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| SCIENCE TRIBUNE | Thursday, July 20, 2000, Chandigarh, India |
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Is there water on the Red Planet? by Amar Chandel ARE we alone? Man being a social animal, the possibility of floating in isolation on the blue planet in this infinitely large universe makes him very uneasy. He is always on the lookout for signs of life on any other planet. The closest he has come to finding a distant cousin is through a potato-sized Martian rock that fell to the earth 13,000 years ago. A section of scientists believes the meteorite found in Antarctica had chemical traces that could have been left by tiny bacteria. His quest has been hampered by the fact that all planets except the earth are believed to be bone-dry. Even the evidence that water did exist on Mars millions of years ago is not much of cheerful news because that does not leave any scope for life today. Science Quiz Response |
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Is there water on the Red Planet? ARE we alone? Man being a social animal, the possibility of floating in isolation on the blue planet in this infinitely large universe makes him very uneasy. He is always on the lookout for signs of life on any other planet. The closest he has come to finding a distant cousin is through a potato-sized Martian rock that fell to the earth 13,000 years ago. A section of scientists believes the meteorite found in Antarctica had chemical traces that could have been left by tiny bacteria. His quest has been hampered by the fact that all planets except the earth are believed to be bone-dry. Even the evidence that water did exist on Mars millions of years ago is not much of cheerful news because that does not leave any scope for life today. Suddenly, all the human race’s dreams and hopes were revived last month when certain physical features were found on Mars which suggested that water not only did exist on Mars a long time back but it might very well be there even today. Combing through more than 65,000 images that NASA’s Mars Global Surveyor spacecraft has returned since 1997, researchers announced what appeared to be signs of water seeping into features that looked like fresh gullies, channels and alcoves cut into the Martian surface. Channels carved by flash floods in the US West look very similar to these Martian gullies. The gullies are rare landforms that are too small to have been detected by the cameras of the Mariner and Viking spacecraft that examined the planet prior to Surveyor. Most occur between latitudes 30 degrees and 70 degrees in both Martian hemispheres and are usually found on slopes facing away from midday sunlight. The discovery of “weeping layers” of rock at more than 120 locations on Mars perplexed the scientists themselves more than anybody else. Those regions are in the coldest places on the planet and the present-day evidence of water does not fit into the established models of what Mars is like. As Michael Malin of Malin Space Science Systems in San Diego, California, which built the spacecraft’s camera, and his colleague Kenneth Edgett candidly admitted, they were “dragged kicking and screaming to this conclusion”. A paper presented by them described the “very intriguing” discovery of relatively young landforms on Mars that suggest that there is liquid water at shallow depths below the surface. The startling images were taken in January with the help of a camera, which can see features as small as 0.8 km across. The gullies are where the scientists would least expect to find water, in the coldest crannies of craters facing away from the sun and towards the poles. The belief so far was that if at all Mars had water, it could only exist in frozen form, beneath the soil or tied up in polar ice caps, and as extremely sparse clouds in the thin Martian atmosphere. The relative freshness of these features indicates that some of them are still active today and liquid water may exist in some areas at depths of less than 500 metres. The profound implications of the possible find can be well imagined. To find water is the holy grail of orbital reconnaissance because where there is water, there is a very distinct possibility of life. Mr Ed Weiler, Associate NASA Administrator for Space Science, explains that all that is needed for life on the earth is liquid water below boiling point, the organic molecules from which living beings are made, which have been spotted throughout space, and some source of energy, be it from the sun or from some chemical reaction. Bacteria called extremophiles have been found thriving in thermal vents many kilometres beneath the surface of the ocean, in oil wells and even in Arctic ice. Next to the earth, the climate of Mars is the most hospitable for life and there is a possibility that such creatures might exist in its forbidding environment or in slushy seas on some of Jupiter’s moons. What should be borne in mind is that the recent findings are only a suggestion, which can be authenticated only after comprehensive scrutiny and debate. Other scientists will point out flaws or come up with evidence that supports it. As it is, no water has been found at all, only structures that, if found on the earth, would have been formed by water seeping from the underground, then building up under pressure and bursting out in an explosion of mud. Similar optimism raised about water on the moon some time ago had proved premature. It has been repeatedly stressed that water on the surface of Mars is not found in springs or brooks, but in explosive bursts of mud and stream. Even that is hard to reconcile because the average temperature on the surface of Mars is far below freezing point, and it stays so cold that everything should be frozen hard to the depth of several kilometres, say planetary geologists. NASA has suggested a mechanism by which water can flow through the near surface despite the fact that the average temperature of Mars, particularly at those high latitudes, is 70 to 100 degrees centigrade below freezing point. According to this theory, water, warmed by the geothermal process, seeps up towards the surface but freezes in an ice dam. This blocks further flow, which builds up pressure behind the ice dam. Finally, it bursts free in an explosion of mud, flash-frozen ice and vapour created by sublimation. This process is seen on the earth when snow dries up instantly into water vapour without melting first. Malin and Edgett have said they will study the photos being sent by Surveyor to see if they can catch this actually happening. “I personally will feel better when he shows me a picture some day … and a channel has moved, a boulder has moved,” said a cautious Mr Weiler. But other scientists are of the view that the flows may have been caused by a fluid other than water. One theory suggests that an unstable compound called clathrate, made up of carbon dioxide and water, exists under pressure below the surface of Mars. Another theory suggests the fluid could be benzene. It is also possible that the gully features are created by explosive flows of hot gas or water vapour that might be related to volcanism. Outbursts of gas can create fluid-like flows, which may rush downhill along with dust and debris and create the new-found features. After all, we are dealing with the surface of another planet and cannot interpret things with a distinctly earthly bias. One section of scientists believes that the gullies have formed due to landslides. However, if the water hypothesis is correct, it opens up exciting possibilities of its being mined if human explorers ever go to Mars. If water is indeed available in substantial volumes in areas other than the poles, it would make it easier for human crews to access and use it for drinking, to create breathable air, and to extract oxygen and hydrogen for rocket fuel or to be stored for use in portable energy sources. Hydrogen is a key resource in the development of fuels for all kinds of purposes like running surface systems or fuel launch vehicles or create fuel-cell storage devices to manage electricity. If humans have to stay for long periods on Mars, they will have to live off the land. NASA is looking to develop drilling techniques and equipment that could be transported to Mars for use by astronauts or robotic probes. Some day, it may be possible to drill down 300 metres and even find an artesian well where water would rise up by itself. That would be ideal for a Mars base. But before that, the real challenge would be to land accurately enough near a water source. It goes without saying that the space agency struggling for decades with a shrinking budget and Congressional skepticism is thrilled to bits over this unexpected development. After losing two Mars missions in a row last year, there was a big question mark over its Martian endeavours. The water finding has revived its spirits and it is moving full steam ahead towards missions to Mars in 2003 and 2005, which will include the use of a robot to sample the planet’s surface. A mission to orbit another craft around the planet is possible as early as next year. There has been another unrelated announcement by a team at Arizona State University and Los Alamos National Laboratory which in a way corroborates the exciting water finding. These geologists say that they have found evidence that like the earth, Martian oceans were salty. They have reached this conclusion by looking at chunks of rocks that were knocked off Mars and fell to the earth as meteorites. Carleton Moore of ASU and his team say in the July issue of journal Meteoritics and Planetary Science that they had analysed the inside of the 1.2 billion-year-old Nakhla meteorite, which fell on Egypt in 1911, and found water-soluble ions that probably would have been deposited by evaporating brine. “The inference that the early Martian ocean was very similar to our current oceans also implies that the early earth’s ocean may have been very similar to what it is today. This is a clue to what it might have been,” Moore says. The Martian water even today is going to be very salty because it has been in the ground for a long time and it has had a chance to absorb minerals. The excitement over water on Mars is not exactly a new development. Melting polar caps had indicated this possibility to astronomers almost 300 years ago. Mars has seasons quite similar to those on the earth and it also has white polar caps that were easily visible in early telescopes. In 1813, it was noted that the polar caps seem to shrink in the Martian spring and return in the winter, suggesting the seasonal melt and freeze cycles. In 1877, Italian astronomer Giovanni Schiaparelli thought he saw features on Mars that he described with the Italian word “canali”. What he meant was “channels” but it was wrongly translated into English as “canals” conjuring up the image of intelligent canal builders. The myth about little green creatures was born and firmly established leading to H.G. Wells’ War of the Worlds”. But in 1976, the Viking spacecraft dashed these fantasies by showing Mars as a dry, rocky desert with not a drop of water in sight. It was only in the 1990s that we took a closer look and found many features that appeared to be formed by water. One thing is for sure. Even if we do find water, there is no chance of coming across quaint, three-eyed aliens in spaceships. We will be lucky if we find the most basic forms of life. |
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Science Quiz
1. This Portuguese physician and medical researcher shared the 1949 Nobel Prize for Physiology or Medicine for developing the technique known as Leucotomy, a type of brain surgery. Name this neurologist who also developed cerebral angiography, a method for diagnosing brain tumours. 2. The Galileo spacecraft has recently taken pictures of an object in our solar system which show that it is constantly erupting molten rock, super-heated geysers and clouds of poisonous gases. Which is this most volcanically active object in the solar system? 3. MAO is an enzyme found in animals and its function is to break down certain biologically active amines in the body. What is the full form of MAO, which has adrenaline oxidase and tryaminase as its other names? 4. It has been recently found that the solution of a gas in water is very effective in killing micro-organisms like hepatitis A virus, E. coli bacteria and MS2 virus. These are usually present on the surface of fruits and vegetables and can cause food-borne diseases. Can you name the gas the solution of which can kill these micro-organisms in about 5 minutes? 5. Acupressure is a technique which involves the application of pressure to nerve endings in our body, especially those near our hands and feet. It is said to improve blood circulation, induce relaxation and reduce pains and stresses. What is another name for this technique? 6. This Latin American plant was brought to India by the Britishers for ornamental purposes but it turned into a widespread weed eating up large vegetation and wetlands like lakes. Name this environmentally hazardous plant which, when dried, can be used to make paper and cardboard. Which Latin American insect can naturally eat and check the growth of this weed? 7. Name the branch of optics which deals with the production of lines of various colours present in a source of light and the measurement of the intensity and wavelength of these lines. Which instrument is used to make these measurements? 8. Name the component in the engine of a vehicle which consists of two electrodes separated by an air gap, on passing current through which the compressed mixture of fuel and air gets ignited. 9. Suggest another name for “the little neutral one”, well-known in particle physics. Name its three species. 10. Name the first US rocket launched recently which was powered by a Russian engine and carried a European communication satellite, heralding a new era in international cooperation in this field. Answers1. Antonio de Egas Moniz 2. Moon lo of the planet Jupiter 3. Monoamine oxidase 4. Chlorine 5. Reflexology 6. Water
hyacinth; weevils 7. Spectroscopy; spectrometer 8. Spark plug 9. Neutrino; electron, muon and tau neutrino 10. Atlas III. |
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Apropos of “Preventing cracks in building” published in the Science Tribune (July 6), I would like to bring to the notice of the readers some additional information, which resulted from discussions held sometime back between the postgraduate students. The aspects are: When cracks are seen in a building, do not panic and reach that conclusion that these are on account of cement having been misappropriated during the construction of building. Try to carefully examine the cracks. They will reveal a lot, particularly as what has happened? Why it has happened? and what need be done to contain ill-effects of the cracks (if any). Your efforts should be directed, while designing a building, towards goading or coaxing the cracks to form at an assigned location and alignment, so that they do not present an ugly sight. It is a costly affair to prevent formation of cracks in an RC structure, as then strain level in the various regions, has to be kept low and for that permissible level of stresses in steel and concrete will have to be lowered to two-third level, as is done in the case of the water-retaining structures. In case of the common buildings it will result in considerable increase in the cost. While attempting to conceal cracks do not attempt to restrain on the components and their permitted movement should not be restricted. This is essential because by restraining the movement, you would be causing stress in some other adjoining area, which may be dangerous. While attempting repairs of the structural cracks do not simply attempt to restore status quo ante, but try to reduce the stress/strain level which had resulted in crack formation. Concluding, it may be stated that it may not be possible to prevent crack formation in buildings but it is possible to conceal them and prevent ugly appearance. Dr
G. S. Dhillon |
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