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What NASA hopes to learn from Juno spacecraft on Jupiter mission

Jupiter, perhaps more than any object in the solar system, is thought to hold the key to understanding planet formation. On Friday, NASA sends the Juno spacecraft hurtling toward Jupiter to probe the planet's constituent parts.

By Staff writer / August 5, 2011

This 2010 artist's rendering depicts NASA's Juno spacecraft with Jupiter in the background.



Mighty Jupiter once again is on NASA's itinerary.

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At 11:35 a.m. Friday, the agency is set to launch an Atlas V rocket topped with spacecraft dubbed Juno, which will embark on a five-year voyage to the giant planet.

Unlike the successful Galileo mission, which toured Jupiter and its moons from 1995 to 2003, the $1.1 billion Juno mission will focus on Jupiter itself. Among the mission's goals: Uncover in unprecedented detail the planet's structure to determine what it reveals about the environment surrounding Jupiter at its birth.

Perhaps more than any other object in the solar system, Jupiter is thought to hold the key to understanding the conditions and constituents that spawned the planets, researchers say.

Like the Incredible Hulk hitting the fridge for a midnight snack, "Jupiter got most of the leftovers" once the sun formed from a collapsing cloud of gas and dust, says Scott Bolton, a planetary scientist with the Southwest Research Institute in San Antonio, Texas, and the mission's lead scientist.

As a result, Jupiter has twice the mass of all of the rest of the planets, asteroids, comets, and other cosmic detritus in the solar system combined – a mass whose gravity profoundly influenced the formation and evolution of the inner solar system.

'Follow the oxygen'

With its enormous gravitational tug holding material in and a vast, powerful magnetic field holding the chemistry-altering solar wind at bay, Jupiter's interior is thought to present a unique, largely unaltered record of the abundance and distribution of elements present when the planets formed nearly 4.6 billion years ago, Dr. Bolton says.

If the mantra for NASA's Mars missions has been "follow the water," for some members of the Juno team the mantra is "follow the oxygen."

Oxygen is the third most abundant element in the universe, after hydrogen and helium. Because the sun and Jupiter formed from the same gas cloud, one might expect the two to have the same relative abundance of oxygen.

Yet "very little has been observed in previous missions" to Jupiter, says Toby Owen, a planetary scientist at the University of Hawaii and a member of the Juno science team.

Researchers say they strongly suspect Jupiter's storehouse of oxygen lies below the striped layer of roiling clouds that envelops the planet. The oxygen probably is bound up in water formed by combining the oxygen with the atmosphere's abundant supply of hydrogen. Using microwave sensors aboard the Juno spacecraft, scientists will in effect peer below Jupiter's clouds and hunt for water and its abundance, from which they can derive the atmosphere's oxygen content.


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