October 20, 2008
NASA Sends Probe To Outer Limits Of Solar System
NASA is sending a small spacecraft on a two-year mission that will give scientists their first view of the outermost reaches of our solar system.
The Interstellar Boundary Explorer, or IBEX, satellite launched into high-Earth orbit on Sunday from a site at Kwajalein Atoll in the South Pacific, where it will study a chaotic region in space where the solar wind from the sun clashes with cold gases from interstellar space.
The solar wind, a stream of electrically conducting gas continuously moving outward from the sun at 1 million mph (1.6 million kph), blows against this interstellar material and forms a humongous protective bubble around the solar system known as the heliosphere.
The heliosphere collides with interstellar space and creates a shockwave as the solar wind reaches far beyond the planets to the solar system's outer limits.
"These boundaries really protect us from the fairly harsh galactic environment," said Boston University astronomer Nathan Schwadron, who heads science operations for the IBEX mission.
NASA hopes observations from Ibex will help researchers unlock the secrets of this important interaction between the sun and the galaxy, according to David McComas of the Southwest Research Institute in San Antonio, and chief scientist for the $165 million mission.
NASA scientists said the solar wind pressure is mysteriously at its weakest level in 50 years and that Ibex could help confirm whether the heliosphere is shrinking.
"We will be able to discover what the edge of our bubble looks like and learn about the properties of the interstellar cloud that lies beyond the bubble," said physicist Herb Funsten of the U.S. Department of Energy's Los Alamos National Laboratory.
NASA officials said Ibex will be launched 130 miles above Earth and put it into orbit aboard a Pegasus rocket that will be dropped from an aircraft over a Pacific atoll. The spacecraft will then fire its solid rocket motor to loft itself even higher, eventually to 200,000 miles above Earth.
NASA's twin Voyager probes, launched in 1977, were the first to begin to explore this region, which begins about three times further from the sun than the orbit of the dwarf planet Pluto. Voyager 1 passed the inner boundary in 2004 and Voyager 2 crossed over last year.
NASA scientist Eric Christian said the heliosphere's boundary region is enormous, and the Voyager crossings of the termination shock, while historic, only sampled two tiny areas 10 billion miles apart.
Image Courtesy Of NASA
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