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| SCIENCE & TECHNOLOGY |
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India’s mission to moon
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India’s mission to moon America’s Apollo XI landed two men on the moon in July 1969. It blazed a new trail in man’s exploration in space. Of the 24 humans who travelled to the moon, 12 landed on its surface between 1969 and 1972. By then about 382 kg of moon rock had been brought back to earth by various Apollo and Luna missions, providing scientists with ample samples for research. The 1990s saw a major renewal of the interest in lunar exploration with the Japanese sending its Hiten orbiter, followed by the US-built Clementine. In 1998, NASA’s Lunar prospector ignited enthusiasm with the discovery of water-ice in some of the moon’s craters thereby pointing to the possibility of humans not only colonising the moon, but also using it as a base station for future outer-space missions. The discovery of an abundance of helium-3 on the moon’s surface, with its potential to generate power, has also kindled a great interest among earthlings. Also helium-3 is regarded as one of the cleanest fuels but is found in sparse quantities on the earth. To have an early access to these abundant natural resources of the moon, of late, every space power is trying to develop launch vehicles and spacecraft to colonise it. India too is racing ahead with its Chandrayaan-1 project to map the moon and look for minerals. India’s Chandrayaan-1 will lift off in 2007-08. It will go round the moon on a polar orbit. India’s dream of visiting the moon began about five years ago under Dr Kasturirangan’s stewardship of the Indian Space Research Organisation (ISRO). In October, 1999, he organised a seminar at the Indian Academy of Sciences in Lucknow, where every topic under the moon — its evolutionary link in formation of the solar system, sensors for studying the moon, spacecraft design, etc — was discussed. It set the ball rolling as the idea of visiting the moon got planted in the minds of the Indian scientists. During the Astronautical Society of India’s meeting at the Space Applications Centre, Ahmedabad, in February, 2000, Dr Kasturirangan asked Dr George Joseph of the Space Application Centre to look into the possible mission scenarios. Though Dr Kasturirangan retired from ISRO and has gone to Rajya Sabha, yet his successor Dr Madhavan Nair, armed with Dr Joseph’s report and the Cabinet’s sanction is determined to carry on. A modified Indian rocket, called the Polar Satellite Launch Vehicle (PSLV), would deliver into lunar orbit a small spacecraft that would spend several years studying the moon with reflectometers, spectrometers and stereoscopic cameras. The mission would cost around $77.8 million. Dr V. Adimurthy, Group Director, Aerospace Flight Dynamics at ISROs Vikram Sarabhai Space Centre (VSCC) in Thiruvananthapuram, is in charge of souping up the PSLV. In a normal flight, the PSLV ejects its payload of one tonne within 11 minutes of liftoff. But in modified version that Adimurthy is designing, the payload, which will be a lunar orbiter, will weigh only around 350 kilogram (kg). That saving in weight will allow the last-stage motor carrying the orbiter to travel at times at superfast speeds of 28,800 km/per hour needed to break free of the earth’s clutches and put it on course for a lunar tryst. The orbiter itself will be designed and built at the ISRO Satellite Centre in Bangalore. ISRO’s polar satellite launch vehicle will take a 1.5 metre cuboid satellite Chandrayaan-1 at a launch speed of 10 km per second into an earthly orbit for a 3,84,467-km journey in five and a half days. The closet point of the orbit to earth will be 240 km and the farthest 36,000 km. Then the satellite’s liquid apogee motor will fire, pushing it out of earth’s magnetic clasp, and take it to 3.86 lakh km on the road to the moon. Another motor firing will put Chandrayaan in a near circular lunar orbit of about 1000 km. Here the solar panel of the craft will open up. The orbit will then be reduced to 200 km from the moon. Then, at a speed of about 1 km per second, Chandrayaan will spend about two weeks going round the moon over both its poles. Finally the orbital altitude will be reduced to 100 km. And there it will circle the moon for two years. In those two years it will send pictures and data. The scientific objectives of the Chandrayaan are likely to include a high resolution remote sensing of the moon in the visible, near infrared, low energy X-ray and high energy X-ray regions. |
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Understanding
the Universe How can sea mammals drink saltwater? It is unreasonable to assume that sea mammals can live on salt water, any more that we can. The first thing that occurs to me is that their need of fresh water should be less than ours, because a lot of water we ingest, particularly during the summer, is used to cool us through evaporation. Clearly, large sea mammals do not need this - when the skin temperature rises all they need to do is slip down into the water for a while, or splash a bit. Secondly, it is believed that whales can generate their own water by burning food during metabolism. They are lucky to have their own pure water factories. Water is a “waste” product of metabolism that they have learnt not to waste. Thirdly, I would say something about which I am not sure. Could they also have the capability of performing reverse osmosis? By using specific membranes and pressure systems, can they convert salt water into less salty water? After all, selective membranes are essential features of all living things. I have not been able to verify this last bit of information, so consider it just a hunch; it may or may not be correct. How does sunscreen protect skin? Perhaps it does, to an extent. Skin cells produce melanin when exposed to sunlight, which determines the colour of the skin; in darker persons, the melanin production is more efficient. Perhaps a layer of melanin then protects the skin cells from damage or severe sunburn. Sunburn is caused when the skin cells get an overdose of sunlight. The first stage is the suntan that lighter-skinned persons seek so passionately. But if exposure is too long and rich in ultraviolet, as at high altitudes, the skin cells swell and the skin can become red and sore. In our country, the desire is not so much to acquire a tan because most of us are already tanned so well. Instead, a lot of face and skin creams are sold, promising fairer looking skin. The need therefore is to reduce the production of melanin. This could be done to a small extent by reducing exposure to sunlight and, specially, to the ultraviolet end of its spectrum. This might be achieved by lacing any odd face cream with tested amount of a powder like titanium dioxide. Some of the light might be scattered away and some degraded down to more benign wavelengths through absorption and reemission processes. Less melanin is formed and the young lady becomes fairer! I personally think that melanin is a marvelous substance and that black is not only useful but also beautiful. |
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Retina cells act like soap bubbles Soap bubbles delight children and the young at heart, but they also have been objects of scientific study for centuries. Operating under the laws of physics, bubbles always try to minimise their surface area, even when many bubbles are aggregated together. Now two Northwestern University scientists have demonstrated that the tendency to minimise surface area is not limited to soap bubbles but extends to living things as well. In a paper published Oct. 7 in the journal Nature, they show that cells within the retina take on shapes and pack together like soap bubbles, ultimately forming a pattern that is repeated again and again across the eye. Gaining insight into these patterns can help researchers understand the interplay between genetics and physics in cell formation. Sifting a dusty disk Twenty years ago, astronomers peering at the young star Beta Pictoris got their first glimpse of a disk of dusty debris-the sign that planets, asteroids, and comets are forming and then banging together and releasing an abundance of dust. Such debris disks have now been found around many young stars, but the one surrounding Beta Pictoris remains the most revealing about how planets form and evolve. Recording spectra of the disk at midinfrared wavelengths, Yoshiko K. Okamoto of Ibaraki University in Japan and his colleagues now have gleaned new details about the size, composition, and crystal structure of dust particles. The data, which indicate three distinct bands of dust within the Beta Pictoris disk, suggest the location of a possible planet as well as of a trio of asteroid or comet belts. The astronomers describe their study in the Oct. 7 Nature. A room with a great view The world’s ultimate observation deck, a control tower for robotics in space, and a sunroom like no other, has arrived at NASA’s Kennedy Space Center (KSC). It is bound for the International Space Station. Built in Italy for the United States segment of the Station, the Cupola travelled part way around the world to reach KSC. One day it will circle the Earth every 90 minutes, and crewmembers will peer through its 360-degree windows. It will serve as a literal skylight to control some of the most sophisticated robotics ever built. “The Cupola module will be a fascinating addition to the Space Station,” said International Space Station Program Manager Bill Gerstenmaier. “The crew will have an improved view of critical activities outside the station and breathtaking views of the earth below.”
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How can sea mammals drink saltwater?
On many of one’s evening walks, one gets a magnificent view of a rising full moon, the only satellite of the earth. One invariably stops to admire the celestial spectacle. Having studied how the earth’s closest astral neighbour is a dark gray, barren, crater-ridden spherical mass, scientists have long since shed any romantic notions about it. Though they do pause to stare at the moon, but more to size up the challenge of unravelling its mysteries.