Back in 1977 (41 years ago), Voyager 2 Probe has left the earth to explore our Solar System. It was launched 16 days before its twin craft Voyager 1, which also was sent to explore the skies. Both probes are currently traveling in interstellar space – the space where our sun’s winds and magnetic field influences cannot be “felt any more”.
The Voyager 1 completed its mission of exploring Jupiter’s moon back in 1980 and was traveling since away from our sun’s orbit and its planets. Even though 1970’s technology was not as advanced as now, the probe was continuing its journey to outer space with a high speed of 54,000km/h (34,000mph). Voyager 1 is further and faster still, at 22 billion km and 61,000km/h.
Currently, your iPhone is more powerful and advanced comparing the probes Voyager 1 and 2. The probes do not have processors equipped in them, and their photo camera has long been turned off in 1990. Their memory is small, but enough to send various radio signals back into the earth. Voyager 2 data takes about 19 hours to reach Earth.
Today, NASA has confirmed that Voyager 2 also has hit the interstellar space as its brother Voyager 1. Voyager 2’s date of departure from the Solar System was 5 November 2018. The scientists say that on that day, the steady stream of particles emitted from the Sun detected by the probe suddenly dipped. It means it crossed out the “heliopause” area. It reached the sun’s protective bubble of particles and magnetic field.
However, the passing heliopause does not mean that the probes are completely beyond the electromagnetic field reach of the sun. There is also an Oort cloud – the space which has cold ice comets reside. They are weakly influenced by son’s electromagnetic field. We can say that both Voyagers are far away from the sun’s reach only if they get past the Oort cloud. However, that will not happen in our closest generations.
Despite having older information, this image from 2013 will help you to visualize how far away both probes have gone. Currently, both Voyagers are in interstellar medium and they will reach Oort Cloud in 300 years.
The Voyager 2 probe’s present location is some 18 billion km (11 billion miles) from Earth. To know how far away that is in human terms the term Astronomical Unit is used. Earth is 1 astronomical unit (AU) from the Sun. Saturn is at 9 AU, and the heliopause is at more than 100 AU. Neptune is 30.1 AU from the Sun; Thus the edge of interstellar space is more than three times as far from the Sun as the last planet (Wikipedia). This is the farthest place in the universe the human-made device has ever reached.
Both Voyagers will reach Oort cloud in 300 years (by that time, the probes will stop transmitting weak radio signals to earth) and it would take about 30,000 years to pass through it. Voyager 1 is heading towards an encounter with a star called AC+79 3888, which lies 17.6 light-years from Earth, in about 40,000 years. Voyager 2 is heading towards the constellations of Sagittarius and Pavo. In 40,000 years time, it will be 1.7 light years away from a star called Ross 248.
Both Voyager 1 and Voyager 2 currently run with the radiotermal generator, which is basically a lump of radioactive material (the same nuclear power used to power the Atomic Electric Stations to produce the electricity from water). The crafts will run out of power presumably by 2030. The Voyagers will carry on in the same direction as they are going now and at the same speed, even when radio thermal generators stop producing enough electricity to power them.
The scientists believe that the probes’ momentum acceleration will be enough to travel an empty space at the same speed since there will be nothing left to stop them. The Voyagers will continue until they encounter a gravity field strong enough to draw it or slow down or they might hit something else and be destroyed.