In order to make sure that Voyager 1 has reached interstellar space, two researchers are conducting a test, which will help them determine whether the spacecraft is inside or outside the heliosphere. An announcement was made by Voyager 1 mission members last year that the spacecraft has made it into interstellar space in August 2012, but the entire academic community was wary of that claim.
The researchers want to confirm whether or not the spacecraft has entered interstellar space. The heliosphere is the bubble created by the sun. The bubble is made up of solar particles and magnetic fields that the sun creates around itself.