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Pluto-Charon origin may mirror Earth and Moon SOUTHWEST RESEARCH INSTITUTE NEWS RELEASE Posted: January 27, 2005
Dr. Robin Canup, assistant director of Southwest Research Institute's (SwRI) Department of Space Studies, argues for such an origin for the Pluto-Charon pair in an article for the January 28 issue of the journal Science. Canup, who currently is a visiting professor at the California Institute of Technology, has worked extensively on a similar "giant collision" scenario to explain the Moon's origin. In both the Earth-Moon and Pluto-Charon cases, Canup's smooth particle hydrodynamic simulations depict an origin in which a large, oblique collision with the growing planet produced its satellite and provided the current planet-moon system with its angular momentum. While the Moon has only about 1 percent of the mass of Earth, Charon accounts for a much larger 10 to 15 percent of Pluto's total mass. Canup's simulations suggest that a proportionally much larger impactor -- one nearly as large as Pluto itself -- was responsible for Charon, and that the satellite likely formed intact as a direct result of the collision. According to Canup, a collision in the early Kuiper Belt -- a disk of comet-like objects orbiting in the outer solar system beyond Neptune -- could have given rise to a planet and satellite with relative sizes and angular rotation characteristics consistent with those of the Pluto-Charon pair. The colliding objects would have been about 1,600 to 2,000 kilometers in diameter, or each about half the size of the Earth's Moon. "This work suggests that despite their many differences, our Earth and the tiny, distant Pluto may share a key element in their formation histories. This provides further support for the emerging view that stochastic impact events may have played an important role in shaping final planetary properties in the early solar system," said Canup. The "giant impact" theory was first proposed in the mid-1970s to explain how the Moon formed, and a similar mode of origin was suggested for Pluto and Charon in the early 1980s. Canup's simulations are the first to successfully model such an event for the Pluto-Charon pair. Simulations published by Canup and a colleague in Nature in 2001 showed that a single impact by a Mars-sized object in the late stages of Earth's formation could account for the iron-depleted Moon and the masses and angular momentum of the Earth-Moon system. This was the first model to simultaneously explain these characteristics without requiring that the Earth-Moon system be substantially modified after the lunar forming impact. This research was supported by the National Science Foundation under grant no. AST0307933. |
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NASA pays tribute to those lost while furthering the cause of exploration, including the Apollo 1, Challenger and Columbia crews, during this Day of Remembrance memorial from agency headquarters on Jan. 27. (38min 58sec file)
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The Orbiter Boom Sensor System is loaded into space shuttle Discovery's payload bay. The arm will be used to inspect the shuttle for damage following the return-to-flight launch. (4min 18sec file)
The Expedition 10 conducts a successful spacewalk outside the International Space Station to mount a German robotic arm and Russian science package to the Zvezda service module's exterior. (5min 07sec file)
One week after the Huygens probe landed on Saturn's moon Titan, scientists hold a news conference to announce additional results and describe more pictures from the mission. (69min 02sec file)
The upcoming spacewalk by the International Space Station's Expedition 10 crew is previewed by NASA officials at the Johnson Space Center on Jan. 21. (25min 04sec file)
A Boeing Delta 2 rocket blasts off from Cape Canaveral carrying NASA's comet-smashing probe called Deep Impact. This extended clip follows the mission through second stage ignition and jettison of the rocket's nose cone. (5min 37sec file)
A camera located at Cape Canaveral's Press Site 1 location offers this view of the Delta rocket's ascent. (1min 24sec file)