Radio contact/commands to satellites?

Question

Just how strong are the signals coming from satellites which have gone past the orbit of Saturn?

Do the signals come in a straight line (such as a laser), or what? What is the wattage of the signals being transmitted?

Cudos to the programmers who can set all this up, + the math, physics, astronomy, people who do this. I never ceased to be amazed at the technical expertise of these people!

Answer 1

I think all the deep-space probes launched to-date that left the solar system used S-band (~2-3 GHz) radio transmissions. They're very low-power too (Pioneer was something like 8 W - not that much more than the average cell phone). Given the distance involved, I think its pretty impressive that we can pick them up at all.

Answer 2

You can read about how communication works with the Voyager probes here:

http://science.howstuffworks.com/questio...

The signals are transmitted in a straight line with the antennas point directly at each other. NASA uses the largest antenna in it's deep space network to transmit to the probes, transmitting at around 20 kilowatts. The probes on the other hand only have 23 watt transmitters.