Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V15_4/V15NO439.TXT

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Date: Fri, 20 Nov 92 05:00:04
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
Subject: Space Digest V15 #439
To: Space Digest Readers
Precedence: bulk


Space Digest                Fri, 20 Nov 92       Volume 15 : Issue 439

Today's Topics:
                       Human powered flight???
                Mars Simulation in Antarctica (2 msgs)
Minority Kids into Techies (was Re: Free Middle/High School Broadcasts)
   opening of the first self-sufficient solar house, Press Release
                    ROTATION OF THE MOON (2 msgs)
                     Shuttle replacement (5 msgs)
                         Space suit research?
          SSTO Viability (was: Shuttle replacement) (2 msgs)
         What kind of computers are in the shuttle? (3 msgs)

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

Date: 18 Nov 92 16:18:53 CDT
From: Don Schiewer <[e-mail]>
Subject: Human powered flight???
Newsgroups: sci.space

I know there are some aeronautical engineer in the group.

I would like to know the current state of human powered flight.

I have heard of peddle-prop ultralight, but I would like to know
if any progress has been made with flap/soar type systems?

--
Don Schiewer   | Internet  [e-mail]    | Onward Great
Inland Steel   | UUCP:     !uucp!pa881a.inland!schiewer  | Stream...

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

Date: Thu, 19 Nov 1992 05:45:44 GMT
From: Frank Crary <[e-mail]>
Subject: Mars Simulation in Antarctica
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Bruce Dunn) writes:
>        At one point I believe that the US was operating a small nuclear
>reactor as a source of power and heat in one of their Antarctic bases.  Does
>anyone know the details - this would be highly relevant to moon and or mars
>bases (which of course would have to however have alternate methods of
>rejecting heat).

MacMurdo Station, the main US base in the Antarctic, used to operate
such a reactor. It was _not_ a space-related system such as the SNAP
designs, just an ordinary, small, Earth-based system. I don't know
if it is still opperational, but I doubt the assertion that Antarctica
is now a "nuclear free zone": The only treaty on the subject of the
antarctic is about 30 years old, and make no mention of such a thing
(In fact, I _think_ the treaty pre-dates the reactor at MacMurdo...)

                                                Frank Crary
                                                CU Boulder

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

Date: Thu, 19 Nov 1992 14:28:29 GMT
From: "Richard L. Dyson" <[e-mail]>
Subject: Mars Simulation in Antarctica
Newsgroups: sci.space

In article <[e-mail]>, [e-mail] (Frank Crary) writes:
> In article <[e-mail]> [e-mail] (Bruce Dunn) writes:
> >        At one point I believe that the US was operating a small nuclear
> >reactor as a source of power and heat in one of their Antarctic bases.  Does
> >anyone know the details - this would be highly relevant to moon and or mars
> >bases (which of course would have to however have alternate methods of
> >rejecting heat).
>
> MacMurdo Station, the main US base in the Antarctic, used to operate
> such a reactor. It was _not_ a space-related system such as the SNAP
> designs, just an ordinary, small, Earth-based system. I don't know
> if it is still opperational, but I doubt the assertion that Antarctica
> is now a "nuclear free zone": The only treaty on the subject of the
> antarctic is about 30 years old, and make no mention of such a thing
> (In fact, I _think_ the treaty pre-dates the reactor at MacMurdo...)
>
>                                                 Frank Crary
>                                                 CU Boulder
Frank is not completly correct.  The Antarctic Treay does not allow
nuclear testing (and I *believe* this includes USING nuclear devices)
anymore.  The OLD reactor system that was used at McMurdo was
decommissioned a LONG time ago and completely disassembled and brought
back to the US (probably stored up on the big nasty heap in Idaho...).
They even took out MANY barrels of surrounding volcanic dirt because it
showed a trace of low-level radiation.  Later, it was generally
determined that the entire continent has a higher background radiation
level than usual.  The reason the McMurdo reactor was allowed by the
treaty is because it was "grandfathered" in.

        This is what I recall from my discussions and conversations with
others when I lived there.

Rick
OAE, South Pole 83-84
--
Richard L. Dyson               INTERNET:  [e-mail]

  Most people acknowledge that they will never see penguins in the wild.
               But just knowing that they are there is enough.

                                                --Frank S. Todd

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

Date: Thu, 19 Nov 1992 06:15:31 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: Minority Kids into Techies (was Re: Free Middle/High School Broadcasts)
Newsgroups: sci.space

[e-mail] (David Toland) writes:

>Why would ANYONE want to REDUCE the number of students (white or otherwise)
>studying to enter science and technology fields???  We have few enough
>students graduating with even minimal competence in mathematics and
>the physical sciences.

Yes and no.  It's downright scary how little science some people know.  On the
other hand, our economy is currently not interested in hiring scientists and
technologists regardless of race or creed.  The number of highly educated white
collar workers fired in the last two years would fill a few good sized cities.

>I don't really think minority status should ever enter into it.

Again, yes and no.  I'm mildly opposed to special educational treatment for
minorities and women, mainly because I'm one of the people who doesn't get any.
I think the best approach is to start from the ground up and be sure you
encourage kids equally.  That said, it's a good idea to make sure you think
about minorities and women when you do this.  For example, showing a tape of
a flight commanded by Charlie Bolden or narrated by Kathy Sullivan is much more
effective than unintentionally perpetuating the idea that only middle aged
white guys have anything to do with space.
--
Josh Hopkins                                          [e-mail]

    "Why put off 'til tomorrow what you're never going to do anyway?"

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

Date: 18 Nov 92 13:18:49 GMT
From: Jonathan Bayer <[e-mail]>
Subject: opening of the first self-sufficient solar house, Press Release
Newsgroups: sci.energy,sci.environment,sci.space

[e-mail] (Phil Ngai) writes:

>In article <[e-mail]> [e-mail] (Gary Coffman) writes:
>>Remember Apollo 13, the failure modes for these things includes
>>BOOM! Also don't forget the electrolyzer, tankage, and pumps.

>I thought the Apollo 13 failure was due to overheating a dewar,
>something not proposed for this house project.


The Appollo 13 failure was due to an oxygen tank being dropped during
assembly into the service module.  The drop was about three inches, and
the tank was throughly test after it was dropped.  However, a small tube
apparently had been dislodged, and it wasn't detected during the
testing.  It was only functional in weightlessness.  The tube was some
sort of relief tube.  When they turned on the internal mixers in flight
(the mixers kept the O2 from clumping in one area) there was an
explosion.  These facts were determined after the flight and after
extensive and exhaustive analysis and testing.  When they released the
service module they were able to see where the explosion had occurred.

JB
--
Jonathan Bayer        Intelligent Software Products, Inc.
[phone]        37 Winthrop Rd.
[e-mail]        Edison, NJ   08817

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

Date: 18 Nov 92 20:15:29 GMT
From: Bruce Watson <[e-mail]>
Subject: ROTATION OF THE MOON
Newsgroups: sci.space,sci.astro

In article <[e-mail]| [e-mail] (Trevor German) writes:
|
|    There was a question in rec.puzzles asking how to send a message
|    to the future (real time) say a million years or whatever and I
|    send it this responce.
|
|    -----------------------------------------------------------------
|
|    Re: sending a message to the future.
|
|    Obviously anything placed on earth is likely to be destroyed
|    by plate techtonics etc so no good burying something. A transmition
|    that takes that long to get back would be hard to receive even if
|    you were expecting it.
|
|        I have a much better idea. Take a dead satelite. A big one,
|    like say the moon. Then blast its surface with  enough nukes to
|    make an easily recognisable pattern that would be only partly
|    erased by comet and meteoride collisions. Then just for good measure,
|    adjust the rotational velocity of the moon so that the message
|    always faces the earth. The message could be something like
|    a big face......................
|
|    Came to me in a dream.

And put it at a distance so that it subtends the same angular diameter
as the sun.

--
Bruce Watson (wats@scicom)  Tumbra, Zorkovick; Sparkula zoom krackadomando.
....alien language from an SF short story on a 78-RPM record I had as a kid.

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

Date: Thu, 19 Nov 1992 14:44:41 GMT
From: David Geiser <[e-mail]>
Subject: ROTATION OF THE MOON
Newsgroups: sci.space

> The same thing is happening, much more slowly, to the earth --
> friction with the tides and within the "solid" earth is slowing the
> rotation rate by something on the order of 1 sec every century. We can
> actually measure it (the slowdown) nowadays. Love those atomic clocks!

Do you know if that rate is constant?  Say around 63M years ago,
around the time of the end of the dinosaurs, the day would have
been 175 hrs longer!
--

 To the cat, the experimenter is problematic.

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

Date: Thu, 19 Nov 1992 08:07:18 GMT
From: Hugh Emberson <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

>>>>> On Tue, 17 Nov 1992 22:01:50 GMT, [e-mail] (Henry Spencer) said:

Henry> In article <[e-mail]> Dr. Norman J. LaFave <[e-mail]> writes:
>... is it concievable that an SSTO vehicle could be built with the same
>payload weight capability as the shuttle with the same base technologies?

Henry> Gary Hudson claims that you could put six SSMEs on a shuttle external
Henry> tank, without SRBs, and get it into orbit carrying a payload about 50%
Henry> greater than the shuttle's.  It wouldn't be reusable, though.

This sounds a lot like Shuttle-C, whatever happened to that idea?

As I understand it, Shuttle-C was an idea for using up old SSMEs.  The
idea was to take a normal stack (an ET and 2 SRBs) and bolt on a
fairing containing the payload and some SSMEs in place of the shuttle.

This was meant to be a cheap expendable HLV using parts that NASA was
already familiar with.  I guess it's payload would have been at least
100,000 lbs, probably a lot more.  Some of the pictures I saw had 4
SRBs.


Hugh

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

Date: Thu, 19 Nov 1992 07:33:40 GMT
From: Carl Hage <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

[e-mail] (Dr. Norman J. LaFave) writes:
: By the way, I am in the process of trying to convince Gore to back the
: SSTO
: and NASP programs as well as the SEI program. Any ideas you could provide
: would be appreciated.

From a prior post:

                    STATEMENT BY SENATOR AL GORE
                     Goddard Space Flight Center
                       Monday, October 19, 1992
...
      Probably one of the most critical issues facing the space
 program today is the need to reduce the cost of launching payloads,
 whether they be military, scientific, or commercial satellites.  Our
 only existing choices are the Space Shuttle, which currently costs
 more than $4 billion a year to operate, and decades-old technology in
 our fleet of expendable launch vehicles.  The urgency of this problem
 is readily apparent to everyone associated with the U.S. space
 program.
...
      In their own right, each of these systems may have some merit,
 even given the fact that the Space Plane and the Single Stage
 Technology program may provide significant benefits only in the
 long-term future.  But, trying to fund all three in the current
 budget environment is ridiculous.
...
 However, Quayle's National Space
 Council let politics determine how the NLS program would be
 structured.  Rather than tailoring the program to suit realistic
 launch needs of either NASA, the military, or the commercial launch
 industry, the Council made a politically expedient decision.
...
    However, any decision to develop the next generation
 of launch vehicles must be based on cost-effective criteria with a
 clear concept of mission requirements in mind.
...

Although Gore was flamed here for this speech, it would seem to me that he
could be a very strong supporter of SSTO. To convince him and the others
in Washington to support SSTO, they need to believe:
    1. DC-X/Y/1 will provide dramatically lower launch costs.
    2. There is a clear concept of mission requirements in mind.
    3. Benifits will not be "in the long-term future".
    4. The SSTO program is well managed.
    5. SSTO development costs will not be extraordinarily high.
    6. SSTO deserves a higher priority than the alternatives.

As to point 1, there has been significant discussion on the net as to the
potential of lower costs. Since probably everyone would agree that
reducing launch costs is the most critical issue facing the space program,
what will be needed will be making a credible argument. Since SSTO has been
part of SDI, there is probably a built-in bias against credibility.
Development of DC-X has been relatively low cost, but can you convince
everyone that DC-1 will be cheap? Are the cost predictions realistic?
(BTW: I wasn't sure about the engines for DC-1. In scaling up, are
more engines added or larger engines added? If larger, does that mean
using SSME type engines or a whole new design?)

[e-mail] (Allen W. Sherzer) writes:
: At $1 to $10 million per flight it will be a lot cheaper. Just the
: expendable for a HL20 will be over ten times this amount.
:
: This BTW is a source of trouble for SSTO.

A source of trouble? HL20 won't win any arguments claiming to be better
because it's more expensive. They might win if SSTO is making exagerated
claims though. Of course, as Gore said, "trying to fund all [alternatives]
in the current budget environment is ridiculous", so every project is
going to have to compete for it's existence.

Claims of $1M or even $10M launch costs seem too low to be believable.
Since the claims for the Space Shuttle, nuclear power (too cheap to meter),
etc. were very wrong in the past figures like this are taken with a
great deal of skepticism. Does your info kit offer clear and complete
information that will convince a skeptic?

For point 2, lower cost and somewhat lighter payloads meets the bulk
of launch requirements.

For point 3, there seems to be a particular timetable in mind for
producing DC-X/Y/1. How does that timetable compare with the alternatives?
It seems to me that the idea of building a cheap scale prototype (DC-X)
and developing the technology on that is a good idea for a number of
reasons. I would think the total project cost would be lower and the
time to get the final working system would even be lower. Also this
would provide a better opportunity to manage the program with more short
term goals/milestones. I would guess that DC-X will uncover problems that
will delay DC-Y/1, but the delays and extra cost will be less than the
delays and cost overruns from building DC-1 directly.

The unknowns in the timetable probably relate to developing new technologies
to address problems which have not yet been solved. What are the major
new technologies which need to be developed by DC-X and DC-Y?

On point 4, we haven't had an opportunity on the net to find out how well the
project is managed. Conceputally, as stated above, the idea of scaling up
seems like a plus and allows funding to be contingent on success. However,
I don't understand the GAO (?) report which was critical of the project.
How about summarizing the objections given in the report with a response.
Technically, it seems that DC-X makes a lot of sense. If the project is
mismanaged, then maybe some changes need to be made. Could we have some
discussion on this here?

On point 5, the development costs should be less than the alternatives
proposed, at least from what I get from the discussions here. We don't
know the costs on DC-Y/1, but fixing the problems on DC-X will be a lot
cheaper than it would be if we built DC-1 first. Are there some ballpark
estimates for total costs to develop DC-1?

If points 1-5 are true, then point 6 is obvious. One could say that
none of 1-5 are true for the alternatives. I fail to understand why
NASA, etc. isn't enthusiastic about SSTO. I won't buy that the reason
is bureaucracy, or it is an "outside" project. It must be that are not
convinced of points 1-5.

Oh, I forgot one other point.
    7. The chance of success is high

It seems like it is a matter of a few simple calculations to show that
it is theoretically possible/impossible given some basic assumptions
about current rocket technology like, weight, engine efficiency, fuel
weight, etc. Presumably you have shown that it is possible.

What are the areas in which others might conclude that there is an
unsolved problem which presents a significant risk to the success of the
project? The NASP needs to have an engine developed, and this is not a
simple matter of engineering a design. Are there similar sorts of problems
with DC-Y? It seems like from the discussions, that DC-X didn't require
basic research projects, and is mainly a matter of engineering to put
together existing technology to build a prototype.

If there are arguments against SSTO because of risk associated with an
unsolved problem, then perhaps discussing these arguments and possible
solutions will reduce peoples perceptions of risk.

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

Date: Thu, 19 Nov 1992 14:43:09 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space

In article <[e-mail]> phoenix.Princeton.EDU!carlosn (Carlos G. Niederstrasser) writes:

>Whatever program you support lets make sure is flying before the shuttle stops.

That's the rub. Shuttle is a very expensive thing to fly. So much so that
all the money which could go to building a replacement is spent operating
the Shuttle. Every year we fly Shuttle delays its replacement by one year.

Shuttle doesn't do anything which can't be done by existing and near term
systems. Let's phase it out so we can build them!

>and let go of our heaviest capacity lift vehicle.

Titan IV can lift any existing or planned payload Shuttle can lift.

  Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------156 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 19 Nov 92 14:48:42 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:

>>The US shouldn't be putting it's money into the design of ANY expendable
>>launcher. We have done that for too long and it's hasn't reduced launch
>>costs by a dime.

>Actually, this isn't a very sound argument.... [Henry goes on to say
>that it hasn't been tried and examples from China and Russia show it
>CAN be a lot cheaper]

Allow me to rephrase: NASA has shown that it cannot execute large multi-year
multi-billion $$ projects in a cost effective manner. Some blame for this
goes to Congress, and some to NASA. Asking them to do it again will simply
waste more money and delay the creation of a spacefaring civilization.

I don't doubt that much cheaper expendables CAN be build (Zenith Star
launchers for example cut costs in half). I simply don't believe that the US
government can build them.

   Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------156 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: Thu, 19 Nov 1992 15:12:40 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: Shuttle replacement
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Gary Coffman) writes:

>I suspect Shuttle returned a handsome profit for Rockwell.

Irrelevant. That's like saying that American Arilines is profitable
because Boeing is profitable.

>It has cost
>the US Government billions to develop and maintain Shuttle capabilities,
>but the US Government isn't a profit making institution.

The principles can still apply (as indeed the original poster intended).
NASA charges people for Shuttle even if it is just moving money from
one account in NASA to another. Shuttle costs FAR exceed prices charged
which means it looses money.

>It considers those costs fully sunk.

I'm not talking about development costs. NASA doesn't even get enough to
cover OPERATIONAL costs.

>At $350 million per launch *operating* expense,

Nope. Shuttle flights cost half a billion each minimum.

>the Shuttle is giving launch capabilities unmatched by any other system
>at bargain rates per fractional payload.

Sure. Whenever I want to spend half a billion to recover a $150 million
satellite I use Shuttle. Granted I loose a third of a billion $$ for
each satellite but NASA accountants assure me that I will make up for it
in volume. :-)

   Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------156 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 19 Nov 92 05:04:46 GMT
From: Pat <[e-mail]>
Subject: Space suit research?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (Henry Spencer) writes:
>In article <[e-mail]> [e-mail] (Pat) writes:
>>cant you air cool even if the air is a little thin?  i know jet aircraf
>>seem to manage wven with a crappy thin atmosphere at 100,000 ft.
>
>You can air-cool even if the air is a little thin, but 3psi isn't a little
>thin, it's a lot thin.  Nobody air-cools at 100,000ft; there's hardly any
>air left at that altitude.  (Nobody much flies at 100,000ft either; half
>that is a more typical ceiling, and a lot of military avionics is not
>air-cooled.)
>

Okay.  I know commercial jets routinely push 40,000 ft, maybe a bit more.
the cabins are usually only pressurised to 10 PSI. and they use air cooling
on lots of stuff.  they also have gear in unpressurised bays that seem
to cope.  Military jets run up to 70,000 ft and over 100,000 on special
trajectories, but if they dont use air cooling then that would explain it.
I think the blackbirds cruise at 100,000 but then they are not run of the mill.
Actually could a blackbird pilot get astronauts wings?  on some sort of ballistic shot????

>>ALSO in apollo were EVA's part of the planned mission?
>
>Yes, both on early flights for testing, and on the later lunar missions
>for recovery of film canisters from the SM survey-equipment bay.  Not to
>mention a zillion contingency procedures that required that electronics
>continue to function despite EVAs or pressure loss for other reasons.
>--

i thought they needed to get something out of the SM on the trip home.

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

Date: Thu, 19 Nov 1992 06:21:31 GMT
From: Josh 'K' Hopkins <[e-mail]>
Subject: SSTO Viability (was: Shuttle replacement)
Newsgroups: sci.space.shuttle,sci.space

[e-mail] (Edward V. Wright) writes:

>In <[e-mail]> [e-mail] (Allen W. Sherzer) writes:

>>There are two things which need to be validated. First is the aerodynamics of
>>the 'flip maneuver' they use on re-entry. The second thing is to verify
>>their models and simulations on tasks needed for rapid operations (can the
>>engines be serviced as fast as they think, ect).

>The second goal is vastly more important than the first. If the flip
>manuever proves problematical, the next vehicle could be redesigned
>to use a more conventional base-first reentry (like Apollo).

Has any vehicle ever rentered engies first Ed?  Is it not a problem or is there
an obvious reconfiguration?  Personally, I wouldn't want to reuse rocket
engines that double as heat sheilds :-)

>>>Does this program have the ability to fascinate congress and
>>>Al Gore if it demonstrates what it intendend to do?

>>I hope so. We are working hard on that (again, let me know if you want
>>to help). We have shown a few key people that there is support for this.

>Nothing that doesn't have "ecological disaster" in its title has
>the ability to fascinate Al Gore.

Seems to me that's a little harsh.  Sure he's a politician, but he's not the
antichrist.
--
Josh Hopkins                                          [e-mail]

    "Why put off 'til tomorrow what you're never going to do anyway?"

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

Date: Thu, 19 Nov 1992 15:04:00 GMT
From: "Allen W. Sherzer" <[e-mail]>
Subject: SSTO Viability (was: Shuttle replacement)
Newsgroups: sci.space.shuttle,sci.space

In article <[e-mail]> [e-mail] (Edward V. Wright) writes:

>The second goal is vastly more important than the first. If the flip
>manuever proves problematical, the next vehicle could be redesigned
>to use a more conventional base-first reentry (like Apollo).

Agreed but with one minor nit. The flip maneuver allows DC to use existing
conventional bell nozzles. The GD design could enter base first but had
to have an aerospike nozzle to do it. Since aerospike nozzles have never
flown, that would add another risk to the propulsion system.

>Nothing that doesn't have "ecological disaster" in its title has
>the ability to fascinate Al Gore.

Hmmm... this gives me an idea. Maybe the way to sell SSTO to Gore is
to emphasize the non-poluting fuel it uses. Deltas and Titans burn
nasty stuff which wold cause problems in large quantities.

>However, Milton Freidman used to tell a story about geese and politicians...
>[story deleted]

>The critical test, I think, is public opinion.  If the American
>people get really excited about this, Clinton and Gore will quickly
>move into the "I said it was a good idea all along" camp.

Exactly! And we need to let them do it and thank them for it.

>When a project goes from zero visibility to the network news, it makes
>all the difference in the world because most politicians (and most
>Americans) don't care about anything that doesn't make the network
>news.  (Let's just hope the launch happens on a slow news day.)

We need to do other things as well. There was an article on this in
a recent issue of Design News and the British newspaper The Guardian
is also working on an article.

  Allen

--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves        |
|  [e-mail]     |  nothing undone"                                       |
+----------------------156 DAYS TO FIRST FLIGHT OF DCX----------------------+

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

Date: 18 Nov 92 22:17:16 -0600
From: James Campbell <[e-mail]>
Subject: What kind of computers are in the shuttle?
Newsgroups: sci.space

In article <[e-mail]>,
                                           [e-mail] writes:
> In article <[e-mail]>, [e-mail] (John F. Woods) writes...
>>Rad-hard SRAM, 50 bits of ECC for each 32 bits of memory, *and* a background
>>scrub cycle every two seconds.  They didn't buy this at "BACK OF THE TRUCK
>>PEECEES, LIMITED", nosir!
>
> Interesting.  Would you happen to know how many errors this memory can detect
> and correct?
>
> -Mike

Only two:  0's that should have been 1's, and 1's that should have been 0's. ;)

Sorry, I couldn't resist.

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

Date: 19 Nov 92 05:08:49 GMT
From: Pat <[e-mail]>
Subject: What kind of computers are in the shuttle?
Newsgroups: sci.space

In article <[e-mail]> [e-mail] writes:
>In article <[e-mail]>, [e-mail] (John F. Woods) writes...
>>Rad-hard SRAM, 50 bits of ECC for each 32 bits of memory, *and* a background
>>scrub cycle every two seconds.  They didn't buy this at "BACK OF THE TRUCK
>>PEECEES, LIMITED", nosir!
>
>Interesting.  Would you happen to know how many errors this memory can detect
>and correct?
>
>-Mike

Gut feel,  12 bits and detect errors to 16 bits.  that may be a little optimistic..i just dont have the formulas  handy.

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

Date: 19 Nov 92 04:39:39 GMT
From: Kenneth Ng <sugra!ken>
Subject: What kind of computers are in the shuttle?
Newsgroups: sci.space

In article <[e-mail]: [e-mail] (John F. Woods) writes:
:Rad-hard SRAM, 50 bits of ECC for each 32 bits of memory, *and* a background
:scrub cycle every two seconds.  They didn't buy this at "BACK OF THE TRUCK
:PEECEES, LIMITED", nosir!

Good grief, 50 bits ECC for 32 bits of memory?  How many bits wrong can it
correct and detect?

--
Kenneth Ng
Please reply to [e-mail] for now.
Apple and AT&T lawsuits: Just say NO!

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End of Space Digest Volume 15 : Issue 439
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