Going, Going… Gone?

Humans may not have travelled beyond the Moon, but for the Voyager 1 spacecraft, the final frontier of space may fast be approaching. Launched over 35 years ago, the small, unmanned probe finally may now be leaving the confines of the solar system and entering free space – having travelled a mere 18 billion kilometres.

Voyager 1 is already a record holder, having taken the title of furthest man-made object from Pioneer 10 back in 1998, and in 2004 it passed its first major boundary towards leaving the solar system: crossing the so called termination shock, where the solar winds start to slow. Now, though, the increased detection of cosmic rays – originating from outside the solar system – suggests that Voyager may have now passed the heliopause as well, where the Sun’s influence ceases.

“Current indications strongly favour the view that Voyager 1 has actually crossed this boundary and is now really travelling through interstellar space,” explains Professor Andre Balogh of Imperial College London’s Space and Atmospheric Physics research group. “Although, a final confirmation is still required, given when the magnetic field measurements made by Voyager 1 become available in the near future.”  Just like the Sun, there is magnetic field in interstellar space; it is the flip between these two fields that Voyager scientists are eagerly awaiting.

The rise in cosmic rays hitting Voyager, which began in June, came as a surprise to many as Voyager wasn’t expected to cross the heliopause for several more years yet, and may force a reworking of the current models of the solar system.

Voyager 1, along with its sister ship, Voyager 2, was originally launched as part of NASA’s plan for a “grand tour” of the outer solar system. Both craft conducted flybys of Jupiter and Saturn, sending back remarkable imagery and data from the gas giants and their moons. After this, however, their courses deviated. Whilst Voyager 2 went on to explore the ice giants, Uranus and Neptune, Voyager 1 headed for the Kuiper Belt (a group of small, icy rocks at the edge of the solar system) and the heliopause.

Instruments have been sequentially shutting down on Voyager 1 since 2007, and it’s estimated that it will cease transmitting data entirely in 2025. That won’t slow it down, though; in 75,000 years or so, Voyager will reach the next nearest star, Proxima Centauri.