Exploration, and the new frontier start in our solar system.

(CNN) — At least one corner of the solar system may be serving up an ice-and-water sandwich, with the possibility of life on the rocks.
NASA researchers, publishing in the journal Planetary and Space Science, have demonstrated that this “club sandwich” phenomenon may be happening on Ganymede, the largest moon in the solar system and a satellite of Jupiter.

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This finding means that life could have even arisen on Ganymede. The study suggests there may be a layer of salty water directly on top of Ganymede’s rocky core. Chemical interactions between rock and water could lead to the formation of life, scientists say.
“This is good news for Ganymede,” said lead study author Steve Vance of NASA’s Jet Propulsion Laboratory in a statement. “Its ocean is huge, with enormous pressures, so it was thought that dense ice had to form at the bottom of the ocean. When we added salts to our models, we came up with liquids dense enough to sink to the sea floor.”
The oceans of Ganymede may have 25 times the volume of Earth’s oceans, scientists said. But Ganymede is also smaller; it has an average radius of 1,634 miles, about 41% of Earth’s.
There is only a handful of places in the solar system thought to have subsurface oceans. There is strong evidence that Europa, another moon of Jupiter’s, and Saturn’s moons Enceladus and Titan have oceans under ice as well. Jupiter’s moon Callisto is also a contender.
Data from NASA’s Cassini spacecraft suggested last month that Enceladus has an ocean at least the size of Lake Superior under its ice layer.

Signs of underground ocean found on Saturn moon
Vance and colleagues did not visit Ganymede, obviously, but they performed laboratory experiments here on Earth to simulate what would happen to ice and salty water on the Jupiter moon.
They showed that the density of liquids goes up with the presence of salt under extreme conditions inside moons such as Ganymede. Because salt ions attract molecules of H2O, liquid water becomes denser when salt is added.
There are many forms of ice, which makes modeling conditions on icy moons complex. You are probably most familiar with Ice I, the ice that floats in a soda fountain beverage because it is lighter than water.
But ice molecules get packed together more tightly at high pressures, Vance said. In deep oceans, the dense ice would actually be heavier than water, plummeting to the ocean floor. Vance and colleagues use Ice VI to refer to the most dense and heavy ice that Ganymede may have. On this moon, however, scientists believe the saltiest liquid would be so dense that it would be at the very bottom, above the rock.
Computer models taking all of that into account suggest that Ganymede has as many as three ice layers with liquid ocean between them.
The models also suggest that ice could form in the seawater — a process that leaves heavy salts to fall down and lighter ice to float up — an upward snow effect. In the middle of the layers may be slush from that ice that then melts.
Scientists don’t know if this model is correct, of course. Senior author Christophe Sotin, also of NASA’s JPL, said in a statement that the “sandwich” model reflects a stable state, but there are various reasons why the moon might not achieve this structure; it may even alternate between a “club sandwich” phase and a structure with fewer layers: light ice, ocean, high-pressure ice.
Galileo Galilei discovered Ganymede as well as three other moons of Jupiter in 1610. These moons contributed to the knowledge that our sun and other planets in our solar system do not orbit the Earth, but rather the solar system revolves around the sun.
We may learn more about Ganymede and other moons with the potential of life through a space mission called Jupiter Icy Moons Explorer, or JUICE. The mission, being developed by the European Space Agency, will visit Europa, Callisto and Ganymede. It is scheduled to launch in 2022.

Travel Time?

Jupiter and Io. Image credit: NASA
The answer to ?how long does it take to get to Jupiter? has changed in the last few years. The Galileo spacecraft used Hohmann transfer orbits to arrive in orbit. It was launched in October, 1989 and arrived in orbit in December of 1995. That was a 6 year flight. The New Horizons spacecraft was built using a different type of engine than the Galileo and could take a more direct route. It was launched on January 19, 2006 and flew past Jupiter just 13 months later on its way to Pluto. As you can see, propulsion technology made a giant leap in just a few years.
One question that comes to mind is what is a Hohmann transfer orbit. The short answer is that it is a way to use a planet?s gravity to propel a spacecraft toward another planet. Sort of a slingshot affect. The long answer is that a Hohmann transfer orbit is an elliptical orbit used to transfer between two coplaner, circular orbits. It typically requires two engine impulses to move a spacecraft on and off a single transfer orbit. The maneuver is named after Walter Hohmann who published the first description of the maneuver in 1925. As it applies directly to the problem of a spaceflight, a Hohmann transfer would look like this: The spacecraft would have a certain velocity from its initial orbit around Earth. At the end of the initial orbit around the Sun the craft will need another velocity to enter the second orbit, requiring an engine impulse. For Jupiter, the velocity would have to be less than the velocity needed to continue in the initial orbit, so the craft will have to decelerate. That is not the end of it because the spacecraft is still going to fast to be captured by Jupiter gravity. So, it has to move into another orbit of Earth, so another Hohmann transfer is necessary. This is still not the end, another transfer has to be made to make sure the spacecraft can settle in around Jupiter. Calculating fuel and burst durations are the simple parts. Timing the launch of the craft so that it exits the transfer orbit at the same time as the target planet is arriving in that part of its orbit is the trick.

Jupiter and Io. Image credit: NASA
The answer to ?how long does it take to get to Jupiter? has changed in the last few years. The Galileo spacecraft used Hohmann transfer orbits to arrive in orbit. It was launched in October, 1989 and arrived in orbit in December of 1995. That was a 6 year flight. The New Horizons spacecraft was built using a different type of engine than the Galileo and could take a more direct route. It was launched on January 19, 2006 and flew past Jupiter just 13 months later on its way to Pluto. As you can see, propulsion technology made a giant leap in just a few years.
One question that comes to mind is what is a Hohmann transfer orbit. The short answer is that it is a way to use a planet?s gravity to propel a spacecraft toward another planet. Sort of a slingshot affect. The long answer is that a Hohmann transfer orbit is an elliptical orbit used to transfer between two coplaner, circular orbits. It typically requires two engine impulses to move a spacecraft on and off a single transfer orbit. The maneuver is named after Walter Hohmann who published the first description of the maneuver in 1925. As it applies directly to the problem of a spaceflight, a Hohmann transfer would look like this: The spacecraft would have a certain velocity from its initial orbit around Earth. At the end of the initial orbit around the Sun the craft will need another velocity to enter the second orbit, requiring an engine impulse. For Jupiter, the velocity would have to be less than the velocity needed to continue in the initial orbit, so the craft will have to decelerate. That is not the end of it because the spacecraft is still going to fast to be captured by Jupiter gravity. So, it has to move into another orbit of Earth, so another Hohmann transfer is necessary. This is still not the end, another transfer has to be made to make sure the spacecraft can settle in around Jupiter. Calculating fuel and burst durations are the simple parts. Timing the launch of the craft so that it exits the transfer orbit at the same time as the target planet is arriving in that part of its orbit is the trick.

Read more: http://www.universetoday.com/15092/how-long-does-it-take-to-get-to-jupiter/#ixzz35sHk86jR

above referenced : http://www.cnn.com/2014/05/02/tech/innovation/moon-jupiter-ganymede/index.html?iid=article_sidebar

above references: http://www.universetoday.com/15092/how-long-does-it-take-to-get-to-jupiter/

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