crossed into the true interface between the particle radiation from our Sun and that of the great gulf of interstellar space - as it travels through the heliosheath. In this region, 10.8 billion miles or 16 light hours from us, the solar wind is being turned sideways, blowing against the as-of-yet unsampled interstellar medium as we orbit around the galaxy. Eventually Voyager will cross the absolute edge of this zone of balance, through the heliopause and out into the galaxy proper.
Despite its age, Voyager is true to its name. Most of its monitoring instruments still function. It senses the ambient particle environment by registering the impact of charged particles. As their energy appears to decrease we can tell that their forward velocity is dropping, the Sun's influence now too weak to punch any further. Its 3.7 meter diameter radio dish still picks up instructions at about 16 bits/second, and relays back microwave telemetry at a typical 160 bits/second, boosting to 1.4 kilobits/second for plasma-wave data. It is overseen by 3 doubly redundant processors (6 total) that by today's standards are barely recognizable as such. These are wonderfully tough relics, ancestors with 16 and 18 bits compared to the 64-bit architectures of today's most modest laptop. The three radioisotope thermoelectric generators now generate only about 270 watts of power, compared to 470 watts in 1977 when their plutonium-238 contents were freshly minted - possibly the only rational purpose for an advanced civilization to dabble in such toxic and dangerous materials. It is a brilliantly conceived and engineered machine, something for humans to be proud of.
Together with Voyager 2 (traveling at a slower rate, still a mere 8.8 billion miles from Earth), and Pioneers 10 and 11, these amazing craft represent our first tiny steps into the interstellar void. These small specks of cosmically rare elements are for now the only outward physical sign of our presence in the universe. It is quite possible that long after we humans have become extinct, or evolved to something new, or just simply moved on, these devices will continue to serve as monuments to our curiosity and eagerness to join with the cosmos. The odds of their intersecting anything else in the universe are extremely small, it is a fair bet that they will still drift through space long after all the stars have gone out, in about 100 trillion years time. It is a sobering and fantastic thought that despite our all-to-human problems, our daily lack of perspective, we have nonetheless found on occasion the clarity to produce evidence of our existence that may live forever.