[amsat-bb] Re: Can we get them to fix AO-40 first then?

Rocky Jones orbitjet at hotmail.com
Wed Oct 14 18:43:34 PDT 2009


to add a few things to my post (and I admit this is speculation, someone from the command team can shoot me down at anytime).

As a spinner -40 was in trouble power wise.  I "dont know" but wonder if how the "arrays" were folded they would produce power while folded?  If not then the vehicle was seriously out of power (I probably knew this at one point, but it was a bit ago).  Spinners (like the Pioneer 6-9 Venus Pioneer and a lot of the communications satellites) are "sized" so that the part of the array viewing the sun is enough to power the spacecraft without the battery.   The batteries are only used for eclipse periods (which on geo's are very short).  (as an aside I dug out my Pioneer 6-9 technical information and the battery was designed to automatically disconnect with an undervolt...that is one reason the probes are very long lived).

I bet you that in the spinner mode with the arrays folded -40 could only use "some" (One?) of its array sides.   That meant that for some part of the "spin" the battery was discharging, then had to be recharged as the spin continued then discharged etc.  I bet the battery and the associated circuitry were never designed for that.

If  -40 were to "open" the battery, I wonder if there would be enough power from whatever arrays are left to power the receivers (much less the transmitters) during the complete spin cycle.  IE without a battery I wonder as the vehicle spun if the receiver(s) would stay powered long enough to decode a command?   

If the aux battery isnt any good and the vehicle is left in spin mode, the next question would be (if they could get the command link up) is there enough solar exposure to operate anything?  (without a battery?)

It has been years ago (decades) so I have forgotten most of it, but when they tried to reactivate  Skylab before its doom...they had a similar problem with keeping the command recievers powered long enough to orient the arrays with thrusters and gyros..  As I recall they beat that by endlessly sending commands...and eventually they got the solar arrays oriented for real power.

In other words my speculation would be that -40 is useless without some type of battery, as a spinner.  I bet it is not much on three axis either since the arrays probably do not articulate...

As I said in my previous post...the more I think about it (and its all speculation) the less likely I think AO-40 will do a "Seven"

Robert WB5MZO

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