NASA Social DSN50: Why the Deep Space Network?
The Deep Space Network (DSN) is a collection of radio antennas which allows NASA, and their partners, to communicate with the various satellites, probes, and rovers on other worlds and in the vast expanse of space. NASA JPL operates antennas at three locations around the world, however the DSN is in more locations and other partners operate other locations.
These locations are strategic in order to allow for constant communication with assets. Since the Earth is round, and since it rotates, in order to allow for communication at any given time to any specific object in space the antennas have to be positioned around the world. The three locations that NASA JPL operate are located in:
- Goldstone, California, United States
- Madrid, Spain
- Canberra, Australia
There’s a graphic on Wikipedia that really demonstrates the positioning of these antenna and how the positioning is important. This graphic has been included below:
So why is this important? Because once we launch an object into space we need a way to send it new orders so it can keep working. We don’t have a way to program a rover for every possible outcome because we’re sending a rover to learn about what we don’t know about yet! Voyager 1 & 2, for example, are further away than any other man-made object in space. How far, exactly? Well, there’s a nifty site that NASA runs which gives up-to-the-second updates about the position of each of these probes relative to Earth. At the time of this writing Voyager 1 was a little over 19 billion kilometers from Earth and Voyager 2 was about 15.6 billion kilometers from Earth. That’s really really far away.
With numbers this big it’s hard to imagine that distance, so let’s demonstrate it a different way. When you listen to the radio in your car, there’s a delay. If you were to be sitting in the ballpark watching a baseball game and listening to the game on the radio, you’d hear the announcer at the game before you heard the announcer on the radio (let’s ignore the mandated FCC bleep delay for this example). That delay is the time it takes the radio signal to travel from the transmitter to your receiver going the speed of light. The delay only increases as you get further and further away from Earth. A popular example is it takes about 15 minutes to get a signal from Mars. That’s one direction. It’s about 30 minutes for a conversation to happen. Ready for the big numbers, mind-boggling part? Voyager 1, at over 19 billion kilometers away, takes 17 hours, one way, to receive a signal. That’s a signal that’s still traveling at the speed of light.
Let’s stick with the car radio analogy because it works well to demonstrate the importance and power of the DSN. You’re in your car, listening to the radio, while on a road trip to another state that’s hundreds of miles away from your home town. Eventually the station you have tuned in your car radio to will start to fade. The signal from the transmitter is only so powerful and when you get near the ends of the radius you start to lose quality. Maybe you don’t catch every word of a song or broadcast. Keep driving and you lose it completely. The exact same thing happens in space. The DSN has to be powerful enough to be able to blast these signals hundreds of thousands, millions, even billions, of kilometers away from Earth and have our assets pick them up. Therefore the DSN has to send out an extremely strong signal. But our probes don’t have the ability to send out these super strong signals back, so how do we get information sent back? The DSN has to be able to listen for incredibly faint signals and amplify them.
The NASA Social for DSN50 celebrates 50 strong and amazing years of talking to space assets using this network positioned around the world. On April 2nd I’ll be touring one of these locations, the one in Goldstone, CA, and will learn so much more about how this network works and the future of the DSN for many years to come. Interested in learning more about what the DSN is doing right now? NASA has a cool site where you can watch what antennas are talking to what space assets at this very moment. Check it out, it’s really cool!