Posted on 04/29/2010 1:28:12 AM PDT by The Magical Mischief Tour
Water ice has been found on the surface of a nearby asteroid for the first time – a discovery that could help explain how Earth got its oceans, scientists announced Wednesday.
Two teams of researchers independently verified that the asteroid 24 Themis – a large rock hurtling through space in the asteroid belt between Mars and Jupiter – is coated in a layer of frost.
They also found that the asteroid contains organic material, including some molecules that might be ingredients for life. But scientists have not found any evidence for life itself on this asteroid, or anywhere else in the universe beyond Earth.
While comets, which have characteristic tails and generally orbit farther out in the solar system, are known to have water, asteroids in that region were thought to be too close to the sun to contain water on the surface without it evaporating away. The largest asteroid in the solar system, Ceres, is thought to harbor a vast amount of frozen water, but scientists suspect all of it is buried beneath a rocky, dusty surface.
But in this new study, researchers found concrete proof of water ice on the surface of 24 Themis by measuring the specific characteristics of sunlight bouncing off the surface of the asteroid. They saw the tell-tale signatures of H2O coating most of the surface of the 123-mile (198-km) wide rock.
Icy rock
"This is the first time we've actually seen ice – literally H20 – on an asteroid," said one of the study leaders, Andrew Rivkin of Johns Hopkins University.
Previously, hints that water might be present on 24 Themis were found in the form of hydrated minerals, which were thought to have formed from the reaction of water with rock. But this time the researchers saw the direct signature of water itself, he explained.
Another science team, led by Humberto Campins of University of Central Florida, found the same thing. Both teams used the NASA Infrared Telescope Facility atop on Mauna Kea in Hawaii to make their observations, but conducted them on different nights.
"Our work and their work are very nicely confirming and complementary," Campins said.
Campins' team timed their observations so that they caught the asteroid at different points in its rotation, and combined these data to create a rough surface map, showing that not only is ice present on 24 Themis, but it coats much of the surface on all sides.
"To our surprise there was water ice, there were organic molecules, and they were more or less evenly distributed throughout the surface," Campins told SPACE.com. "We thought that was fascinating."
Both teams reported their findings in the April 29 issue of the journal Nature.
Another researcher – Henry Hsieh of Queen's University Belfast in the U.K., who was uninvolved in either study – noted surprise at the extent of ice coverage on the asteroid.
"The average temperatures of asteroids (about 150–200 Kelvin) at this distance from the sun should cause surface ice to sublimate away in a matter of a few years or less, which is inconsistent with the billions of years that Themis is thought to have spent at its current location," he wrote in an accompanying essay in the same issue of Nature.
Earth's water
The discovery might even provide clues about the origin of water on Earth.
Earth has had a violent history, having been bombarded with space rocks throughout much of its life. In particular, a large rock was thought to have crashed into Earth some 4.5 billion years ago, knocking off a chunk that became our moon. This collision would have heated things up so much, any water that was on Earth at that point was vaporized. So how did the oceans arrive?
Some scientists have suggested that most of it arrived via other asteroids that crashed into Earth later in smaller collisions. But for that idea to hold weight, asteroids would have to carry water. Comets aren't a good possibility for this scenario because the water they hold tends to be of a slightly different nature, with atoms in a different configuration, or isotope, than most of the water on Earth.
Though the recent measurements can't tell anything about the isotope ratio of the water on 24 Themis, the fact that there is water there at all is an encouraging sign.
"Our data are certainly at least consistent with the idea that you could bring in plenty of water form impacts," Rivkin said.
If it sounds surprising that the vastness of Earth's oceans built up from deposits of water by asteroids, Rivkin said it isn't that crazy an idea.
"We know that the rate of [asteroid] impacts was very high," he told SPACE.com. "If each impactor, each asteroid, were 20 to 30 percent water by weight, then that could potentially add up."
I would think the ice would have sublimated away.
Themis reaches perihelion at around 2.7 AU, at edge of the 'ice line'. If it were a little closer to the sun, then, yes the ice would probably evaporate.
Starting the countdown before the EPA tries to regulate it...
Evaporate and create an atmosphere... isn’t that the theory of how earth was created?
And tax it’s use....
Though the recent measurements can't tell anything about the isotope ratio of the water on 24 Themis, the fact that there is water there at all is an encouraging sign.
This statement is completely misleading and nonsensical. Different 'configuration or isotope'? Water is configured as water is, 2 Hydrogens, one Oxygen. Water does not have isotopes. Hydrogen might, Oxygen might. But all water molecules, whether they are constructed with H-1, H-2, H-3, O-16, or other Oxygen isotope, ALL behave the same chemically. This article is useful for composting only.
bflr
Caused by the planet it broke off of’s global warming.
Isn’t heavy water toxic to living organisms?
Toxic? No. Chemically, heavy water is the same as light, it is two hydrogens and an oxygen.
The same as the banana you may enjoy is radioactive from Potassium-41. Toxic? No.
Toxic? No. Chemically, heavy water is the same as light, it is two hydrogens and an oxygen.
The same as the banana you may enjoy is radioactive from Potassium-41. Toxic? No.
You sure about that? This website disagrees:
http://www.straightdope.com/columns/read/2135/is-heavy-water-dangerous
“Despite the fact the light water and heavy water are chemically identical, heavy water is mildly toxic. How can this be? Since heavy water is heavier than normal water, the speed of chemical reactions involving it is altered somewhat, as is the strength of some types of bonds it forms. This affects certain cellular processes, notably mitosis, or cell division, due to the difference in binding energy in the hydrogen bonds needed to make certain proteins. Mouse studies have shown that drinking only heavy water along with normal feed eventually causes degeneration of tissues that need to replenish themselves frequently, and leads to cumulative damage from injuries that don’t heal as quickly. One study likens the effects to those suffered by chemotherapy patients. Heavy water toxicity manifests itself when about 50% of the water in the body has been replaced by D2O. Prolonged heavy water consumption can cause death.”
I read somewhere else that it’s specifically the hydrogen isotope that causes problems. (With other isotopes the proportional difference in mass is too small to matter much.)
You asked, yet did not refute what I said. Ok then.
–adjective
1. of, pertaining to, affected with, or caused by a toxin or poison: a toxic condition.
2. acting as or having the effect of a poison; poisonous: a toxic drug.
–noun
3. a toxic chemical or other substance
Water, of and by itself, is Toxic. Over drink it, it will KILL you. Heavy water, either deuterium or tritium, behaves chemically the same as light water. The difference is that the other two forms of water use an isotope of hydrogen that is radioactive.
So, is heavy water toxic? Drink 20 gallons in an hour, probably so. But then light water would be too. For all intents and purposes, it is not. So, listen to fear mongers. Please stay away from all heavy water (Not possible, as it does occur naturally, but let’s not confuse this issue with facts). And do remember, even light water is toxic and dangerous.
Mouse studies have shown MANY substances to be toxic, but in everyday concentrations, not so much. Actually, it is the white mice that cause cancer.
Breathing straight oxygen is VERY dnagerous, don’t do that, you may burst into flame.
I’m not trying to be combative, but I don’t think we’re on the same page.
That website not making the point that drinking 20 gallons of heavy water would kill you, but that replacing your normal dose of light water with heavy water would kill you eventually due to differences in bond strengths (or something like that, I’m no chemist).
Not that this question is even important to the article really, except that I would find it pretty interesting if—as I interpreted the article to claim—the ice on comets tends to be comprised of water containing mostly deuterium, or some other variant.
It just lead me to wonder whether life would have been possible in a world containing greater proportions of deuterated water, or if we would have just evolved differently to utilize it normally. But then you said it wasn’t toxic, and I thought it was, leading to my response.
Jack Daniels with just a splash of Asteroid water please
Were you to replace any substance with something that is foreign, or intake any substance to excess, it is toxic.
But for all intents and purposes, in everyday life, the only practical difference is that heavy water (D2O or T2O) is radioactive.
Working at a heavy water reactor plant in Canada, where intakes of Tritium were expected, the course of action is to drink extra water, keep the kidneys flushing and active, because, chemically, Tritium behaved the same as light water. Monitoring was done via urinalysis.
But, I stand behind my contention that it is not chemically toxic. The only difference in the three is the number of neutrons present in the nucleus. All three have the same number of protons and electrons and it is the electrons that determine the chemical properties of an element.
As an aside, it is also my belief that we were created not eveolved.
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