An increase in the cosmic rays which stem from the outside of our solar system has been discovered by NASA’s Voyager 2 probe, launched by the agency in the year 1977. This indicates that the voyager is now nearing the interstellar space, said the US space agency. Voyager 2 is nearly 17.7 billion kilometres away from the Earth. Since the year 2007, the spacecraft has been travelling in the heliosphere’s outermost layer, called the heliopause. The heliosphere is a bubble around the planets as well as the sun which acts as a protective shield from interstellar radiation.
The Voyager researchers have been waiting for Voyager 2 to reach the heliopause. Heliosphere blocks some of the cosmic rays, and so, the Voyager 2 mission planners expect that the spacecraft will detect an increase in cosmic rays as it exits the heliosphere.
And just when the spacecraft finally crosses from the heliosphere’s outermost layer, it will be known as the second human-made object to have entered interstellar space, said NASA via a statement. Moreover, the Voyager 2 is the only spacecraft to have visited the four giant planets of our solar system: Jupiter in the year 1979, Saturn in the year 1981, Uranus in the year 1988 and Neptune in the year 1989.
The ‘Cosmic Ray Subsystem’ instrument installed on Voyager 2 has detected around 5 per cent increase in the cosmic rays around the spacecraft since late August than compared to the measurements detected in early August. Moreover, the Low-Energy Charged Particle instrument on Voyager 2 has also measured the same increase in high energy cosmic rays.
However, the mission planners note that an increase in the rate of cosmic rays isn’t a definite sign that the spacecraft will cross the boundary of the heliosphere. Voyager 2 is at a different location of the heliosphere’s outer region called the heliosheath than compared to Voyager 1. Hence, the chances are that Voyager 2 might experience a different exit timeline compared to Voyager 1.