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petey

Banned

From: New Jersey

Registered: 2004-09-21

Posts: 3

Re: Astronaut communication Mars to Earth - Question on the above

Hi,

I've been reading a ot of books about proposed missions to Mars, but none talk all that much about the communications systems.
I'm wondering specifically whether a special focusing antenna is NEEDED to relay communications, or if an astronaut could theoretically face Earth, yell in its direction, and eventually be heard.
What frequency would such a Mars mission be likely to use? Would there be any way that non-NASA people could pick up signals from the mission with, say, a ham radio?
As you can tell by my questions, I'm a bit of a novice when it comes to radio engineeering. What I'm wondering is: could an astronaut, separated from the main Mars lander, relay a message directly to Earth (if possible, without an antenna or special equipment), without going through the lander?

Thanks very much for any help you can provide,
Pete

Rxke

Member

From: Belgium

Registered: 2003-11-03

Posts: 3,669

Re: Astronaut communication Mars to Earth - Question on the above

Hi Petey,

Theoretically possible, at certain times, with the 2,3  biiiig antenaes on Earth... But impractical to monitor I think...

They'll probably work with relay sats in Mars orbit which will boost the suits signal before relaying to Earth etc... So smaller antenaae can pick up the signal?

Martian Republic

Member

From: Haltom City- Dallas/Fort Worth

Registered: 2004-06-13

Posts: 855

Re: Astronaut communication Mars to Earth - Question on the above

Petey

You can go to the "Martian Politics" and the "Laser Communication-Earth/Mars" section and it goes over communication of the future and what we will probably be using.

Larry,

petey

Banned

From: New Jersey

Registered: 2004-09-21

Posts: 3

Re: Astronaut communication Mars to Earth - Question on the above

Thanks for the help, guys.

Pete

MarsDog

Member

From: vancouver canada

Registered: 2004-03-24

Posts: 852

Re: Astronaut communication Mars to Earth - Question on the above

http://www.gate.net/~tomk/mgs/mr_report.html]1.3 watt beacon reception

What if you tried to take your cordless phone to Mars ?

At 2.4 ghz the maximum path http://flakey.info/wirelesstools/]loss is 211 db.
Add 5 meter http://home.online.no/~jensts/Satellite … htm]dishes for total of 80 db gain and the loss is now approx 130 db.

Cordless phone puts out tenth of a watt (20dbm=100mw), received signal is -110 dbm.

http://wirelessreview.com/ar/wireless_e … ise/]Noise is -130 dbm for 300K. (receiver and sky noise will be less than 100K)

Carrier/Noise ratio = 20 db (signal 100 times stronger than noise.)

Use your cordless phone handset from Mars, and keep your Earth phone number ?

(For wideband FM, only 12 db carrier/noise, http://www.rwt.co.uk/satspecs.htm]threshold extension, gives good reception.)

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http://people.qualcomm.com/karn/mpf_budget.html]Mars Pathfinder Radio link information