Spacecraft, Galileo

In 1994, a unique incident occurred the impact of the Shoemaker-Levy comet on the Jovian atmosphere. Die strong gravitational field of Jupiter caused the comet to break up before it could enter the atmosphere, and the parts of the comet crashed separately into the atmosphere one after the other. This unique spectacle was observed by many observatories and also by the Galileo spacecraft and the Hubble telescope. It led to the discovery of yet another phenomenon the most intensive aurora effects in the solar system, observed at Jupiter s poles. Astronomers assume that the energy for these comes from the planet s rotation, possibly with a contribution from the solar wind. This process differs from that of the origin of the aurora on Earth, where the phenomenon is caused by interactions between the solar wind and the Earth s magnetic field. 

The SSI (solid-state imaging) camera on board the Galileo spacecraft transmitted impressive high-resolution pictures of Io s volcanic activity. Active lava lakes, lava curtains , calderas, mountains and plateaus can be seen (McEwen et al., 2000). The Hubble telescope detected both S2 gas and SO2 in a SO2 to S2 ratio of 1 4 in the smoke trail of the volcano Pele. This value suggests an equilibrium between silicate magmas in the neighbourhood of the quartz-fayalite-magnetite buffer (see Sect. 7.2.2). 

Aspects of the chemical composition of the atmospheres of Jupiter, Saturn, Uranus, and Neptune were measured by the Voyager and Galileo spacecraft in the 1980s and 1990s,... 

In contrast to the terrestrial planets, the giant planets are massive enough to have captured and retained nebular gases directly. However, concentrations of argon, krypton, and xenon measured in Jupiter s atmosphere by the Galileo spacecraft are 2.5 times solar, which may imply that its atmosphere preferentially lost hydrogen and helium over the age of the solar system. 

A recent laboratory comparison of the shape of the water of hydration bands with the spectra obtained by the Galileo spacecraft indicates that the hydrated material mentioned above might in fact be frozen, hydrated H2S04. This material would be produced by the charged particle irradiation of sulfate salts, sulfur or SO2 in an ice matrix. Therefore, a sulfur chemical cycle is maintained by the incident radiation, a cycle similar to that occurring at higher temperatures in the atmospheres of the Earth and Venus. On Europa, this involves oxidants such as SO ", H202 and 02 which have potential importance for the proposed prebiotic chemistry. 

Recent data from the near IR mapping spectrometer (NIMS) of the Galileo spacecraft has also identified areas on the moons in which the water bands axe shifted and suppressed, consistent with large surface areas... 

Sagan C., Thompson W. R., Carlson R., Gurnett D., and Hord C. (1993) A search for life on Earth from the Galileo spacecraft. Nature 365, 715-721. 

The mission to Venus, hy the Galileo spacecraft in 1989-90, produced relatively modest new data. The mission s primary objective was the planet Jupiter, and a visit to Venus was included only to provide a "gravity assist —a way to give the spacecraft the impetus it needed to get to the outer planet. During its closest approach of about 10,000 miles (16,000 km) from the planet, however, Galileo was able to carry out additional spectroscopic studies of Venus s clouds, collect photographs of its middle atmosphere clouds, and analyze radioactive sources present in the clouds. 

Fischer, Daniel. Mission Jupiter The Spectacular Journey of the Galileo Spacecraft. New York Copernicus Books, 2001. 

Pappa, R. S. and Juang, J. N. Galileo spacecraft modal identification using an eigensystem realization algorithm. Journal of Astronautical Sciences 33(1) (1985), 95-118. 

Cole, Michael D. Galileo Spacecraft Mission to Jupiter. Countdown to Space. New York Enslow, 1999. 

The Galileo spacecraft was launched in October 1989 it arrived at Jupiter in 1995 on September 21,2003, the mission was terminated by sending the orbiter into Jupiter s atmosphere at a speed of nearly 50 km/s to avoid any chance of it contaminating local moons with bacteria from Earth. 

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