Icy Crust of Jupiter's Europa --Does It Reveal the Existence of a Huge Ocean Bel
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Sent: 3/14/2014 6:05:40 P.M. Eastern Daylight Time
Subj: The Daily Galaxy: News from Planet Earth & Beyond
Posted: 14 Mar 2014 08:22 AM PDT
The European Space Agency (ESA) also plans to launch the JUpiter ICy moons Explorer mission (JUICE) in 2022. When the spacecraft arrives at its destination, the icy moons of Jupiter, in 2030, it will fly over Europa two times to measure the thickness of its mysterious crust and explore its habitability. Scientists suspect that inside Europa, one of the icy moons of Jupiter, reservoirs of liquid water exists, the essential element for life on Earth. This theory emerged from information obtained on the Voyager and Galileo missions, which also registered fractures and `chaotic´ terrains associated to reddish materials, which contrast with the glacial white of the dominant water ice of the surface.Water, salts and gases dissolved in the huge ocean that scientists believe could exist below Europa´s icy crust can rise to the surface generating the enigmatic geological formations associated to red-tinged materials that can be seen on this Jupiter's satellite. This is confirmed by the experiment carried out in the laboratory with water, carbon dioxide and magnesium sulfate by researchers at Centro de Astrobiología (CAB, Spain).
Some of these geological structures seem to be related to the rise of fluids coming from inside, as the space missions observations suggest. Data also suggest that red materials are hydrated salts, mainly of magnesium sulfate (MgSO4). Volatile compounds like carbon dioxide (CO2), sulphur dioxide (SO2) and hydrogen peroxide (H2O2) have been also detected.
Now, with all these premises, researchers at Centro de Astrobiología (CAB, INTA-CSIC) have developed an experiment to explain how these fluids evolve in their way between the deep reservoirs and the moon's surface.
"Just like Earth's magma emerges to the surface, a similar phenomenon could occur in Europa. Although, in this case it would be a watery cryomagma that would evolve and emerge outwards from the interior of the icy moon," says Victoria Muñoz Iglesias, one of this work's authors, published in the journal Geochimica et Cosmochimica Acta.
To confirm their hypothesis, the scientists have simulated in the laboratory the extreme conditions of the fluid reservoirs in the crust; particularly the high pressure (reproducing up to 300 bars) and the low temperature (around -4 ºC). They have observed what happens to an aqueous solution with CO2 and MgSO4 from these conditions when it emerges and cools to the surface.
The result is a variety of processes similar to Earth's volcanism, but at temperatures below zero. Three types of minerals are formed depending of the fluid's evolution: water ice, clathrates of carbon dioxide and very hydrated magnesium sulfates (epsomite, meridianiite).
"These crystallization processes are exothermic (they release energy); they also produce volume changes inside the crust, when the cryomagma solidifies," says Victoria Muñoz-Iglesias. "If in the final mineral assemblage the quantity of clathrates is less than that of hydrated salts, the volume increases causing positive topographical features and fracturation in the crust. However, if the proportion of clathrates is bigger than the rest of solids, or these phases are destroyed releasing the gas, volume decreases and the terrains above might collapse. Some of the chaotic terrains of Europa´s surface could have been produced in this way".
The researcher indicates that at present the reddish colour of these formations is explained as produced by the alteration of the salts due to the strong irradiation of Jupiter's charged particles, forming sulfurous compounds. Other theories point to the bombardment of sulphurous elements coming from volcanic emissions from the neighbouring satellite Io.
"Either way, our experiments show that certain characteristics of Europa´s surface regarding its composition, morphology and topography might be explained if a saline aqueous medium is involved, which has important consequences for living beings on Earth," concludes the researcher.
Europa is one of the best candidates for life in the solar system. Actually, president Barack Obama presented NASA's budget for 2015 including an item for 15 million dollars to look for signs of life on this moon in the next decade.
The composite image at the top of the page of the Minos Linea region on Jupiter's moon Europa taken by NASA's Galileo spacecraft shows mottled terrain that appears in brown and reddish hues, indicating the presence of contaminants in the ice. The icy plains, shown here in bluish hues, subdivide into units with different albedos at infrared wavelengths probably because of differences in the grain size of the ice.
Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment.
The Daily Galaxy via FECYT - Spanish Foundation for Science and Technology
Posted: 14 Mar 2014 08:47 AM PDT
Using a cutting-edge research technique, UCLA researchers have reconstructed the temperature history of a region that plays a major role in determining climate around the world. The team chose the specific area examined in the study because it is Earth's warmest open ocean region and a primary source of heat and water vapor to the atmosphere. As a result, temperature changes there can influence climate not just regionally, but globally."The tropical Pacific ocean-atmosphere system has been called a sleeping dragon because of how it can influence climate elsewhere," said lead author Aradhna Tripati, a UCLA assistant professor in the departments of Earth, planetary and space sciences, and atmospheric and oceanic sciences.
The findings, published online Feb. 27 in the journal Nature Geoscience, will help inform scientists about the processes influencing global warming in the western tropical Pacific Ocean.
The study analyzes how much temperatures have increased in the region near Indonesia, and how ocean temperatures affect nearby tropical glaciers in Papua New Guinea and Borneo. Researchers also evaluated the accuracy of existing climate model predictions for that region. The findings illustrate that the region is very sensitive to climate change and that it has warmed considerably over the last 20,000 years, since the last ice age.
Tripati and her team used a technique known as clumped isotope thermometry, which examines the calcium carbonate shells of marine plankton for subtle differences in the amounts of carbon-13 and oxygen-18 they contain. The researchers analyzed extensive modern and geological datasets, conducted theoretical calculations and examined climate model output. The group discovered that temperatures have changed by about 8 to 10 degrees Fahrenheit (4 to 5 degrees Celsius) over that span — more than scientists had previously thought, and more than most models have estimated.
"Most global climate models underestimate the average temperature variations that the region has experienced," Tripati said, adding that the other models' simulations may be incomplete or the models are not sensitive enough.
The UCLA team's conclusions about temperature changes in the region also imply that there have been major fluctuations in the volume of water vapor in the atmosphere there.
As part of the study, Tripati and her colleagues also investigated what sets the past and present height of glaciers in the tropics, and why they have been retreating. To accurately estimate the height of tropical glaciers and average temperatures at altitude in this region, they found that atmospheric mixing, through a process known as entrainment, needs to be factored in.
"We found that the large amount of ocean warming goes a long way to explaining why glaciers have retreated so much," said Tripati, a faculty member in the College of Letters and Science and a member of UCLA's Institute of the Environment and Sustainability. "Throughout the region, they have retreated by close to a kilometer since the last ice age, and are predicted to disappear in the next one to three decades. Previously understanding this large-scale glacial retreat has been a puzzle. Our results help resolve this problem."
Among the implications of the study are that ocean temperatures in this area may be more sensitive to changes in greenhouse gas levels than previously thought and that scientists should be factoring entrainment into their models for predicting future climate change.
The group has already begun a follow-up study, looking at sediment from Indonesia's Lake Towuti to develop data that can be used to further improve models of climate and water cycling for the region. Researchers will also look at other places in the tropics, the Western U.S. and China.
Co-authors of the study are Sandeep Sahany, postdoctoral researcher in the department of atmospheric and oceanic sciences, Dustin Pittman, graduate student in the department of atmospheric and oceanic sciences, Robert Eagle, assistant researcher in the department of Earth, planetary and space sciences, Jonathan Mitchell, assistant professor in the departments of Earth, planetary and space sciences and of atmospheric and oceanic sciences, J. David Neelin, professor in the department of atmospheric and oceanic sciences and Luc Beaufort, a research scientist at the Center for Research and Teaching of Environmental Geosciences in Aix-en-Provence, France.
The research was supported primarily by the National Science Foundation.
The Daily Galaxy via http://newsroom.ucla.edu/
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