HAMBURG (dpa) – After the most successful interplanetary research mission in history, the German-American space craft Galileo has now been put on course for a crash landing with the planet it has been studying for more than half a decade: Jupiter.
Next November, the “miracle space probe” will pass by Jupiter more closely than it ever has in its previous 33 fly-bys, and then almost a year later, it will, as planned, disappear into the planet’s atmosphere.
That event will close the logbook on a mission which, despite the early loss of the main antenna, provided for a whole series of “firsts” in space exploration and ushered in a new era of planetary research.
As with so many things with this probe, even the way it got started on its journey was unusual.
Brought aloft on October 18, 1989 by the U.S. space shuttle “Atlantis”, the Galileo was the first to be sent into the interior of our solar system in order to use the gravitational fields of Venus and the Earth to send it, slingshot-style, soaring towards Jupiter.
The darkest chapter came on April 11, 1991, when the main antenna, which had been folded up for protection against the heat as Galileo passed by the sun, failed to properly unfold again. Months of attempts to open the antenna up proved to be futile.
It still appears to be something of a miracle that, with the help of a small auxiliary antenna, 70 per cent of Galileo’s research program could still be carried out.
After an odyssey of several years the probe, with its propulsion system built by the former German aerospace company MBB, achieved its orbit around Jupiter in December 1995. Before that, Galileo succeeded in training its eye on the “Gaspra” asteroid and in discovering a moon in Jupiter’s system.
Astronomers say a pioneering feat was the first documented collision of objects in our solar system: in July 1994, Galileo witnessed the crash of the Shoemaker-Levy 9 comet onto Jupiter.
Initially, Galileo’s mission to study Jupiter and its moons was to have lasted until 1997. But it was extended three times. In this period, the probe absorbed three and one-half times the amount of dangerous radiation than its builders had conceived.
Galileo’s arrival at Jupiter was accompanied by a number of highlights, including the dropping of a smaller capsule into the thick atmosphere of a planet with 318 times the mass of the earth, providing new scientific data. Later, Galileo would collect scientific information in flying closely past the four main moons of Io, Europa, Ganymede and Callisto.
The probe discovered that Ganymede had its own magnetic field, and also found out that Io has the most active volcanic activity of any moon in the solar system. The silicate-sulphur volcanic gases were found to be as hot as volcanoes are believed to have been two billion years ago on earth.
Surprise discoveries came in the form of finding out that on Europa and Callisto, there may be salt water oceans beneath those moons’ frozen surfaces. This discovery, coupled with the prospect that there might be primitive forms of life, has led to plans being made for a new space probe mission to Europa.
The radiation on Jupiter has impaired some parts of the Galileo probe. Due to the danger which would be posed by a probe orbiting out of control, the scientists have abandoned the original plans of simply letting Galileo freely roam the Jupiter system.
Above all, they wanted to avoid the moon Europa, where primitive organisms might be living, from becoming radioactively contaminated by the space probe.
So instead, Galileo has been put on a course to crash it into Jupiter, that event foreseen for September 2003.
By that point, it will have been around 30 years since the first plans for the probe were being drawn up at the Jet Propulsion Laboratory in Pasadena, California. Thousands of people have been employed to work for the 1.4 billion dollar Galileo project.
And it is certain that Galileo’s discoveries and scientific data will continue to provide puzzles for scientists for many years to come.
