Scientists working on the European Space Agencys Rosetta probe mission have found xenon on Comet 67P a discovery that introduces a link between the cosmic rock and Earth for the first time. <\/p>\n
The Rosetta spacecraft was launched in 2004, and its companion lander unit, Philae, arrived at the comet a decade later. Both were tasked with finding signs of how comets could uncover the origins of the solar system and life on Earth. <\/p>\n
The latest findings have found a connection that might answer the question of how material may have been delivered to our planet, when Earth was beginning to take shape about 4.6 billion years ago. <\/p>\n
Its all to do with xenon; a colourless, odourless noble gas that makes up less than a billionth of the volume of Earths atmosphere. <\/p>\n
Seven different isotopes of xenon and traces of krypton were identified by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis. The spacecraft had to fly very close - about 5 km to 9 km from the surface of the comets nucleus - to pick up the xenon signatures, which are spread thinly. <\/p>\n
The unique blend of the gas might match the concentrations found in the Earths early atmosphere, according to the results published in Science. <\/p>\n
\"Xenon is the heaviest stable noble gas and perhaps the most important because of its many isotopes that originate in different stellar processes: Each one provides an additional piece of information about our cosmic origins,\" said Bernard Marty, lead author of the study and a researcher at the Universit de Lorraine, France. <\/p>\n
It can be formed in different ways such as the swelling of low- and intermediate-mass stars and supernova explosions, which lead to nuclear fusion reactions. Each method leads to a different isotope of xenon, allowing researchers to work out where the samples come from. <\/p>\n
One of the hypotheses is that the xenon in the solar system comes from the protosolar cloud, a ball of gas and dust out of which the Sun and the planets were formed. The xenon on Earth, however, is thought to have been delivered at a later stage by comets. <\/p>\n
The relative abundances of the various isotopes vary in the atmospheres of Earth and Mars, in meteorites, and the solar wind. It is believed that Earth once contained a higher abundance of lighter xenon isotopes, a primordial mixture known as U-xenon. But present concentrations have heavier isotopes, as the lighter ones have escaped Earths gravitational pull and floated off into space. <\/p>\n
Bernard has called the discovery a potential candidate for U-xenon, which would indicate that the noble gas was indeed delivered by impacting asteroids and comets like Comet 67P. <\/p>\n
It is estimated that comets may have brought up to 22 per cent of the xenon once present in Earths atmosphere. <\/p>\n
The results also support the idea that comets could also have been carriers of pre-biotic molecules such as phosphorus and glycine, an amino acid, necessary components for life on Earth. <\/p>\n
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Originally posted here:<\/p>\n
Science megablast: Comets may have brought xenon to Earth - The Register<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" Scientists working on the European Space Agencys Rosetta probe mission have found xenon on Comet 67P a discovery that introduces a link between the cosmic rock and Earth for the first time. Continue reading