Communications System

How does NASA communicate with spacecraft?

More about radio waves and electromagnetic radiation

Electromagnetic radiation (which includes radio waves, light, cosmic rays, etc.) moves through empty space at the speed of 299,792 km per second. Sunshine is a familiar example of electromagnetic radiation that is naturally emitted by the Sun. Starlight is the same thing from "Suns" that are much farther away.

Electromagnetic radiation travels in waves that "vibrate" at different frequencies. Radio waves are in the range of about 10 kHz (or ten thousand waves per second) to 100 GHz (which is one hundred million vibrations per second).

Although these aren't electromagnetic waves, you can compare these speeds to other kinds of wave:

All together, electromagnetic waves make up what is called the electromagnetic spectrum. Radio waves are used for wireless transmission of sound messages, or for passing information.

Figure from NASA's Jet Propulsion Laboratory's publication: Basics of Space Flight Learner's Workbook.

Electromagnetic radiation with frequencies between about 10 kHz and 100 GHz are referred to as radio frequencies. Radio frequencies are divided into groups which have similar characteristics, called "bands," such as "S-band," "X-band," etc. The bands are further divided into small ranges of frequencies called "channels," some of which have been set aside for the use of deep space telecommunications. Many deep-space vehicles use S-band and X-band frequencies which are in the neighborhood of 2 to 10 GHz. These frequencies are among those referred to as microwaves, because their wavelength is very short, only a few centimeters. Deep space telecommunications systems are being developed for use on the even higher frequency Ka-band.

Band Range of
Wavelengths (cm)
Frequency (GHz)
L 30 -15 1 -2
S 15 - 7.5 2 -4
C 7.5 - 3.75 4 - 8
X 3.75 - 2.4 8 -12
Ka 2.4 - 0.75 12 - 40

How is data put on radio waves?
What interferes with radio waves?
What is wavelength?
What are radio waves?
What is frequency?
What is energy?

How is extra data sent in the radio signal?
Why does it take so long for the radio waves to travel through space?
How are frequency and wavelength related?
How does reflection affect radio waves?
What is em radiation?

What is the Doppler effect?
How do you make a radio wave?
What radio frequency does DS1 use for communications?
Where does energy come from?
What makes EM radiation?