The news has all had details that the US space probe Voyager I has transitioned out of the domain of solar space and is now in interstellar space. I was reading on article on this in the Atlantic magazine and they had a fascinating detail: the NASA scientists monitoring this used a frequency-response test to determine this. They tracked a solar explosion as it travelled out to where Voyager was and noted that its frequency as detected indicated the plasma around the spacecraft was 40x denser than it was in the outer reaches of the heliosphere (solar space). AND they had a recording on Soundcloud that depicts the sounds the spacecraft would have heard. Utterly wonderful.
Here's the URL to the Atlantic article:
http://www.theatlantic.com/technology/a ... -humanity- has-arrived-at-interstellar-space/279624/
And here's the Soundcloud link directly
https://soundcloud.com/theatlantictech/ ... 1-heard-in "
I spent some time (far too much!) moving out from the link he provided, and came across some other stuff -
We apparently sent a gold record out on Voyager. Made of gold! It was our collective human "calling card" - photos, mathematical symbols and proofs, a map of how to find us (gulp!), and ... music!!
Chuck Berry made it on this gold record (singing Johnny B. Goode). Louis Armstrong did too. Blind Willy Johnson. Bach, Beethoven, Mozart, Stravinski. Pygmies, and Aborigines. What, no Beatles??
The link has about a million fascinating things to click on!
The Soundcloud .wav is, as best as I can tell from reading these things, *not* what was actually heard by Voyager - I did not read of any actual audio audio microphones on the spacecraft (and even if there were, there's not much matter out there to be compressed!). My best understanding of the NASA material is that it is some kind of audio representation of the frequency of the oscillations in velocity of magnetic field around the spacecraft. I wonder if those are the actual frequencies, or "octaved down" (or up?) by a few powers of ten ...
http://www.nasa.gov/mission_pages/voyag ... UjU5an-4IT p
http://www.nasa.gov/mission_pages/voyag ... .UjU6Mn-4I To
What blew my mind as much as anything else is that Voyager's signals are emitted with a total power of 23 Watts, described as the approximate power of the average refrigerator light bulb. By the time we receive them, the signals are a billionth of a billionth of a Watt. That is some fine software to pick the signal out from the noise of space! (160 bits/second transmission).
It's also kind of cool how we humans determined the best way to tell those aliens how to play the record http://voyager.jpl.nasa.gov/spacecraft/ ... iagram.jpg - expressing the rotational speed (16-2/3 RPM!) as a power of the "period of the fundamental transition of the hydrogen atom". We sent a cartridge and stylus for convenience (Pioneer brand?? ). Oh, and there's a picture to let the other guys know - the record is meant to be played from the outside in, not vice versa!
As one of the articles says ... "It will be forty thousand years before they make a close approach to any other planetary system. As Carl Sagan has noted, 'The spacecraft will be encountered and the record played only if there are advanced spacefaring civilizations in interstellar space. But the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet.'"
"Deep down Louisiana close to New Orleans
Way back up in the woods among the evergreens ..."