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Re: Mars? Why not P3x in moon orbit...?



>From: "Robert Oler" <cvn65vf94@msn.com>
>William.
>
>Well to toss in my two cents worth...
>
>I think that any discussion of any AMSAT class probe to anywhere that the 
>"light times" are measured in minutes is on the face of creating a 
>communications package alone quite silly.  My take on life is that the 
>"range" of a viable communications package is going to be probably the 
>LaGrange points and thats just based on the "time delay".  now signal 
>strength of course is another consideration.  We have left simple sat here 
>and are into something like "large" directional antennas OR making the 
>difference up on the ground.

ED>  As showed in my prior reply.  I did not consider time delay factors,
either.  The RTLT to Mars is about 1.5 hours if I remember correctly
[Viking-I].  Sounds like a pac-sat concept vs linear transponder.  

>Now as an aside I would note that a lunar orbiter or a lunar surface package 
>that makes "Oscar Zero" a reliable communications mode to "modest" (read 
>smallish EME stations) stations might be a worthwhile goal.
>
>However the other thing that frankly kills a lunar orbiter or a L1 stand 
>alone amateur package (not to mention a Mars one) is the need for mastery of 
>skills which the satellite community has not come close to demostrating and 
>thats primarily propulsion.  Both the L and lunar orbiter are heavy orbit 
>maintenance places.  We almost lost 40 to propulsion efforts which to be 
>kind were "incomplete success".
>
>I think that its silly to try and develop that expertise or spend the money 
>on such systems.

ED>  Obviously, this implies getting a free ride with NASA.  A remote
possibility might be a program similar to ARISS for a moon base...but in my
lifetime?  Any moon surface package would require active antenna pointing
to track-out libration effects assuming high gain antennas...or a huge
solar-power budget if low-gain antennas were coupled with QRO!

>Now what might a Mars 'amateur' probe be "useful" for?  It might be neat 
>just from a "complete" science package BUT if you think that lunar or 
>Libration point comm is "antenna" intensive...Well take a look at what it 
>takes to get a signal back from mars.

ED>  Ground station requirements for Mars are not at the amateur level
[~85-foot dish].  Besides if you want to just prove you can hear that far,
then NASA provides a signal from its Mars orbiters on 8415 MHz...good luck!
 Oh, I supose with a super-huge antenna with extremely stable freq.
control/advanced-DSP sub-hertz bandwidth techniques, signal detection is
possible...The SETI-Institue calibrated its instruments using signal from
Pioneer-10 at distances beyond Pluto [using the 1000-foot Aricebo dish].

>We will see the first lunar repeater/transponder at some point.  One day 
>when we have a decent space program America will return to the Moon.  Thats 
>a few years in the offing.
>
>Robert
>
>WB5MZO Houston TX

ED>  Quite a few years!  Unmanned robotic missions are providing lower cost
alternatives to manned spaceflight.  We might return to the moon by my
100th birthday ;-) 
 


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