Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v11_0/v11_043.txt

Internet Message Format | 1991-07-08 | 18KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/MZqYmpe00VcJA0hU4d>;
          Thu, 15 Feb 90 01:31:18 -0500 (EST)
Message-ID: <[e-mail]>
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Thu, 15 Feb 90 01:30:55 -0500 (EST)
Subject: SPACE Digest V11 #43

SPACE Digest                                      Volume 11 : Issue 43

Today's Topics:
               Re: Recreation in Space
             RTGs / Pu-238 supply
              Re: Measurements and space
            Re: Galileo Update - 02/12/90
            What is an aerospike?
                Re: Nasa Freq.
                 RE: Metrics
            Measurements and space
               Re: inter stellar travel
           Re: space news from Jan 8 AW&ST
                  Mir &Soyuz
----------------------------------------------------------------------

Date: 14 Feb 90 20:16:04 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!uwm.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Recreation in Space

In article <[e-mail]> [e-mail] (Evan Bigall) writes:
>>>  Let me give you a hint... if I were going to be on a multiyear
>>>mission, I would want female astronauts.
>
>We have had women in space for a while now, and you have to wonder
>weather or not anybody has experimented...

It seems unlikely.  Current vehicles are small, there is no privacy
to speak of, the astronauts are kept pretty busy, and the sponsoring
agencies are seriously prudish.  (The USSR's morals on this sort of
thing are basically Victorian, and NASA -- apart from not being exactly
a bastion of liberalism itself -- is terrified of provoking an uproar
from the Bible Belt.  It's not an accident that the two or three
husband-wife pairs of astronauts never get assigned the same mission.)
--
"The N in NFS stands for Not, |     Henry Spencer at U of Toronto Zoology
or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry [e-mail]

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

Date: 14 Feb 90 23:36:14 GMT
From: cs.utexas.edu!hellgate.utah.edu!helios.ee.lbl.gov!ncis.tis.llnl.gov![e-mail]  (Scott Finfrock)
Subject: RTGs / Pu-238 supply

[I have only been following this group for a few days, if this
has been discussed already - my apologies]

As you probably know Pu-238 is an essential power source for deep
space probes and some other long term missions.  This material is
produced in a reactor by irradiation of other isotopes.  In the
past this has been done at the Savannah River Plant (SRP) and at
the Hanford nuclear site.  Neither of these facilities currently
have operable Pu-238 production facilities.  The need to develop
new production facilities has resulted in the future supply of
this material becoming a bit of a political volleyball.

Until recently DOE (which is responsible for producing Pu-238)
was considering modifying the Fast Flux Test Facility (FFTF)
reactor at Hanford to produce this material.  The FFTF is by far
the newest (10 years old) of DOE's big reactors. It is a state of
the art research reactor with an operating and safety history
that is among the best in the world.

Now DOE has decided to shut down the FFTF and shift all funding
to reviving it's tritium (for warheads) production reactors at
the Savannah River Plant (SRP), the idea being that they would be
modified to produce Pu-238 as well.  The SRP reactors are almost
40 years old and have been shut down for over a year due to
safety problems.  Their actual restart date is as yet
unforeseeable.  They have been plagued throughout their history
with long shutdowns for various reasons.

As I understand it new supplies of Pu-238 will be needed by about
1995.  This does not allow much time to gear up either facility
and there will be no room for lengthy delays.

IMHO relying on SRP as the sole producer of Pu-238 will make the
supply of that material unpredictable in the 1995 - 2005 time
frame (a new production reactor MIGHT be on line by 2005).

Something to think about.

--

                      -Scott Finfrock-

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

Date: 15 Feb 90 00:13:44 GMT
From: zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Measurements and space

In article <[e-mail]> [e-mail] (John Roberts) writes:
>Another policy which could help with ease and speed of repairs (with a slight
>weight penalty) is to build with fasteners of just a few sizes, eliminating
>many intermediate standard sizes. Is that done to any extent on US space
>hardware, or does "the compleat astronaut mechanick" have to bring along
>the normal set of 20-30 wrenches, etc.?

When it's the aerospace contractors building it, 200-300 is more like it.
Apart from things that are *expected* to be removed -- and it's always the
ones you don't expect, of course -- their bias is towards cost-is-no-object
weight saving.  The space station could be built far more cheaply if one
traded off a few more launches for much less fine-tuning of the hardware.
--
"The N in NFS stands for Not, |     Henry Spencer at U of Toronto Zoology
or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry [e-mail]

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

Date: 15 Feb 90 00:17:49 GMT
From: zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Galileo Update - 02/12/90

In article <[e-mail]> [e-mail] (Bamf) writes:
>>     The spacecraft is currently in excellent health; the latest
>>imaging session concluded about 6 a.m. (PST) today...
>
>    Maybe I'm a bit early here, but what is the possibility of
>public access to the images returned by the craft, (at some later
>date, I figure)  Are they generally made available in some format,
>somewhere?  Or do we just have to wait for the newsweek photo's?

The usual policy for science data is that the principal investigators of
the particular experiment have control for a limited period (e.g. 1 year)
after which the data becomes freely available.  "Freely" does not mean
"free", mind you, as you may have to pay handling costs to get a copy.

For imaging data and other high-profile stuff, I'm not sure whether the
principal-investigator rule still holds.  Possibly only selected images
are exempt from it?

In any case, we don't get to see the Galileo Venus images for quite a
while yet, since they'd take too long to transmit through the low-gain
antenna.
--
"The N in NFS stands for Not, |     Henry Spencer at U of Toronto Zoology
or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry [e-mail]

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

Date: 14 Feb 90 18:48:59 GMT
From: cs.utexas.edu!halley![e-mail]  (David M VomLehn)
Subject: What is an aerospike?

There has been lots of discussion of aerospikes, including several descriptions,
but I am not sure that I have the right picture of what one looks like.  I
have the following mental image:

                     Conventional            Aerospike

     Rocket          |            |       |            |
     Body            |            |       |            |
                     |            |       |            |
                     |            |       |            |
                     |            |       |            |
                      \          /         \          /
                       \        /           \        /
                        \      /             /......\
                         \    /             /........\
                         /....\            /..........\
     Combustion         |......|          |............|
     Chamber             \..../            ..\spike /..
                         /....\             ..\    /..
     Nozzle             /......\             ..\  /..    <- A
                       /........\            ...\/...
                      /..........\           .......
              ............          .........

The dots indicate high pressure (hot) gases.  I gather from discussion that the
"spike" is actually a bit longer than in the above picture.  It also sounds
like the "spike" could be truncated below the location indicated by "A" and
instead a small amount of high pressure gas could be run through the middle of
the "spike", exiting at the bottom.  This would produce almost the same
efficiency as if the spike had not been truncated.

Is all of this correct?
--
David M. VomLehn                    work: [phone]
...cs.utexas.edu!halley!vomlehn                home: [phone]
Disclaimer:  These are my opinions and should not be construed as those of
my employeer, associates or anyone else.

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

Date: 13 Feb 90 12:30:21 GMT
From: mcsun!hp4nl!phigate!prle!prles2!cstw10![e-mail]  (Harm Munk)
Subject: Re: Nasa Freq.

The following is from the Communications of the ACM, Volume 27, nr. 9
(september 1984):

David Gifford (ACM Editor):
"Is the uplink encrypted ?"

Tony Macina (IBM):
"An operating system-type program in each running computer takes the uplink
in and examines the header information to determine the appropriate software
destination. To protect ourselves from any malicious ground senders, the
system will not accept anything when the Shuttle is out of sight of NASA
ground stations. The link, however, isn't encrypted."

Lynn Killingbeck (IBM):
"There are ways to protect against transmission errors. We have end-to-end
checking, since many commands are in two stages. A command will not be acted
on untill it's been send back to the ground and confirmed. Criticial things,
like the loading of state vectors, are always done in two stages."

Barry Eiland (IBM):
"There's also range testing on some of the variables, depending on which
application receives the uplink message. That's a second level of
protection."

Bill Spotz (IBM):
"Keep in mind that the uplink does not usually relay much information for
controlling the vehicle. The most important thing is the updated state
vector, which is sent up about once every two orbits and is only about 100
bytes."

Hope this answers your question. If, however, you do have more, read the
CACM; it's very informative.

--------------------------------------------------------------------------
Harm Munk.                                       |Standard Disclaimer goes
Centre for Software Technology, Philips Eindhoven| here.
PO BOX 80000                                     |
5600 JA  EINDHOVEN                               |
The Netherlands                                  |
--------------------------------------------------------------------------

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

Date: Wed, 14 Feb 90 10:03:36 CST
From: [e-mail] (AT&T, makers of glitches and Unix ... connections?)
Subject: RE: Metrics

First of all, the English should be insulted that we insist on calling our
measurement system the "English system".  It's really the American Standard
System (acronyms derived at your own risk).

I lived in Germany for a number of years, and have never had any problems.  I
have a good feel for a foot and a metre, but don't try to figure that there are
30 odd centimetres in a foot!  A story:  I own/am owned by a '76 MGB, which is
a wonderful mixed-measure car.  Recently, I asked a friend to hand me a 12mm
wrench.  He asked if that was like almost a 1/2 inch.  I responded, "No, it's
the one with the 12 on it".

That's the way we should handle metrication (there's that ugly word).

But isn't this a tangential track?????????

Dillon Pyron                         | The opinions are mine, the facts
TI/DSEG VAX Systems Support          | probably belong to the company.
[e-mail]                  |
[phone]                        |"I'll take 10 sundaes,
                                     | I've had a real bad day."
                                     |     - Q

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

Date: Tue, 13 Feb 90 17:15:11 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Measurements and space


>From: mnetor!utzoo![e-mail]  (Henry Spencer)
>Subject: Re: Imperial measurements

>...There
>is *one* acceptable format for SI expressions, and only one, basically a
>cleaned-up version of m-k-s.  C-g-s is pre-SI and has nothing to do with it.
Thanks for clearing that up. I'm glad C-g-s is officially out, though one still
comes across it occasionally.

>> Both of these formats suffer from an
>>idiosyncrasy left over from the beginnings of the system - measures are in
>>terms of either a hundredth of one basic unit (length) or a thousand of
>>another basic unit (mass)....
>...SI stresses 10^3 as the basic multiplier very
>heavily, with tenths and hundredths strongly discouraged....
That's not quite the point I was making. It's that the basic unit of mass
(in m-k-s) is skewed from the other units by three orders of magnitude. It's
as if the American standard of monetary exchange were defined as the
"tendollar", and an amount formerly described as $37 redefined as "3.7
tendollars". Incidentally, if the kilogram is the standard unit of mass,
then shouldn't a thousandth of that value be the "millikilogram"?
This isn't really a serious problem, but it is a nuisance, and reflects
a bad design decision.

>>...Thus, bolt sizes should be "number 1", "number 2",
>>and so on...
>In fact, this is what is normally done.  Sometimes there is a unit attached
>to the arbitrary numbering, but it is often meaningless....
Another policy which could help with ease and speed of repairs (with a slight
weight penalty) is to build with fasteners of just a few sizes, eliminating
many intermediate standard sizes. Is that done to any extent on US space
hardware, or does "the compleat astronaut mechanick" have to bring along
the normal set of 20-30 wrenches, etc.?
                      John Roberts
                      [e-mail]

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

Date: 14 Feb 90 18:58:20 GMT
From: portal!portal!cup.portal.com![e-mail]  (H Keith Henson)
Subject: Re: inter stellar travel

In response to  [e-mail] (Scott Silvey) 's posting about
the dangers of other biologic systems, I doubt we will reach the stars
prior to the advent of nanotechnology.  That should be able to ignore
or brush aside anything except another nanotech based "biology," but
who need planets anyway?
Keith Henson

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

Date: 14 Feb 90 21:47:42 GMT
From: pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!uwm.edu!cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: space news from Jan 8 AW&ST

In article <[e-mail]> [e-mail] (Nick Watkins) writes:
>>observers have been claiming for some time:  Soyuz was meant to fly
>>on Proton, not the slightly modified Vostok booster it now uses.
>Which Western observers, and do they mean all Soyuz missions or just the
>Moon related ones?  The latter could use the extra lift, the former
>would seem  very wasteful of the Proton (rather like launching a Gemini on
>a Saturn IB.)

Harry Stine in particular has long been keen on the idea; I've heard him
talk about it more than once.  As for it being wasteful, that depends.
Under this theory, the original Soyuz was too big for the Vostok launcher,
so putting it on Proton was a reasonable idea.  Think of having to cut
an Earth-orbit Apollo mission down to fit on a Titan because the Saturn IB
wasn't working right.  Apollos 7 (Earth orbit) and 8 (lunar orbit) used
the same spacecraft type, so there's no obvious reason why a lunar Soyuz
would have to be lots heavier.

>>claim which has been heard is that Soyuz 1 went up on a Proton...
>Again where was this claimed? I appreciate that the official version may
>still be incomplete, but wouldn't the launch azimuth tell you which
>booster was used unambiguously?

I think Stine was the one I heard this from.  What on Earth would the
launch azimuth tell you about the choice of booster?  They launch both
A boosters and Protons from Baikonur, and the azimuth would presumably
be chosen based on things like tracking and communications.
--
"The N in NFS stands for Not, |     Henry Spencer at U of Toronto Zoology
or Need, or perhaps Nightmare"| uunet!attcan!utzoo!henry [e-mail]

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

Date: 13 Feb 90 06:50:40 GMT
From: research![e-mail]  (A.C.Beresford)
Subject: Mir &Soyuz

This post ystarted at 0540ut feb 13.
On Feb 12 at both 1116 Ut and 1922UT I observed Mir
In neither observation was any sign of any accompaning
object seen, either at moderate distances say 500Km,
or close ( say about 1 Km) Mir itself was about
magnitude 0.5 at 700Km range , and mag 0
at 1117 at 400Km. Both situations had a fairly optimal
phase angle. Another pass tonite in twilight at 1022UT
I will report later.

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

End of SPACE Digest V11 #43
*******************