|SCIENCE TRIBUNE||Thursday, July 3, 2003, Chandigarh, India|
energy in flywheel for continuous supply
The Mars Express space probe, the first European mission to Red Planet which was launched on June 2 aboard a Soyuz-Fregat launcher from Baikonur cosmodrome in Kazakhistan, after reaching the planet in late December will perform detailed studies of the planet’s surface, its subsurface structure and its atmosphere. It will also deploy Beagle-2, a small autonomous station which will land on the planet, studying its surface and looking for possible signs of life, past or present.
Significantly, Mars Express has been described as the first example of European Space Agency’s new style of developing scientific missions, faster, smarter and more cost effectively. Of course, without compromising reliability and quality. "Europe is on its way to Mars to stake its claim in the most detailed and complete exploration ever done of the Red Planet. We can be very proud of this and of the speed with which we have achieved this goal," said David Southwood, ESA’s Director of Sciences.
Mars Express will travel away from earth at a speed exceeding 30km per second on a six month and 400-million kilometre journey through the solar system. And by the end of November Mars Express will be close to Mars and get ready to release Beagle-2. As envisaged now, the 60 kg. Beagle-2 will enter the Martian atmosphere on December 25. As it descends, the lander will be protected in the first instance, by a heat shield two parachutes will than open to provide further deceleration. With its weight down to 30 kg. at most, it will land in an equatorial region known as Isidis Planitia. Three airbags will soften the final impact. This crucial phase in the mission will last just 10 minutes from entry into the atmosphere to landing.
Having landed on Mars, Beagle-2 named after HMS Beagle on which Charles Darwin voyaged round the world, developing his evolutionary theory will deploy its solar panels and the payload adjustable workbench, a set of instruments — two cameras, a microscope and two spectrometers mounted on the end of a robot arm. It will proceed to explore its new environment, gathering geological and mineralogical data that should for the first time, allow rock samples to be dated with absolute accuracy. Using a grinder and corer, and the "mole", a wire guided minirobot able to burrow its way under rocks and dig the ground to a depth of two metres, samples will be collected and examined. The spectrometer will have the job of detecting possible signs of life and dating rock samples.
On its part, the Mars Express will carry out a detailed investigation of the planet, pointing its instruments at Mars for between half an hour and an hour per orbit and then for the remainder of the time, at earth to relay the information collected in this way and the data transmitted by Beagle-2.
The orbiter’s seven onboard instruments are expected to provide considerable information about the structure and evolution of Mars. A very high resolution stereo camera onboard will perform comprehensive mapping of the planet at 10-metre resolution and will be even capable of photographing some areas to a precision of two metres. OMEGA spectrometer will draw up the first minerological map of the planet to 100 metre precision. This minerological study will be taken further by the PFS spectrometer —which will also chart the composition of the Martian atmosphere, a prerequisite for investigation of atmospheric dynamics.
The MARSIS radar instrument with its 40-metre antenna will sound the surface to a depth of 2 km, exploring its structure and above all searching for pockets of water. Another instrument, ASPERA. will be tasked with investigating interaction between the upper atmosphere and the interplanetary medium. The focus here will be on determining how and at what rate the solar wind, in the absence of a magnetic field capable of deflecting it, scattered the bulk of the Martian atmosphere into space. Atmospheric investigation will also be performed by the SPICAM spectrometer and the MATS experiment, with special emphasis on stellar occultation and radio signal propagation phenomena.
The mission’s scientific goals are of
outstanding importance. Mars Express will, it is hoped, supply answers to the
many questions raised by earlier missions — questions concerning the planet’s
evolution, the history of its internal activity, the presence of water below its
surface, the possibility that Mars may at one time have been covered by oceans
and thus have offered an environment conducive to the emergence of some forms of
life, and even the possibility that life may still be present, somewhere in
putative subterranean aquifers. In addition, the lander doing direct analysis of
the soil and the environment comprises a truly unique mission.
energy in flywheel for continuous supply
The trouble with electricity is that it is very difficult to store. Unlike coal and oil, which are easily stored, electricity, therefore, has to be generated as, when and where, it is needed.
Consumers generally do not always need electricity at the same time and rate, as it is generated in the coal fired or hydroelectric powerhouses. The demand for electricity is maximum in evenings and is low after midnight and in daylight hours.
The electricity is available from renewable energy sources such as the sun or wind, when the sun is shining or the wind is blowing respectively. This is not always in the evenings and at night.
Peak power demand could be met by building large capacity power houses, but their full capacity would remain idle during low demand hours.
The answer to this problem is a means of storing generated electricity, when demand is low until it is high. Several storage methods are familiar, at least in concept; for example, pumped-storage facilities in which water is pumped back into the high reservoir when surplus electricity is available and then released, to turn a generator through a turbine at times of peak demand. Such a system is in operation at Tata power house at Bhira near Pune.
Another system is to use surplus electricity to compress air and store it in caverns. The compressed air is used to generate electricity at times of peak demand, say in the evening.
A flywheel is another example. A flywheel is a heavy wheel attached to the shaft of an engine to keep its speed nearly constant. A potter’s wheel, is the simplest example of a flywheel. The potter throws the clay onto a rapidly rotating disc and shapes the pot by manipulating it with both hands. The wheel is set in motion by a stick that fits into a notch in the wheel. It is often activated by an assistant.
A flywheel’s rotation, and therefore energy, is built up at times of low power demand and drawn at peak-power demand hours.
The phrase "flywheel battery" describes a system consisting of a flywheel, a motorgenerator, and control electronics for connection to a larger electric power system. What it does is to take electrical energy from a source. store it as kinetic energy of rotation in the flywheel, and deliver it to a user at the time, and in the form, that the user needs.
Flywheels appear to be the ideal energy storage means in solar electric or wind power systems. They can smooth the load on the generators by providing the energy to generate electricity when the sun is not shining or the wind is not blowing; and they can also provide power to consumers, when demand exceeds supply. Indeed, once spinning, flywheels can deliver energy rapidly for variable electricity demand.
Unlike old-fashioned flywheels, the modern flywheels are lightweight and rotate at extremely high speeds, in the vicinity of 50,000 rpm.
To withstand such high speeds, they are made of advanced composite materials and are supported by magnetic bearings in which there is no actual metal-to-metal contact. Instead, the rotating masses are held in place by carefully controlled magnetic fields.
Engineers in the UK have developed the first commercial flywheel-powered tram. It has gone into service on a mile-long track in Bristol. Rather than drawing power from overhead electric cables, the tram draws power from low-voltage electric charging points at passenger stops.
The electricity runs an electric
motor that spins a 500 kg steel-encased flywheel. The flywheel then
releases its stored energy in the form of electricity to propel the
tram silently along the track to the next charging station. The
vehicle, which has 20 seats and room for 14 standing passengers, has a
range of up to two miles before it needs to recharge its flywheel.
The closest look yet at the Y chromosome — which makes men different from women at the most basic level — shows it is not as puny as scientists believed, researchers have reported.
The tiny chromosome, in fact, carries more genes than mainstream wisdom had dictated. Most seem to be devoted to sperm production, the US researchers have reported.
And the chromosome uses an unusual mechanism to repair these genes when they become damaged, the researchers report in this week’s issue of the science journal Nature.
"Does analyzing the sequence of the Y chromosome tell us why men are incapable of stopping to ask for directions?" asked Dr David Page, a Howard Hughes Medical Institute investigator who led the study.
"I don’t think we have an answer to that yet. It remains a great mystery."
People carry 23 pairs of chromosomes, which in turn carry the genes. These pairs — one inherited from the father and one from the mother — include a pair of X chromosomes in females and an X and a Y in males.
It was believed for years that the Y, a small, fragile chromosome compared to the X, was a genetic wasteland. Scientists believed it was not capable of paig up with its partner, the X, to repair defects the way other genes can.
"The idea was that in this male-specific region of the Y, genes were singletons. They had no one to swap with and they had no way to rid themselves of ... genetic injuries," Page, who works at the Whitehead Institute at the Massachusetts Institute of Technology, told a news conference.
But to their surprise, the scientists found that the genes in this region are in fact palindromes — the sequences read the same backwards and forwards, similar to the numbers in the year "2002", only much, much longer.
And the chromosome can form little loops in which the genes at one end can press against the genes at the other end of the palindrome, swapping sequences and thus repairing — or passing along — mutations.
"What we infer is that these two arms of genes can actually swap parts," Page said.
"This, we propose, keeps the Y chromosome in business and keeps it stocked with healthy genes for human reproduction," he added. "It is not merely a rotted-out version of an ancient, ordinary, chromosome."
The Y can also do a limited amount of gene swapping with the X, but for the most part manages to repair itself, the researchers, which included a team at Washington University in St. Louis, found.
"This gene says ‘I can do it myself'," joked Dr Francis Collins, head of the National Human Genome Research Institute.
Scientists once believed that the Y chromosome carried only one gene — the SRY gene, which instructs the body to make testes instead of ovaries.
"Testes make testosterone. Testosterone makes for male behavior. That is the prevailing view," Page said.
It will take much closer research to determine just how much influence the tiny Y chromosome has on male behaviour and biology, the researchers said. It could cast light, for example, on differences between male and female disease patterns.
In telephone talk the speech is transmitted and received almost at the same time irrespective of whether a person is talking from America or the same city. But sound wave cannot travel as fast through the atmosphere with wire transmission. Please explain this.
Your question itself contains the germ of an answer. Your speech does not travel as a sound wave through the atmosphere. It is first converted into electrical signals that can travel through wire, satellite or cable with the speed of light. On the other side they are converted back to sound. That is why the conversation does not seem to have breaks. Sometime when you get a satellite connection there is a delay of about half a second because even at the speed of light the distance to and fro between the satellite at 36,000 kilometers and the earth takes some time. These days lot of trans-oceanic traffic is carried through optical fibers. In this case the signal is converted into laser pulses that can propagate through these fibers. The speed of travel is again equal to the speed of light.
Why same charges repel and opposite charges attract? Please explain this on the basis of physics.
You have asked a difficult question. Why should there be this two-ness in the properties of fundamental particles? I could just say that we have found it to be so. Nature is like that. We may also say that we happen to be because it is so. If it were not we would not have the universe we do. Atoms, molecules, whole of chemistry and biology we know won’t be there. This is the nature of the electromagnetic field that controls it all. Imagine if this field was like the gravitational field and all particles attracted all other particles. The very nature of that field would be different.
Indeed we cannot even have a theory of photons without postulating the existence of electrons and positrons that on combining annihilate charge. In fact the theory of electron itself demanded that there exist a particle of equal and opposite charge. I do not know whether you can make more sense out of what I have said than I do. I hope so.
Can any object become invisible?
If by invisible you mean not visible to our eyes I would say just switch off the light in a dark room. But if you have infrared binoculars you would be able to see it. Or if you throw stones in all directions one of them would hit the object and you would know it is there. If by invisible you mean completely disappear without any trace of its previous existence, without a bang or release of energy then you are close to imagining some thing unreal. There are of course ways of arranging things that you see someone but he does not see you. Separating the room in which that person is sitting with a partially silvered screen from the one in which you are easily does this, if his room is well lighted and yours is not.
You are probably impressed with lot
of stories, even movies, in which physical disappearances are common.
You might have even seen magic shows of this type. Both are far from
reality even though enjoyable as stories.
Low-cost cleaning of
An experimental mix of chemicals permits low-cost home treatment of highly contaminated water. The packet has been designed for use in developing countries, where some 5,000 children die each day from diarrheal disease — primarily because of poor sanitation and infected drinking water.
The new treatment turns even dark, foul-smelling, germ-laden water into a drink as clean as most US tap water, says Stephen Luby of the Centers for Disease Control and Prevention in Atlanta. The chemicals’ cost should run about a penny per litre of treated water, according to Greg Allgood of Procter and Gamble’s Health Sciences Institute in Cincinnati.
During tests in Guatemala, Kenya, Pakistan, and Bangladesh, residents were instructed to stir a four-gram packet of the chemicals into a 10-litre jug of river or other water for five minutes, until dirt and other suspended materials settled out. Villagers then filtered out the sediment by pouring the water through tightly woven cloth. Over the next 20 minutes, the water’s residual chlorine bleach vanquished germs.
In the June Journal of Water and Health, Souter’s team offers data on dirty water collected from sites around the world. The scientists spiked their samples with large quantities of pathogens, including 14 types of bacteria, two viruses, and two parasites. The PUR mix reduced bacterial loads to less than a hundred-millionth of starting concentrations, the viruses to less than a ten-thousandth, and the parasites to less than a thousandth of initial values. The flocculation also removed more than 99 per cent of the naturally occurring arsenic in water from a Bangladesh well.
Final concentrations of these toxicants met World Health Organisation guidelines for safe drinking.
New catalyst for cheap hydrogen
Scientists have developed a hydrogen-making catalyst that uses cheaper materials and yields fewer contaminants than do current processes, while extracting the element from common renewable plant sources. Further, the new catalyst lies at the heart of a chemical process the authors say is a significant advance in producing alternate fuels from domestic sources.
In the June 27 issue of the journal Science, James Dumesic, John Shabaker and George Huber, of the University of Wisconsin at Madison, report developing the catalyst from nickel, tin and aluminum and using it in a process called aqueous-phase reforming (APR), which converts plant byproducts to hydrogen. The process performs as well as current methods that use precious metals such as platinum, yet runs at lower temperatures and is much cleaner.
"The APR process can be used on the small scale to produce fuel for portable devices, such as cars, batteries, and military equipment," said Dumesic. "But it could also be scaled up as a hydrogen source for industrial applications, such as the production of fertilisers or the removal of sulfur from petroleum products."
Stopping the noise
Squealing brakes cost auto manufacturers several hundred million dollars a year in warranty repairs and are among consumers’ top 20 vehicle complaints – even in luxury cars. Now, acoustics researchers at the Georgia Institute of Technology have developed a solution that could stop the problem of noisy brakes once and for all.
In disc brakes, squeal can
occur when the brake pads contact the rotor while the vehicle is moving
at low speeds, setting up a vibration that manifests itself as an
annoying high-pitched squeal. The noise doesn’t affect brake
operation, but the problem –which occurs in cars, trucks and buses –
leads to needless replacement of brake pads and the addition of shims,
damping materials and other parts designed to stop the noise.