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EXTRA TERRESTRIAL LIFE - A SEARCH IN SPACE
By Sheetal Chibber
The earth is surrounded by atmosphere. To explore the empty space beyond the atmosphere is not so easy b4ecause everything is far away and thus creates a big mystery. Astronauts have started visiting the heavenly bodies. Now they have a very elaborate description about the moon as they have landed on it and have made many researches.
The development of science and technologies has helped man to explore the mystery prevailing in space, to some extent. People began studying the planets thousands of years ago. They kept records of how the planets move and how they change in brightness The motion of the planets was not well understood until 1600. Today there are still many unmeasured questions about conditions an the planets, origin of planets an life on them. The mystery remains unanswered.
Formation of the planets:-
Most of the astronauts believe that the sun, planets and the other smaller bodies present in the solar system are formed from a large cloud of loosely packed gas and dust about 4.6 billion years ago. The gravitational pull of particles within the spinning cloud caused it to contract a great deal and become more dense. Most of the matter was pulled toward its centre and formed the sun and became flattened into a thin proplanetary disc.
The gas and dust in the proplanetary disc could eventually have formed small chunks. Gentle collisions of these chunks then built up larger objects. As the objects grew, their gravity increased. The larger objects could have pulled in dust, gas etc., and grown quickly. Astronomers believe that these large bodies became the planets and their moons.
Life on planets:-
There have been a number of space probes launched and a number of researches have been made to gain knowledge about the constituents of the solar system and to search for the possible existence of plant and animal life.
A few conditions must be held up in order, for plant and animal life to exist.
1. The plant must have a suitable temperature range. It should not be very hot or very cold. This directly depends on the distance of the planet from the sun.
2. The planet must have the right kind of atmosphere. Presence of sufficient quantities of the two gases CO2 and O2 is very important for life to exist. Moreover there should not be any kind of poisonous gas.
3. The planet must not only have the right kind of atmosphere but also sufficient amount of it with a suitable escape velocity.
4. Presence of considerable amount of water on the planet is not of least importance for life to exist on the planet.
Possibility of existence of life on inferior planets:
Planets near the sun receives more among of heat. For instance, the temperature of mercury during day is 340 degree C where as on earth, the average temperature is 16 degree C. The size of mercury is three times the size of moon which means absence of any atmosphere makes life completely impossible on its surface.
But, Venus which is called as the earth’s turn reflects about 85% of the light falling on it and has a temperature of 480 degree C. This is because, the clouds present around the surface of Venus prevents heat from radiating away from its surface. The atmospheric pressure is about 100 times the atmospheric pressure on earth with 95%CO2. Under these circumstance, there is no possibility of life on this planet also.
The temperature on a planet is estimated from measurement of infra red radiations and radio waves that the planet send out.
Possibility of existence of life on Mars
:-Mars seems to have some possibilities of life, due to the presence of earth like conditions on it. From photographs from mars, one can see the eroding action of the boundaries of craters present on mars and existence of dry river beds. These confirmed that there is sufficient atmosphere and water on this planet. This made mars an interesting planet for astronomers. Many biological experiments were conducted to detect micro organisms, etc., if any. The result of these experiments were unfortunately supporting a negative answer. Thus it was conducted that there is no trace of life on mars.
Possibility of existence of life on Moon:-
Exploration of the moon by named and unnamed vehicles sent from the earth is providing information which is of more value to humans. From telescopic studies it was known that moon is an airless and waterless expanse of desert and rocks without vegetation and life. Lack of atmosphere and long duration of day of nearly 15 earth days increases the temperature to 110 degree Celsius at midday and -150 degree Celsius at night. It is said that age of rocks on moon is almost the same as the age of earth . so it was eventually concluded that the moon is a vast desert with no life on it which was formed at about the same time as the earth.
Possibility of the existence of life on superior planets:-
Planets beyond mars are so cold that living organisms are not likely to survive there
further their atmospheres are full of poisonous gases like methane and ammonia. From the informations send by various probes which were sent for the study of planets beyond mars, we reach a conclusion that life as we know it probably does not exist elsewhere in our solar system.
Space probes:-
Robot space craft sent to explore other planets are called probes. Pioneer and voyager space by US for the close study of outer planets took beautiful shots of planets like Jupiter, Saturn, Uranus and Neptune. Some explorers other planets and some the earth itself
Radar was used to map Venus. Pluto was not yet been visited.
Lunakhod 1and 2 , crawled the moon’s surface testing its soil. The Russian Probe Luna - 3 joined this work.
Two Viking probes were used to explore Mars to search for life in the planet. Space crafts landing on other planets must be made very tough as to withstand heat, atmosphere, pressure etc. Using these we can get closer loops and explore the planets.
Even on such unmeasurable steps taken by man to explore space, the mystery is not yet solved and many questions remains unanswered.