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Stardust briefing
Scientist present new findings from the Stardust spacecraft's encounter with Comet Wild 2 in this news conference from NASA Headquarters on June 17. (26min 12sec file)
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New pictures explained
New pictures of Comet Wild 2 from NASA's Stardust spacecraft are shown here with narration by lead mission scientist Donald Brownlee. (3min 06sec file)
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Stardust's comet flyby
Animation depicting Stardust's flyby of Comet Wild 2 and the powerful jets of dust streaming from the comet's surface is presented with narration by scientist Benton Clark. (1min 59sec file)
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Moon-Mars commission
After releasing its report, the President's Commission on Moon, Mars and Beyond holds a news conference in Washington. (60min 18sec file)
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NASA workers respond
NASA Administrator Sean O'Keefe and commission chairman Pete Aldridge address the NASA workforce and answer questions after the Moon, Mars and Beyond report is released. (75min 24sec file)
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Scientists ask if comets once flooded Earth's oceans
EUROPEAN SPACE AGENCY NEWS RELEASE
Posted: June 19, 2004

Did the Earth form with water locked into its rocks, which then gradually leaked out over millions of years? Or did the occasional impacting comet provide Earthıs oceans? The Ptolemy experiment on Europe's Rosetta comet probe may just find out.

The Earth needed a supply of water for its oceans, and the comets are large celestial icebergs - frozen reservoirs of water orbiting the Sun.

Did the impact of a number of comets, thousands of millions of years ago, provide the Earth with its supply of water? Finding hard scientific evidence is surprisingly difficult.

Ptolemy may just provide the information to understand the source of water on Earth. It is a miniature laboratory designed to analyse the precise types of atoms that make up familiar molecules like water.

Atoms can come in slightly different types, known as isotopes. Each isotope behaves almost identically in a chemical sense but has a slightly different weight because of extra neutrons in its nucleii.

Ian Wright is the principal investigator for Ptolemy, an instrument on Rosettaıs Philae lander. By analysing with Ptolemy the mix of isotopes found in Comet 67P/Churyumov-Gerasimenko, he hopes to say whether comet water is similar to that found in Earthıs oceans. Recent results from the ground-based observation of another comet, called LINEAR, suggested that they probably are the same.

If this is true, then scientists have solved another puzzle. However, if the comets are not responsible for Earthıs oceans, then planetary scientists and geophysicists will have to look elsewhere.

For example, the answer could be closer to home, through processes related to vulcanism. Also, meteorites (chunks of asteroids or comets that fall to Earth) have been found to contain water but it is bound to the minerals and in nothing like the quantity found in comets.

However, since the Earth formed from rocks similar to the asteroids, it is feasible that enough water could have been supplied that way.

If comets did not supply Earthıs oceans then it implies something amazing about the comets themselves. If Ptolemy finds that they are made of extremely different isotopes, it means that they may not have formed in our Solar System at all. Instead, they could be interstellar rovers captured by the Sunıs gravity.

Rosetta, Philae and Ptolemy will either solve one scientific mystery, or open another whole set of new ones.

John Glenn Mission Patch

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The historic first orbital flight by an American is marked by this commemorative patch for John Glenn and Friendship 7.
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Final Shuttle Mission Patch

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The crew emblem for the final space shuttle mission is available in our store. Get this piece of history!
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Celebrate the shuttle program

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This special commemorative patch marks the retirement of NASA's Space Shuttle Program. Available in our store!
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Anniversary Shuttle Patch

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This embroidered patch commemorates the 30th anniversary of the Space Shuttle Program. The design features the space shuttle Columbia's historic maiden flight of April 12, 1981.
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Mercury anniversary

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Celebrate the 50th anniversary of Alan Shephard's historic Mercury mission with this collectors' item, the official commemorative embroidered patch.
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Fallen Heroes Patch Collection
The official patches from Apollo 1, the shuttle Challenger and Columbia crews are available in the store.
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Ares 1-X Patch
The official embroidered patch for the Ares 1-X rocket test flight, is available for purchase.
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Apollo Collage
This beautiful one piece set features the Apollo program emblem surrounded by the individual mission logos.
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Expedition 21
The official embroidered patch for the International Space Station Expedition 21 crew is now available from our stores.
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Hubble Patch
The official embroidered patch for mission STS-125, the space shuttle's last planned service call to the Hubble Space Telescope, is available for purchase.
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