They're leaving us behind. When we manage to get a little lucky, their stories come through and we know just a little bit more about our journey through time and space within this universe.
30 years after its launch from Earth Voyager 2 has reached the boundaries of our system and, this time, scientists here on Earth have heard Sol's surf crashing against the shores of the universe surrounding.
Pushing the boundary
The spacecraft crossed the boundary on 30 August 2007 at a distance of 84 astronomical units (AU) from the Sun (1 AU is the distance between the Earth and Sun). By comparison, Pluto is now about 32 AU from the Sun.
"We were very lucky this time," Voyager chief scientist Edward Stone of Caltech in Pasadena, California, US, told New Scientist. "We have the first direct measure of the shock."
Voyager 2 actually crossed the boundary five times (and was directly observed making the passage three of those times). That is because the location of the termination shock is constantly changing in response to the Sun's activity. Plasma burps from the Sun called coronal mass ejections (CMEs) temporarily push the boundary outwards, for example, so that it washes back and forth over the spacecraft like a wave on the beach.
Mission scientists are not sure how to explain the gradual slowdown preceding the shock. But Stone says neutral atoms from beyond the termination shock may be interacting with the solar wind to produce speedy charged particles called cosmic rays, thereby sapping some of the wind's energy.
Voyager 1 and 2 are now both in a region of slower solar wind lying past the termination shock called the heliosheath. That region ends at the heliopause, which is where the solar wind ends and interstellar space begins.
[Hang 10 Dudes y Dudettes! Eh, what the feck, Make it 30.]
It'll be interesting to see what new knowledge this supplies. What applications for space exploration in our near future might be theorized from clearing up yet more misconceptions; misunderstandings; from alleviating yet one more wee bit of ignorance about the Nature of Reality.
We'll be to see, eh.