Voyager 1, the spacecraft that was launched in 1977 to explore the outer solar system, might have been propelled into interstellar space by now according to NASA. Interstellar space is the physical space filled with ionized gas, within a galaxy which is not occupied by stars or any of their planetary systems. The confirmation comes after NASA’s report that Voyager 1 has been “again” struck by Solar Tsunami Waves.
This has not happened for the first time that the spacecraft got hit by these waves. In 2012 and 2013 it had met with such waves as well – these shock waves were sent outwardly by the sun, reaching Voyager a year later.
What is the origin of these shock waves?
The sun usually expels huge amounts of particles into space – coronal mass ejections (CMEs). When this happens, shock waves are created, reaching out to great distances extending from the sun. The spacecraft had embedded a plasma wave detector as well as a cosmic ray sensor – just what it needs to spend some time in space, huh? These gadgets are able to identify shocks waves when they happen.
In that area of the space where the Voyager 1 was traveling, plasma is 40 times more dense that it is within the solar system. Its high density near the sun is due to the latter sending solar winds which compels the gas into a bubble-like system. The plasma wave detector is the instrument that measures the frequency at which the tsunami wave hits the plasma, while the cosmic ray sensor detects the origin of what hit the bubble of gas. That was how the scientists were able to conclude that it was a shock wave from the sun.
Voyager 1 is said to have gone through the heliosphere – the first time ever something sent from planet earth has reached there. But, it does not imply that it is no more contained in the solar system.