NEIL ARMSTRONG had described his landing on the moon as “one small step for a man, one giant leap for mankind”. Thrill-spilling Hollywood movies like Independence Day, Contact, Men in Black and Mars Attacks, has romanticised this leap by depicting how mysteries of a different world come virtually true. On July 4, coinciding with the Independence Day of the US, a spacecraft from the earth called the Mars Pathfinder landed on our nearest neighbouring planet Mars. “Sci-fi became Sci-fact,” said a scientist with the National Aeronautics and Space Administration (NASA), US. The Pathfinder landed on the Red planet’s boulder-stricken terrain after bouncing wildly three times in the Martian atmosphere. It is now named as Carl Sagan Memorial Station after the world famous cosmologist Carl Sagan. NASA administrator Dan Goldin said that it was only right to remember Carl Sagan, who served as a consultant for all NASA’s spacecraft and whose television show Cosmos retraced 15 billion years of cosmic evolution. The mission which was launched last December, has thrilled millions of sci-fi fans not only in the US but also in other parts of the whole world. Ninety minutes after the Pathfinder landed successfully on the red planet, Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, were in the seventh heavens after the first data started coming. Brian Muirhead, deputy project manager, said, “This is the first interplanetary celebration of the birth of our nation. So it is a proud moment. And its nirvana for us space guys.” NASA scientists described this phenomenal scientific endeavour as a “success”. After 21 years of the landing of the Viking 2 spacecraft on the Mars on September 3, 1976, the Pathfinder’s quest is being highly lauded. The route of the spacecraft was so fine-tuned that the Pathfinder was headed for a 100-km-by-19.3-km ellipse in the southwest part of its original 160- km-by-97-km target. That could give the Pathfinder a view of a 16,000-ft (488 m) Martian island carved out by an ancient flood —sheer delight for geologists. The spacecraft entered the Martian atmosphere at an angle of 14 degrees. At an altitude of less than 11.2 km, the parachute unfurled. Then airbags inflated, descent rockets fired for a few seconds and the Pathfinder dropped to the surface at a velocity of 37 km an hour. It was still night while the Pathfinder landed on the rocky, dusty plains of Ares Vallis. The Ares Vallis landing site was selected after geologists studied photographs taken by the earlier Viking orbiters. The site appeared to be a flood plain where a variety of ancient highland rocks have been deposited most probably after catastrophic floods. Six hours after landing on the red planet, the spacecraft transmitted its first three-dimensional images from the Mars. Muirhead said, “We are on the surface of Mars and have received our first telemetry.” The first transmitted photographs showed the spacecraft and its attached roving vehicle in the foreground, upright, as well as a broad field of rocks and sand stretching to hills on the far horizon. An analysis of the pictures reveals a hitch that would almost certainly delay the deployment of the six-wheeled rover, Sojourner, but the delay would be not surprising and should not reduce the mission’s research, feel scientists. The 10-kg Sojourner is the first mobile vehicle to operate on another planet and is a test model for more advanced roving vehicles to be used on future missions to Mars. Although the Pathfinder and its rover are not fully equipped to identify signs of life, there is a device on the rover called an ‘alpha proton X-ray spectrometer’ to determine the mineral content of rocks scattered around the landing site. It is believed that the rocks were washed on the plain from the ancient highlands nearby and that their mineral composition should provide clues to the planet’s early environment. Moreover, it is believed that the rover will give detailed data on the geology, seismology, mineralogy, meteorology and half a dozen other sciences of the planet Mars. Besides, the Pathfinder is equipped with instruments for recording weather conditions, a twolense camera (which can rotate 360°) and 24 filters for producing colour photographs of the Martian landscape. Over the years, Russian spacecrafts have had seven failures and scored only four partial successes. The US had six successes, beginning with the Mariner 4 fly-by of the planet in 1965 and three failures. The most recent of these came in 1992, when the Mars Observer was lost as it approached the planet for a planned orbiting mission. No wonder then, there was a massive sense of relief on the Pathfinder’s success. The mission is not only the first in an ambitious programme of Mars exploration in the next coming years, but is also a critical test of a new approach to planetary expeditions by the US. The emphasis now lies on building several relatively low-cost crafts with limited objectives which would be sent to Mars regularly. Wesley T Huntress Jr, chief of space sciences at NASA said that this “amounts to the second era in the exploration of Mars”. The entire Pathfinder mission is estimated to cost $266 million. The last US mission, the unsuccessful Mars Observer, cost one billion dollar. NASA plans to have two missions for future: a lander and an orbiter to be flown to Mars at each subsequent 26-month, culminating in a mission in AD 2005 to bring back samples of carefully selected Martian rocks and soil for analysis. Scientists believe that there is little hope of life on Mars until they can study those rocks. Arthur C Clarke, renowned science fiction writer who wrote a guide to good gardening on Mars, sees the Pathfinder mission as a significant move towards the planet’s human colonisation. “It is still too much to hope whether there is life. If at all, traces would be on underground fossils,” he said. Even if no green beings are found on the planet by the time the Pathfinder series ends in AD 2005, earthlings may find answers to questions like what makes the Mars sky pink; whether Marsquakes occur; how the surface has been scarred, or if life forms — whether in the form of microbes — define Mars’ biochemistry.AFTER the demolition of Newport Number II dam on the Clyde river in Newport, Vermont, in last autumn, now there is a recent spate of dam-busting sweeping the US. According to jubilant campaigners, it took two years of intensive lobbying by people living near the dam on the Clyde to convince the government that they would rather have fish in the river than the two megawatt of power that Number II generated. “If I could catch salmon, I’d turn my television off, my electric blanket and my stereo, so that we could save electricity,” said 10-year-old Kate Grim at a citizen’s gathering. In fact, for the last 40 years, the dam has been preventing the salmon from reaching its spawning ground.

Damn these dams

While dam-busting, engineers should take care to save the entire river
system from degradation

After the dam disappeared with a loud roar and a bang, within a few weeks, the fish was back jumping in the free running water. Following this incident which is considered a turning point in the US’ history of hydroengineering, in Maine, the Kennebec Coalition is fighting to have the Edwards dam on the Kennebec river in Augusta demolished. Several dams on the Rogue river in Oregon and the Snake river in Idaho face a similar fate. Plans are also on the anvil to dismantle two dams on the Elwha river in Washington State. Organisations like the Trout Unlimited and American Rivers aim to take their campaigns to Washington DC. Under the umbrella of the Hydropower Reform Coalition, these groups are challenging federal government plans to relicense about 500 dams that have been operational for 50 years. Activists in Tasmania want the dam on the Franklin river dismantled so that the pink quartz beaches of Lake Pedder which were submerged by the reservoir, be uncovered. And in France, the environmental group SOS Loire has convinced the government to remove the Saint Etienne du Vigan dam on the upper Allier and the Maisons-Rouges on the Vienne river to restore passages for migratory fish through the upper Loire Valley. However, campaigners are of the opinion that for dismantling a dam, engineers must consider the entire river system, not just the concrete structure itself. Although, smaller dams like the Newport Number II may pose relatively lesser problems, costing just about $1 million to be removed within six weeks, large ones would present several problems, and even cause degradation to the environment. A nightmarish example on hand is the Fort Edwards dam on the northern stretch of the Hudson river in New York State, whose removal in 1973 caused environmental problems that are persistent even today. It is only now that the engineers are bringing together the expertise gained from two decades of removing dams. The American Society of Civil Engineers is looking at the lessons they have learnt so far and publishing technical guidelines for dam removal. According to Stephen Born, professor of planning and environmental studies at the University of Wisconsin, communities residing around dams want to ensure that dam removal improves river environment rather than degrades them. Born’s research shows that people are particularly worried about sediments in water which may be toxic. Inside a reservoir, organic material decomposes by using up the oxygen and leaves the water acidic. This in turn, reduces heavy metal salts to insoluble metals; iron, manganese and other metals accumulate in sediments at levels that prove fatal for the wildlife. Once liberated, the sediments wash downstream over fish spawning areas, damaging aquatic species habitats and altering water channels. Most often, all that is left after draining is a foul-smelling mudflat. “Over time, systems will stabilise,” says Born, “Excess sediment will be flushed out and water quality will be reestablished.” He argues that a carefully planned strategy for sediment removal and restoration can minimise the impact of the damage. In the longterm, environmental gains should outweigh any losses. For instance, a recent report from the Bureau of Reclamation showed that removing the Savage Rapids Dam on the Rogue river in Oregon could generate as much as $5 million a year from fishing alone. Ôûá

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