SCIENCE TRIBUNE Thursday, January 25, 2001, Chandigarh, India

Enigma of life on Ganymede
by D.P. Singh
IQUID water gets people excited because wherever it is found on earth, life is found too. The existence of water on Ganymede is all more exciting because it is the largest moon in the solar system (even larger than the planets Mercury and Pluto).

Network security and hacking
by Deepak Bagai
N its most traditional sense, a computer network is defined as a collection of desktop computers connected for sharing access to computing resources. These resources include printers, hard disk drives, files and programmes. 


  • Simulating emergencies

  • Full Moon makes animals loon

  • Unseen world of atoms

J.P. Garg tests your IQ



Enigma of life on Ganymede
by D.P. Singh

LIQUID water gets people excited because wherever it is found on earth, life is found too. The existence of water on Ganymede is all more exciting because it is the largest moon in the solar system (even larger than the planets Mercury and Pluto). Ganymede has an icy surface—and with it the possibility of liquid water and of life on it is likely. Like earth, it has a permanent magnetic field too, which protects parts of its surface from bombardment by life destroying radiation from outer space.

Galileo announced the discovery of Ganymede in 1610. The discovery provided strong support for the Copernican solar system. For over three and half centuries following its discovery, Ganymede remained a tantalising point of light in astronomers’telescopes, a tiny disc barely discernible even under the best atmospheric conditions.

In 1970s new observations and techniques resulted in the new awareness of the importance of Ganymede. Telescopic observations of the Ganymede’s spectra led to the knowledge of its surface composition. The Pioneer 10 and 11 flybys provided the first in situ measurements of the magnetospheric environment. And finally in 1979 the Voyager spacecraft transformed our view of it from a dot of light into a place, a New World seen clearly for the first time.

Jupiter is the largest of the planets in the solar system. Among Jupiter’s 16 satellites, the four Galilean satellites, Io, Europe, Ganymede and Callisto, are each planet-sized bodies. Ganymede is the ice giant of the satellite system. It is having a radius of about 2638 km. The density of the Ganymede is about 1930 kg/m. John Lewis, in his pioneering work done in the early 1970s pointed out that density like those of Ganymede is precisely what one would expect from condensation of solar-composition gas at temperatures where water ice is stable. Such a body would have approximate equal weights of silicates and water. With latest observations it has been proved that Ganymede has ice crust, convecting water or ice mantle and silicate-rich core.

For some time, astronomers suspected that Ganymede might harbour a watery ocean beneath its icy surface. They were right. The technique used earlier last year to demonstrate the existence of an ocean on Europa, another Jovian satellite, has been employed to detect an ocean on Ganymede. The results of these investigations have been reported at the American Geophysical Union meeting held in San Francisco recently.

Dr. Margaret Kivelson and her colleagues at the University of California, Los Angeles deduced the existence of an ocean on Ganymede using the data collected by Galileo, an American spacecraft that has been orbiting Jupiter. Their method was based on the observation that electrical currents will be induced in a conductor (such as water) when it is faced with a magnetic field that varies over time. Because Jupiter’s axis of rotation does not quite line up with its magnetic axis, the Ganymede feels such a fluctuating magneting force.

This induces an electrical current in the sub-surface ocean of Ganymede. That in turn induces a magnetic field oriented in the opposite direction to the field created by Jupiter. It is this induced magnetic field that Galileo measured when it flied past Ganymede during 2000. But, any magnetism induced in a putative Ganymede ocean risks being swamped by the Ganymede’s own magnetic field. Dr. Margaret was, however, able to adjust for this complicating factor.

She has reported at the recent American Geophysical Union meeting that an extensive analysis of the data from a number of Galileo’s Passes of the Ganymede is consistent with the presence of a conducting layer—almost certainly water—a few hundred kilometers beneath the ice. Dr. Margaret says that the chances of existence of a watery, albeit buried, ocean on Ganymede are real good. What is more, her study is in good agreement with other work announced at the meeting.

Dr. Robert Pappalardo and his team at the Brown University, Rhode Island has been studying high—resolution pictures of extremely smooth areas of Ganymede surface. Dr. Pappalardo has reported that it seems that these are areas where the crust has been pulled apart and water —or at least slushy ice—has risen from beneath to fill the gap. Thus, if there be an ocean on Ganymede, then we could consider looking for life which might be similar to the one known on earth, in that ocean.

Man has always been fascinated by the heavens. Discovery of Earth-like space-bodies will bolster the confidence of those who are convinced that we are not alone in this universe. At the same time, surprises cannot be ruled out. A systematic search of various satellites of the solar system has just begun. NASA expects to launch a series of space missions, which would help in detecting existence of water and consequently the existence of life on these satellites. As we enter the new millennium the solution to the enigma of extraterrestrial life appears to be round the corner!Top



Network security and hacking
by Deepak Bagai

IN its most traditional sense, a computer network is defined as a collection of desktop computers connected for sharing access to computing resources. These resources include printers, hard disk drives, files and programmes. Technically a computer network is a network of computers connected by specific type of transmission media and adapters and monitored by a number of operating systems that support all relevant communication protocols and standards. The overall solution is a system that allows easy communication, information sharing, and collaboration among all relevant users.

A computer network, like any other shared resource is subject to breaches of security. Such breaches can be accidental or international, and their effects on network operations can range from harmless to irritating to devastating. A secure network is one that is resistant to disruptions caused by unauthorised network use. Computer hacking is defined as the art of making changes to software after it has been compiled. Hacking is generally done for removing copy protection adding important features to existing programmes, cracking password control access, stealing code and finally for amusement.

An international survey on computer networks, over the last one-year, indicates that 50 per cent of the computer networks had been successfully attacked and penetrated by external sources. An unprotected network faces an intrusion threat. This enables unauthorised access to customer databases, business processes, key financial information and software codes. Service denial is another serious attack. Here the access to the network is denied and sometimes the network is brought down. Access to Internet has resulted in dubious downloads and transfer of junk mails. Open ports are a risk to a computer network. These ports offer an easy way for unauthorised access. SATAN (System Administrator’s Tool for Analysing Networks) is a software tool which helps the network managers to implement network security. The hackers use this utility to scan the open ports and thereby gain an access to the network. Phone banking services provided by the banks are prone to network intrusions. This is a potential risk to e-commerce.

The solutions enabling network security are in great demand. Passwords, digital certificates and time-base-authentication are some of the prominent measures in the area of network security. Time access is made possibly by encryption. Firewall installations comprise a unique signature coupled with IP address and thus protect the network. It has been proven beyond doubt that Internet is a boon for electronic commerce but at the same time it poses a great threat to internal security. There is no lock that cannot be picked, given sufficient time and inclination. Technology alone is inadequate to ensure network security. True network security ia a human issue, with responsibility divided between users and managers. Network security will ultimately pave the way for increased network reliability.Top




Simulating emergencies

You are in the bowels of a ship and water is pouring in through a gaping hole in the plating; the overhead pipework is gushing out hot steam and you have an injured crewman. What is your first move?

This is an example of the sort of problem that can be encountered by students training on this British damage control simulator. The simulator is in three easily transportable containers and normally contains a main training area [seen here] where students can practice plugging leaks, removal of flood water etc; a section into which smoke and fumes can be introduced and a control room for the instructors. In addition there is a broadcast system that can relay noises — such as gunfire — to add to reality.

The simulator can be designed as a multi-deck, multi-compartment complex built on the lines of a major warship, or in smaller, compact units suitable for training crews of smaller craft. The scope of the training include repairing holes in plating, mending broken pipework, shoring, pumping and flooding, rescue work and firefighting.

Full Moon makes animals loony

The widespread superstition that the lunar cycle affects creatures as well as the tide appears to be supported by a study which says animals bite more during a full moon, reports AFP.

Doctors at Bradford Royal Infirmary in Northern England took the hair of the dogma, deciding to test the hypothesis on hard facts.

They found that the chance of a human being bitten was twice as high or around full moon days compared with other days in the lunar cycle.

“An association exists between the lunar cycles and changes in animal behaviour and animals’ propensity to bite humans accelerates at the time of a full moon,” they wrote in the weekly British Medical Journal (BMJ).

The research was based on 1,621 admissions to the hospital’s accident and emergency department from 1997 to 1999.

Down under, however, animals appear to prefer to bare their fangs at different times. — (PTI)

Unseen world of atoms

Final checks are being made to one of the world’s most powerful mass spectrometers, capable of detecting all elements known to man to levels as minute as one part in one billion in solid samples.

Called the VG 9000, the British-developed machine is the first one of its kind to use a new technique known as “glow discharge” to examine samples. This avoids the complexity which surrounds many other methods for solids analysis and brings remarkable ease of operation to the procedure, making the glow discharge mass spectrometer suitable for both demanding research and process control, such as on a semiconductor production line.

The sample is bombarded by excited argon gas molecules which remove atoms from the surface of the material to be analysed. The charged atoms, which have been produced in the source, are accelerated through combined magnetic and electrostatic fields in the mass spectrometer which separates the atoms by atomic weight. The separate atoms are then collected and identified by a detector to reveal the amount of each element in the sample.

The VG 9000 is ideal for investigation into the purity of semiconductors, high purity metals and high temperature metals such as jet engine turbine blades. It also has a direct application for any process where impurities in the end-product can have critical effects on performance.


J.P. Garg tests your IQ

1. This qualified doctor of medicine is known more for his contributions to psychology than to medicine. His theories influenced not only sciences but many other fields as well. Name this great Austrian thinker who made a scientific study of human and social behaviour and postulated that this behaviour is primarily determined by our hidden mental processes.

2. Having 32,800 solar cells in it, this will be the third brightest object in sky after moon and Sirius (Dog Star). Can you name it?

3. Reflexed, Spider, Pompom, Button and Spoon are different shapes of a beautiful winter flower found in many different colours. Which is this flower?

4. ADAM is a condition that normally occurs in men above the age of 40. What is the full name of ADAM and what is its basic cause?

5. Carborundum is a substance nearly as hard as diamond. It is used for polishing and grinding tools, in grinding papers, in refractory bricks and blocks, etc. What is carborundum chemically?

6 Which instrument did the French watchmaker Eugene Bourdon patent in 1849? What for is this instrument generally used?

7 Which unit is generally used in calculating the energy value of foods and fuels?

8 What is a nuclear reactor called which produces energy as well as generates more fissionable material than is used in running it?

9 This fish can live outside water for even 3-4 years. When the conditions are not favourable,it borrows into the mud, emits out a viscous fluid and forms a shell around itself, and then goes into deep sleep for a long period, awaking only when the conditions improve. which is this fish that is found in south Africa, Africa and Australia?

10 A conference “ strings 2001’ based on the theme of the latest theory in Physics, called string theory and related areas was held recently in which a galaxy of theoretical physicists of the world participated. In which institute of India was this conference held?


1. Sigmund Frued 
2. International Space Centre 
3. Crysanthemum 
4. Androgen Deficiency in Ageing Males, also called male menopause; reduced production of the hormone testosterone 
5. Silicon carbide 
6. Bourdon Gauge, generally used to measure the pressure of compressed gas in a cylinder 
7. Calorie 
8. Breeder reactor or fast breeder reactor 
9. Lungfish; it has lungs in addition to gills which enable it to breathe outside water 10. Tata Institute of Fundamental Research, Mumbai. Top