June 16, 2011

Voyager Nears Edge Of Solar System

NASA said Wednesday that Voyager 1 could cross over into the frontier of interstellar space at any time and much earlier than previously thought.

Data from Voyager's low-energy charged particle instrument have indicated that the outward speed of the charged particles streaming from the sun has slowed to zero.

The stagnation of this solar wind has continued through at least February 2011, marking a thick, previously unpredicted "transition zone" at the edge of our solar system.

"There is one time we are going to cross that frontier, and this is the first sign it is upon us," Tom Krimigis, principal investigator for Voyager's low-energy charged particle instrument and Cassini's magnetospheric imaging instrument, said in a statement.

The researchers combined the new Voyager data with unpublished measurements from the ion and neutral camera on Cassini's magnetospheric imaging instrument. 

The Cassini instrument collects data on neutral atoms streaming into our solar system from the outside.

The analysis indicates that the boundary between interstellar space and the bubble of charged particles the sun blows around itself is between 10 and 14 billion miles from the sun.  Since Voyager 1 is already about 11 billion miles out, it could cross into interstellar space at any time.

"These calculations show we're getting close, but how close? That's what we don't know, but Voyager 1 speeds outward a billion miles every three years, so we may not have long to wait," Ed Stone, Voyager project scientist, said in a statement.

Scientists will keep analyzing the Voyager 1 data to look for a confirmation.  They will also be studying the Voyager 2 data, but Voyager 2 is not as close to the end of the solar system as Voyager 1.

The Voyager twin spacecraft have been on a 33-year journey.  They are the farther working deep space sentinels enroute to reach the edge of interstellar space.


Image Caption: This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. Image credit: NASA/JPL-Caltech


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