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NASA’s Voyagers: 35 years of inspiration

August 20, 1977 turned out to be a before-and-after moment for me—and probably a lot of other people as well. None of us knew it at the time, though, since the launch of Voyager 2 (followed a few weeks later by Voyager 1) wasn't obviously a big deal to most people. In fact, I wouldn't fully appreciate the change until sometime in 1980.

To understand why, a bit of history is in order. NASA had been sending probes to other planets, like the Mariner and Pioneer series, since the 1960s. However, even the best technology of the time was pretty limited in terms of what it could do remotely. And for most of that time, they were badly overshadowed by manned exploration, first the Apollo missions and Skylab, and later the planning for the space shuttle. In fact, even as the Voyagers flew past Jupiter, I seem to recall more attention being paid to the impending de-orbit of Skylab, which scattered charred pieces of itself over Australia later that year.

But for me, everything changed with the arrival of the January issue of National Geographic early the next year. Its picture, of an erupting volcano on Jupiter's moon Io, was simply stunning. The contents continued to amaze. Supersonic winds in Jupiter's atmosphere. Stunning photos of the Great Red Spot. Water ice reshaping the surface of Europa. I can't even begin to imagine how many times I reread the issue.

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ESA’s JUICE will voyage to Jupiter’s moons

ESA

The European Space Agency announced last week that it has chosen the Jupiter Icy moons Explorer, aka JUICE, as its next large science mission. JUICE was chosen over the New Gravitational wave Observatory (NGO) and the Advanced Telescope for High-Energy Astrophysics (ATHENA) by ESA's new Cosmic Vision 2015-2025 program.

JUICE will launch about ten years from now, and won't arrive at Jupiter until 2030. JUICE's solar-powered ion drive means the spacecraft will require more than 25 gravity assists. A stronger energy source could get it there faster, but as an ESA-only probe, JUICE doesn't currently have access to the roughly eight pounds of plutonium it would need to power its ion engine to Jupiter much more quickly. Both NASA and ESA are trying to solve the plutonium shortage for future spacecraft.

Upon arrival, JUICE will study Callisto first, imaging the moon's surface. It will fly on to Europa, making two passes, before orbiting at Ganymede, mapping its unique magnetosphere, imaging the moon's surface, and attempting to determine whether Ganymede has oceans underneath its water ice. Of all the moons in the Solar System, only Ganymede is known to have a magnetosphere, probably caused by convection within its iron core.


ESA’s JUICE will voyage to Jupiter’s moons

ESA

The European Space Agency announced last week that it has chosen the Jupiter Icy moons Explorer, aka JUICE, as its next large science mission. JUICE was chosen over the New Gravitational wave Observatory (NGO) and the Advanced Telescope for High-Energy Astrophysics (ATHENA) by ESA's new Cosmic Vision 2015-2025 program.

JUICE will launch about ten years from now, and won't arrive at Jupiter until 2030. JUICE's solar-powered ion drive means the spacecraft will require more than 25 gravity assists. A stronger energy source could get it there faster, but as an ESA-only probe, JUICE doesn't currently have access to the roughly eight pounds of plutonium it would need to power its ion engine to Jupiter much more quickly. Both NASA and ESA are trying to solve the plutonium shortage for future spacecraft.

Upon arrival, JUICE will study Callisto first, imaging the moon's surface. It will fly on to Europa, making two passes, before orbiting at Ganymede, mapping its unique magnetosphere, imaging the moon's surface, and attempting to determine whether Ganymede has oceans underneath its water ice. Of all the moons in the Solar System, only Ganymede is known to have a magnetosphere, probably caused by convection within its iron core.

Read more on Ars Technica…


Huge lake could increase chance of life on Jupiter moon

The icy crust of Jupiter's moon Europa may contain a body of water the size of the Great Lakes sitting just 1.8 miles below the surface. If confirmed, the findings could heat up the prospects of finding alien life on the chilly moon.

Deep underneath its frozen exterior, Europa is known to house a vast ocean, with two to three times the volume of Earth's oceans. And researchers have previously speculated that small amounts of water might exist near the moon's surface in pores or cracks.

"Now we've found evidence that there are giant liquid lakes perched inside the ice shell," said planetary scientist Britney Schmidt from the University of Texas at Austin and lead author on the paper, which appears in Nature on Nov. 17.

Looking at data from NASA's Galileo spacecraft—which orbited Jupiter from 1995 to 2003—Schmidt and her team identified a region called Thera Macula that sits 1,300 feet lower than the surrounding surface.

A hypothetical visitor to Europa standing on the edge of Thera Macula would look down at a choppy, brownish field of ice full of knobs and spires, and see tall icebergs trapped here and there. Extrapolating from analogous situations occurring in Greenland or Antarctic ice, the researchers developed a model to account for the chaotic frozen terrain.

Plumes of water heated from below would form salty brine that could gather into a lens-shaped subsurface lake. This would cause fractures in the brittle exterior, collapsing the surface ice and bringing it down to mix with the water below. "This would be evidence that there is water below you," said Schmidt.

Sulfates from Jupiter's volcanic moon Io as well as other chemicals such as oxygen and hydrogen peroxide are present on the Europan surface. These would get stirred into the salty lake sitting beneath Europa's shell.

"This creates a potential source of energy for life to tap," said geophysicist Don Blankenship, also of the University of Texas and another author of the recent paper. Such findings are exciting to astrobiologists and others searching for life in the solar system beyond Earth.

"I definitely think it's plausible," said planetary scientist Kevin Hand of NASA's Jet Propulsion Laboratory, who was not involved in the study. The best thing to increase confidence in the model would be further data, he added.

Unfortunately, NASA does not currently have missions to explore Europa on its schedule. The Juno spacecraft, which should arrive at Jupiter in 2016, will mostly study the gas giant's composition and magnetic field, not focusing on the planet's moons. A proposed Jupiter-Europa Orbiter has an estimated price tag of $4.6 billion, making it unlikely to launch during a time of budget squeezes.

Nature, 2011.  DOI: 10.1038/nature10608  (About DOIs).

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