|SCIENCE TRIBUNE||Thursday, February 7, 2002, Chandigarh, India|
A meteorite from India gives proof of water on Mars
current from heat
from India gives proof of water on Mars
Dr Hap McSween from the University of Tennessee (UT) and fellow researchers have found new evidence for water on Mars by re-examining the Shergotty Stone, a meteorite found in India in 1865.
Until five years ago, Mars was viewed as a dry and dusty planet, unable to support life, as we know it. Recent images from the Mars Global Surveyor have prompted some scientists to propose a much more watery past for the red planet, one that might even have supported life.
The images from space show evidence of oceans and lakes — evidence that has, until now, been contradicted by findings from the Martian meteorites like ALH 81005, found on earth.
However, Dr McSween
and colleagues from UT, Oak Ridge National Laboratory, the
Massachusetts Institute of Technology and the University of South
Florida show, for the first time, that a Martin meteorite that fell in
India contained water.
According to Dr McSween, scientists had accepted, mostly from the rock evidence, that Mars is dry. However, now they are seeing evidence that Mars was actually wet and that there may be water seeping out even now.
McSween and fellow researchers found evidence for water in the Shergotty Stone through two independent lines of research, one that involved studying the patterns of water-soluble trace elements, the other reproducing the order in which the meteorite’s crystals were formed.
Both showed evidence that the meteorite was formed in a watery magma layer before being propelled to the surface by one of the volcanic eruptions that probably formed the Martian ocean.
Dr McSween has studied the Shergotty meteorite for 23 years now.
It’s somewhat amazing that after more than two decades we are still finding out new things from this one rock. It is an indication of the increasing sophistication of the techniques available to scientists now.
A meteorite fell near the village Shergotty, in Gaya district of Bihar in 1865. As meteorites are generally known by the site where they are found, the meteorite came to be known as Shergotty. The meteorites similar to it are now called as Shergottites.
No one at that time even thought that it could have come from the planet Mars, our nearest neighbour in the Solar System.
Meteorites from Mars belong to one of the following group of meteorites. They are or Shergottites, Nakhlites and Chassignites and are believed to have their origin in Mars.
Earlier, it was believed that these meteorites came from the asteroid belt lying between the orbits of Mars and Jupiter. There are more than 100,000 asteroids larger than 1 kilometre in diameter, but these objects are distributed within the huge volume of the asteroid belt.
The isotopic age, which represents the time during which, the Shergottites crystallised indicates that they are of a much younger age than other meteorites. In other words, they need not have originated in the asteroid belt.
Their chemical and isotopic
composition and flight through space indicate an origin in a heavenly
body other than Moon and asteroids. Moreover, the noble gases like
argon, krypton and xenon trapped within these meteorites are similar
in composition to the Martian atmosphere, claims Dr Donald Bogard of
Johnson Space Centre, U.S.A.
Electric current from heat
A new kind of microchip capable of turning waste into electric current is being bench-tested in the USA, Britain’s New Scientist magazine reports.
The device, called a thermal diode, is being put through its paces at Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts.
It could be used to harness heat from a car’s engine and provide power for its electronics, charge laptop batteries by recycling heat from the computer’s microprocessor, or simply bask in the baking desert sun generating electricity, say the inventors.
The device makes use of an effect first noted by inventor Thomas Edison in 1883, generating electricity by using heat from the environment.
Normally the temperatures needed to generate a tiny current are very high — around 1,000 degrees centigrade and as a result thermal diodes have found only limited applications, such as making electricity from nuclear sources in space probes or satellites.
Attempts to make semiconductor versions of these devices have always been foiled by the technical difficulties of creating a very narrow vacuum gap between chip layers.
Peter Hagelstein, a physicist at MIT, and Tan Kucherov at energy conversion start-up ENECO in Salt Lake City, Utah, have a better idea. Their first attempt at a semiconductor version of a thermal diode operates at the comparatively low temperature of 200 degrees centigrade.
Hagelstein and Kucherov’s big idea is to replace the normal vacuum gap with layers of an electron-rich semiconducting material. They found that this significantly boosted the current generated.
NEW PRODUCTS & DISCOVERIES
Drawbridges are quaint, but they are so medieval. So when city planners in the industrial town of Gateshead, in northeast England, picked a design for a new pedestrian and bike bridge to connect Gateshead with the historic city of Newcastle across the winding river Tyne, they decided that a break from tradition was in order. For most of the day, a single steel arch vaults high above the water, fixed by 18 harp like suspension cables to a 413-ft.-long, curved pathway below.
When a boat approaches, however, the entire bridge pivots to one side. As the lower deck rises into the air, the upper arch descends on the other side until both halves are suspended opposite each other some 90 ft. in the air.
Powered by hydraulics, the $25 million Millennium Bridge can tilt back and forth in four minutes. The bridge is the centerpiece of a multimillion-dollar urban-renewal plan that will eventually connect a new arts centre to hotels and restaurants on either shore.
A MIND-INTERNET INTERACTION
Researchers have devised a scheme for sending signals from the brain of a monkey over the internet to control a robotic arm which could have far reaching consequences like putting paralised people in control of artificial limbs and improving the understanding of how humans might do better at controlling machines at a distance.
Scientists at the Duke University at Durham, N.C., led by Miguel Nicolelis, implanted electrodes into the cerebral cortex, a part of the brain that helps control movement.
Cells there become electrically active in the planning stages of a movement, hundreds of milliseconds before the motion is executed, a report in IEEE Spectrum said.
The Duke team developed software algorithms that would let them forecast the movement the monkey was planning — in this case, to reach for a morsel of food — by reading the pattern of activity picked up in the electrodes.
A separate software programme then translated that pattern into signals that were sent via a local area network to a robotic arm in Nicolelis’ laboratory. PTI
RADIO FREQUENCY COIL FOR MRI
Scientists have developed the world’s first radiofrequency coil to be sued for magnetic resonance imaging (MRI) of the human lung with helium — a method that provides higher resolution and prevents exposure to X-rays and harmful radioactive substances.
The first signs of emphysema, excessive swelling of the pulmonary alveoli which can lead to death through heart failure, can be detected by magnetic resonance imaging, provided that gaseous and non-radioactive isotope helium-3 is used as a contrast medium.
But the "magnetic resonance" team at the Fraunhofer Institute for Biomedical Engineering IBMT, based in St Ingbert in Saarland, and several departments of the University of Mainz, have done a great deal to promote the routine and clinical application of the helium method.
Frank Volke, head of the IBMT’s group says "We have developed the world first radiofrequency coil approved for use in clinical applications of MR scanning of the human lung with helium, and certified by the German Technical Inspectorate (TUV)." PTI
SHOWCASE FOR MUSEUMS
Researchers have successfully developed a virtual showcase which enables people to view the original shape of any broken antique object by merging the real artifact with virtual computer-generated information.
Museum visitors often have to stretch their powers of imagination as to what would have been the original shape of the antique vase, of which now only the broken fragments can be viewed in the display cabinet.
Science & Technology crossword
1. A surveyor’s point of reference.
8. This concept is need of the hour in housing.
10. A primary mean of transportation.
12. International unit system.
14. A cantilever is supported at one... only.
15. This point determines the type of failure in slopes.
16. A divisional engineer in a department (abbr.)
17. Used to conduct UV stabilisation test on plastic materials.
18. A method for design of rigid pavements.
19. This type of steel bridges are very useful for long spans.
20. A major Indian construction company.
22. Rail provided at the switch angle in rail-line.
23. Surkhi used as a substitute for sand is of this colour.
1. One of the most precise hand instruments used to measure angles.
2. The heart of an equipment.
3. A fine plastic soil with low permeability.
4. Long handed tool for scrapping of weeds.
5. A term to denote generation capacity of power plants.
6. Term to denote annual appraisal reports (abbr.)
7. Upper covering of a building.
9. A type of sedimentary rock.
11. An instrument that indicates the distance travelled to the aircraft pilot.
13. Line of rocks and gravel carried by Glacier.
18. The hydrogen ion concentration of a liquid.
21. A method for design of flexible pavements.
Solution to last week’s crossword: