Skip to comments.Rosetta Instrument Reignites Debate on Earth's Oceans
Posted on 12/11/2014 2:15:28 AM PST by iowamark
The question about the origin of oceans on Earth is one of the most important questions with respect to the formation of our planet and the origin of life. The most popular theory is that water was brought by impacts of comets and asteroids. Data from the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument aboard the European Space Agencys Rosetta spacecraft indicate that terrestrial water did not come from comets like 67P/Churyumov-Gerasimenko. The findings were published today in the journal Science.
Researchers agree that water must have been delivered to Earth by small bodies at a later stage of the planets evolution. It is, however, not clear which family of small bodies is responsible. There are three possibilities: asteroid-like small bodies from the region of Jupiter; Oort cloud comets formed inside of Neptune's orbit; and Kuiper Belt comets formed outside of Neptune's orbit.
The key to determining where the water originated is in its isotopic flavor. That is, by measuring the level of deuterium a heavier form of hydrogen. By comparing the ratio of deuterium to hydrogen in different objects, scientists can identify where in the solar system that object originated. And by comparing the D/H ratio, in Earths oceans with that in other bodies, scientists can aim to identify the origin of our water.
The ROSINA instrument on the Rosetta spacecraft has found that the composition of comet 67P/Churyumov-Gerasimenkos water vapor is significantly different from that found on Earth.
The value for the D/H ratio on the comet is more than three times the terrestrial value. This is among the highest-ever-measured values in the solar system. That means it is very unlikely that comets like 67P/Churyumov-Gerasimenko are responsible for the terrestrial water.
The D/H ratio is the ratio of a heavier hydrogen isotope, called deuterium, to the most common hydrogen isotope. It can provide a signature for comparison across different stages of a planet's history.
We knew that Rosettas in situ analysis of this comet was always going to throw us surprises," said Matt Taylor, Rosettas project scientist from the European Space Research and Technology Center, Noordwijk, the Netherlands. The bigger picture of solar-system science, and this outstanding observation, certainly fuel the debate as to where Earth got its water.
Almost 30 years ago (1986) the mass spectrometers on board the European Giotto mission to comet Halley could, for the first time, determine D/H ratio in a comet. It turned out to be twice the terrestrial ratio. The conclusion at that time was that Oort cloud comets, of which Halley is a member, cannot be the responsible reservoir for our water. Several other Oort cloud comets were measured in the next 20 years, all displaying very similar D/H values compared to Halley. Subsequently, models that had comets as the origin of the terrestrial water became less popular.
This changed when, thanks to the European Space Agency's Herschel spacecraft, the D/H ratio was determined in comet Hartley 2, which is believed to be a Kuiper Belt comet. The D/H ratio found was very close to our terrestrial value -- which was not really expected. Most models on the early solar system claim that Kuiper Belt comets should have an even higher D/H ratio than Oort cloud comets because Kuiper Belt objects formed in a colder region than Oort cloud comets.
The new findings of the Rosetta mission make it more likely that Earth got its water from asteroid-like bodies closer to our orbit and/or that Earth could actually preserve at least some of its original water in minerals and at the poles.
Our finding also disqualifies the idea that Jupiter family comets contain solely Earth ocean-like water, said Kathrin Altwegg, principal investigator for the ROSINA instrument from the University of Bern, Switzerland, and lead author of the Science paper. It supports models that include asteroids as the main delivery mechanism for Earths oceans.
Comets are time capsules containing primitive material left over from the epoch when the sun and its planets formed. Rosetta's lander obtained the first images taken from a comet's surface and will provide analysis of the comet's possible primordial composition. Rosetta will be the first spacecraft to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the sun's radiation. Observations will help scientists learn more about the origin and evolution of our solar system and the role comets may have played in seeding Earth with water, and perhaps even life.
Rosetta is an ESA mission with contributions from its member states and NASA. The Jet Propulsion Laboratory, Pasadena, California, a division of the California Institute of Technology in Pasadena, manages the U.S. contribution of the Rosetta mission for NASA's Science Mission Directorate in Washington. JPL also built the MIRO instrument and hosts its principal investigator, Samuel Gulkis. The Southwest Research Institute (San Antonio and Boulder) developed the Rosetta orbiter's IES and Alice instruments, and hosts their principal investigators, James Burch (IES) and Alan Stern (Alice).
For more information on the U.S. instruments aboard Rosetta, visit:
More information about Rosetta is available at:
If you are the first to buck conventional wisdom (and, especially if you are right), you will suffer for it. The sciences can be particularly vicious that way.
God is the source you seek.
Personally I wouldn’t expect short period comets like this one to have much water. They have made so many passes around the sun the water would be baked out of them years ago.
Long period comets with million year orbits would probably have much more water.
However, that doesn’t necessarily exclude asteroids.
A little common sense reveals that it is utterly nonsensical that bodies falling to earth delivered oceans of water to earth.
And yet secular humanist science believers are all told to believe this and they do.
I remember reading somewhere that the Earth is constantly bombarded by small space debris, and that this debris increases the amount of water on the Earth by about 40 tons per day. Does anyone else remember seeing that?
Thanks for the ex cathedra view, but you don’t know what you’re talking about.
Wow, I didn’t know he’d passed, :’( thanks for that information, and for this topic.
My theory is that comets are the source of Earth’s land but, I could be wrong.
Maybe they were talking about this thing called rain, it’s gazillions of tiny droplets of water that fall from the sky to the ground. However rain does not add any net “new” water to earth.
Sorry for being so sarcastic - it was not directed “at” you - it was just too inviting an opportunity to pass up for a little attempt at sarcastic humor.
I think the oceans were created by a massive project that was a joint effort of KBR, Bechtel and Halliburton, financed through the Carlyle Group.
They had a massive space program, with its corporate headquarters based in their solar system, on their home plant, NeWO, which gathered up the raw materials from various galaxies, transported them to our solar system, and deposited and arranged them here on earth.
I’ve read that carbonaceous chondrites can have up to 22% water and that during the early post “great thwack” formation of the moon period they rained down, bombarded, the early earth. They were formed from the dust in the region of earth. However, I can’t recall the D/H composition.
The sciences can be particularly vicious that way.
If intense radiation can strip H2 of a neutron, would this not affect the detected ratios in comets?
Deuterium (symbol D or 2H, also known as heavy hydrogen) is one of two stable isotopes of hydrogen. The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common hydrogen isotope, protium, has no neutron in the nucleus... deuterium accounts for approximately 0.0156% (or on a mass basis: 0.0312%) of all the naturally occurring hydrogen in the oceans... Because deuterium is destroyed in the interiors of stars faster than it is produced, and because other natural processes are thought to produce only an insignificant amount of deuterium, it is thought that nearly all deuterium found in nature was produced in the Big Bang 13.8 billion years ago, and that the basic or primordial ratio of hydrogen-1 (protium) to deuterium (about 26 atoms of deuterium per million hydrogen atoms) has its origin from that time. This is the ratio found in the gas giant planets, such as Jupiter. However, different astronomical bodies are found to have different ratios of deuterium to hydrogen-1, and this is thought to be as a result of natural isotope separation processes that occur from solar heating of ices in comets. Like the water-cycle in Earth’s weather, such heating processes may enrich deuterium with respect to protium. In fact, the discovery of deuterium/protium ratios in a number of comets very similar to the mean ratio in Earth’s oceans (156 atoms of deuterium per million hydrogens) has led to theories that much of Earth’s ocean water has a cometary origin.
OK, so no nuclear stripping, but infra red heat to "distill" as it were, and then perhaps stripping the comet of one isotope over another as the comet proceeds through the intense magnetic influence of the sun
I only ponder if going in and out of the sun's electromagnetic and radiation fields could have an effect on the detected ratios of H2/H1 on comets?
I do realize planets would tend to be stable in their detected ratios, because of their stable orbit. But comets are not so stable.
Is it possible, just possible, that over sufficient passes close to the sun (relatively speaking) the ratios could change?
And if it is possible, then the comparison for purposes of stating where water came or did not come from becomes less clear.
Related, just what is the tail composed of?
The ratio in comets and the oceans works out to about 1:6410, the ratio in Jupiter and other large extraterrestrial sources is about 1:6420; since the deuterium or heavy water is more prevalent in comets and in Earth’s oceans, stripping the neutrons would give the opposite result, similarly to differential heating.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.