What hears a whisper a billion miles away?

What hears a whisper a billion miles away?

What do you think is . . .

  • Wittier than a wiley wizard?

  • More powerful than an apatosaurus?

  • Able to sweep across the whole sky without a sound?

It's Super Space Place Girl!

Cartoon of super space Place girl.

Her powers are awesome! But not as awesome as what ordinary humans have invented to solve a big problem of space exploration:

How do we communicate with the tiny spacecraft we send to explore deep, dark space and strange other worlds?

The answer is . . . (drum roll here, please) the

Deep Space Network!

The enormous antennas of the Deep Space Network are so sensitive they can hear what amounts to a tiny whisper from millions, or even billions, of miles away.

Carried on this tiny whisper from the spacecraft explorers are beautiful images of planets, moons, asteroids, and comets.

Locations of the three DSN antenna complexes.

This world map shows the three locations of the Deep Space Network's antennas. As Earth rotates on its axis, a spacecraft way out in space will be able to "see" at least one set of antennas. Each of the three locations has several antennas for tracking different spacecraft at the same time.

20-Watt appliance light bulb.

The spacecraft transmitter that sends the signal to Earth is about as powerful as the light bulb in your refrigerator. By the time it reaches Earth, the spacecraft signal delivers only 0.000000000000000003 watts of power to the 70-meter antenna. But the antenna can still detect it!

It is very hard to imagine how weak that signal is. The chart below may help.

If you could collect and store all the energy the antenna receives from the spacecraft, you'd have to do it for time in the first column (400 years, for example) to have enough energy to light a standard 4-watt Christmas tree bulb for the time shown in the second column (a 100-millionth of a second!).

Store the Signal for

Animated down arrow

To Light a Bulb for

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400 years 1 100-millionth of a second Flash in the dark
40,000 years 1 millionth of a second
For as long as it has been since the dinosaurs became extinct Less than 2 thousandths of a second
For as long as Earth has existed 1/10 second (this is how long the bulb at the right is staying on)
article last updated May 6, 2015
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