ARIS :The European Space Agency will soon be launching a cosmic armada; in a unique scientific experiment to explore space weather and discover how the Sun affects our world.
For the first time, a fleet of four identical satellites will fly in group formation along elliptical orbits around the Earth, allowing scientists to make the first detailed, three-dimensional maps of the space environment within 1,20,000 kilometers of the planet's surface.
The spacecraft will be hoisted aloft from the Russian-operated space centre at Baikonur in Kazakhstan in two pairs, by two Soyuz launch vehicles in mid-June and July.
The Cluster II mission has been timed to coincide with the violent solar storms that eject high energy particles, which streak across the 150-million-kilometre gulf between the Sun and our planet in just a few hours.
The storms frequent every 11 years, with the next peak expected in the middle of this year, when the cluster satellites are sent into orbit.
Scientists at the Paris-based EAS are hoping that the $310 million mission will be a success. The first attempt to launch cluster satellites failed in June 1996.
The new satellites are due to be transported next month to the Baikonur centre, where a 30-strong German team will be waiting to prepare them for their mission.
Eleven of the identical instruments on board each of the space craft were developed wholly or in part by German scientific institutions.
The four satellites, improved versio`n of the ones lost in 1996, will spend two years gathering data on solar winds and the high-energy particles ejected from solar storms that they carry.
Together with the US-European project, solar and Heliospheric Observatory (SOHO), launched in November 1995, the cluster spacecraft will examine the long-term effects the Sun has had on our climate.
The four cylinder-shaped satellites, each weighting 1.2 tons, contain 50-metre wire antennas that will send back information on electrical fields and waves.
Occasionally, the Earth's protective magnetic field is so overwhelmed by particles blasted out during solar storms that the magnetic field fluctuates wildly, creating enormous electrical currents.
These currents can induce major power cuts, like one in 1989, when six million Canadians spent hours in freezing darkness during the middle of winter, when electricity transformers were knocked out.
Minor gusts in the solar wind can also interrupt short wave radio communications, damage communication satellites, which transmit television signals and telephone calls, and even increase corrosion in oil pipelines. "It's like a never-ending football game," says Cluster II project scientist Philippe Escoubet. "The Sun is kicking particles to us, like footballs. The Earth is the goal and its magnetic field is the goal-keeper. It's always trying to push the balls away, but some get past. When particles score goals, they disrupt the Earth. Sometimes the Sun is very quiet, but when it's very active, we get a lots of balls coming through."
The ESA is taking no chances with the launch this time. A test start with a Russian carrier rocket without a satellite pay-load is planned for March 20. Should this launch fail, an Ariane rocket is ready as a back up, to carry all four satellites in a single journey into space. (DPA)
The Times Of India, Mumbai
March 19, 2000.
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