Every 175 years, a rare phenomenon occurs in space wherein, the giant gaseous outer planets; Jupiter, Saturn, Uranus and Neptune line up in a manner, enabling just one single spacecraft to hop from one to the next, using the gravity of each planet to keep speeding it on its way. Mission experts predicated this in 1960, a decade earlier than the occurrence of the phenomenon, as it would start in the late 1970's. Taking advantage of this, NASA approved the launch of the Voyager Project, designed to send twin spacecraft to the outer solar system.
Launched in 1977, the twin spacecraft is still in orbit and continues to send data. It completed 26 years of space travel and is approaching new milestones. The twin spacecraft opened new areas in space research and increased our knowledge of Jupiter and Saturn. Voyager 2 extended its space travel and flew by Uranus and Neptune, and became the only spacecraft ever to visit these planets.
Voyager 1 is now the most distant human-made object in the universe at a distance, more than twice as distant as Pluto, and Voyager 2, is soon to join its twin spacecraft. The spacecraft is at the boundary region; the heliopause and its current mission is to study the region where the Sun's influence ends and the dark areas of interstellar space begins.
The main aim of the Voyager 1 was to the explore Jupiter and Saturn. After discovering active volcanoes on Jupiter's moon and details of Saturn's rings, the mission was extended. Voyager 2 went further to explore Uranus and Neptune, and is still the only spacecraft to have visited those outer planets. The Voyager Interstellar Mission (VIM) is the current mission of the spacecraft, which includes exploration of the outermost edge of the Sun's domain and beyond that.
Voyager Interstellar Mission
The Voyager Interstellar Mission (VIM) is an extended mission of Voyager 1 and 2. The aim of this mission is to discover the various characteristics of the outer solar system environment and look for the heliopause boundary (the outer limits of the Sun's magnetic field) and outward flow of the solar wind. Penetrating into the heliopause boundary between the solar wind and the interstellar medium will enable measurements of the interstellar fields, particles and waves
Both Voyagers are moving towards the outer boundary of the solar system looking for the heliopause, the region where there is minimal influence of the Sun and the beginning of interstellar space can be sensed. No spacecraft has explored the heliopause and the Voyagers may be the first to pass through this region. This region exists around 8 to 14 billion miles away from the Sun. Probably, in the next 5 years; the two spacecraft could cross an area known as the termination shock. In this region the million-mile-per-hour solar winds reduce to a speed of about 250,000 miles per hour, which is the first indication that the wind is close to the heliopause. The Voyagers should cross the heliopause after 10 to 20 years after it reaches the termination shock.
The Voyagers have sufficient electrical power and thruster fuel to operate at least until 2020. After that, the Voyagers may just wander in the Milky Way.
The VIM can be divided into three distinct phases:
This interstellar exploration is the ultimate goal of the Voyager Interstellar Mission.
Let us now see the different components of these spacecraft