For Pluto-Bound Probe, Jupiter Flyby Promises Early Science Harvest

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NEW YORK — A NASA probe traveling to Pluto will hit the accelerator in February when it flies past the planetary giant Jupiter.

The New Horizons spacecraft is due to make its closest pass by Jupiter Feb. 28, adding another 14,484 kilometers per hour to its velocity on its trek to a July 2015 rendezvous with Pluto.

“This is a big test for our mission,” said Alan Stern, NASA’s New Horizons principal investigator at the Southwest Research Institute inc. BoulderColo. “We’re actually beginning to get data, important scientific data, which my team is going to be rabid to work with as soon as we get it on the ground.”

During its swing past Jupiter, New Horizons’ will not only study Jupiter’s turbulent atmosphere, but it will scan its auroras, rings, moons and the planet’s trailing magnetic field.

“There is no mission plan to do another flyby like this of the Jupiter system,” said Stern, who spoke during a Jan. 18 mission briefing at NASA headquarters in Washington.

Pit Stop to Pluto

NASA launched its New Horizons mission Jan. 19, 2006, on what the space agency has billed as its fastest flight to the outer rim of the solar system.

With its seven instruments, New Horizons is designed to study Pluto, its three moons – Charon, Hydra and Nix – and distant icy objects in the Kuiper Belt that lie beyond the orbit of Neptune. Researchers are hoping those objects contain 4.5 billion-year-old traces of the solar system’s building blocks.

What New Horizons finds at Pluto and in the Kuiper Belt should help astronomers answer “some fundamental questions about the origin of the solar system,” James Green, acting director of NASA’s solar system division, said during the briefing.

The probe is currently 65 million kilometers from Jupiter, moving at a speed of about 71,242 kilometers per hour.

At its closest approach, New Horizons will swing within 2.3 million kilometers of Jupiter to grab a gravity boost that will reduce its flight to Pluto by three years, researchers said.

“We’ve designed this particular flyby to be a stress test on our spacecraft to work out the kinks,” Stern said.

Uncharted territory

Scientists have 700 separate Jupiter system observations planned for New Horizons during its flyby.

“We’ll be making the most of this opportunity to learn a lot about Jupiter itself,” said John Spencer, deputy chief of New Horizons’ Jupiter encounter science team at Southwest Research Institute.

New Horizons already has made an unexpected find within Jupiter’s atmosphere: Its initial set of black and white images of the planet’s Great Red Spot taken earlier this month revealed that a turbulent region to the storm’s northwest — as seen by the Cassini probe in 2000 — appears to have calmed.

“That region loops really quite cloud-free,” Spencer said. “So that’s not what we expected.”

New Horizons also will provide a fresh look at Jupiter’s four largest moons: volcanic Io, Europa, Ganymede and Callisto. The spacecraft also will study the planet’s auroras and hunt for new satellites within its faint rings, researchers said.

But the highlight of this leg of the trek comes when New Horizons will pass through Jupiter’s magnetotail, the trailing portion of the planet’s magnetic field that extends outward away from the sun.

“No spacecraft has ever been there. We don’t know what happens there,” Spencer said of Jupiter’s magnetotail. “It just so happens by good luck that the path to Pluto leads us right down the magnetotail.”

Astronomers estimate Jupiter’s magnetotail sweeps across six astronomical units — or six times the distance between the Earth and Sun — to reach the orbit of Saturn. One astronomical unit is about 149 million kilometers.

“This is a whole new zone of the solar system,” Stern said. “It opens up a window into the outer solar system and a window back in time 4.5 billion years to the birth of the planets.”