NASA's Voyager 1 spacecraft on 12 September 2013 officially became 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.
During its journey Voyager 1 has travelled through plasma or ionized gas, present in the space between stars for about one year. At present the Voyager is in the transition region, outside of the solar bubble. This transition region still has evidences of the effects of the sun.
The Voyager NASA mission is at a distance of 19 billion kilometer from home and thus a radio signal sent from the voyager takes 17 long hours to reach its receivers on the earth. Launched in 1977, Voyager was sent initially to study the outer planets, but then just kept on going.
For the first time, the increased pressure of the interstellar space on the heliosphere (the bubble of charged particles surrounding the sun that reaches far beyond the outer planets) was detected by the Voyager 1 in 2004.
Due to the lack of working plasma sensor on Voyager 1 scientists took the support of the coronal mass ejection (massive burst of solar wind and magnetic fields) that erupted from sun in March 2012 to measure the spacecraft's plasma environment to make a definitive determination of its location. After spacecraft's interstellar arrival the plasma around the spacecraft started vibrating like the strings of the violin and the pitch of the oscillations helped the scientists to determine the density of the plasma.
This exceptional oscillations provided clues that 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.
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.
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.
The report on the analysis of this new data was published in journal Science.
Important Terms to be remembered
Interstellar Space: The Interstellar Medium exists in the space and it is a matter that lies between the star systems in a galaxy. This is made up of gas in ionic forms, atomic form and molecular form as well as the dust and cosmic rays.
Solar Bubble: It is also termed as the heliosphere and it is the region that has the effect of the sun and acts in the space as a charged particle bubble across the solar system.
Solar wind: It is a stream of charged particles that is blown away from the sun and it travels at the Supersonic Speeds like White Arrows
Termination shock: Termination shocks are felt in the space in the areas where sun begin to slow and clash with matter from deep space