deep-space network

DSN Uplink-Downlink

Link Up and Listen!

When the antennas of the Deep Space Network ask "What's up out there?"— a lot of far away spacecraft get ready to call home with the news.

Why are there three antennas in the game?
And what are those spacecraft in the sky?
Keep on reading to find out!

Photos of antennas a Goldstone, California, Canberra, Austrailia, and Madrid, Spain.

These are the Deep Space Network (DSN for short) of antennas that stay in touch with the many NASA spacecraft that are out exploring the solar system.

The spacecraft are so far away, that relative to Earth's rotation, they might as well be standing still. That's why the antennas that must stay in touch with them are located at three places around the Earth. As Earth turns, there is always one antenna in view of every spacecraft.

Map of world showing locations of DSN antennas in Southern California, Canberra, Australia, and Madrid, Spain.

As Earth turns, each DSN location comes into "view" of some spacecraft. To talk and listen to a spacecraft, the DSN antenna must link up with the signal from the spacecraft's antenna. Then the DSN antenna must rotate to maintain that link as Earth continues to rotate through the day. Just when the DSN antenna is about to rotate out of view, the next DSN location on Earth's surface is rotating into view. The link is "handed over" to the "new" antenna before the "old" antenna loses it. That way, the spacecraft is always in touch with Earth.

When the DSN antenna is transmitting a message to the spacecraft, the link is called an "uplink." The uplink is for sending commands or new software programs to the spacecraft. When the spacecraft is sending its data and images down to the DSN antenna, the link is called a "downlink." An antenna "uplinks" instructions to the spacecraft and "downlinks" the spacecraft's data and images.

Play DSN Uplink-Downlink. Help the DSN to gather the data from these five missions:

Drawing of Cassini spacecraft. Cassini: Studying the Saturn system
Drawing of New Horizons spacecraft. New Horizons: On its way to study Pluto and other icy objects.
Drawing of Kepler space telescope. Kepler: Looking for Earth-like planets in other solar systems.
Drawing of Mars Reconnaissance Orbiter spacecraft Mars Reconnaissance Orbiter: Studying Mars from orbit.
Drawing of Epoxi spacecraft. Epoxi: Flyby study of comet Hartley II.
article last updated June 9, 2016
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