{"id":16766,"date":"2014-12-11T21:53:38","date_gmt":"2014-12-11T13:53:38","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/rosetta-raises-questions-on-how-water-got-to-earth\/"},"modified":"2014-12-11T21:53:38","modified_gmt":"2014-12-11T13:53:38","slug":"rosetta-raises-questions-on-how-water-got-to-earth","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/rosetta-raises-questions-on-how-water-got-to-earth\/","title":{"rendered":"Rosetta raises questions on how water got to Earth"},"content":{"rendered":"
\"A
A four-image mosaic of comet 67P\/Churyumov-Gerasimenko using images taken by Rosetta\u2019s navigation camera on Dec. 7 at a distance of 19.7 kilometers (12.2 miles) from the center of the comet. Credit: ESA\/Rosetta\/NAVCAM<\/figcaption><\/figure>\n

New readings from the European Space Agency\u2019s Rosetta mission have challenged the theory that comets brought water to Earth in a series of cataclysmic collisions during the solar system\u2019s chaotic youth.<\/p>\n

Rosetta found the type of water on comet 67P\/Churyumov-Gerasimenko does not match up with the water on Earth, meaning comets of its type could not have solely seeded the oceans billions of years ago and helped life take hold.<\/p>\n

Scientists wonder where Earth\u2019s water came from because the planet\u2019s surface was so hot after the solar system\u2019s formation 4.6 billion years ago that any water present would have boiled off, leaving Earth a desert wasteland.<\/p>\n

Water somehow got to Earth later, and researchers identified water-rich comets and asteroids as the most likely candidates. With Rosetta\u2019s results, attention could shift to asteroids as potential source of the water.<\/p>\n

\u201cWe knew that Rosetta\u2019s in situ analysis of this comet was always going to throw up surprises for the bigger picture of solar system science, and this outstanding observation certainly adds fuel to the debate about the origin of Earth\u2019s water,\u201d said Matt Taylor, ESA\u2019s Rosetta project scientist.<\/p>\n

Within a month of the probe\u2019s arrival at Churyumov-Gerasimenko in August, an instrument on the Rosetta spacecraft measured water vapor streaming away from comet 67P and found it much different than water sampled from Earth\u2019s oceans.<\/p>\n

\u201cThe key to determining where the water originated is in its \u2018flavor,\u2019 in this case the proportion of deuterium \u2014 a form of hydrogen with an additional neutron \u2014 to normal hydrogen,\u201d ESA said in a press release.<\/p>\n

Comparisons of the deuterium\/hydrogen ratios of water on Earth and on other objects in the solar system can help solve the puzzle of how water filled the oceans. Scientists believe the ratio changes based on when and where an asteroid or comet formed after the birth of the solar system.<\/p>\n

The ROSINA instrument on the Rosetta spacecraft discovered the water from comet 67P\/Churyumov-Gerasimenko has a D\/H ratio more than three times higher than water on Earth.<\/p>\n

\"Deuterium-to-hydrogen_in_the_Solar_System\"
The different values of the deuterium-to-hydrogen ratio (D\/H) in water observed in various bodies in the solar system. Credit: Data from Altwegg et al. 2014 and references therein<\/figcaption><\/figure>\n

Rosetta\u2019s comet belongs to the Jupiter family of comets scientists think formed in the Kuiper Belt beyond the orbit of Neptune. The mini-worlds were bumped into the inner solar system and became trapped there by the gravitational influence of Jupiter.<\/p>\n

Space probes and telescopes have recorded the D\/H ratios of water from 11 comets in the search for the origin of Earth\u2019s water.<\/p>\n

Europe\u2019s Giotto mission made the first measurement of a comet\u2019s D\/H ratio in 1986 when it flew by comet Halley \u2014 an Oort cloud comet that initially formed near Uranus and Neptune and then was gravitationally ejected into the farthest reaches of the solar system.<\/p>\n

Halley\u2019s ratio was twice the D\/H number of Earth\u2019s water, leading scientists to discount Oort cloud comets as the source of the oceans, according to a NASA press release.<\/p>\n

Only one comet contained water like Earth\u2019s.<\/p>\n

ESA\u2019s Herschel telscope looked at comet 103P\/Hartley 2 in 2011, finding it harbored water with a D\/H ratio very close to the value observed on Earth. The measurement surprised scientists because Hartley 2 is a Jupiter-family comet, which should have even higher D\/H values than Oort cloud comets like Halley.<\/p>\n

The results from Rosetta \u2014 published in this week\u2019s edition of the journal Science \u2014 show comet 67P\/Churyumov-Gerasimenko has the highest D\/H ratio of any comet ever measured.<\/p>\n

The measurement also questions where Jupiter-family comets like Churyumov-Gerasimenko and Hartley 2 originated. Going by scientists\u2019 previous understanding of D\/H ratios and Jupiter-family comets, the two worlds should have formed in the same region of the solar system and should contain similar flavors of water.<\/p>\n

\u201cThis surprising finding could indicate a diverse origin for the Jupiter-family comets \u2014 perhaps they formed over a wider range of distances in the young solar system than we previously thought,\u201d said Kathrin Altwegg, principal investigator for ROSINA and lead author of the paper reporting the results in Science.<\/p>\n

\u201cOur finding also rules out the idea that Jupiter-family comets contain solely Earth ocean-like water, and adds weight to models that place more emphasis on asteroids as the main delivery mechanism for Earth\u2019s oceans,\u201d Altwegg said.<\/p>\n

Water detected in asteroids is a match for Earth\u2019s oceans. Asteroids carry less water than comets but may have impacted Earth more frequently.<\/p>\n

\"Artist's
Artist\u2019s concept of the Rosetta spacecraft releasing the Philae lander. Credit: ESA\/ATG medialab; Comet image: ESA\/Rosetta\/Navcam<\/figcaption><\/figure>\n

Rosetta\u2019s mission will continue until at least the end of 2015 \u2014 and possibly months longer \u2014 as Churyumov-Gerasimenko\u2019s orbit brings the spacecraft and the comet closer to the sun. Flying in tight formation with the comet, Rosetta and Churyumov-Gerasimenko will reach their closest point to the sun in August 2015.<\/p>\n

Scientists expect the comet\u2019s jets and outgassing to fire up as it is heated by sunlight in the coming months. Officials plan to monitor the comet\u2019s changes and fly Rosetta through plumes of material pouring out of the comet over the next year.<\/p>\n

The \u201cescort phase\u201d of Rosetta\u2019s mission comes after the orbiter dispatched the Philae lander to touch down on the comet on Nov. 12.<\/p>\n

\u201cAs Rosetta continues to follow the comet on its orbit around the sun throughout next year, we\u2019ll be keeping a close watch on how it evolves and behaves, which will give us unique insight into the mysterious world of comets and their contribution to our understanding of the evolution of the solar system,\u201d Taylor said.<\/p>\n

Follow Stephen Clark on Twitter: @StephenClark1.<\/i><\/b><\/p>\n","protected":false},"excerpt":{"rendered":"

A four-image mosaic of comet 67P\/Churyumov-Gerasimenko using images taken by Rosetta\u2019s navigation camera on Dec. 7 at a distance of 19.7 kilometers (12.2 miles) from the center of the comet. Credit: ESA\/Rosetta\/NAVCAM New readings from the European Space Agency\u2019s Rosetta mission have challenged the theory that comets brought water to Earth in a series of […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[3097,3098,246,3373,4223],"class_list":["post-16766","post","type-post","status-publish","format-standard","hentry","category-news","tag-comet","tag-comet-67p-churyumov-gerasimenko","tag-esa","tag-rosetta","tag-water"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16766"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=16766"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/16766\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=16766"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=16766"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=16766"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}