I have a kind of odd, but not very disturbing, technical question.
You know the gold record on the Voyager spacecraft? I know it has a few images stored on it, in analog form. But could it be used to store video, in the same way? And, if so, how much video? Seconds? Minutes? Maybe even HOURS?
Well, thanks for your kind patience,
Ranchoth
Well, if it were simply a gold-plated LaserDisc, the video capacity would be 30 minutes in CAV or 60 minutes in CLV mode.
But this one’s meant to be spun at “transcription record” speed - 16 and 2/3 RPM. From a JPL site there’s roughly 100 minutes of audio and 115 still images. Audio playback is easy. The images won’t be so easy - it appears the instructional diagrams on the other side are depicting how to extract images in the North American NTSC video format. This 115 images translates to about four seconds of moving video.
There’s something I’ve wondered about: How is the proper playback speed indicated? Most of the information for decoding the messages is fairly straightforward: To indicate size of objects in pictures, for instance, you show them next to the Voyager spacecraft itself. But time wouldn’t be so simple.
Don’t they reference time to one or more pulsars? Sure, they’re slowing down over time, but even over the next few million years the rate of rotation is stable to a few 1/10ths of a percent.
After doing some reaserch, no, the pulsar map on the disc is only to show where Earth is (Hey, you aliens! Come attack us. Here we are!) The time constant is a state-change of the hydrogen atom as illustrated here:
No, the pulsars reference our location in relation to the pulsars. They are slowing down, but since there is a small piece of uranium attached to the record, the finder can extrapolation the time elapsed since Voyager’s departure using the half-life decay of the uranium, and adjusting the pulsar data for the inevitable slowing down.
Time is referenced by the hydrogen atom.
The spin transition state of the hydrogen atom gives the fundamental time unit, as stated previously. This is represented as a binary “1”, so the time of the transition state is 1t (t represents the time unit, which in seconds is equal to 0.7 billionths of a second (approx))
Around the picture of the record, you will see a series of vertical and horizontal lines, starting counterclockwise from the stylus. This represents a binary number. And since the number starts with a “1” digit instead of a leading “0” digit, we can determine which way the record should spin (clockwise). The binary value around the circumference reads:
100110000110010000000000000000000 binary = 5,113,380,864 decimal.
So, one rotation should take 5,113,380,864 time units. Multiplying t by this number (remember t = 0.7 billionth of a second)…
3.5999 secs per rotation, or 16 2/3 rotations per minute.
I’m afraid that data isn’t going to do Q.E.D. much good. He passed away last year.
More often than not, I don’t notice that I’m reading a zombie thread–but when I got to the posts from Q.E.D., I did a double-take. 
Please help me understand this, because there’s obviously some basic science I’ve never picked up in regards to this…
I understand an element and its half-life. Here’s what I don’t understand…
A chunk of uranium will decay to half its radioactivity in the span of its’ half-life. So far, so good.
But how can that be used to measure time? The uranium starts to decay based on…when it’s pulled out of the ground? When it’s refined?
-Joe
I’ve always thought the Voyager gold records were a cool idea. I remember Sagan lyrically talking about them on Cosmos. I also remember Saturday Night Live having a news brief in which aliens discover the spacecraft and make a simple request: “Send more Chuck Berry!” 
Years ago I saw an LP that had all of the Voyager sounds - I checked not long ago, though, and it looks like it’s not available anymore, acc. to my local library, Amazon and Ebay. Long out of print, alas. I wish someone would put them on CD.
The uranium starts to decay as soon as the uranium atoms are created in the nuclear process that produced them in the first place, such as the decay of a more massive element, or in a supernova explosion long before the atoms are gathered up in the process of planetary formation. However, note that the most prevalent isotope of uranium (U-238) has an extremely long half-life of 4.468 billion years, which is why it can still be mined from uranium-containing ores.
In any event, according to this website, the Voyager spacecraft contained an ultra-pure sample of U-238. In this manner, because the U-238 was purified using artificial, man-made techniques, it is possible to date the sample of U-238 to when the sample was purified by comparing the ratio of U-238 still present to that of the daughter products.
There is a book about the making of the Voyager Records that goes into great detail called Murmurs from Earth I still have a copy.
BTW JPL was recently having problems communicating with one of the Voyagers, I don’t know if the trouble was resolved.
I remember Murmurs from Earth. Good book. I’d still just like to hear the musical excerpts and the spoken greetings (from Jimmy Carter and Kurt Waldheim, among others) myself.
I don’t know if it’s on CD, but you can download the sounds from NASA.