February 23, 2000
BERLIN, FEB 22: The Jupiter probe Galileo is about to embark on the biggest adventure of its four-year mission to investigate Jupiter, the largest planet in the solar system.
On its 27th orbit, the joint US-German project on Tuesday moves to a distance of just 230 kilometres from Io, one of the planet’s four main moons. Steered by the navigation team of the US Jet Propulsion Laboratory in Pasadena, California, into the middle of the radiation belt of Jupiter’s magnetic field, its cameras will take sharp and detailed pictures of the gaping hot mouth of the giant volcano Pele and the lava flow known as Tvashtar.
Most of the probe’s instruments are still working, in particular the camera, although Galileo left the earth more than 10 years ago. Last autumn it made close contact with Io, approaching to within 300 kilometres of the moon and entering Jupiter’s strong radiation belt. To the astonishment of the engineers, the electronic system on board has withstood twice the radiation intensity it was originally designed for. Scientific interest was awakened in Io when the US Voyager probe made an unexpected discovery. Io, the innermost of Jupiter’s four moons discovered by Galileo in 1610, is covered with a large number of volcanoes.
Previously thought to be a cold world covered in craters, modern space travel has revealed Io as a moon heaving with the fiery mouths of volcanoes from which sulphurous gases shoot up into the path the probe will take. Galileo, which cost 1.5 billion dollars, has been orbiting Jupiter since December 1995, powered by a system made by what was then MBB/MUNICH and is now Daimlerchrysler Aerospace, becoming the first artificial satellite of the huge planet, which is 318 times the mass of the Earth.
After the original flight around Jupiter, planned to last only two years, Galileo began a subsequent two-year trip using gravity to explore the icy moon, Europa. Despite a jammed main antenna, the unmanned craft has been able repeatedly to generate headline news and stimulate discussion over its 10-year odyssey. Following this most risky of its adventures with Io, the probe will embark on the Galileo Millennium Mission, which involves further investigation of Jupiter itself as well as two close approaches to the moon, Ganymede.
On December 30 this year the Cassini/Huygens probe will approach to 10 million kilometres (approximately) from Jupiter while on its way to Saturn. The two probes will allow the possibility for the first time of measuring Jupiter’s magnetic field from two points at once. After the encounter with Ganymede, fuel reserves on the probe, which is condemned to orbit the gas giant into eternity, will be running low. How much remains will decide whether Galileo will be able to transmit further pictures from Jupiter as it orbits the sun at a distance of an average 778.3 million kilometres.
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