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Now on to Chandrayaan-II Algorithms to prevent car crashes Prof Yash
Pal THIS UNIVERSE Malaria may have come from chimps
Scientists study huge plastic patch in Pacific |
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Now on to Chandrayaan-II THANKS to the innovative strategies devised by the scientists of the Indian Space Research Organisation (ISRO), India’s maiden lunar probe Chandrayan-1 was back from the brink of” certain collapse” following the loss of its vital star sensor. Chandrayaan-1, whose orbit has been raised to 200-km above the lunar surface with a view to shelter it in a “benign environment”, continues to provide data on various aspects of the moon including its resources. As pointed out by G. Madhavan Nair, Chairman, ISRO the Indian lunar orbiter is doing fine as “is evident” from the images made available by the Indian built payload—Terrain Mapping Camera (TMC)—onboard Chandrayaan-1. As it is, TMC has provided some of the excellent pictures of the July 23 total solar eclipse. Meanwhile, the Bangalore based ISRO Satellite Centre (ISAC) is busy working on the follow on lunar mission Chandrayaan-II. While Chandrayaan-1 is an orbiter, Chandrayaan-II will feature a lander/rover for studying the lunar surface in depth. According to the latest annual report of the Indian Space Department, Chandrayaan-II will be made up of an orbiter craft and a lunar craft that will carry a soft-landing system up to lunar transfer trajectory. Unlike the fully Indian Chandrayaan-1, which of course features six international payloads, Chandrayaan-II will be an Indo-Russian project. While ISRO is responsible for the main orbiter, Russia will be responsible for developing the lander and rover. Chandrayaan-II will be launched by means of the three-stage Geosynchronous Satellite Launch Vehicle (GSLV) featuring an indigenous upper cryogenic engine stage. Incidentally, Chandrayaan-1 was launched by the four stage Indian space workhorse PSLV (Polar Satellite Launch Vehicle) featuring an alternate liquid and solid fuel driven stages. The biggest challenged involved in the successful realisation of Chandrayaan-II mission planned for launch during 2011-12 is how to engineer the soft-landing of the robotic rover on the lunar surface. The robotic rover is designed to collect samples of soil and rocks from the lunar surface. The collected lunar samples will be subjected to in situ chemical analysis and the data transmitted to the mother spacecraft in lunar orbit. “We are looking at having a soft-landing for Chandrayaan-II. We should be working on technologies that will be a part of the proposed lunar base. If we were to become a developed country by 2020, it will be crucial for us to build such technologies” says M. Annadurai, the project director of Chandrayaan-1 mission. In fact, as a logical step beyond Chandrayaan-II, ISRO is looking at the possibility of going in for a return mission to moon. However, right at the moment the idea is in embryonic stage. For a sample return mission ISRO would need a heavy lift off vehicle with a minimum capacity to launch a 20-tonne class payload into a near earth orbit. With USA and China going serious on their plans for lunar human landing missions India will be tempted to work on a project to send a manned vehicle to moon. Though as of now ISRO has no specific project on hand for sending a man to moon, there is speculation that an Indian manned mission to moon could become a reality by 2020. |
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Algorithms to prevent car crashes Bhibhya Sharma of the University of South Pacific, headquartered in Fiji, who led the research, said that the series of equations would instruct robotic cars when and how to merge lanes, which could lead to fewer accidents and ease traffic congestion. Flocking is a biologically inspired technique and a strategy commonly used in robotics. “One of the advantages of flocking is that robots can work together and achieve what would take individuals far longer,” he said. He further explained that each car will be controlled by a centralised brain guided by a series of algorithms to control the car. The brains will talk to each other and instruct the cars to merge lanes and move in formation together. The team demonstrated the technique using computer simulation and is currently testing it in two wheel robots. Fellow researcher Utesh Chand said that the cars have targets they move towards and maintain and when the cars find themselves in a merging situation, one of them will be given the position of leader, the rest will follow. The team has written equations for attraction towards the target, enabling cars to stay inside their lanes and avoid crashing into each other. The challenge now is to allow the robot to automatically plan how to avoid crashing with the side of the road and cars
travelling close by. Sharma and Chand presented these findings at the first Rim Mathematical Association (PRIMA) conference in Sydney, said a University of South Pacific release.
— IANS |
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THIS UNIVERSE
We know that acceleration due to gravity is same for all objects, but why then does a heavy stone fall sooner than a paper or a light stone? When things are falling in the atmosphere they are subject to two forces. One them is the force of gravity. But there is also a retarding force which depends on the speed at which the object is falling. This is the force of friction. This friction is due to the fact that air has to be pushed out of the way. It should be obvious that this opposing force would depend on the rate at which the molecules of air collide with the falling body. When a body is heavy, like a stone and is falling at slow speed the retarding force is small. It also depends on the area of the surface facing the downward direction. You can find through an experiment that if you roll a sheet of paper into a tight ball it falls almost at the same speed as a stone. Your remark about the difference in the rate of falling between a large stone and a small stone is not absolutely correct. It might depend a little on the ratio of the surface to the mass of the stone. Think of a fly sitting on the ledge of a high building or the branch of a high tree. It is not afraid that it would get hurt if it falls down. This is because compared to its surface area its weight is small. You might also think of some other phenomena. Fairly large pieces of rockets we launch into space sometimes break off and start falling to the earth. As their speed increases the air resistance also increases. This produces intense heat and these fragments can disintegrate, melt and even evaporate before they reach the ground. The rain drops often originate from clouds that are a few kilometres high. Due to increase of air resistance with speed they finally reach a terminal velocity and do not hit us like bullets.
Does hydrogen have any
neutrons?
Ordinary hydrogen has only a proton as its nucleus. But there is heavier hydrogen that is much rarer. Its nucleus is a proton and a neutron. As a result we also have heavy water which is a molecule containing two atoms of heavy hydrogen and one of oxygen. Heavy water is used as a coolant in many atomic
reactors. Readers wanting to ask Prof Yash Pal a question can e-mail him at palyash.pal@gmail.com |
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Malaria may have come
from chimps WASHINGTON: Malaria may have jumped to humans from chimpanzees much as AIDS did, U.S. researchers reported on Monday in a study they hope could help in developing a vaccine against the infection. They found evidence the parasite that causes most cases of malaria is a close genetic relative of a parasite found in chimpanzees. Genetic analysis suggests the human parasite is a direct descendant of the chimp parasite, they reported in the Proceedings of the National Academy of Sciences.
Scientists study huge plastic patch in Pacific LOS ANGELES:
Marine scientists from California are venturing this week to the middle of the North Pacific for a study of plastic debris accumulating across hundreds of miles (km) of open sea dubbed the “Great Pacific Garbage Patch.” A research vessel carrying a team of about 30 researchers, technicians and crew members embarked on Sunday on a three-week voyage from the Scripps Institution of Oceanography, based at the University of California at San Diego.
— Reuters |
A set of algorithms developed by Indian origin researchers will enable robotic cars to communicate with one another and avoid collisions. 