Just over a year ago,the venerable old Voyager I spacecraft left the solar system,although not the sun's influence entirely,and entered interstellar space,the space between the stars,NASA scientists reported this week.It is now in the transition zone just outside the solar bubble,and in the ionised gas between the stars.Some solar disturbance still obtains in this transition zone.
We believe this is mankind's histric leap into interstellar space,said Ed Stone,Voyager Project Scientist at Caltech,Pasadena.Voyager had entered the heliosphere,or solar bubble of charged particles which defines the edge of the solar system,in 2004.It first entered interstellar space on 12 August,2013,when an abrupt change in the density of energetic particles was first detected by Voyager I.
Suzanne Dodd,Voyager Project Manager at NASA's Jet Propulsion Laboratory,Pasadena,said 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 I's twin,Voyager II,was actually launched a few weeks ahead of Voyager I in 1977.Both spacecraft flew by Jupiter and Saturn,but Voyager II veered off to fly by Uranus and Neptune as well.Scientists talk to or receive data from both spacecraft almost every day.It takes the weak 23 watt signal of Voyager I about 17 hours to reach earth.As of its February 21,2013 radio telescope image,Voyager I was 11.5 billion miles/18.5 billion kilometers from earth.It is now about 19 billion miles away.
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