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Re: Special Bulletin ANS-063.02 BOD Meeting



Phil Karn wrote:

> A CD4015 8-bit serial-to-parallel converter listens to the engineering
> beacon generated by the IHU...

Oh. 

Yuk. I hate it when that happens. 

And an interesting perspective on some of the "hardware vs. software" and
"spacecraft complexity" discussions that have gone on around here lately.

Thanks for keeping that bit of history alive, Phil; "those who do not remeber
history are condemned to repeat it." 

And as much of a technical history buff as I am (you should see some of my
computer books from the late 1960s) I just don't happen to have back issues of
1983 CQDL available here--beng a radio amateur was not even a gleam in my eye in
those days.

I *do* have a copy of the Presidential Commission report on the Challenger
accident; it interests me both as an astronautics fan and an aviator.  

There does seem to be a feeling floating around in some circles that hardware is
somehow implicitly more reliable than software. I think some of that may derive
from the feeling that many more software failure modes can result in total
systems failure, whereas hardware failures are somewhat more likely to have a
more limited scope. 

The art of reliable and robust software design has advanced quite a bit in the
last decade, though. And we're not running C-64s anymore. (Most of us, anyhow.)

The days are retreating fast where *any* piece of electronics has no software in
it; we're seeing digital stuff making *very* significant inroads into even so
conservative an engineering arena as man-rated aircraft cockpit
instrumentation--we will see soon cockpits with *no* 'steam-gauge' type
instrumentation at all.  

Giving our spacecraft significant momentum differences from the launch vehicle
we hitch a ride on does add both expense and systems complexity, no matter how
we control the thrust systems. Maybe in future designs we need to look more
closely at the cost for that delta-V, and what the operational benefits really
are. Some orbits are a *hell* of a lot more expensive than others. 

73 de Maggie K3XS

-- 
-----/___.   _)   Margaret Stephanie Leber    / "The art of progress  /
----/(, /|  /| http://voicenet.com/~maggie   / consists of preserving/
---/   / | / |  _   _   _    `  _AOPA 925383/ order amid change and /
--/ ) /  |/  |_(_(_(_/_(_/__(__(/_  FN20hd / change amid order."   /
-/ (_/   '  K3XS  .-/ .-/    ARRL 39280   /___ --A.N.Whitehead ___/
/____ICQ 7161096_(_/_(_/__AMSAT 32844____/ <maggie@voicenet.com>
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