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Re: question for the experts

Douglas and Richard,

The IHU-2 is an experimental computer, which was very helpfull to download
the separation images and use the camera as an additional tool for
navigation. Otherwise the IHU-2 has no other function and no access to
the spacecraft bus.  It shared however the Middle Beacon with the IHU-1
and since there is only a MB (due to the smaller bandwidth on 2m) on the
V-TX, a repeater program was needed to get IHU-1 telemetry.
We could also simply have turned the IHU-2 off and than the MB will
automatically carry the IHU-1 telemetry using a hardware switching logic.

The IHU-1 is made of radhard components, in particular the 1802 Cosmac CPU
from Harris/Sandia and also the EDAC Memory is made of radhard RAMs. I suggest
reading articles about the IHU-1 design, which was published elsewhere.

Indeed, it can not be excluded that a part got hit by a particle and produced
an SEU, causing the IHU to crash.  We will see when the Reset/Reload procedure
for the IHU-1 get's started, which will happen probably already today..

73s Peter

"Richard D. Burgan" wrote:
> Douglas,
> Your question is a good one.  According to the AMSAT bulletins the IHU-2 was
> suffering from radiation caused memory (upsets) corruption.  In fact the IHU-2 had
> to be rebooted three times (??).  It was running a work around program to repeat the
> telemetry onto the 145 MHz downlink.  I looked for information on solar activity
> with similar thoughts to yours.  We are near "solar max" as you know.  Here are two
> web sites that have good information:  http://www.sec.noaa.gov/ace/ and
> http://www.spaceweather.com  Both of them have good information.  I could not find a
> specific event the happened at the same time as AO-40 went off the air.
> Happy Holidays!
> 73's de Rich Burgan, WC8J
> ----
> Douglas Cole wrote:
> > I guess I will break my silence on this and ask a question that has been bugging
> > me and hopefully those that are more knowledgeable will be able to answer for me
> > .
> >
> > As I seem to recall in my surfing ( does anyone do that anymore ) around on the
> > web that I came up with some info about a rather large CME event ( coronal mass
> > ejection ) that ended up coming right at good 'ole planet earth , this one
> > seemed to be one that caught the eye of a lot of scientists , or at least it
> > made the rounds on the web , as I found a website , which I have since lost ,
> > that had full length .mpeg movies in the different spectral ranges of the CME
> > event , quite the display and I was able to download the 32meg file (thanks to
> > whoever invented DSL) for later playback .....
> >
> > Now this CME if I recall happened before AO-40 went silent , so my very big
> > brain started doing what it likes to do , it thought about it over and over
> > again and hoped that this big CME wouldn't raise hail and terror with our new
> > 'sat ......
> >
> > My real question is this , as we have been talking about 'rad hardened chips and
> > the like , how do satellites of any kind handle things like these CME events ? ,
> > it would seem to me that these things could be of a much greater danger to any
> > satellite than even leonids type damage ?  Is this something that has been a
> > known but tolerable risk with satellites and could this possibly cause a
> > corruption of data on any satellite ?
> >
> > Ok , now really I am not speculating as to what caused AO-40 to be in the shape
> > it is in , but dangit , I had the desire to ask this on the very day that ao-40
> > went silent , and felt real creepy to even try once I found that it did go
> > silent , so here I am hoping that I won't get nuked for asking , I am really
> > curious as to what if any effects these CME's have on things up there :^}
> > They seem like such serious things , yet not much in the alarmist media is made
> > of them ....
> >
> > tia
> >
> > Ok , I go now and run and hide ;^}
> >
> > --
> > Douglas Cole   N7BFS
> > AMSAT#26182 , K2 # 544
> > Spokane IRLP node 145.250 owner
> > http://www.users.qwest.net/~cdoug3
> > Registered Linux user # 188922
> > ----
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