Voyager 1 Has Left the Solar System   
       
   Sept. 12, 2013:  NASA's Voyager 1 spacecraft officially is the first   
   human-made object to venture into interstellar space. The 36-year-old probe is   
   about 12 billion miles (19 billion kilometers) from our sun.   
       
   New and unexpected data indicate Voyager 1 has been traveling for about one   
   year through plasma, or ionized gas, present in the space between stars.   
   Voyager is in a transitional region immediately outside the solar bubble,   
   where some effects from our sun are still evident. A report on the analysis of   
   this new data, an effort led by Don Gurnett and the plasma wave science team   
   at the University of Iowa, Iowa City, is published in Thursday's edition of   
   the journal Science.   
       
   https://www.youtube.com/watch?v=L4hf8HyP0LI   
       
   Voyager 1   
   A new NASA video describes how Voyager 1 crossed the threshold into   
   Interstellar Space. Play it   
       
   "Now that we have new, key data, we believe this is mankind's historic leap   
   into interstellar space," said Ed Stone, Voyager project scientist based at   
   the California Institute of Technology, Pasadena. "The Voyager team needed   
   time to analyze those observations and make sense of them. But we can now   
   answer the question we've all been asking -- 'Are we there yet?' Yes, we are."   
       
   Voyager 1 first detected the increased pressure of interstellar space on the   
   heliosphere, the bubble of charged particles surrounding the sun that reaches   
   far beyond the outer planets, in 2004. Scientists then ramped up their search   
   for evidence of the spacecraft's interstellar arrival, knowing the data   
   analysis and interpretation could take months or years.   
       
   Auroras Underfoot (signup)Voyager 1 does not have a working plasma sensor, so   
   scientists needed a different way to measure the spacecraft's plasma   
   environment to make a definitive determination of its location. A coronal mass   
   ejection, or a massive burst of solar wind and magnetic fields, that erupted   
   from the sun in March 2012 provided scientists the data they needed. When this   
   unexpected gift from the sun eventually arrived at Voyager 1's location 13   
   months later, in April 2013, the plasma around the spacecraft began to vibrate   
   like a violin string. On April 9, Voyager 1's plasma wave instrument detected   
   the movement. The pitch of the oscillations helped scientists determine the   
   density of the plasma. The particular oscillations meant the spacecraft was   
   bathed in plasma more than 40 times denser than what they had encountered in   
   the outer layer of the heliosphere. Density of this sort is to be expected in   
   interstellar space.   
       
   The plasma wave science team reviewed its data and found an earlier, fainter   
   set of oscillations in October and November 2012. Through extrapolation of   
   measured plasma densities from both events, the team determined Voyager 1   
   first entered interstellar space in August 2012.   
       
   In February 2013, the National Radio Astronomy Observatory's 5,000-mile-wide   
   Very Long Baseline Array (VLBA) made this image of Voyager 1's radio signal   
   from interstellar space.More"We literally jumped out of our seats when we saw   
   these oscillations in our data -- they showed us the spacecraft was in an   
   entirely new region, comparable to what was expected in interstellar space,   
   and totally different than in the solar bubble," Gurnett said. "Clearly we had   
   passed through the heliopause, which is the long-hypothesized boundary between   
   the solar plasma and the interstellar plasma."   
       
   The new plasma data suggested a timeframe consistent with abrupt, durable   
   changes in the density of energetic particles that were first detected on Aug.   
   25, 2012. The Voyager team generally accepts this date as the date of   
   interstellar arrival. The charged particle and plasma changes were what would   
   have been expected during a crossing of the heliopause.   
       
   "The team's hard work to build durable spacecraft and carefully manage the   
   Voyager spacecraft's limited resources paid off in another first for NASA and   
   humanity," said Suzanne Dodd, Voyager project manager, based at NASA's Jet   
   Propulsion Laboratory, Pasadena, Calif. "We expect the fields and particles   
   science instruments on Voyager will continue to send back data through at   
   least 2020. We can't wait to see what the Voyager instruments show us next   
   about deep space."   
       
   Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both   
   spacecraft flew by Jupiter and Saturn. Voyager 2 also flew by Uranus and   
   Neptune. Voyager 2, launched before Voyager 1, is the longest continuously   
   operated spacecraft. It is about 9.5 billion miles (15 billion kilometers)   
   away from our sun.   
       
   Voyager mission controllers still talk to or receive data from Voyager 1 and   
   Voyager 2 every day, though the emitted signals are currently very dim, at   
   about 23 watts -- the power of a refrigerator light bulb. By the time the   
   signals get to Earth, they are a fraction of a billion-billionth of a watt.   
   Data from Voyager 1's instruments are transmitted to Earth typically at 160   
   bits per second, and captured by 34- and 70-meter NASA Deep Space Network   
   stations. Traveling at the speed of light, a signal from Voyager 1 takes about   
   17 hours to travel to Earth. After the data are transmitted to JPL and   
   processed by the science teams, Voyager data are made publicly available.   
       
   "Voyager has boldly gone where no probe has gone before, marking one of the   
   most significant technological achievements in the annals of the history of   
   science, and adding a new chapter in human scientific dreams and endeavors,"   
   said John Grunsfeld, NASA's associate administrator for science in Washington.   
   "Perhaps some future deep space explorers will catch up with Voyager, our   
   first interstellar envoy, and reflect on how this intrepid spacecraft helped   
   enable their journey."   
       
   Scientists do not know when Voyager 1 will reach the undisturbed part of   
   interstellar space where there is no influence from our sun. They also are not   
   certain when Voyager 2 is expected to cross into interstellar space, but they   
   believe it is not very far behind.   
       
   Credits:   
       
   Production editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   Related Links and More Information:   
       
   Voyager Interstellar Mission  -- home page from JPL   
       
   JPL built and operates the twin Voyager spacecraft. The Voyagers Interstellar   
   Mission is a part of NASA's Heliophysics System Observatory, sponsored by the   
   Heliophysics Division of NASA's Science Mission Directorate in Washington.   
   NASA's Deep Space Network, managed by JPL, is an international network of   
   antennas that supports interplanetary spacecraft missions and radio and radar   
   astronomy observations for the exploration of the solar system and the   
   universe. The network also supports selected Earth-orbiting missions.   
       
   The cost of the Voyager 1 and Voyager 2 missions -- including launch, mission   
   operations and the spacecraft's nuclear batteries, which were provided by the   
   Department of Energy -- is about $988 million through September.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.94   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)