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From: "Klaus Vestergaard Kragelund"
References: <firstname.lastname@example.org> <email@example.com> <5eucnXNgleKum0GgXTWcoA@comcast.com>
Subject: Re: Non-space-rated parts in LEO
Date: Fri, 22 Nov 2002 20:53:38 -0500
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Organization: TDC Internet
"Brill Pappin" wrote in message
> I'm no expert in radiation hardening electronics, but I suspect it would
> fine if you put the device in a shielded container of some sort. What
> exactly the container would have to be made from, I have no idea.
> I'm sure there is someone around who has also looked into this, lets hope
> they are reading this groups as well (I'm also interested, but for
> sake alone).
> - Brill Pappin
> "Dave VanHorn" wrote in message
> > What's the odds that a small micro, not specifically rad-hard, will
> > in LEO?
> > I've been asked to do a small project, not flight critical, for a
> > short-lived sattelite, and I'd like to do it on the Atmel AVR, which
> > does not have rad-hard parts available.
> > What does it take to make them rad-hard anyway?
I've worked in the space industry for a couple of years. We got a Unitrode
UCC1801 PWM controller approved for flight on a 11 year mission into deep
space (7AU - 7 Austronomical Units). The controller was not a dedicated
space part - as I remember it was a mil-spec'ed part and we approved it by
doing radiation tests in a facility within CERN. One of the problems they
discovered was the collapse of the Vdd node (it shorted for short periods -
simelar to a SEU - Single Event Upset) - solved by adding a resistor to the
supply and by the fact that it was a triple-redundant system. The important
thing was that a SEU would happen at regular intervals, but if the surround
circuits recovered from the fault and were triple redundant, then it was not
a major design hassle.
Hmm - onto the subject - I never actually participated in shielding parts,
but the "wise guys" talked of sheets of metal to increase the immunity to
radiation. In severe cases they used thick sheets of lead that is the only
material that would block certain kinds of radiation. Also it is important
to keep the sensitive deviced deep in the satelite - so that any radiation
particles have to travel through several layers of FR4, copper etc.
I know that on launches from NASA and ESA the last couple of years they have
used cheap and non-space approved (even commercial) devices for e.g the
cameraes monitoring the departure of fairrings and so on. The espected
lifetime was very low - probably in the region of a couple of days or even
P.S I would have loved to have been able to use new devices like the AVR
one. I actually resigned my job because of the frustration of only getting
to use 2N2222 and LT1079 op-amps and other old devices. It was however
interesting what could be done with simple discrete parts - without the
fancy new devices.
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