Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v16_2/v16no260.txt

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Date: Wed,  3 Mar 93 05:00:00
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V16 #260
To: Space Digest Readers
Precedence: bulk


Space Digest                Wed,  3 Mar 93       Volume 16 : Issue 260

Today's Topics:
                       Aurora (rumors) (2 msgs)
                    Battery help needed! (2 msgs)
                          Blaming the victim
                           Bullets in Space
                          ESA press release
                Galileo Earth-Moon Animation (2 msgs)
          How about Skylab II? (was: Re: New name for Fred)
                 I have a dream! People into Space..
                 Orientation of the shuttle in orbit
                   Query on sun synchronous orbits
Small Expendable Deployer System Mission (Was Re: Refueling in orbit) (3 msgs)
                    Spaceflight for under $1,000?
                         The NASA Budget Myth

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Date: Tue, 02 Mar 93 18:12:14 MET
From: [e-mail]
Subject: Aurora (rumors)

>[e-mail] writes:
>>Suppose Aurora wants to spy on some installation deep inside a big
>>country. Suppose it flies over the border at 30,000 ft up.

>Well, you can stop supposing right there!  That is not a credible
>suggestion. Early U-2 flights were done at 65,000 feet, and SR-71
>missions were at around 85,000 feet.  Aurora would very likely be
>flying at operational altitudes of over 100,000 feet.
>D. Adams (Sat, 27 Feb 93 10:39:09 GMT)

I was answering these guys who wrongly said that the noise was not a
problem. Of course, if nobody hears the plane, the problem disappears.

However, where is the proof that Aurora can reach these altitudes ?
It seems that it has (if it exists) a new kind of engine. There are
rumors of liquid methane and "Pulsed Detonation Engine". Up to what
altitude can this engine work ?

>>Why is it extremely audible in the Los Angeles area?

>Because it is on a LANDING profile.  It comes in off the Pacific,
>decelerating and reducing altitude for a landing in the Nevada desert.

The distance between Los Angeles and Tonopah, where Aurora is said to
land, is about 280 miles. If Aurora were 100,000 ft up over Los Angeles
(no noise) this would make a descent angle between 3.5 and 4 degrees.
Is this too much for Aurora ?

J. Pharabod

------------------------------

Date: Mon, 1 Mar 1993 15:49:49 GMT
From: Dillon Pyron <[e-mail]>
Subject: Aurora (rumors)
Newsgroups: sci.space

In article <gfXZdbm00WB9NXQNw=@andrew.cmu.edu>, [e-mail] (Lawrence Curcio) writes:
>I'm impressed by the side-looking radar argument. I find the argument
>regarding speed less impressive. If you spy on me frequently, and I hear
>enough booms, you're going to find me ready for you one day. It matters
>only a little that you're gone when I find out you've been there.

But the SR-71 is a "hype"rsonic aircraft.  By flying at FL 850, the intended
never heard a pop, nevermind a boom.  I would be sorely disappointed to learn
the the Aurora was anything less than 100,000 ft (32000 m) and Mach 3.5.  Not
that we will learn any of that this century  :-)

The booms LA hears, assuming they come from the Aurora, are due to a Mach 1
aircraft coming home at about 25,000 ft.  I've lived on enought airbases to
recognize it by now.  As to why there aren't more.  Consider how many approach
options there are.  I'll bet we don't hear many more.

Finally, SSR is just not an effective surveillence tool.  Especially not when
it is the only tool.  I might use it to look for the "Lost City of Zur", but
not for the "Lost Scuds of Saddam".
--
Dillon Pyron                      | The opinions expressed are those of the
TI/DSEG Lewisville VAX Support    | sender unless otherwise stated.
[phone] (when I'm here)     |
[phone] (when I'm home)     |No people gave up their rights all at once.
[e-mail]          |Preserve the Bill of Rights.
PADI DM-54909                     |Protect the Second Amendment.

------------------------------

Date: Mon, 1 Mar 1993 17:38:44 GMT
From: [e-mail]
Subject: Battery help needed!
Newsgroups: sci.space,sci.electronics,sci.aeronautics,sci.chem,sci.engr

[e-mail] (Benjamin John McCall) writes:
: One major problem we've encountered is the battery pack - we need about 200
: Amp-hours of power (at about 0.5 Amps), but it has to weigh less than 100
: pounds.
:
: SLA (Sealed Lead-Acid) doesn't seem to have the energy density, and
: Alkaline-Manganese (aka Duracell lantern batteries) have a very sloping
: discharge curve, making them undesireable.  NASA will not allow us to use
                   ^^^^^^ ^^^^ ^^^^^^^^^^^^^
This may be a dumb question but is the only problem you have with
Alkaline-Manganese in the voltage curves? They certainly have a lot of
desirable characteristics in energy density, shelf life, etc. although I must
admit that most commercial versions don't recharge very well.

If voltage is the only problem it can be easily remedied with a switching
regulator. You should be able to get >80% conversion efficency and <3% output
voltage regulation from what is (these days) a very simple and inexpensive
circuit. The best result is probably obtained if the battery voltage into the
circuit is in the say... 18 to 35 volt range. This maximizes efficiency and
circuit simplicity while keeping all the voltages in a range where everything
is inexpensive and reliable. Commercial ICs are available for a few dollars
which can do this with only 2 external components. Alternatively there are
packaged DC-DC convertors available for a few hundred dollars where all you
have to do is hook up the input and output.

Out here in the world of commercial product R&D we consider a sloping
discharge curve an asset: It makes it really easy to sense the state of
charge of the battery.

I feel like a Bozo proposing something other than one of the exotic battery
technologies that everybody else is discussing. I just wanted to make sure
that an obvious, simple, and inexpensive answer wasn't overlooked.

----------------------------------
Pete Nicholson
Hewlett-Packard Vancouver Division
[e-mail]
----------------------------------

------------------------------

Date: 1 Mar 1993 10:51 EST
From: Pat Loyselle <[e-mail]>
Subject: Battery help needed!
Newsgroups: sci.space,sci.electronics,sci.aeronautics,sci.chem,sci.engr

In article <[e-mail]>, [e-mail] (Henry Spencer) writ
>
>I think I'd look into the sexier battery technologies, like nickel-hydrogen
>or silver-zinc, first.
>--

Nickel-hydrogen batteries have self-discharge problems, If this experiment has
to be put together and ready a relatively long while before launch unless
provision is made to recharge the batteries there could be problems.  I
think get-a-way specials have to be low maintanence experiments.

                             Pat
----------
Patricia Loyselle                             [e-mail]
NASA Lewis Research Center                    [phone]
Cleveland, Ohio 44135

------------------------------

Date: Tue, 02 Mar 93 21:19:44 EST
From: Tom <[e-mail]>
Subject: Blaming the victim

I said;
>>No no.  You've got it wrong.  The victims are completely innocent.

Fred replied;
>Well, I'll agree with that.  That's why I think it's a stupid position
>to say that if a directory is left open that it's ok to read it,
>notices to the contrary notwithstanding.

But, if it's left open, it's possible to read it.  Sure, it's not the
fault of the person who left it open, if it's read, but, that person
would probably like a solution to her/is problem, rather than just
assurances of thier innocence.

All the blaming and pointing and talking of 'stupid positions' isn't
nearly as effective as, say, locking the directory.

>>They are merely the ones who got raped or burglarized.

>>If you can't see the difference between 'watching out for yourself'
>>and 'taking the blame', well, no wonder you feel angry.

>Gee, thanks for the mind reading, Tommy.  What makes you think I feel
>angry?  Would you like to tell me what emotion I'm feeling now, too,
>since you must think you know better than I do?

Sorry about that Fred, I was merely applying a reasonable guess for
intonation, based on the context of the post.  I apologize if I
got it wrong.  I could be wrong again, but since you took issue with
my guess, I imagine I was pretty close the first time, and probably
close again, when I guess that you now feel snitty, affronted, perhaps
flustered.

The point is, making reference to a possible solution, and the fact
that the victim may have not been a victim, if that solution was
used, is not the same as blaming the victim.  One is true, the other
is not.  Many people mistake the one for the other, and they feel
angry when others address one issue without being clear in the fact
that they aren't addressing the other.

The (para)phrase above is from, I believe, _Bridge_Across_Forever_ by
Richard Bach.  He imagines finding this out-of-the way fly-in, of illegal
pilots, himself a completely legal one.

An argument ensues, in which Richard accuses the unliscensed pilots,
who are practicing their flying skills, of being dangerous.  They,
in turn, accuse him of relying on the license of the FAA, rather than
his own skill, for his safety in the air.

"But I'm completely certified.  I know I'm legal and safe."

"Sure," says the other pilot, "But that little piece of paper won't
get you out of a spin.  Sure, you're certified, and if you die despite
it, you are completely innocent.  You're just the one who does the
dying."

-Tommy Mac
-------------------------------------------------------------------------
Tom McWilliams | 517-355-2178 (work) \\     Inhale to the Chief!
[e-mail]  | 336-9591 (hm)\\  Zonker Harris in 1996!
-------------------------------------------------------------------------

------------------------------

Date: Mon, 1 Mar 1993 18:00:05 GMT
From: Herman Rubin <[e-mail]>
Subject: Bullets in Space
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Frank Crary) writes:
>In article <[e-mail]> [e-mail] (George Hastings) writes:
>>    You would have succeeded in putting the bullet (and
>>yourself) into elliptical rather than circular orbit.
>>    Question back to you: if the bullet in its new orbit
>>spends part of its time travelling faster than the original
>>geo-synchronous speed and part of the time travelling slower
>>than geo-synchronous speed, is its new orbital period still 24
>>hours?

>An object's orbital period depends only on the semi-major axis of
>it's orbit, and the semi-major axis in turn depends only on
>the object's energy. Since the shot increased the bullet's energy
>(because of the direction in which it was fired), the bullet's
>semi-major axis will be reduced and therefore it's orbital period
>will be shorter. There is some specific angle, (theta =
>2* arcsin(Vbullet/2*Vorbit). If the shooter fires this many degrees
>west of the Earth, the bullet's energy will be unchanged, and
>it will have a period of 24 hours still. Of course, that means the
>bullet will come back and hit the shooter exactly 24 hours later
>(assuming he hasn't moved...)

My reasoning comes out the other way.  Since the laws of physics are
invariant under time-reversal, and no more energy is applied after the
shot, the orbit will be the same as if the current position-momentum
data was projected backward in time, but under gravity alone.  Clearly
the maximum distance from earth would be increased.
--
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
Phone: [phone]
[e-mail] (Internet, bitnet)
{purdue,pur-ee}!snap.stat!hrubin(UUCP)

------------------------------

Date: Monday, 1 Mar 1993 17:25:27 CET
From: Hermann Schneider <[e-mail]>
Subject: ESA press release
Newsgroups: sci.space

         Paris, 1 March 1993
         ESA PR Internal Info Nr.05-93

         March 14 set as launch date for Spacelab D-2/STS-55 mission.

         The launch date for Shuttle mission STS-55 has now been set on
         March 14, 1993. The launch announcement follows the removal,
         inspection and replacement of the high pressure turbopumps on
         Columbia's three main engines.

         The launch window on 14 March extends from 15:00hrs till 17:30hrs GMT
         (10:00 - 12:30hrs local time).

------------------------------

Date: Mon, 1 Mar 1993 17:42:49 GMT
From: Leigh Palmer <[e-mail]>
Subject: Galileo Earth-Moon Animation
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]> Ron Baalke,
[e-mail] writes:
>Earth_Moon_Movie.Hqx is in BinHex format for the Macintosh. The
>unHexed file can be opened as a stack and animated by NIH Image,
>a public domain package available from Wayne Rasband at the
>National Institutes of Health. When uncompressed, the movie takes
>up about 6 Mb of memory.

This is, perhaps, the most impressive and emotionally evocative graphic
presentation yet released, and that is saying a whole lot, given the
marvelous pictues we have seen from NASA, especially those from JPL
during the Voyager encounters.

I couldn't find the combination to display the movie using NIH Image, but
it opens quite naturally using "Popcorn" under Macintosh Quicktime 1.5.
The "uncompressed" file is only about
300 kbytes (the "compressed" version is somewhat larger). There
are 46 frames alright. Am I missing something?

Leigh

------------------------------

Date: 1 Mar 1993 16:20 UT
From: Ron Baalke <[e-mail]>
Subject: Galileo Earth-Moon Animation
Newsgroups: sci.space,sci.astro,alt.sci.planetary

In article <[e-mail]>, [e-mail] (Ron Baalke) writes...
>The animation was formed from 46 images taken by Galileo
>spacecraft shortly after its Earth flyby on December 16, 1992, and is in a
>compressed PICT format to be used with the NIH Image software on the Macintosh.

Forgot to mention this, but you can get the NIH Image program from
alw.nih.gov in the pub/image directory.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [e-mail]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | If you don't stand for
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | something, you'll fall
|_____|/  |_|/       |_____|/                     | for anything.

------------------------------

Date: Tue, 2 Mar 1993 21:06:02 GMT
From: David Pugh <[e-mail]>
Subject: How about Skylab II? (was: Re: New name for Fred)
Newsgroups: sci.space

I asked this before, but it seemed to go out with a limited distribution.
Here's a shot at a wider audience...

Is it technically feasible to do the following (ignore the political aspect
for the moment):
    Build a core station that can be launch fully assembled by a single
    shuttle flight that can support a crew of 3 or 4 for six months
    without resupply.

    If so, then build a core station and launch it on one shuttle flight.

    On the next flight, bring up a crew + ACRV + science module(s).

    Six months later, bring up a new crew, ACRV & science modules and
    repeat as needed.

    Eventually, use the core station (or launch additional ones) as
    a platform from which to build a Fred-type station (i.e. one that
    is too big to be launched on one piece).

Note that a science module can either be something like a bioscience module that
would be attached to the core station or a man tended material processing module
that would be placed in an orbit from which the core station crew could "tend" it
periodically.

I would think it would be possible to design and launch the core station in
under 4 years for a fraction of Fred's budget. Looking at Skylab might provide
some insight: how long did it take to design Skylab & how much did it cost?

--
... He was determined to discover the        David Pugh
underlying logic behind the universe.        ...!seismo!cmucs!dep
    Which was going to be hard, because
there wasn't one.    _Mort_,  Terry Pratchett

------------------------------

Date: 21 Feb 93 04:23:12 GMT
From: Henry Choy <[e-mail]>
Subject: I have a dream! People into Space..
Newsgroups: talk.politics.space,sci.space

[e-mail] wrote:
: As the President has asked what sacrifices are we the US propulation willing to
: make. Well maybe it is our dependence on the FED that is one of the
: sacrifices.. Namely in the area of Space related research. Mayeb what is needed
: is to dismantle much of NASA, more commericalisation/private area research
: (including non-profit organizations).. To go for less costly but just as
: effective ways for space research. USe royalties from NASA and other US
: government reseacrh to help defray costs of the Space Programs (such as NASA)
: work on Space Development and not Space Programs..
: Work on a clearer direction and course for Space usages..

Space travel needs an organization with a lot of know-how, but there
are some problems:
 - a big organization takes a long time to make decisions and is
   afraid to work out some details for petty reasons such as having
   to tell a lot of people what the decisions are
 - the present knowledge may be inadequate for space travel--no matter
   what we do now, it may be just too expensive. Perhaps we can travel
   into space to gather resources to boost us into space, but that is
   a big gamble. We always need more efficiency.

: Catch the common peoples imagination, and give them a reason to want to support
: the space research of the Federal Government.

The common people may have to see opportunities for their own way into
space. This could happen if airline flights become inexpensive.

: Get the individual states of the
: union involved..
: More pan-national space projects..

A competition may give an incentive to work.

: We need to sell the dream to the next generation of US population/citizen.

A good looking technology will attract supporters. The space station
is taking way too long to construct for such a simplistic looking
structure. It looks so basic that a robot should be able to do it.
If people see robots hammering a space station together, they'd
assume that space travel is attainable.

: If we leave the common people out of the clique of space,
: all we get is an apathetic population who care little about wether we even have
: a space program..

It's more fun to watch grass grow. Why should I care about the space
program if it so rarely touches my life? At least I have to water and
mow my lawn once in a while.

: We need to work on ways to let the people of the US to know what the benefits
: of Space research are

A quick and dirty way to do this is to do space research and get some
benefits from it.

--

Henry Choy
[e-mail]

What rolls down stairs alone or in pairs            This has been brought to
Rolls over your neighbor's dog?                     you by the numbers 4
What's great for a snack and fits on your back?     and 9 and the letter P.
It's Log, Log, Log!  -- "The Log Song", from            -- Big Bird
                         Ren & Stimpy

Math is tough!       -- Barbie

------------------------------

Date: Mon, 1 Mar 93 18:20:43 GMT
From: Frank Robijn <[e-mail]>
Subject: Orientation of the shuttle in orbit
Newsgroups: sci.space

    Hi,

    Recently I tested a computer program that showed a space shuttle in a
circular orbit around the earth. The shuttle was oriented in such a way that
its nose pointed in the same direction as its velocity, just like a plane.
Someone then remarked that this is wrong: according to him the shuttle has a
fixed orientation with respect to the stars, not the earth. I'm not sure
whether that is really the case. Anyone who can help me out?

                                           Frank
--
    _____ ____
   /     /   /
  /___  /___/          Frank Robijn      Internet: [e-mail]
 /     /  \         Sterrewacht Leiden     Bitnet: Robijn@HLERUL51
/     /    \       Phone [phone]     Local: Robijn@HL628

------------------------------

Date: Mon, 1 Mar 1993 11:53:07 GMT
From: Joe Cain <[e-mail]>
Subject: Query on sun synchronous orbits
Newsgroups: sci.space

In article <[e-mail]> [e-mail] () writes:
>
>Can anybody email me an explanation of what is meant by
>a sun-synchronous orbit is?

A sun-synchronous orbit is one about the Earth where the precession of
the orbit plane tracks the motion of the Earth about the Sun. Magsat
flew at 350-550 km altitude initially and was launched about dawn
southward from Vandenberg. Its inclination was about 97.5 degrees, or
a little retrograde.

The spacecraft thus remained in sunlight for its approximate 7 month
lifetime. The orbit at mid latitudes remained at 6 am and 6 pm whereas
the southern high latitude portion stayed on the Sun side about 8.5
degrees of the pole and the northern portion the same distance away
from the Sun.

I believe other altitudes would require slightly different
inclinations to achieve the same tracking. It is done partly as a way
of avoiding power loss during eclipse with the accompanying changes of
temperature, etc.
Joseph Cain        [e-mail]
[e-mail]        scri::cain
[phone]        FAX [phone] or -0098

------------------------------

Date: 28 Feb 1993 21:11 CST
From: [e-mail]
Subject: Small Expendable Deployer System Mission (Was Re: Refueling in orbit)
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Matthew DeLuca) writes...
>In article <[e-mail]> [e-mail] (Allen W. Sherzer) writes:
>
>>>MD: "Nobody's tried that...
>
>>Ah, but it HAS been tried and works quite well. The Russians and their
>>primitive space program have been doing it for years. Surely your not
>>saying our superior program can't duplicate it?
>
>Allen, did you read the article I wrote?  I was referring to tethering objects
>down into the atmosphere as a return mechanism, as you have proposed in the
>past.  Nobody's done it, not us, not the Soviets.
>--
>Matthew DeLuca


I love posts such as this. Hey Matt! Guess what? NASA (remember that mean old
ugly no count agency that Allen hates) is about to do a mission called the
Small Expendable Deployer System (SEDS).  This mission will deploy a fifty
pound end mass from the spent second stage of a McDonnell Douglas Delta II
7925. How much does it cost you ask? How many billions did NASA waste to
do this job? How many thousands of people did it take to get it in orbit?
When will it fly?

Well my net friends SEDS will fly next month! As a secondary payload to
an Air Force GPS bird. This will be the first test of a tether system to
reenter payloads from orbit without a retropropulsion system.  How much did
it cost? Well my disbelieving NASA bashing friends the entire mission is
costing less than 5 million dollars! This INCLUDES lauch costs.

Sorry for the dripping with sarcasm style here, but stay tuned to see how
this turns out. NASA is really doing some neat stuff here.  This is what
happens when the funding agency gives you the money you asked for to get
the job done and then leaves you alone! Could you imaging the interstate
system of this nation getting built if it was funded the same way NASA is?
I think not. Let us get to the source of the problem and not the symptoms.
Then we might get some of the neat theings from the probgram that we all
want to see.

Dennis, University of Alabama in Huntsville

PS our tether mission will fly in March of 94!

------------------------------

Date: Mon, 1 Mar 1993 18:23:23 GMT
From: Thomas Clarke <[e-mail]>
Subject: Small Expendable Deployer System Mission (Was Re: Refueling in orbit)
Newsgroups: sci.space

In article <[e-mail]>
[e-mail] writes:
> Sorry for the dripping with sarcasm style here, but stay tuned to see how
> this turns out. NASA is really doing some neat stuff here.  This is what
> happens when the funding agency gives you the money you asked for to get
> the job done and then leaves you alone! Could you imaging the interstate
> system of this nation getting built if it was funded the same way NASA is?
                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^
> I think not. Let us get to the source of the problem and not the symptoms.
> Then we might get some of the neat theings from the probgram that we all
> want to see.

I am reminded of how the last 30 (?) mile segment of I-95 into South
Florida was help up for years because someone feared that I-95 would
take traffic away from the sacred Florida Turnpike, the only good
road into South Florida.  Even when the South FL I-95 was finally linked
to the rest of the country, it took a mysterious 20 mile jog in its
route which still leaves the Turnpike as the shortest route into
South FL.  I'm sure there must be similar examples from other parts
of the country,

NASA has no monopoly on bureaucratic and politcal meddling.

Hopefully, now that Ronny Raygun and his heirs are out of office
things will change :-) [in the US space program, that is]

--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
[phone], FAX: [phone], [e-mail]

------------------------------

Date: Mon, 1 Mar 1993 17:02:17 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Small Expendable Deployer System Mission (Was Re: Refueling in orbit)
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:

>I love posts such as this. Hey Matt! Guess what? NASA (remember that mean old
>ugly no count agency that Allen hates) is about to do a mission called the
>Small Expendable Deployer System (SEDS)....

Dennis, I am glad to see that NASA is doing this experiment. However your
implied arguement that since NASA is doing SEDS right it folleows that
NASA does everything right isn't logically valid.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------106 DAYS TO FIRST FLIGHT OF DCX----------------------+

------------------------------

Date: Mon, 1 Mar 1993 15:02:42 GMT
From: Gary Coffman <ke4zv!gary>
Subject: Spaceflight for under $1,000?
Newsgroups: sci.space

In article <1mp9bp$[e-mail]> [e-mail] (George William Herbert) writes:
>
>It is worthwhile noting, in these arguments, that if one works the numbers
>on how much dedicated radiation shielding is needed to make say a 486/33
>space-rated as a package (a mini motherboard + various I/O cards and a hard
>drive within the shielding, and the power supply etc. external) that you get
>only moderate shielding (under 2" thick) and for a minimum package mass
>in the tens of kg you get more MIPS/kg with a well shielded current-tech
>chip than with older technologies that are rad-hard.
>
>This is not true of say the rad-hard RISC chips that (for one, AMD) has
>built for space applications, that combine the best of both worlds.
>But if you have the mass, and need the CPU, it can be done with current
>non space rated CPUs.

It's also worth noting that AMSAT found out that some shielding is worse
than no shielding at all. Many SEUs are the result of cosmic rays generating
secondaries in the shielding or structural materials of the craft. One
cosmic ray can generate hundreds or thousands of secondaries. It is often
better to just let the one particle pass through, likely missing a memory
cell completely, than to add shielding and have to deal with many many
particles irradiating the chip cells.

Rad hard chips don't reduce SEUs markedly, but they do extend the
useful lifetime of the chip by resisting lattice defects caused by
the radiation flux. The original rad hard structure, silicon on
saphire, is still often used for housekeeping CPUs. MOS memories
usually include ECC bits and are periodically "washed" by a background
software task to remove the effects of SEUs.

Gary

Gary
--
Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary
534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |                     |

------------------------------

Date: Mon, 1 Mar 1993 17:40:51 GMT
From: fred j mccall 575-3539 <[e-mail]>
Subject: The NASA Budget Myth
Newsgroups: talk.politics.space,sci.space

In <[e-mail]> [e-mail] (Joe Cain) writes:

>In article <[e-mail]> Dr. Norman J. LaFave <[e-mail]> writes:
>>
>>                                AMOUNT       FY 1993 OUTLAYS
>>                              (BILLIONS)   (PERCENT OF BUDGET)
>>
>> 2. DOD Military and Civilian           317.0           19.1
>>
>>What NASA gets                           14.2            0.85
>>
>>.. concentrating on NASA and other civilian science
>>appropriations as your main target for cutting the deficit is
>>ridiculous..

>I agree. Now how do we go after DOD?

It's already been done.  See the proposed budget.

--
"Insisting on perfect safety is for people who don't have the balls to live
 in the real world."   -- Mary Shafer, NASA Ames Dryden
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[e-mail] - I don't speak for others and they don't speak for me.

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End of Space Digest Volume 16 : Issue 260
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