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Voyager 1 Encounters the Edge of the Solar System, According to Bell Labs Space Physicist and Other Scientists

Posted on: Wednesday, 5 November 2003, 06:00 CST

MURRAY HILL, N.J.--(BUSINESS WIRE)--Nov. 5, 2003--

Spacecraft Provides Tantalizing Data from Previously Unexplored

Region of Space

Hurtling through the frigid expanse beyond the planets, NASA's aging spacecraft Voyager 1 has reached the edge of the Solar System, where it has encountered a massive shock wave, according to a paper that will be published in Nature tomorrow by a team of scientists that includes Louis Lanzerotti of Bell Labs, the research and development arm of Lucent Technologies (NYSE:LU).

More than eight billion miles from Earth, the farthest an operating spacecraft has ever journeyed, Voyager 1 is providing scientists with data from a fascinating yet little understood region of space - the frontier where the Sun's influence begins to wane, and the tenuous vastness of interstellar space takes over.

It is here that charged particles streaming out from the Sun - called the solar wind - bump into the ionized gas and dust that is spread thinly between stars, causing a shock wave in the process.

Data of how the solar wind behaves will provide scientists with knowledge useful not only to astronomy but to terrestrial concerns such as how solar emissions affect wireless telephone calls, satellite communications and electric power grids.

"When the Voyager missions were launched in 1977, we never thought the instruments we developed more than three decades ago would one day probe the edge of the Solar System," said Lanzerotti, an expert on how the solar wind affects terrestrial communications. Lanzerotti joined Bell Labs in 1965 and has been involved with NASA's Voyager missions since their inception in 1972. In honor of his contributions to space physics, the International Astronomical Union has named an asteroid after him, Minor Planet 5504 Lanzerotti. He now divides his time between Bell Labs, where he is a consultant, and the New Jersey Institute of Technology, where he is a distinguished professor at the Center for Solar Terrestrial Research.

"Voyager 1 and 2 provided us with unparalleled views of the planets. I find it very exciting that Voyager 1 will soon begin to explore the vastness of the interstellar medium," he said.

Astronomers now know that the space between stars, once thought to be completely empty, is filled with a dilute plasma of gas and dust termed the interstellar medium. The solar wind blows out a giant bubble called the heliosphere within the interstellar medium, and the boundary between the heliosphere and the interstellar medium is a place where a lot of interesting physical phenomena take place.

Much like a shock wave precedes a supersonic airplane, astronomers think that a "termination shock" occurs near the edge of the solar system. This is a region where the speed of the solar wind drops dramatically as the wind brakes as it mixes with the interstellar medium, and where the density of ionized particles increases many times. It is also a region where some ions from the interstellar medium, relics of previous generations of stars, manage to diffuse through the edge of the Solar System and are accelerated tremendously.

Using an instrument on Voyager 1 called the low energy charged particle detector, Lanzerotti and his colleagues found evidence of all three effects. They saw a hundred-fold increase in the number of charged particles detected during a six-month period starting in August 2002; they deduced that the speed of the solar wind had dropped by a factor of seven; and they detected ions that came from beyond the Solar System.

"When we saw all that, we were pretty sure that we had reached the termination shock," Lanzerotti said.

Other members of the scientific team were Stamatios Krimigis (team leader), Robert Decker and Edmond Roelof of Johns Hopkins University; George Gloeckler, Douglas Hamilton and Matthew Hill of the University of Maryland; and Thomas Armstrong of the University of Kansas.

As the team analyzed its data from Voyager 1, it noticed something strange. It seemed that after six months, in early 2003, the termination shock region moved outwards, possibly as a result of increased solar activity. Scientists postulate that the heliosphere is a dynamic entity, which expands and contracts with the Sun's 11-year activity cycle.

"Solar eruptions must have caused the solar wind to pick up speed," said Lanzerotti. "That forced the heliosphere to expand outwards, and the termination shock must have moved outwards as well. Voyager 1 will probably encounter it again."

The team expects to get confirming data from a similar detector on Voyager 2, which is expected to follow Voyager 1 to the edge of the Solar System. The Voyager probes, among NASA's most successful spacecraft, are expected to provide data until approximately 2020, when they will exhaust their power supply from nuclear isotopes and drift off into space.

"Meanwhile, they will continue to provide a treasure trove of wonderful, sometimes unanticipated data about the far reaches of the Solar System and push the frontiers of our knowledge," Lanzerotti said.

About Lucent Technologies' Bell Labs

Bell Labs is the leading source of new communications technologies. It has generated more than 30,000 patents since 1925 and has played a pivotal role in inventing or perfecting key communications technologies, including transistors, digital networking and signal processing, lasers and fiber-optic communications systems, communications satellites, cellular telephony, electronic switching of calls, touch-tone dialing, and modems. Bell Labs scientists have received six Nobel Prizes in Physics, nine U.S. National Medals of Science and eight U.S. National Medals of Technology(R). For more information about Bell Labs, visit its Web site at http://www.bell-labs.com.

Lucent Technologies, headquartered in Murray Hill, N.J., USA, designs and delivers networks for the world's largest communications service providers. Backed by Bell Labs research and development, Lucent relies on its strengths in mobility, optical, data and voice networking technologies as well as software and services to develop next-generation networks. The company's systems, services and software are designed to help customers quickly deploy and better manage their networks and create new, revenue-generating services that help businesses and consumers. For more information on Lucent Technologies, visit its Web site at http://www.lucent.com.

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