Voyager 2 at the Brink of Deep Space
One of my favorite missions made the news this past week. The Voyager 2 spacecraft, which is on its way out of the solar system on a trajectory to deep space, is nearing the limits of the Sun’s influence on space. In August of this year it crossed the solar wind termination shock, a point in space where the solar wind smashes into the thin gas that exists between the stars. The solar wind basically blows a big bubble of gas (from the Sun) into surrounding space; the “edge” of that bubble is called the heliopause. Crossing the “membrane” of that bubble registers as a blip in the data the spacecraft sends back, alerting astronomers that a momentous event has occurred. Voyager passed this goalpost in space did so a bit earlier than astronomers expected, which implies that the heliopause is not as symmetrical as they thought. Because the solar wind varies a bit in its extent, Voyager may well bounce and out of the heliopause.
I first heard about the Voyager mission back in the late 70s, just after it was launched. It sent back some amazing images of Jupiter, and by the time Voyager 2 got to Saturn in 1981, I was working at a newspaper in Denver, Colorado. I asked the managing editor if I could go out to Jet Propulsion Labs in Pasadena, California for the Voyager 2 Encounter of Saturn, and before I knew it, I was on my way, duly accredited as a reporter.
It was an interesting experience, and only whetted my appetite for more planetary science. A few years later, I went back to school to study more astronomy and planetary science, and so I always look back on the Voyager 2 flyby of Saturn with fond memories. Sometime in the next few years, Voyager 2 will get completely free of the heliopause and truly be in deep space. I remember back in 1981 thinking about Voyager 2 and its future mission; here we are, three decades later, and it’s just NOW getting to the heliopause. This tells us in a very visceral way that space is big!
