absence of water. Almost 2/3 of biomass is water. Apart from this, water is needed in the process of osmosis that takes place in the various organs of a living body as well as in root absorption of nutrients from the soil in the plant kingdom.. Being a versatile solvent, water in its liquid form is needed for all biological functions.
Life is believed to have been created in the early days of the history of the Earth in an environment of water with a few inorganic substances dissolved in it interacting with the energy of the Ultra Violet rays from the Sun reaching its surface. Earth’s atmosphere then was very different from what it is today. There was no Ozone layer in the atmosphere to filter the UV radiation coming from the Sun. Three billion years ago when some of the basic organic compounds like amino acids were synthesised “by accident”, the water could have been warmer because the Earth was still cooling, radiating its own heat into space. This basic step, it is believed, was essential for the origin of organic life in our planet.
More than 2/3 of the Earth’s surface is covered by water as oceans, lakes, rivers and streams. There is plenty of liquid water under the surface of the Earth which is available in wells and springs. Water from deep down gushes up in some places as hot springs and geysers. Even under such conditions of water close to boiling point and amidst deposits of sulphur and other inorganic salts in the vicinity of such hot springs, living organisms of lower order thrive. So do micro-organisms on the underside of polar ice at temperatures much below zero. Primitive life have been found in deep dark caves, humid, damp and uncomfortably warm. But in all these cases the background of life support is water in its liquid form.
Water vaporises, rises high above the surface of the Earth, condenses into clouds and precipitates as drops of water, thereby forming a link in the water cycle. The usefulness of rains cannot be over emphasised. Besides ushering in the wet season it waters the fields and forests, fills the lakes and gives a fresh lease of life to organisms that lay dormant in hibernation during the dry months. Plant kingdom awakens to fresh existence. The air is laden with moisture during the rainy season and humid atmosphere nurtures sericulture and mushroom farms and helps to improve their quality and productivity.
The vast masses of ice that covers the North and South poles of the Earth to a depth of several kilometres control the weather pattern of the rest of the world and provide krill which occupies the base of the food chain of marine life. The periodic advancing and receding of the ice fields around the North pole gave rise to several period of “Ice Age” extending to tens and thousands of years resulting in alternate habitat and animal and plant life
It is well established that the Moon has no water on its surface. If it ever had water, it has all leaked into space long ago. The gravity of the body is too weak to hold back the water molecules. In the absence of water, the presence of life there is not possible, not even bacterial life.
Mars is believed to have some water, possibly as a thin layer of ice in its polar region. The white layer observed from the Earth and photographed by space probes sent to the planet could also be solid CO2. Neither of them could support life, in the absence of liquid water. The temperature obtained at the poles is – 200o C which is far too low for any life form to evolve or exist.
The surface feature of Mars at some locations does show evidence of running water, possibly in the earlier period of its life, but all the water have vaporised and leaked out of the planet into space because Mars’ escape velocity is as low as 5 Km / Sec. Space probes that landed on two different spots on Mars analysed the soil and found no evidence of organic life.
The composition of the Earth’s atmosphere had not been the same throughout the life of the planet. In its infancy, when the crust was being formed, there were incessant volcanic eruptions all over the surface spewing out large volume of volcanic ash and gases like CO2 from below. There was no oxygen in the atmosphere. It was after a couple of billion years that blue-green algae appeared in the primitive water bodies and photosynthesis began. It took million of years to replace the CO2 of the atmosphere by Oxygen through the process of photosynthesis. At present our atmosphere is stabilised at 78% of Nitrogen, 21% of Oxygen and 0.03% of Carbon dioxide, Much of the CO2 was trapped in luxurious ferns and conifers that covered the surface of the Earth 400 million years ago. These forests later got buried under the surface of the Earth and lay buried for over 300 million years during which period they got metamorphosed into coal that we use today as solid fuel. Uncontrolled and unscientific burning of coal and other liquid fossil fuel tend to reverse the composition of the atmosphere by increasing the percentage of CO2, causing global heating called ‘Green-house Effect’.
The Earth’s atmosphere in its early days consisted of CO2 which is transparent to Ultra Violet radiation from the Sun. The UV radiation which reached the surface of the Earth without any hindrance helped in the synthesis of organic molecules in the primitive oceans. It is believed that simple amino acid molecules were synthesised by the interaction between the liquid water with its dissolved components of inorganic salts, the CO2 of the atmosphere and the Ultra Violet radiation reaching the surface of the Earth from the Sun. From the elementary organic molecules more complex molecules capable of reproducing themselves evolved.
The Ultra Violet which helped in the formation of amino acid molecules are also capable of killing living organisms, like bacteria, and causing skin cancer in the humans. Fortunately, for the life on the Earth, the Oxygen in its atmosphere forms a layer of Ozone, a derivative of Oxygen, high up in the atmosphere. Ozone is capable of interacting with the UV radiation from the Sun and preventing the radiation from reaching the surface of the Earth, thereby protecting the living organisms on the Earth from the destructive effect of the rays.
The Moon has no atmosphere and hence it is continuously receiving the UV from the Sun. In the absence of water and CO2 there is no chance of life there. Even if primitive life did exist they must all have been destroyed by the UV radiation from the Sun.
The atmosphere of Mars is as thin as the Earth’s atmosphere at an altitude of 32 Km and consists entirely of CO2 and Nitrogen and no water vapour or Oxygen. In the absence of surface water and continuous bombardment of the UV from the Sun there is no possibility of any organic life in the planet, even in the level of bacteria. It has been shown by satellite photographs that the surface of Mars is dusty, red in colour, and subjected to low sandstorms extending over vast areas and persisting for long duration of time without let up. These factors indicate that there is no possibility of life on Mars.
Atmospheric Pressure and Escape Velocity
The Earth’s atmosphere exerts a pressure of 76 cm. Of mercury which is approximately 15 lbs/in2. All living and non-living things on Earth are subjected to this pressure, though none of us is conscious of being subjected to such a pressure. The atmospheric pressure is also equal to the pressure exerted by a vertical column of water 30 feet high. All marine animals are subjected to water pressure in addition to the air pressure. A whale which dives to a depth of 3000 ft. experiences a pressure 101 times that of the atmospheric pressure at mean sea level. Deep sea fish are accustomed to high pressure at their habitat. If such a fish is brought suddenly to the surface of the ocean it will burst and die. A person rising to high altitude in a balloon experiences difficulty in breathing because of the thin air and low pressure at high altitudes. An astronaut, if he tries to walk on the moon without his space suit will bleed through his nose, eyes and ears because the capillary in his circulatory system which is accustomed to the pressure of the earth’s atmosphere, will bulge and burst. All life on Earth has a certain limitation of physical environment within which it will exist and thrive and any drastic change in the environment may cause the death of the individual or the extinction of the species.
Martian atmosphere is not only devoid of Oxygen but it is also as thin as the Earth’s atmosphere at an altitude of 32 Km. No organism similar to that on the Earth can exist in such low pressure atmosphere which also has no Oxygen in it. If life in its low level of a bacteria exists on Mars it has to be confirmed by an astronaut landing on that planet. Two space probes which landed on Mars at different locations have reported on testing the soil samples that there was no evidence of organic matter. One reason why Martian atmosphere is so thin is because the escape velocity of the planet is so low that all gases lighter than Oxygen have escaped into space, leaving Mars a barren planet which cannot support higher form of life.
Temperature on the Earth ranges from – 50o C at the poles to 50o C in arid deserts where it rains once in two or three years. Life forms exist in these conditions of temperature. A desert wilting under long periods of dry spell suddenly springs to life after a shower and blooms with beautiful flowers. The vast areas of land in polar regions, cold, frozen and hard under permafrost come out with flowering plants when the surface ice melts and the top soil softens when spring arrives. Life lay dormant during unfavourable periods and comes up alive when favourable conditions return. So do hibernating animal life. Tropical deciduas trees shed their leaves in summer and sub-tropical forests shed theirs in winter, both to protect themselves from the harsh effects of environmental temperature changes and thus preserve and protect their lives. The life on Earth is so robust that they thrive even in immensely unfavourable temperature obtained in deep, dark caves, hot water springs and cold polar regions. Further all life on Earth are synchronised to maximum and minimum interval of temperature obtained on the planet.
In the Moon the day temperature is as high as 110o C and night temperature as low as – 150o C. And day/night on the Moon is as long as 14.5 Earth days. (the moon turns on its axis once in 29 days which is also its period of revolution round the Earth; one lunar day is equal to 29 Earth days) So life on the Moon musts be accustomed not only to the extreme variations of temperature but also the long duration of day and night. The Moon has no atmosphere and hence there is no twilight, dawn or dusk. The rising Sun suddenly shows itself flooding the Moon surface with light and the setting Sun suddenly disappears leaving the surface instantly dark. The shadows are dark and sharply defined. The sun lit areas can be as hot as 110o C but the adjacent shaded area can plunge into minus degree Celsius. There is no gradual transition from hot to cold or cold to hot. The sky always appear black (unlike the blue sky of the Earth) and the stars bright points of sharp light. Under these conditions life is not likely to exist there.
Experiments were conducted on our planet to grow plants under conditions of lunar day/night cycle of 14.5 days. This experiment called Luniculture, failed to produce any positive result. Terrestrial plants used to twelve hour cycle of day and night could not be induced to adopt to lunar day-night cycle.
In the planet Mars the temperature variation on an average day at the equator is from 0o C to 25o C. This compares favourably with the conditions on the Earth. The duration of day/night is 12 hours 20 mts. (A day in Mars is 24 hrs 40 mts.) But the temperature at the poles could be as low as – 200o C. The inclination of polar axis to ecliptic is nearly equal to that of the Earth and hence the pattern of season is the same as on our planet, but each season extends to 172 days i.e. almost 6 months on Earth. This is because the orbital period of Mars is 687 days. Lower forms of life can survive under such condition, if only water in liquid form and oxygen are available.
Coordination of Internal Rhythms of Organisms with External Cycles
It is not surprising that terrestrial life is synchronised to natural cycles around. Our sleep-wake cycle, flowering plants blossoming at fixed hours of day or night, the feeding pattern of marine crabs following the tidal pattern and lunar month. The sowing and reaping of food crops following the seasons as also the bearing of fruits by fruit trees. The migratory instincts in animals, birds and even in butterflies synchronize with the rhythm of change of season during a year. This coordination of internal and external cycles have been the result of millions of years of evolution.
If any life exists in Mars, even bacterial and primitive, it may respond to the rhythmic cycles obtained in that planet. There is no way of knowing it now unless man lands on Mars and studies the life there, if any, in objective and scientific detail.
All our argument for or against the possibility of life in Moon or Mars are purely speculative and based on our experience of life on Earth. That there could be no life in the Moon and there could only be life in the level of bacteria in Mars appears to be our tentative conclusion. Any future astronaut landing on Mars can carry , without his knowledge, Martian microbes to our planet and contaminate ours. And if the alien microbe happens to thrive in its new environment and prove inimical to terrestrial life, we might be inviting trouble for humanity. We hope such a condition does not arise.