Galileo (Spacecraft and Satellite Navigation)

A final discovery occurred during the last two orbits of the mission. When the spacecraft passed the orbit of Jupiter’s moon Amalthea, the star scanner detected unexpected flashes of light that were reflections from moonlets. HP G62-140ES BatteryNone of the individual moonlets were sighted twice, hence no orbits were determined and the moonlets did not meet the International Astronomical Union requirements to receive designations.[40] It is believed that these moonlets most likely are debris ejected from Amalthea and form a tenuous, and perhaps temporary, HP G62-140ET Battery ring.

An image of Earth taken by Galileo during the GOPEX test, clearly showing bright laser pulses coming from a transmitting telescope on the night side. Galileo’s imager was panned downward during the exposure to separate the pulses, thus blurring Earth’s image on the right. HP G62-140SF Battery

[edit]Remote detection of life

Carl Sagan, pondering the question of whether life on Earth could be easily detected from space, devised a set of experiments in the late 1980s using Galileo’s remote sensing instruments to determine if life indeed could be detected during the first Earth flyby of the mission in December 1990. HP G62-140SS Battery After data acquisition and processing, Sagan et al. published a paper in Nature in 1993 detailing the results of the experiment. Galileo had found what are now referred to as the “Sagan criteria for life”; these were: strong absorption of light at the red end of the visible spectrum (especially over continents) which was caused by absorption by chlorophyll in photosynthesizing plants, HP G62-140US Battery absorption bands of molecular oxygen which is also a result of plant activity, infrared absorption bands caused by the ~1 micromole per mole (µmol/mol) of methane in Earth’s atmosphere (a gas which must be replenished by either volcanic or biological activity) and modulated narrowband radio wave transmissions uncharacteristic of any known natural source. HP G62-143CL Battery Galileo’s experiments were thus the first ever controls in the newborn science of astrobiological remote sensing. [41]