Voyager Two: Earth’s Second Interstellar Spacecraft
There will be others of course, but they won’t live to see it…at least not the probes that are in flight right now.
The Voyager probes are almost as old as me, and my teeth are loosening. Just kidding, my teeth are fine, but Voyager 2 still has it’s plasma temperature sensor working, which is more than I can say for Voyager 1.
Scientists now know, now that Voyager 2 has exited the Sun’s heliospheric shell, that it is more symmetrical than they anticipated. Both Voyagers detected the transition at close to the same distance from the Sun, even though they exited by different paths. The Interstellar Medium (ISM) is rather like the solar wind, but originates from other sources around the nearby stellar neighborhood such as novas, super novas, and very large stars. Voyager 2 is able to tell us that the ISM is both denser and colder than the solar wind that forms the shell that surrounds the Sun and us. Also, even though both Voyagers have entered Interstellar Space, the Sun’s magnetic field still rules. In fact, it will be a very long time indeed before the two voyagers exit that shell and much, much longer before they leave its gravitational influence.
So yes, we can now study Interstellar Space, thanks to spacecraft that were launched four decades ago by people who cared about studying space. An older generation of scientists placed those probes on course knowing that they’d be retired or dead before today’s scientists could use them. There’s a lesson in there for anyone paying attention.
Did I peak your interest? The scientific papers that have been written about the things they have learned so far about the heliosphere and the ISM from the Voyagers has been published, but I don’t have time to read them today.
Here they are. Enjoy.
Source: Voyager 2 plasma observations of the heliopause and interstellar medium
Source: Cosmic ray measurements from Voyager 2 as it crossed into interstellar space
Source: Magnetic field and particle measurements made by Voyager 2 at and near the heliopause
Source: Energetic charged particle measurements from Voyager 2 at the heliopause and beyond
Bill Housley 