Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v10_4/v10_428.txt

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Subject: SPACE Digest V10 #428

SPACE Digest                                     Volume 10 : Issue 428

Today's Topics:
            Re: Nuclear Reactors in Space
     Re: Why did Solar Max fall but space junk stays up?
             Re: Airlocks & Life support
            Re: Nuclear Reactors in Space
   Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space)
Re: Question: Was American Moon landings on China's news back in 1969?
              AEROSPACE SOFTWARE
         Re: Payload Status for 01/08/90 (Forwarded)
        Re: Any NASA COBE Personnel Out There?
            Re: Nuclear Reactors in Space
----------------------------------------------------------------------

Date: 14 Jan 90 17:32:51 GMT
From: rochester![e-mail]  (Paul Dietz)
Subject: Re: Nuclear Reactors in Space

In article <[e-mail]> [e-mail] (Tim Maroney) writes:

>In article <[e-mail]> [e-mail]
>(Paul Dietz) writes:
>>No, superconducting batteries could not give a sufficiently high
>>specific energy to replace RTGs.  The reason is fundamental, and
>>cannot be avoided by design changes.
>
>Which would be very interesting information, if the question had been
>whether superconductive loops could equal the energy density of RTGs.

I said to replace RTG's, not have equal specific energy.

As I argued, SMES specific energy faces the same theoretical limits as
chemical batteries.  About the best specific energy you can get with
chemical batteries is to use a fuel cell with hydrogen/oxygen.  At
100% efficiency, 500 watt-years of electricity would require about a
ton of LOX + LH2, plus the mass of insulation, tanks, fuel cell, and
so on.  Too much.

If you have a nonnuclear way of storing energy that has much better
performance than hydrogen/oxygen, NASA would *love* to talk to you.
The specific energy limits of chemical rocket fuels are a major reason
why it's hard to get into space.

    Paul F. Dietz
    [e-mail]

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

Date: Sun, 14 Jan 90 16:30:37 PST
From: [e-mail] (Peter Scott)
Subject: Re: Why did Solar Max fall but space junk stays up?

cs.utexas.edu!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer) writes:

>>And every so often the Soviets render a dying
>>military satellite worthless to scavengers by simply exploding it!
>
>Normally this is done only for birds that are about to make an uncontrolled
>reentry anyway.  The Soviet Asat tests were a different, and much more
>troublesome, story, but they haven't run one of those for years.

Thereby propelling back into orbit fragments that otherwise wouldn't be
there.  Space debris is more of a problem than what's left of a satellite
making an uncontrolled reentry hitting the ground.

Peter Scott ([e-mail])

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

Date: Sun, 14 Jan 90 15:13:08 PST
From: [e-mail] (Peter Scott)
Subject: Re: Airlocks & Life support

att!watmath!watserv1!utgpu!utzoo![e-mail]  (Henry Spencer) writes:

>The EVAs themselves are lengthy because work in free fall while wearing
>a clumsy suit is difficult.  Preparation for them is lengthy because keeping
>the suits' clumsiness to a minimum requires running with an absolute minimum
>of pressure in them.  To do that, one has to run the suits on something
>approaching pure oxygen.  For various reasons, current preference is to
>run spacecraft cabins at near one atmosphere and use a near-normal mix
>of oxygen and nitrogen.  The transition from a high-pressure atmosphere
>rich in nitrogen to a low-pressure one requires lengthy pre-breathing
>of pure oxygen to get the nitrogen out of the astronauts' bodies.  (The
>alternative is a strong possibility of decompression sickness, "the
>bends", potentially crippling or fatal, as that nitrogen comes out of
>solution as bubbles.)

I wonder if this could be solved by going to an oxygen-helium mixture in the
main cabin?  The research and experience has already been performed in deep
diving, and they could electronically correct the astronauts' voice
frequencies.  Then pre-breathe time should be much shorter.


Peter Scott ([e-mail])

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

Date: 13 Jan 90 08:16:06 GMT
From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket![e-mail]  (Leonard Erickson)
Subject: Re: Nuclear Reactors in Space

[e-mail] (Greg S. Hennessy) writes:

>In article <[e-mail]> [e-mail] (Neal Woodall) writes:
>#which you you rather be hit by, a bunch of fast neutrons or a bunch of beta
>#particles?

>As if there was a difference.

This is quite a difference. Which would you rather have me drop out a
window on your head, shot puts, or tennis balls? That's a pretty
good analogy.

Fast neutrons will penetrate deeply and deposit most of their energy
inside you, causing all sorts of damage. It takes multiple *feet* of
shielding to stop them effectively.

Beta particles are lucky to penetrate as much as half an inch of
paper. They can cause surface damage to you. But they aren't likely
to penetrate far enough to do serious damage.

Oh yeah, the beta particle deposit their energy and that's that.
But since your body is mostly water which is good at slowing neutrons,
the neutrons are liable to end up by creating radio-isotopes inside
you. And then you have to worry about them decaying.

--
Leonard Erickson        ...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short

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

Date: 13 Jan 90 08:01:58 GMT
From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket![e-mail]  (Leonard Erickson)
Subject: Re: Electromagnetic Braking (was Re: Nuclear Reactors in Space)

[e-mail] (Leonard Erickson) writes:

>So let's say the probe masses 1 metric tonne. And you have an hour to chop
>the velocity from 20 km/sec to 10 km/sec. We start with 4e11 joules. At
>the end we'll have 1e11. The difference is 3e11 joules. So we need to
>dump 8.3333e7 joules/sec. That's over 83 Megawatts!!! Unless you have a
>good way of using (or at least getting rid of) that much power, your
>probe will be a rapidly expanding cloud of plasma.

Ooops! I goofed. I forgot to multiply by .5....

So we start with 2e11 joules. At the end we have 5e10 joules. And
the difference is 1.5e11 joules. We need to dump 4.166667e7 joules/sec.
Which gives us *only* 41.66666 Megawatts. Still an unreasonable amount.

I wrote a quick and dirty program to check on the energy required to
chop 10 km/sec of off  the velocity of a 1000 kg object. The graph
of energy vs initial velocity is a straight line. So it increases
linearly with the velocity. I ran into numeric overflow problems before
I got up to .01 c though.... :-)
--
Leonard Erickson        ...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short

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

Date: 14 Jan 90 11:37:09 GMT
From: munnari.oz.au!cluster!metro!bunyip!moondance!batserver.cs.uq.oz.au![e-mail]  (Anthony Lee)
Subject: Re: Question: Was American Moon landings on China's news back in 1969?

[e-mail] (Robert Casey;6282;3.57;$0201) writes:
>So, was it true that the Man on the Moon landing didn't make it onto
>the News in China back in July 1969 (that's when it happened).  Why
>would the Chinese goverment not tell its citizens about the Moon
>landing?  (I'm just a dumb ordinary American.)  I realize that many of
>you college students were very young then (0 to 4 years old), and would not
>remember this anyway.  I was 15 years old then.  So, anyone my age

Well, I am not your age neither, I was only 5 then, but I have heard the
same thing from a lot of other people.  I believed the reasons why
the Chinese government did not tell her citizens about the Moon landing
is because of the culture revolution.  After all, the Chinese communist
party have to show that she is better then everyone else.  In a way
it is also related to the fact that China play such a big deal about her
first hydrogen bomb and the first satellite.

Actually talking about moon landing, I saw a space magazine a few months
back and there was a mention that China is training her own astronauts.
With the current playload of the LongMarch when would they be able to
send anyone ?

Also does anyone know what Soviet ICBM family does the LongMarch belongs
to ?

--
Anthony Lee (Humble PhD student) (Alias Time Lord Doctor)
ACSnet:    [e-mail]    TEL:+(61)-7-371-2651
Internet: [e-mail]        +(61)-7-377-4139 (w)
SNAIL: Dept Comp. Science, University of Qld, St Lucia, Qld 4067, Australia

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

Date: 12 Jan 90 05:00:00 GMT
From: samsung!umich!netnews.engin.umich.edu!caen.engin.umich.edu![e-mail]  (Thomas A Kashangaki)
Subject: AEROSPACE SOFTWARE

I AM A GRADUATE STUDENT IN THE AERO DEPARTMENT AT THE UNIVERSITY OF MICHIGAN
AND AM WORKING ON THE NASA SPACE EDUCATION GRANT PART TIME.  ONE OF THE
ACTIVITIES WE ARE TRYING TO ORGANIZE IS A SERIES OF PROGRAMS FOR MIDDLE AND
HIGH SCHOOL STUDENTS TO TRY AND INCREASE INTEREST IN ENGINEERING IN GENERAL
AND AEROSPACE ENGINEERING IN PARTICULAR.  I AM POSTING THIS TO SCI.SPACE IN
THE HOPE THAT YOU SPACE JUNKIES CAN HELP ME LOCATE SOME AERO RELATED
SOFTWARE FFOR THE MAC II OR UNIX MACHINES.  I AM LOOKING FOR ANYTHING WITH
A LOT OF GRAPHICS SUCH AS SHUTTLE SIMULATORS, ASTRONOMY CHARTS, ORBITAL
MECHANICS PROGRAMS, AIRCRAFT DESIGN, JJUST ABOUT ANYTHING THAT WILL HOLD THE
INTEREST OF A BUNCH OF 11-17 YEAR OLDS.  IF YOU HAVE ANY INFO ON SOFTWARE,
MANUFACTURERS, DOCUMENTATION,ETC PLEASE RESPOND TO "[e-mail]"
I APPRECIATE ANY INPUT.


  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ~   Thomas A-L Kashangaki                 |       [e-mail]   ~
  ~   University of Michigan                |       [e-mail]  ~
  ~   111 Research Activities Building      |                                   ~
  ~   Aerospace Engineering Department      |       phone:  [phone]        ~
  ~   Ann Arbor, Mi 48104                   |                                   ~
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



.

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

Date: 15 Jan 90 02:49:42 GMT
From: munnari.oz.au!cluster!metro!bunyip!brolga![e-mail]  (George Michaelson)
Subject: Re: Payload Status for 01/08/90 (Forwarded)

[e-mail] (Peter E. Yee) writes:

>
>- STS-35 ASTRO-1/BBXRT (at O&C) -
>
>Cite testing continued over the weekend and will pick up
>again this morning.  Broken backshell has been repaired.
>The fuse area was evaluated and the bad fuse on the SPDB
>was removed and replaced.  During Saturday's testing the same
>fuse blew again.  Today will work troubleshooting steps to
>evaluate the fuse.

Ok, so a volt is a volt is a volt. if a fuse blows twice, how come
"troubleshooting steps to evaluate the fuse" are done? I thought once
this happened you jammed a coin in between the slots in the fusebox,
and switched it back on with a long wooden pole or got your mother to
do it. Gee, it always seems to work at home, we just follow the smell
of burning bakelite and try shaking the conduit a bit.

Two blowouts and they start looking at the fuse. No comments on the circuit
which makes the fuse blow? Is this NASA jargon for "hit the f**ker with a
wrench and see where the sparks come from"?

I guess NASA buys fuses from T*ndy just like everybody else.

Apologies,
        George

Internet: [e-mail]                     Phone: [phone]
  Postal: George Michaelson, Prentice Computer Centre
          Queensland University, St Lucia, QLD Australia 4067.

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

Date: 14 Jan 90 23:31:58 GMT
From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Any NASA COBE Personnel Out There?

In article <[e-mail]> [e-mail] (Greg Goebel) writes:
>"Spectral Resolution" for FIRAS:
>
>   0.2 cm^-1
>
>I must've stared at that for five or ten minutes.  Either that's a typo or
>I'm missing something.  Any illumination out there?

Looks fine to me.  The spectroscopists have this curious habit of using
waves per unit length ("wavenumber") rather than length per wave (normal,
conventional "wavelength").  A wavenumber resolution of 0.2 cm^-1 is a
wavelength resolution of 5cm.
--
1972: Saturn V #15 flight-ready|     Henry Spencer at U of Toronto Zoology
1990: birds nesting in engines | uunet!attcan!utzoo!henry [e-mail]

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

Date: 14 Jan 90 23:01:38 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!watserv1!watdragon!watyew![e-mail]  (Brian or James)
Subject: Re: Nuclear Reactors in Space


 I am curious about the source of information Mr. Maroney is using that
allows him to say "... Or we can be patient and wait for the considerably
safer fusion technologies. Though a fusion drive probably shouldn't operate
in the atmosphere, obviously there's no problem with it being lifted into
orbit (or returning to Earth) by chemical means...". Since there are no
currently functioning 'fusion drives' I am unclear as to how Mr. Maroney
managed to assess their safety. The constraints on the design of a hypothetical
'fusion drive' are both physical and social. While there could easily be a
fusion powerplant design that meets the limitations placed on it by the
laws of physics and which is 'considerably safer' than existing fission
(or other, perhaps less expensive fusion) power plants, I see no reason to
expect that such a technology would inevitably be developed and used. Humans
have a talent for folly. Short term political or economic goals have lead to
foolish design choices in the past. The Challenger mishap, the difficulties
experienced at Chernoble, and the less than masterful management techniques
that lead to the current size of the British Empire are all examples of this.
As well, while there are fusion techniques we now believe could be possible
that do cause smaller and/or safer waste management problems that we now
face, it is also quite posible that we are unaware of flaws in our models
that make these hypothetical designs either usable or more dangerous than
we now realise. I find the use of terms like 'considerably safer fusion
technologies' difficult to justify, given the current absence of these
systems. It is easy to proclaim that fusion -will- be safer that other
power sources, since disproof of these statements is difficult, if not
impossible. It is just as easy to say that God Himself will descend from
the heavens to solve all our problems, if we all just *believe* purely
enough. It is, however, difficult to use absolutist and unverifiable statements
like these to plan a coherent plan of action.
    On a slightly different note, does anyone know of research into
the effects of chemical boosters on the atmosphere? I dimly recall something
about this being discussed in the mid '70s, but don't recall the details.
If the propellant exhaust does have unfortunate side effects (Degradation
of the ozone layer, catalysis of ice ages/run away green house effects,
continual victories by the Republicans :), what limits on tonnage to orbit
does this place on us?
                    James Nicoll

of the atmosphere

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

End of SPACE Digest V10 #428
*******************