Dessinnée by Otto Struve, the fragments of Comet Biela during his visit © 1846 University of Cambridge, Institute of Astronomy
With the arrival of large glasses and telescopes , the photography and spectroscopy, astronomers employed to scrutinize the appearance of comets , their nucleus, the coma (atmosphere), the tails. Giovanni Donati was the first in 1858 to deliver clichés and systematic physicochemical studies. Over the following decades, as has been mentioned above, traces of carbon diatomic, cyanide and other molecules were detected in their wake. Of collected data that allowed the researchers to the second half of the XX th century to compile the most comprehensive portraits of these bodies made of ice and dust ... The "dirty snowballs" in the words issued in 1950 by Professor Fred Whipple, professor at Harvard. http://enjoycoloring.com/ His model, then confirmed by observation suggests small body, made of ice (primarily water, the ammonia , methane and carbon dioxide ) and dust. Meanwhile, his colleague Johannes Oort proposed that they may come, in part, a huge "reservoir of comets" that is on the edge of the solar system. Hundreds of millions of potential comets, composed of the elements witnesses of the birth of our star and sometimes désorbitées ... In 1951, Gerard Kuiper propose meanwhile, the existence of a belt (which bears his name now) beyond the orbit Neptune originally short time elements.
Always fascinated by these icy stars, which are believed to hold some key to the origins of life - and oceans - on Earth, our species , which has since the 1950s, ever more efficient technology to explore its cosmic environment begins to consider approaching them or even address them. In 1985, the American space agency was the first to embark on the adventure with the Mission Ice / ISEE-3 ( International Cometary Explorer ) which continue 21P / Giacobini-Zinner just 7,800 km away. But the great year for this type of meeting is 1986 because it marks the return in our neighborhood of the most famous of all comets: Halley (she comes every 76 years). At that time, many space probes are then programmed as the Soviet Vega-1 and Vega-2 (they will venture, respectively, about 8,900 km and 8,000 km from its surface), Japanese Sakigake and Suisei. Not to mention Giotto , the most ambitious and promising of all.