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Solar Power
Posts: 1,904
Reply with quote  #1 

As with many women who have been scorned, the payback is hell to live with… or in this case, live on. Venus may have been warm and inviting early on but something bad happened along the way that forever changed her temperament.


Will mankind ever find a way to calm Venus down and restore her warm and inviting disposition? Who can say today… but with our long record of callous manhandling of this Earth we live on, I would not place any bets that man will ever learn to appease a woman scorned… or Venus either. 








New Findings Underscore an Earth-Venus Kinship



Published: November 29, 2007

The New York Times


Other than the hellish heat, a crushing carbon dioxide atmosphere and corrosive clouds of sulfuric acid, Venus is a lot like Earth, scientists said yesterday.


In a news conference at the Paris headquarters of the European Space Agency, the scientists, working on the agency’s Venus Express mission, played up the Venus-as-Earth’s-twin angle in presenting their newest findings, including signs of lightning, surprising swings of temperature and additional evidence that Venus could have once had oceans the size of Earth’s.


“They’re really twins which are just separated at birth,” said Dmitri Titov, the mission’s science coordinator. “The key question is why those twins are so different.”


Understanding the dynamics and history of Venus’s turbulent atmosphere could lead to a better understanding of the role that heat-trapping gases like carbon dioxide play in shaping the climate of planets including Earth.


Eight scientific articles describing the observations of Venus Express, the first spacecraft to visit the planet in more than a decade, appear in today’s issue of the journal Nature.


Venus is about the same size and mass as Earth, and of roughly the same composition. And before the space age, planetary scientists imagined an Earth-like environment, perhaps even tropical jungles, obscured by Venus’s perpetual cloud cover. But in 1958, when astronomers measured intense microwaves emanating from the planet, they first got a hint that it was not as lush as they had imagined.


Subsequent visits by spacecraft confirmed that the surface temperatures exceed 800 degrees Fahrenheit, hot enough to melt tin and lead. Although Venus is closer to the Sun than is Earth, the clouds reflect much of the sunlight, and the high temperatures largely result from the heat-trapping effects of an atmosphere that is almost pure carbon dioxide and about 100 times as dense as Earth’s.


Scientists imagine that Venus formed with much liquid water, just like Earth, but that because it is closer to the Sun, with sunlight twice as intense as on Earth, the water began to evaporate. Water vapor, also a greenhouse gas, trapped heat.


“That heats up the surface and leads to more evaporation,” said David Grinspoon of the Denver Museum of Nature & Science. “It’s a powerful feedback.”


The evaporation accelerated until all the liquid water had turned into a thick atmosphere of water vapor. As the water molecules floated in the air, scientists hypothesize, ultraviolet rays from the Sun broke them apart into hydrogen and oxygen atoms. Chemical reactions with minerals in the rocks transformed the oxygen into carbon dioxide. The hydrogen, the lightest of atoms, escaped into outer space.


Measurements from Venus Express, which arrived at the planet last year, support that hypothesis, looking at amounts of hydrogen remaining in the atmosphere compared with concentrations of deuterium, a heavier version of hydrogen. The heavier deuterium would escape more slowly into space, and Venus Express detected a deuterium-to-hydrogen ratio 150 times as high as on Earth, a finding that agreed with earlier measurements. What was surprising, though, was that the deuterium concentration turned out to be 2.5 times as high in the upper atmosphere as near the ground.


“We haven’t completely figured out what it means yet,” Dr. Grinspoon said. “Once we crack this mystery, this will be an important clue to this overall question of the history of water.”


In other measurements, Venus Express detected the bursts of radio waves known as “whistlers,” which, at least on Earth, are generated by lightning, and also found large temperature swings, up to 70 degrees Fahrenheit, between the daytime and nighttime sides of Venus.


The much thicker atmosphere would have been expected to minimize the temperature differences, said Andrew P. Ingersoll, a professor of planetary science at the California Institute of Technology who wrote a commentary in Nature to accompany the scientific papers.


Dr. Ingersoll said he remained skeptical of lightning despite earlier observations by space probes and Earth telescopes. The clouds of Venus are much different from those that produce thunderstorms on Earth. “They’re more like smog in L.A.,” he said. “It’s really just a haze of sulfuric acid. That kind of cloud, at least on Earth, doesn’t produce electrical charge. And thus it’s a little puzzling to have lightning.”


The New York Times

“They can shoot me dead but the moral high ground is mine!” The 10th Doctor

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Solar Power
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Reply with quote  #2 


When the Earth was hit by a planet about the size of Mars in the ancient past we got more mass and a moon out of the deal. When Venus was hit by a Mars sized, or bigger, planet, it got a raw deal. Not only did Venus not get a moon, its rotation was knocked backwards and its oceans (if it ever had any) were wiped out of existence and never recovered. Yeah, Venus gained mass from its ancient collision, and became nearly as large as the Earth, but that by itself did not help Venus all that much.


The Earth, a paradise planet, got all the lucky breaks while Venus never got a lucky break at all.







Venus mysteries blamed on colossal collision

New proposition explains lack of water on planet



By Dave Mosher

updated 10:28 a.m. PT, Thurs., Feb. 28, 2008


Venus is made of the same stuff of Earth, but is bone-dry, hot enough to melt lead and has a chokingly thick atmosphere. It even spins backwards.


Astronomers have spent decades trying to explain Venus' mysterious properties. Now one scientist thinks the planet's formation may explain all: Two huge, protoplanetary bodies collided head-on and merged to form our planetary neighbor, but obliterated nearly all water in the process.


"The probability that two protoplanets collided to form Venus is not at all implausible," said John Huw Davies, a geodynamicist at Cardiff University in the U.K. who developed the idea.


A majority of scientists think Earth's moon formed when a protoplanet about the size of Mars smacked into the planet at an angle. Davies thinks Venus was born of a far worse cosmic train wreck.


"What if the moon-Earth collision isn't that big in planetary terms?" Davies told "A head-on blow between two similarly sized bodies would have been about twice as energetic."


Astronomers have had little time to react to Davies' proposition, which is detailed in a recent issue of the journal Earth and Planetary Science Letters, but already some are wary. Despite the cautionary responses from other scientists, Davies thinks his idea is worth exploring.


Earth harbors an enormous volume of water, even in its searing interior. The life-giving molecule emerges as a vapor with molten lava, carrying with it a radioactive gas known as argon-40. The isotope is generated from radioactive potassium deposits inside of our planet, as well as in Venus.


Davies thinks the relatively low amount of such argon detected in Venus' atmosphere — about 400 times scarcer than on Earth — is a sign that water never really seeped out of the parched, volcano-covered planet.


"The only way water could have out-gassed is very early in Venus' history," Davies said. "The argon-40 gives us a timescale of water leaving the ground because it's produced over time, and only a little of it has been released."


A mega-collision between two bodies of roughly equal size could have provided the energy necessary to rip water, which is made of two hydrogen and one oxygen, into pieces. The hydrogen would escape into space while oxygen would bond with iron and sink to the planet's core.


Although the Earth suffered a catastrophic impact that formed the moon, Davies explained that the process did not dry out the two bodies.


"It wasn't as energetic, limiting the reaction of iron and water," he said.


Diabolical deuterium
Tobias Owens, a planetary scientist at the University of Hawaii, thinks Davies has "swept
deuterium under the rug." This form of hydrogen gas, Owens explained, can form high in a planet's atmosphere when ultraviolet sunlight breaks apart a water molecule.


"When a Venus probe sent back readings of deuterium on the planet, everybody was astonished," Owens said of a Russian Venus lander mission. "There was a huge fraction of deuterium 150 times greater than you see on Earth. You have to explain that."


Owens and other scientists argue that at 836 degrees F, Venus' surface would have instantly baked water into vapor and pushed it into the upper atmosphere, where sunlight is two times more intense than at Earth. Over time, he said, the water would degrade.


Davies, however, said a lack of molecular oxygen — the same type we breathe — produced by the photo-degradation process does not support such an origin of deuterium.


"Venus has virtually no oxygen, whereas Earth's atmosphere is about 20 percent oxygen," Davies said. "If not trapped in the atmosphere, then rocks would have to absorb it." And evidence from Venus, he said, does not suggest that this is the case.


Spin factor
Another clue that Davies said gives his theory legs is the odd rotation of Venus.
The planet rotates in a clockwise or retrograde direction, which is the opposite spin of every planet in the inner solar system. "Another peculiarity is that it has no moon," Davies said. "If the head-on impact I've hypothesized was a little off of the mark, it could explain Venus' retrograde rotation without making a moon."


Alan Boss, a scientist at the Carnegie Institution in Washington, D.C., thinks massive collisions — including head-on mergers — were the norm for terrestrial plants early in their histories and could explain our sinister twin's backwards habits.


"Venus must have suffered a giant impact during its formation, as did all the terrestrial planets. That is how the final phase of terrestrial planet formation occurs," Boss said in an e-mail. "This could have been a head-on impact, which might not have produced a moon, or it could have been an off-center impact, like the impact that led to Earth's moon."


If the latter was the case, then where is Venus' moon? Boss explained that if a Venusian moon formed via a giant impact, its orbit could have decayed and spiraled the body into the planet's surface.


Davies thinks the simpler explanation is his own.


"Of course it is possible, but it is unclear whether it is probable," Davies said. Whatever the case, Davies, Boss and most other scientists think big collision events were common in the solar system's formative years.


New Venusian visitor?
Aside from planning to create a detailed computer model for the hypothesized mega-collision, as has been done for moon formation theory, Davies said another way to test his idea is to send a new spacecraft to Venus.


Russia's space program successfully landed nearly 10 spacecraft on Venus' surface in the 1970s and 1980s. But Davies said none of them scouted for water-containing minerals such as mica — evidence that would challenge his hypothesis.


"They made remote chemical measurements of the surface," Davies said, but none indicated hydrated rocks. "If a new spacecraft finds a lot of hydrated minerals, it would show there is still abundant water on Venus. Then my hypothesis would be out."


Spacecraft that have recently encountered Venus can't detect such minerals from space, he said, because of a layer of reflective hydrogen sulfide in the atmosphere.


"A rover of some sort could scout for such minerals before it fails from the intense heat, or maybe a satellite below the hydrogen sulfide (layer)," he said.


Boss, however, said even detecting such minerals might not rule out a collision.


"Water can always be added as a 'late veneer' by ... icy planetesimals that helped finish building the planet," Boss said, although Davies thinks comets and other such bodies could only deliver a small amount of water to the planet.


Even if hydrated rocks on Venus' surface could rule out a cataclysmic formation, other data could provide better clues to the planet's origins, Francis Nimmo of the University of California Santa Cruz thinks.


"There a lot of things that would be very nice to do on Venus, like put a seismometer on the surface," said Nimmo, a planetary scientist. "The reason we know anything about Earth's interior is from such devices."


Whether or not someone launches a new spacecraft to scout out Venus' surface, and whatever its scientific mission is, Davies said it will have to investigate quickly.


"You have to take all of your measurements before the lander, or whatever it is, quite literally burns up," Davies said. "The longest any spacecraft has lasted is less than two hours."


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“They can shoot me dead but the moral high ground is mine!” The 10th Doctor
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