Deep Space Network

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Original post by Xtremehobo
How come we need huge antennas here on earth to communicate with the rover on mars, but the rover on mars doesn''t need nearly as large of an antenna as us?

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I don''t know, but I''ll give a retarded try:

Our atmosphere is thicker so um, we need big antennas. There, there is the most retarded answer today.

As we have a huge antenna, it can pick up the (relatively) small signal the rover is sending out, and it can also send out a (relatively) large signal, which the rover is able to pick up with it's much small antenna. Well that's what I reackon it is.

[edited by - Monder on January 13, 2004 6:14:16 PM]

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Original post by Nervo

quote:

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Original post by Xtremehobo
How come we need huge antennas here on earth to communicate with the rover on mars, but the rover on mars doesn''t need nearly as large of an antenna as us?

...

:/

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I don''t know, but I''ll give a retarded try:

Our atmosphere is thicker so um, we need big antennas. There, there is the most retarded answer today.

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actually, yes, this is a large part of it.

However, the rover probably does have a large antenna on the lander module. Then, the rover only needs a small antenna to communicate with the lander module, which can in turn narrow-cast (as opposed to broadcast) back to Terra.

One reason why antennas are so large on Terra is so that they can see over the horizon. If you pay close attention, you will usually see the largest radio antennas on mountain ridges. This way, broadcasts can be relayed around the world.

Finally, Mars is much further from Sol than Terra. Sol accounts for quite a bit of interference, so much so that radio transmission power has to be turned down at night to prevent radio transmissions from being beamed TOO far. If the broadcast power of day were used at night, you would easily be able to hear a west coast radio station on the east coast.

An interseting note, given the proper allignment of certain atmospheric events, radio transmissions can make it half way around the world (the farthest it could possibly go and still be on Terra) on one antenna.

Simple explanation:

Big antenna''s receive better as well as transmit better. The larger dish can collect more of the weaker rover signal.

Monder had it right.

It takes power to broadcast strong signals. why waste power on it at mars when we can do it here?