[amsat-bb] Re: Can we get them to fix AO-40 first then?
peter.guelzow at kourou.de
Thu Oct 15 03:11:16 PDT 2009
Hi Samudra et all,
very interesting article and links you've sent out.
So far, I did not heard about attempts to take photographs, at least not
in the public.
However, there is no reason to believe that the satellite disintegrated,
since there are now other objects tracked around it.
The command stations regularly sent commands to AO-40 in the last years,
but I guess with larger time between those attempts now.
AO-40 was launched with the IHU "hot", that means: After separation and
release of the safety/separation switch, the 24V power for the
transmitter was switched ON and after some waiting time, the Beacon was
commanded ON by the IHU (integrated housekeeping unit).
The electronics were designed that way, if for example the IHU crashes,
the I/O ports will remain in their last state and the transmitter would
be kept on.
However if there is a complete power loss (as we expect with the battery
shortened), all Output ports will indeed reset to their default state,
which is "all off"...
(The BCR's default values normaly should still produce enough power)
For this reason, the command stations prepared a small boot-block for
the IHU to configure the BCR (battery charge regulator) and the
Trasmitter status, for example S-band Beacon On.
If this would be successful, command stations could start to reload the
We also still plan to use our 20m dish in Bochum to uplink commands with
high power or listen for some week signals.
73s Peter DB2OS
Samudra Haque wrote:
> Has there been any serious attempt to take a photograph of the damaged
> bird using ground based optical telescopes while it is in sunlight ?
> With modern telescopes such as
> or similiar and a modern digital camera and a known RA/DEC co-ordinate
> of the satellite at any point in its orbit, it should be possible get
> a fairly decent picture of what is still up there...
> Note RA / DEC are astronomy co-ordinates which should be able to be
> calculated from AZ/EL or TLE, but I may not be able to do it myself.
> We don't need to track it, but just to image it in several consecutive
> frames. From: http://www.emergentspace.com/pubs/AIAA_GNC_2002_AMSAT_A040.pdf
> Table 1. Nominal Orbit Parameters for AO-40
> Orbit Parameter Value
> Semimajor Axis (km) 36,245
> Perigee Height (km) 1,042
> Apogee Height (km) 58,691
> Eccentricity 0.797
> Inclination (deg) 6.04
> Period (hours) 19.1
> On Wed, Oct 14, 2009 at 9:49 PM, Rocky Jones <orbitjet at hotmail.com> wrote:
>> I think both those things are accurate.
>> Robert WB5MZO
>>> Date: Wed, 14 Oct 2009 21:31:30 -0400
>>> From: mat_62 at netcommander.com
>>> To: amsat-bb at amsat.org
>>> Subject: [amsat-bb] Re: Can we get them to fix AO-40 first then?
>>> I guess I need to go back and read the archives because what I remember
>>> reading didn't give me any hope AO-40 would ever be back. Wasn't there
>>> something about that they believed the spacecraft was leaking corrosive
>>> fuel? Doesn't sound to conducive to any type of recovery of anything
>>> where electronics are involved.. I also thought there was talk of a
>>> "catastrophic explosion".
>>> Michael, W4HIJ
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