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Do Pluto's moons pose risks for NASA spacecraft? (+video)

Scientists are planning a new route for NASA's New Horizons space probe as it approaches a potentially perilous path toward Pluto. They aim to chart a safe, but interesting course.

By Charles Q. / October 16, 2012

This artist’s concept shows NASA's New Horizons spacecraft during its 2015 encounter with Pluto and its moon, Charon.

Southwest Research Institute


The moons of Pluto, and a potential set of rings, may create dangerous debris zones for a NASA spacecraft currently speeding toward the distant world, researchers say.

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Dwarf planet Pluto is a world of mystery waiting to be visited for the first time. NASA's New Horizons probe is racing across the solar system for a ground breaking close encounter that could dramatically alter what researchers "know" about Pluto and other small worlds.

Scientists are now designing alternate courses for the Pluto-bound New Horizons spacecraft that would steer it out of harm's way, while at the same time helping the probe explore its mysterious targets.

"We want people to understand just how interesting and how nail-biting New Horizons' mission might be," study lead author Alan Stern, principal investigator of the New Horizons mission at Southwest Research Institute in San Antonio, Texas. "This is part of the excitement of first-time exploration, of going to a new frontier."

New Horizons is the first probe ever designed to investigate worlds in the Kuiper Beltof icy bodies. After nearly seven years, the spacecraft is now more than 24 times farther away from the sun than Earth is, placing it past the orbit of Uranus. [Photos: Pluto and its 5 Moons]

Next stop: Pluto

New Horizons is currently about 1,000 days away and 730 million miles (1,180 million kilometers) from closest approach to Pluto.

Since the spacecraft blasted off in 2006, the distant world has become an even more enticing goal, with a fifth moon discovered around it in July. The impacts that may have created this system of moons as well as collisions they have likely had with other bodies in the Kuiper Belt where the distant world resides also suggests debris might have collected into rings around Pluto.

Although these finds reveal that Pluto is a trove of treasures worth exploring, "we're worried that Pluto and its system of moons, the object of our scientific affection, may actually be a bit of a black widow," Stern said. "We've come to appreciate that those moons, as well as those not yet discovered, act as debris generators populating the Pluto system with shards from collisions between those moons and small Kuiper Belt objects."

Given how New Horizons is currently zooming away from the sun at more than 33,500 mph (54,000 kph), "a collision with a single pebble, or even a millimeter-sized grain, could cripple or destroy New Horizons," said New Horizons project scientist Hal Weaver at Johns Hopkins University Applied Physics Laboratory. "We need to steer clear of any debris zones around Pluto."

To search for debris orbiting Pluto, the New Horizons team is now scanning it with ground and space telescopes and carrying out computer simulations of where this shrapnel might lie.

"We're not going to blindly send a billion-dollar-class mission into harm's way," Stern told "We're going to rewrite what we know to achieve victory."

Does Pluto have rings?

Although researchers have spotted no signs of debris zones around Pluto yet, computer models have not ruled out such gauntlets of rubble. "We have to take the conservative approach and assume the worst," Stern said.

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