<\/div>\nThese play an important role in the reactions that occur on the dust particles, explains Mathies.<\/p>\n
\u201cWhen the carbon dioxide, ammonia, water<\/span> and hydrocarbons are blasted by galactic cosmic rays they get activated <\/span>and can make new molecules,\u201d he says.\u00a0<\/span><\/p>\nTo recreate this extreme bombardment the team fired electrons at the icy sample, then analysed it to see what had been made. The result was remarkable.<\/p>\n
\u201cWhat we\u2019ve shown is that, once you make amino acids in these ices the continued irradiation with galactic cosmic rays also leads to the formation of simple polymers \u2013 the first step in the evolution of more complex molecules,\u201d says Mathies.<\/p>\n
In space those complex molecules could find their way into comets as the dust particles clumped together and eventually, it\u2019s thought, those comets that may have eventually collided with the young Earth.<\/p>\n
While the work of Mathies and his colleagues paints an incredible picture of the reactions that are likely to be occurring on interstellar dust particles, the idea of a comet smashing into Earth will no doubt evoke terrifying images of Armageddon for many.<\/p>\n
A present-day comet strike may not be the end of the world, but it would wreak considerable havoc. Credit: ANDRZEJ WOJCICKI\/SCIENCE PHOTO LIBRARY<\/span><\/figcaption><\/div>\nYet in our planet\u2019s distant past these violent collisions may have been the sources of yet more intriguing chemistry.\u00a0 \u00a0<\/span><\/p>\nDr Nir Goldman from the Lawrence Livermore National Laboratory and Prof Isaac Tamblyn from the University of Ontario Institute of Technology examine what reactions might have occurred at the heart of a comet as it slammed Earth.<\/span>\u00a0<\/span><\/p>\n\u201cComets contain a lot of raw material that could be useful for prebiotic chemistry \u2013 the chemistry of the building blocks of life \u2013 and the impact contains a lot of energy,\u201d explains Goldman.\u00a0<\/span><\/p>\nThis energy can drive chemical changes.<\/span><\/p>\n\u201cPrebiotic<\/span> materials, like amino acids for example, have fairly high energetic barriers for their formation.<\/span> If things happen in the right way this raw material gets just enough energy to push it over these barriers. You start with very simple things and then the impact event carries it one step higher in complexity.\u201d<\/p>\nThe impact itself produces an incredibly powerful compression wave inside the comet, which results in extraordinarily high temperatures and pressures.<\/p>\n
Yet just how extreme the conditions are during impact depends largely on the angle the comet strikes at, says Goldman, and that has important implications for the chemistry going on inside it.\u00a0 \u00a0 \u00a0<\/span><\/p>\nWhat happens if a comet hits a planet?<\/strong><\/h2>\n Impact zones on Jupiter created by the Comet Shoemaker-Levy 9, as seen by the Hubble Space Telescope. Eight impact sites are visible. Credit: Hubble Space Telescope Comet Team and NASA\/ESA<\/span><\/figcaption><\/div>\n\u201cIf a comet were to make a direct impact with a planet, this that could yield extremely high temperatures [around 10,000\u00b0C] and pressures, and it\u2019s not clear that any interesting chemistry could happen because the conditions are so intense,\u201d explains Goldman.<\/p>\n
\u201cNow if the comet comes in at a shallower angle, let\u2019s say 20\u00ba<\/span>, then the conditions are much tamer. The temperature might be more like 3,000\u00b0C, while the pressure is more in the order of 300,000 times normal atmospheric pressure.<\/p>\n\u201cThat\u2019s very hot and very compressed, which promotes reactivity, but not so hot that everything just gets obliterated.\u201d<\/p>\n
With the help of a supercomputer, Goldman and Tamblyn were able to model the chemical reactions that resulted within a comet undergoing these searing temperatures and crushing pressures.<\/p>\n
\u201c[Our simulations] zeroed in on an icy grain deep within the comet,\u201d says Goldman.<\/p>\n
The computer models showed that several biologically significant materials can be formed in the turmoil of a cometary impact.<\/p>\n
\u201cWe see things like precursors to amino acids, amino acids and aromatic compounds such as carbon ring structures, which are very stable rings of carbon molecules,\u201d says Goldman.<\/p>\n
A Hubble Space Telescope image of Comet (C\/2012 S1) ISON photographed on 10 April 2013 when the comet was 635 million km from Earth. Credit: NASA\/ESA\/STScI\/AURA<\/span><\/figcaption><\/div>\nThe results of Goldman and Tamblyn\u2019s simulations are perhaps most interesting when they\u2019re considered in the context of what was occurring in the chaos of the early Solar System.\u00a0<\/span><\/p>\n\u201cThere were periods of heavy bombardment in which trillions of tonnes of organic material could have been delivered to the early Earth per year,\u201d says Goldman.<\/p>\n
\u201cThat\u2019s a really fascinating thing to ponder because the cometary material is likely to have collided with Earth at all sorts of different angles \u2013 yielding a wide variety of impact pressures and temperatures \u2013 which ultimately could have produced an enormous amount of different kinds of chemistry.\u201d<\/p>\n
Yet for all we\u2019ve found out about cometary chemistry the question of how life itself arose on the Earth still remains.<\/p>\n
\u201cThere\u2019s a huge gap in our knowledge,\u201d says astrobiologist Dr Louisa Preston.<\/p>\n
\u201cWe get the chemistry and we get what life needs but what was that moment that it became biology?\u201d<\/p>\n
On that question, just like the comets out in the distant reaches of the Solar System, we may be in the dark for some time to come.<\/p>\n
This article originally appeared in the November 2013 issue of <\/strong><\/em>BBC Sky at Night Magazine<\/strong>.<\/strong><\/em><\/p> <\/body><\/html>\n Scientific research has strengthened theories that the ingredients for life could have been brought to Earth by comets. <\/p>\n","protected":false},"author":24,"featured_media":41040,"template":"","categories":[1],"acf":{"readingTimeMinutes":"8"},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/01\/did-comets-bring-life-to-earth.jpg",2192,1368,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/01\/did-comets-bring-life-to-earth-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/01\/did-comets-bring-life-to-earth-300x187.jpg",300,187,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/01\/did-comets-bring-life-to-earth-768x479.jpg",768,479,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/01\/did-comets-bring-life-to-earth-1024x639.jpg",800,499,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/01\/did-comets-bring-life-to-earth-1536x959.jpg",1536,959,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/01\/did-comets-bring-life-to-earth-2048x1278.jpg",2048,1278,true]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"Scientific research has strengthened theories that the ingredients for life could have been brought to Earth by comets.","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/rss_feed\/41039"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/rss_feed"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/types\/rss_feed"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/users\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media\/41040"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media?parent=41039"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/categories?post=41039"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2021\/01\/Comet-67P-645f6c2.jpg?quality=90&resize=620%2C491"\" "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2022\/10\/11.-IRAS055062414-c7268ec.jpg?quality=90&resize=620%2C558"\" "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2020\/07\/How-see-comet-neowise-d6b8b4f.jpg?quality=90&resize=620%2C381"\" "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2022\/05\/Spaceradiation-1961cf7.jpg?quality=90&resize=620%2C379"\" "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/01\/GettyImages-1148109654-06296bf-e1675076126241.jpg?quality=90&resize=620%2C402"\" "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/05\/Jupiter-impact-zones-comet-80a702f.jpg?quality=90&resize=620%2C585"\" "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\"""\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/04\/Comet-C-2012-S1-cpy-804058e.jpg?quality=90&resize=620%2C350"\" "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>