Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_4/V13_473.TXT

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Subject: SPACE Digest V13 #473

SPACE Digest                                     Volume 13 : Issue 473

Today's Topics:
           Magellan Status for 04/25/91 (Forwarded)
               Re: Saturn V and the ALS
                 Venus's face
            Re: Buckyballs and ion engines
          Re: Atlas Centaur bites the big one, 4/18
            Re: Airships R-100/101
         Re: "Bussard Ramjets" AKA duct space drives
             Re: Saturn V vs. ALS
          POTENTIAL MINOR GEOMAGNETIC STORM WARNING
          Re: Atlas Centaur bites the big one, 4/18
             Re: Saturn V vs. ALS
           Re: Launch Scrubs due to Weather
             Re: Saturn V vs. ALS

Administrivia:

    Submissions to the SPACE Digest/sci.space should be mailed to
  [e-mail].  Other mail, esp. [un]subscription requests,
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----------------------------------------------------------------------

Date: 26 Apr 91 09:08:48 GMT
From: [e-mail]  (Peter E. Yee)
Subject: Magellan Status for 04/25/91 (Forwarded)


                     MAGELLAN STATUS REPORT
                         April 25, 1991


     The Magellan spacecraft and its radar system are performing
very well. All star calibrations and momentum wheel
desaturations Wednesday were fully successful.

     After a day of 12-minute "hide" periods in which the
spacecraft is turned to put it in the shade of its high-gain
antenna for thermal control, the project reports a definite
cooling trend. Most parts of the spacecraft and radar sensor are
down an additional two degrees.

     Today, controllers sent up a non-standard command to reset
the solar array drive mechanism. In addition to shading the
spacecraft instrument bays, the solar arrays are turned to
prevent too much reflected sunlight on the spacecraft.

     Magellan passed its 1,525th mapping orbit today and is
approaching the 80 percent mark in its coverage of Venus'
surface, which will be passed by this weekend. The primary
mission cycle requirement was 70 percent.

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

Date: 26 Apr 91 13:38:57 GMT
From: snorkelwacker.mit.edu!usc!samsung!noose.ecn.purdue.edu!en.ecn.purdue.edu![e-mail]  (/dev/null)
Subject: Re: Saturn V and the ALS


Actually, I understand that $4000/lb is more on line with costs.

THe $2000/lb figure wasn't meant as an estimate, I used it previously
to say "if the Saturn V or any big launcher had a 'good' cost -
$2000/lb for 250,000 lbs, you are talking $500MILLION per payload!"

Too d*mn expensive, even for something like Hubble! ($1 bil?)

--
+-----------------------------------------------------------------------+
| Brent L. Irvine     |            These are MY opinions   |
| Malt Beverage Analyst     |            As if they counted...:) |
+-----------------------------------------------------------------------+

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

Date: 26 Apr 91 18:54:02 GMT
From: sdd.hp.com!swrinde!zaphod.mps.ohio-state.edu!rpi!uwm.edu!csd4.csd.uwm.edu![e-mail]  (Mark William Hopkins)
Subject: Venus's face

Fooled ya!  You thought I was going to talk about a "face found on Venus".

Here is the question.  Venus shows nearly the same face to Earth on each close
passage.  Maybe this could be ascribed to a gravitational lock, incremental
torques, or tidal friction or whatever.  But why then:

   (1) Is the period of nearest approach and rotational period off from one
       another by 6 hours, given all these billions of years to have become
       synchronized?
   (2) Was the Earth's rotation not similarily affected?

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

Date: Fri, 26 Apr 91 17:00:16 -0600
From: [e-mail] (Moses M. Gallegos)


I just want to ask you if you have any information
on the aerospace plane and how burning hydrogen will affect the upper
atmosphere. Particularly the ozone layer.

I would appreciate it if you have any information on to
e-mail it to me send it to    u108896

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

Date: 26 Apr 91 12:51:59 GMT
From: agate!bionet!uwm.edu!zaphod.mps.ohio-state.edu!van-bc!rsoft!mindlink![e-mail]  (Bruce Dunn)
Subject: Re: Buckyballs and ion engines

> [e-mail] writes:
> I read with interest that some researchers are investigating
> "buckyballs" (buckminsterfullerenes, soccer-ball shaped molecules
> consisting of 60 carbon atoms) for use as reaction mass in ion
> engines.  Recently, a simple and potentially low cost means of making
> buckyballs was discovered; Smalley is projecting the cost should drop
> to a few dollars per pound.
>
>
> C60 has a mass of 720 AMU, vs. ~130 for cesium or xenon.  The
> advantage of C60 over other molecules would be that C60 appears to be
> very rugged, yet easily ionized, so it should be possible to ionize it
> without generating large numbers of low mass fragments, which would
> degrade engine efficiency (ion engines are most efficient when all the
> ions have about the same mass/charge ratio).  I read that buckyball
> ions accelerated to 15,000 mph have been observed to survive impact
> with metal surfaces, which illustrates how resilient they are.
>
>
>         Paul F. Dietz
>         [e-mail]


     Sounds interesting!  Existing ion engine propellants all have their own
problems.  Mercury and cesium work well, but present spacecraft contamination
problems - some material emitted by ion engines doesn't get ionized, and the
metal vapor tends to come back and cause space craft problems (so I'm told).
Xenon works very well, giving efficiencies similar to that of mercury (thrust
system efficiency of about 0.7 at a specific impulse of 3000).  Xenon however
is a rare and expensive gas and even a modest program of ion engined craft
using it may well use more xenon than can be isolated each year.  Argon can be
used as a substitute for xenon, but the argon ions take more energy to create
than xenon ions and have a lower mass.  Thrust system efficiences with argon
are about 0.4 at a specific impulse of 3000.  Lower thrust system efficiency
does not mean lower specific impulse, but does mean that for a given thrust
level an argon ion engine requires about 60% more power than a xenon or mercury
engine.  This translates either into a bigger solar array or into a bigger
reactor and radiator system, depending on the source of thruster power.

Propellant     Mass     First Ionization Potential

Hg             200.6    10.43 volts
Cs             132.9     3.89 volts
Xe             131.3    12.13 volts
Ar              39.9    15.75 volts
Buckyballs     720      ????? volts
--
Bruce Dunn   Vancouver, Canada    [e-mail]

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

Date: 27 Apr 91 17:05:37 GMT
From: usc!samsung!rex!rouge![e-mail]  (Fraering Philip)
Subject: Re: Atlas Centaur bites the big one, 4/18

Can the data for the reliability of these launch systems
be considered accurate? Might there be failures noone in
the west knows about?

--
Phil Fraering
[e-mail]
Joke going around: "How many country music singers does it take to
change a light bulb? Four. One to change the bulb, and three to sing
about the old one."

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

Date: 26 Apr 91 01:37:55 GMT
From: voder!pyramid!ctnews!unix386![e-mail]  (Ward Griffiths)
Subject: Re: Airships R-100/101

[e-mail] (Fraering Philip) writes:

>I like the idea about second-sourcing the SSF. I know it's too late,
>but could they have 'second-sourced' the contract, with the second
>consortium going with a totally different design?


Like possibly the Livermore Labs design, which is strangely
similar to some things I was doing on the backs of envelopes
about ten years back when I was trying to figure how to get
the most space station out of the fewest shuttle launches?
(After just rereading Fritz Lieber's great little story,
"The Beat Cluster".)

No, I am not qualified as an aerospace engineer, I just
like to rough these things out for fun using whatever good
concepts and references I can find.  I'm not qualified as
an aeronautical engineer either, but I've got an awful lot
of airship design work roughed out as well.  It's amazing
what little improvements in technology, material and
engineering have shown up since the airship industry died.

--
   Ward Griffiths, Unisys NCG aka Convergent Technologies  San Jose, CA         The people that make Unisys' official opinions get paid more.  A LOT more.
===========================================================================          To Hell with "Only One Earth"!  Try "At Least One Solar System"!

Much of the Miskatonic University's special collection of literature, artwork,    artifacts and specimens may only be studied by certified scholars.  As many    psychiatrists can tell you, getting a Miskatonic scholar certified is rarely    difficult.

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

Date: 27 Apr 91 03:41:13 GMT
From: agate!lightning.Berkeley.EDU![e-mail]  (Frank Crary)
Subject: Re: "Bussard Ramjets" AKA duct space drives

In article <[e-mail]> [e-mail] writes:
>Isn't it reasonable to expect that hydrogen density variations in space
>will be comparable to the density variations we experience in the
>tellurian atmosphere?  One or two very bumpy airplane rides suggest
>there are drastic variations in mass flow input to production jet
>engines.
In an aircraft there are (I believe) variations in mass flow input
(from variations in the outside air) but not in s fuel flow, which
comes from the aircraft's fuel tank, via a pump. In a interstellar
ramjet, the nonuniformity of the interstellar medium would produce
a nonuniform mass AND fuel flow.
As far as the uniformity of the ISM, all astronomical methiods of measuring
its density give results which are the average over, at least, light years.
Local density clumps are not detectable at this time.

                      Frank Crary
                      UC Berkeley

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

Date: 27 Apr 91 23:05:12 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Saturn V vs. ALS

In article <[e-mail]> [e-mail] (Frank Crary) writes:
>However US companies CAN make long term investments. Orbital Sciences
>Corporation has yet to make a cent on the Pegasus launcher... Is this not
>a long term investment in space infrastructure by a US company, who
>thinks there is a market?

It is.  Now for the hard part of the assignment:  name three more such
investments, to justify the plural in "companies".  The OSC/Hercules
Pegasus effort is a rare exception, not the rule.
--
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  [e-mail]  utzoo!henry

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

Date: Sat, 27 Apr 91 22:44:04 MDT
From: oler <@BITNET.CC.CMU.EDU:[e-mail]> (CARY OLER)
Subject: POTENTIAL MINOR GEOMAGNETIC STORM WARNING
X-St-Vmsmail-To: st%"[e-mail]"

                /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

                     POTENTIAL GEOMAGNETIC STORM WARNING

                          VALID: UT DAY OF 28 APRIL

                /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\


WARNINGS ISSUED:

  - POTENTIAL MINOR GEOMAGNETIC STORM WARNING


ATTENTION:

     Geomagnetic activity has become increasingly unstable over the past 12
to 24 hours.  A brief period of minor to major storming was observed over
many middle and high latitude regions early in the UT day of 27 April.  There
is a risk of minor geomagnetic storming for 28 April (or at least very active
conditions).  As a result, a Potential Minor Geomagnetic Storm Warning has
been issued for the UT day of 28 April.  The cause of this activity is most
likely a well positioned coronal hole, although several disappearing
filaments on 24 April may also be contributing to some of the activity.

     No significant middle latitude storming is expected, although periodic
high latitude geomagnetic activity could reach minor to low intensity major
storm levels.  Activity is expected to remain at least unsettled until the
early part of May.

     HF propagation conditions should remain fair to good over the middle and
low latitudes during the daylight hours.  Increased fading, absorption and
noise is likely during the local evening hours of 28 April.  Fairly
significant amounts of auroral flutter is possible on these evenings.

     There is a chance for some minor auroral backscatter possibilities on
VHF frequencies over middle and high latitude regions, particularly during
the evening hours near local midnight.

     Auroral activity will be moderate to high over the high latitude regions
near the auroral zone.  Northerly middle latitudes should also experience
low to moderate levels of auroral activity.  However, lunar phase will make
observing auroral activity very difficult.  Nevertheless, the secondary
effects will be present.


                /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

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

Date: 27 Apr 91 00:25:14 GMT
From: hub.ucsb.edu!ucsbuxa![e-mail]  (Charles Frank Radley)
Subject: Re: Atlas Centaur bites the big one, 4/18



There are as you say only 2 published failures of the Soyuz,
however the same booster ( different upper stage only ) has
been used on MANY other programs other than Soyuz, where
there are believed to be many other failures.
  The Soyuz booster iuses the same core as Sputnik-1

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

Date: 26 Apr 91 22:47:36 GMT
From: mcsun!ukc!edcastle!aiai!aipna!cstr![e-mail]  (Richard Caley)
Subject: Re: Saturn V vs. ALS

In article <[e-mail]>, Karl Stapelfeldt (ks) writes:

ks> We do need a rocket that can lift more than the shuttle, but not
ks> *six* times more.

Out of interest, is that six times to shutle type mountain top
skimming orbit or six times to somewhere reasonable?

The shuttle is really only a first stage and given that they won't use
a decent second stage for safety reasons, it might be nice to have
something bigger.

For instance, how long would Galleleo have taken to get to Jupiter if
launched on something with an engine under it? Would it be so much
more expensive when things like the ground support for all that time
are costed in?

Besides, there is nothing sacred about one payload per rocket. If you
have reasonable reliability, put two or three on it and have some
capacity left to be able to design heavier, cheaper payloads.

--
[e-mail]        Looks like a brick, flies like a
                brick, costs like a radium brick.

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

Date: 27 Apr 91 23:27:36 GMT
From: snorkelwacker.mit.edu!usc!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Launch Scrubs due to Weather

In article <[e-mail]> [e-mail] (John A. Weeks III) writes:
>There's something else the Saturn V did not have to worry about,
>based on the Apollo 12 flight 8-).

They did get a *bit* more cautious after that one. :-)

It's still rather striking, after seeing the precautions taken when moving a
shuttle, to read about the first Saturn V rolling out to the pad through a
driving rainstorm.  (They did have to stop for twenty minutes, midway to
the pad, because the rain was so heavy that the drivers had trouble seeing
the support vehicles moving ahead of the crawler.)

>... In Nevada, how would a sand storm affect
>the shuttle?  I suspect that a sand storm would seriously contaminate
>the shuttle.

Fair chance of it.  One reason why White Sands is the last choice among the
official landing sites is that fine blowing salt there was a contamination
problem on the one or two occasions when the shuttle did land there.
--
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  [e-mail]  utzoo!henry

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

Date: 26 Apr 91 21:58:20 GMT
From: fxgrp![e-mail]  (Mike Wexler)
Subject: Re: Saturn V vs. ALS

[e-mail] (Karl Stapelfeldt) writes:


>     The problem with resurrecting the Saturn V today is the same
>same problem that caused the launcher to go out of production in the
>1970s :  It is just too damn big for our current needs.
I agree that this is probably true.

>     We do need a rocket that can lift more than the shuttle, but not
>*six* times more.
Actually we probably don't even need to lift more than the shuttle, just
more cheaply, reliably. If we had a rocket that could launch 10-20 times
a year, was 1/10 the price of the shuttle, could lift the same amount and
didn't blow up very often that would be a good thing.

Why couldn't we just build a small heavy lift vehicle (SHLV) that can
launch about the same as the shuttle (same payload fairings?). We could
use engines from the Saturn (just not as many). We could use electronics
from the Shuttle, etc. It would be a major project, but if we kept it
on a relatively small scale. Use existing, reliable components and didn't
try to push any technology we could probably get something pretty useful.
--
Mike Wexler ([e-mail])

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

End of SPACE Digest V13 #473
*******************