Today we announce the first dataset, of what we hope to be many, from the Breakthrough Listen initiative to be hosted on Radwave: the Voyager 1 dataset conducted back in 2015 at the onset of the Breakthrough Listen initiative.
Voyager 1&2 are space probes launched in the 1970's. They explored all the outer planets of our solar system, and are now the furthest man-made objects ever launched. As they continue exploring our cosmos, they also serve as a important calibration source for Breakthrough Listen, enabling everyone to maintain confidence in the quality of the observations. And it's pretty cool all by itself. You're looking at a signal that was transmitted from outside our solar system. It took more than 20 hours to reach Earth.
This particular signal was transmitted from Voyager 1 back in 2015, at the beginning of the Breakthrough Listen project. The signal is centered near 8420.21 MHz, and if you zoom way into it, you'll be able see the carrier in the middle and the two data portions on each side. The carrier is often used for tracking the center frequency and phase, which is necessary to decode the data portion of the signal. As you can see zooming further into the signal, these signals aren't purely vertical. From what I can tell, there's a drifting Doppler shift due to Earth moving relative to voyager. The Earth is orbiting the sun while spinning in its axis, whereas voyager is cruising out into space, pointed straight back at Earth. Can any of you confirm this or offer a more accurate explanation? If it is Doppler, then it'd be cool to calculate the relative differential velocity. I'm fairly sure that Voyager is traveling on a near constant velocity trajectory at this point, so it'd be fun to calculate the expected Doppler range due to Earth's motion. If any of you have details on this, it'd be great to learn more.
The data portions of the signal are pretty interesting too. You can observe the Doppler shift with them, but there are also periodic high energy spurs on the edge of the signal bandwidth. I'm personally really curious what those spurs are caused by. Is it an intentionally engineered signal feature? If so, what does it help with? Or is it due to some limitation with voyager's transmit capability? If so, what does that limitation stem from? Or maybe it's an artifact from the Green Bank Telescope receiver? It'd be awesome if an expert from NASA, JPL, or Breakthrough Listen could jump in and offer some insight.
This dataset is 50 GB in raw form, and had to be expanded to 800 GB before it could be processed properly using digital signal processing techniques. That's a lot of data to process, and a whole lot of data to serve. But it's actually just a tiny part of the 1PB of data that we're trying to dig through.