Welcome to brain Stuff from how Stuff Works dot com where smart Happens. Hi, I'm Marshall Brain with today's question, how are the Voyager spacecraft able to transmit radio messages? So far? The two Voyager spacecraft certainly have an amazing track record. They were sent to photograph planets like Jupiter, Saturn, and Neptune, and they've just kept on going towards the outer edge of the Solar System. Voyager one is currently over ten billion miles or about sixteen billion kilometers away
from Earth and it's still transmitting. It takes about fifteen hours for the signal to travel from the spacecraft to Earth. The Voyager spacecraft used twenty three watt radios. For comparison, your cell phone typically has a three watt radio inside, So in the grand scheme of things, the voice Woyager radios aren't really that high power in terms of transmitters. Big radio stations on Earth transmitted ten thousand watts or more,
and they still fade out fairly quickly. The key to receiving the signals here on Earth is therefore not the power of the radio, but a combination of three other things. First, NASA is using extremely large antennas. Second, those antennas are directional and they point right at each other. And third, the radio frequencies used by Voyager don't have a lot of man made interference on them. The antennas that the Voyager spacecraft use are huge. You may have seen people
who have large satellite dish antennas in their yards. These are typically two or three meters or six to ten feet in diameter. The Voyager spacecraft has an antenna that is three point seven meters or about fourteen feet in diameter, and it transmits to a thirty four meter a hundred feet or so antenna on Earth. The Voyager antenna and
the Earth antenna are pointed right at each other. When you compare your phone stubby, little omnidirectional antenna to a thirty four meter directional antenna, you can see the main thing that makes a difference in getting signals back from Voyager. The Voyager satellites are also transmitting in the eight giga Hurts range, and there's not a lot of interference at this frequency. Therefore, the antenna on Earth can use an extremely sensitive amplifier and still makes sense of the faint
signals it receives. Then, when the Earth antenna transmits back to the spacecraft, it uses extremely high power tens of thousands of watts to make sure the spacecraft gets the message for moral this and thousands of other topics because it how stock works. Dot com