Launched back in 1977, the 33-year odyssey of NASA’s Voyager 1continues, chalking up another milestone.
The spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind.
Voyager 1 has crossed into an area where the velocity of the hot ionized gas — or plasma — emanating directly outward from the Sun has slowed to zero.
In order for scientists to deduce this finding, data was used from Voyager 1’s Low-Energy Charged Particle Instrument. When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft’s speed, researchers knew that the net outward speed of the solar wind was zero.
This occurred in June, when Voyager 1 was about 17 billion kilometers (10.6 billion miles) from the Sun.
According to the Jet Propulsion Laboratory – builder and operator of Voyager 1 and Voyager 2 — because the velocities can fluctuate, scientists made use of four additional monthly readings before they were convinced the solar wind’s outward speed actually had slowed to zero.
Our Sun churns out a stream of charged particles that form a bubble known as the heliosphere around our solar system.
Scientists are now putting the Voyager 1 data into their models of the heliosphere’s structure and should be able to better estimate when the spacecraft will reach interstellar space.
Researchers currently estimate Voyager 1 will cross that frontier in about four years.
“In science, there is nothing like a reality check to shake things up, and Voyager 1 provided that with hard facts,” said Tom Krimigis, principal investigator on the Low-Energy Charged Particle Instrument, who is based at the Applied Physics Laboratory and the Academy of Athens, Greece.
“Once again, we face the predicament of redoing our models,” Krimigis noted.
Want more information about the Voyager spacecraft?
Go to: http://www.nasa.gov/voyager
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