Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_6/V13_658.TXT

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Subject: SPACE Digest V13 #658

SPACE Digest                                     Volume 13 : Issue 658

Today's Topics:
             satellite refuelling
               MAJOR SOLAR FLARE ALERT
            Re: New launch dates?
               Re: Calculating delta-V
          Re: vacuum energies for propolsion
Watching Out for Supernovae? (was Re: Extra Terrestrial Intelligence)
                  Astrolabes
               Re: Saturn V and the ALS
              Re: Good for the Japanese
           Re: Rational next station design process

Administrivia:

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

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

Date: 27 May 91 16:53:48 GMT
From: news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: satellite refuelling

In article <[e-mail]> [e-mail] (Steve Hix) writes:
>Refueling doesn't address the previously-mentioned problems with hydrazine
>catalysts.  (So use something besides hydrazine...)

Unfortunately, hydrazine is the overwhelming choice at the moment.  Most any
monopropellant is going to give you the catalyst issue, and monopropellants
are preferred because they make for simple hardware.  There is some interest
in bipropellants, but the main motive is... reduced fuel consumption, which
is going to undermine the rationale for on-orbit refuelling.

>How are electric thrusters coming along?

Very slowly.  There is some interest in small electric thrusters for comsat
stationkeeping, but I don't think anyone has flown them yet.  The hottest
new development (pun unintentional) in comsat thrusters is using resistance
grids or electric arcs to superheat the exhaust from a hydrazine thruster.
--
"We're thinking about upgrading from    | Henry Spencer @ U of Toronto Zoology
SunOS 4.1.1 to SunOS 3.5."              |  [e-mail]  utzoo!henry

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

Date: Tue, 28 May 91 23:16:12 MDT
From: oler <@BITNET.CC.CMU.EDU:[e-mail]> (CARY OLER)
Subject: MAJOR SOLAR FLARE ALERT
X-St-Vmsmail-To: st%"[e-mail]"

                        --  MAJOR SOLAR FLARE ALERT  --

                                 MAY 28, 1991

                              Flare Event Summary
                          Potential Impact Assessment


                                    --------



MAJOR ENERGETIC EVENT SUMMARY

     A new region which recently rotated into view around the eastern solar
limb has managed to spawn a tremendous flurry of flare activity.  Over the
past 24 hours alone, Region 6654 (N06E54) has produced a total of nine
M-class flares, one of which was a major-category event.  The major flare was
a class M5.3/1B event which began at 10:16 UT, peaked at 10:22 UT and ended
at 10:59 UT on 28 May.  The event was not associated with any significant
radio emissions.

     The other minor flares which originated from this region are tabulated
as follows:

Class M1.1    - Start: 01:16, Peak: 01:23, End: 01:29 UT, Location: UNKNWN
Class M1.5/1F -        03:30,       03:37,      03:45 UT,           N05E62
Class M2.2/1F -        05:20,       05:34,      05:42 UT,           N09E64
Class M3.2/2B -        06:57,       07:30,      07:50 UT,           N06E61
Class M2.4/1B -        13:06,       13:14,      13:27 UT,           N08E55
Class M1.7/1B -        15:12,       15:21,      15:55 UT,           N07E59
Class M1.5/1B -        16:17,       16:24,      16:35 UT,           N06E55
Class M1.4/1B -        22:05,       22:11,      22:22 UT,           N05E51

     Region 6654 is still too near to the eastern limb for reliable magnetic
imaging data.  Optically, this region is only modest in size (a DAI optical
configuration at present - this will change as it rotates into better view),
but obviously has a contorted magnetic structure and a fair amount of shear.


POTENTIAL TERRESTRIAL IMPACT ASSESSMENT

     The last major solar flare (class M5.3) will not have a terrestrial
impact.  However, if this region is able to hold together or sustain growth
over the next week, it could become a threat.

     M-class flaring will continue to be observed from Region 6654.  However,
the flaring is not expected to be as frequent as was observed over the last
24 hours.

     There is a distinct possibility and a moderately high risk for another
(or several other) major flares from Region 6654.  X-class flares do not
appear to be very likely candidates for major activity from this center, but
cannot be dismissed as impossible.  The potential for further major flaring
will be better determined when the region rotates into better view for
more extensive analysis.

     The Potential Major Solar Flare Warning has been issued and will remain
in progress until otherwise noted.  Occassional major flaring may be possible
from this region throughout its transit of the solar disk.


**  End of Alert  **

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

Date: 29 May 91 09:14:55 GMT
From: psuvm!esoc![e-mail]
Subject: Re: New launch dates?

The current launch date for ERS1 is 17th July 1991 at 03:46:41.00 C.E.T with
a proviso retry date of 27th July at the same time.

Mike Tolman

(European Space Operations Centre, Darmstadt, Germany)

p.s. How do you intend to record the live coverage?

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

Date: 29 May 91 16:51:23 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!news.nd.edu!mentor.cc.purdue.edu!mace.cc.purdue.edu![e-mail]  (Perry G Ramsey)
Subject: Re: Calculating delta-V

In article <[e-mail]> [e-mail] (Matthew DeLuca) writes:
>In article <[e-mail]> [e-mail] (Loren Petrich) writes:
>
>>    In "English" units, there is a unit of mass called the "pound"
>>and a unit of force called a "pound". Their ratio is the acceleration
>>of gravity, about 9.8 m/s^2. In this type of system, the ratio of
>
>Actually, the unit of mass in the English system is the slug.  At one
>g, the weight of this unit is 32.2 pounds.
>--
>Matthew DeLuca

Well, sort of, but not really.  Nobody uses the slug.  It is customary
practice to use the pound-mass as the mass unit and the pound-force as
the force unit, and just be careful about keeping track of which is
which.  An engineering mechanics professor told me that in Europe many
engineers use the "kilogram-force" rather than the newton, just
because it is a more familiar quantity, leaving them in the same mess
we're in in the US.

If you really want to confuse things, start talking about "poundals"
which are the moral equivalent of  Newtons when the pound-mass is used
as the mass standard instead of the kilogram.

1 poundal = 1 lbm - ft/sec^2

Doesn't all this just make you want to puke?

--
Perry G. Ramsey         Department of Earth and Atmospheric Sciences
[e-mail]  Purdue University, West Lafayette, IN USA
perryr@purccvm
N9LFF

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

Date: 29 May 91 18:00:20 GMT
From: tristan![e-mail]  (Loren Petrich)
Subject: Re: vacuum energies for propolsion


    "Quantum vacuum engines" tapping zero-point energy sound like
a cute thought, but they'll NEVER work. That's because the zero-point
energy is the energy that is always present at the lowest state. Since
one cannot go lower than that, zero-point energy can never be
extracted.


$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Loren Petrich, the Master Blaster: [e-mail]

Since this nodename is not widely known, you may have to try:

[e-mail]

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

Date: 29 May 91 17:57:14 GMT
From: tristan![e-mail]  (Loren Petrich)
Subject: Watching Out for Supernovae? (was Re: Extra Terrestrial Intelligence)

In article <[e-mail]> [e-mail] (Fraering Philip) writes:
>In article <[e-mail]> [e-mail] (Stephen Walton) writes:

>\...a nearby supernova.  If we learned anything from SN 1987A, we learned
>/that there is essentially no outward warning that a star is about to
>\blow.  Besides, unless your putative colony ships take terraforming
>/...

>Well, the combination of proximity given by interstellar travel and
>more advanced science will probably give the colony plenty of warning
>if the star is indeed about to blow up.

    First off, I doubt that a supernova explosion would be a
serious catastrophe at a distance of 1 parsec or thereabouts (a
typical interstellar separation). All one would see is that one of the
stars became VERY bright. Radiation hazard? I think that that might be
interesting to calculate. In all likelihood, there will be a big burst
when the shock from the collapsing core reaches the surface, but that
is about all until the exploding shell expands past the observers. A
magnetosphere and atmosphere like Earth's should protect against the
bulk of the flux (it already does so for the Sun). A free-flying
colony probably has an equivalent amount of shielding. Earth's column
density of atmosphere is about 1 kg/cm^2, which translates into 10
meters of water, 3 meters of typical rocks, or 1 meter of iron.
Providing this shielding is probably no great expense for spacefaring
colonists who travel in sufficiently large spacecraft.

    But if the star itself is the colony's primary? Then, you are
certainly in trouble. However, if one has a big enough neutrino
detector, one can follow the activity of the core. The star acquires a
multi-layered structure, with the following reactions going on:

H -> He
He -> C, O
O -> Si
Si -> Fe

The first reaction takes 10^7 years, while the last one takes about 1
day to go to completion. The neutrino flux should be very great for
the latter reactions, and should be easy to detect and find the
spectrum of. How much warning? It would be best to try to escape when
the O -> Si reaction starts, since that may take a couple of years
until the Si -> Fe reaction starts. Even then, one may have to move
VERY fast to get to a safe distance. To move 1 AU at an acceleration
of 1 g takes 10^5 seconds with a velocity of 1000 km/s -- much faster
than any chemical propellant can provide. If one wishes to get to 10^4
AU (where the apparent magnitude may be comparable to that of the Sun
from the Earth), one will have to travel 10^7 seconds at 10^5 km/s --
nearly c!. Thus, one may not be able to make it even if one has a
year's warning.

    Massive red giants may thus be too dangerous to even approach
if it will take several years to escape to a safe distance.


$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Loren Petrich, the Master Blaster: [e-mail]

Since this nodename is not widely known, you may have to try:

[e-mail]

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

Date: 29 May 91 19:28:55 GMT
From: network.ucsd.edu!inls1.ucsd.edu![e-mail]  (Doug Brownell)
Subject: Astrolabes


Greetings

I was just introduced to a reproduction of a 13th century astrolabe
(I think that's what it's called), and was mightily impressed when it
accurately predicted the hour (to within +/- 5 minutes) based upon a
sighting of the sun (at ~3:30 pm) and knowledge of the date.  Does
anyone know where such marvels can be purchased for less than a small
fortune?  The one I saw was nearly $300 (gold electroplated), but the
design is so simple that there's got to be one for under $100, and
maybe even $50.  I'd really apprecieat any leads as to where I might
search for one.

It was quite a blast seeing it used.  I highly recommend a
demonstration if you see one wandering by one day.  (They work at
night too :-)



Douglas M. Brownell                     |  Thomas Brownwell
Institute for Nonlinear Science, R-002  |  Barony of Calafia
University of California, San Diego     |  Kingdom of Caid
La Jolla, CA 92093                      |
                                        |  Anachronist (noun):
Internet: [e-mail]            |  Out of time;
          [e-mail]            |  Gotta go!

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

Date: 28 May 91 23:16:17 GMT
From: ucivax!p4tustin!ofa123![e-mail]  (David Anderman)
Subject: Re: Saturn V and the ALS

Why buy Soyuzes to launch on Titans, when it might make more political
sense to purchase 2 Hermes spacecraft. With the additional funding, ESA
just might actually build the Hermes, and the purchase might make ESA
feel better about the cancellation of the Freedom Space Station....

Hermes could easily be launched on a Titan IV. Soyuz, on the other hand,
is too small to be economically launched on a Titan IV (or even the
Commercial Titan). Actually, an upgraded Atlas Centaur would be more
appropriate for the Soyuz launcher, and the Atlas (was) man rated...



--
David Anderman
Internet: [e-mail]
Compuserve: >internet:[e-mail]
--------------------------------------------------------------------------

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

Date: 29 May 91 20:46:01 GMT
From: prism![e-mail]  (Matthew DeLuca)
Subject: Re: Good for the Japanese

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

>BTW, where were all the astronaut supporters screaming about
>"international agreements" when Solar-Polar got cut to feed the overgrown
>Shuttle budget?  What a bunch of hypocrites.

Well, there was one here in Atlanta.  As an equal-opportunity supporter
of manned and unmanned projects, I think it reflects very poorly on us
that we cancelled our end of ISPM, and it reflects just as poorly on us
when we cancelled Freedom.  Keep the name-calling to yourself, will you?

(Incidentally, if it's hypocritical to cheer the death of ISPM while
bemoaning the death of Freedom, is is just as hypocritical to support
the demise of Freedom and bemoaning the loss of unmanned science.)

--
Matthew DeLuca
Georgia Institute of Technology      "I'd hire the Dorsai, if I knew their
Office of Information Technology      P.O. box."  - Zebadiah Carter,
Internet: [e-mail]    _The Number of the Beast_

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

Date: 29 May 91 15:58:18 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!wa4mei!ke4zv![e-mail]  (Gary Coffman)
Subject: Re: Rational next station design process

In article <[e-mail]> [e-mail] (Nick Janow) writes:
>[e-mail] (Allen W. Sherzer) writes:
>
>> I'm sure Nick would volunteer to be the test subject given his confidence in
>> the field. Anybody want to stick a needle in Nick by remote control?
>>
>> :-):-):-):-):-):-):-):-)
>
>:)   My confidence is in the _potential_ of the field, not the present
>capabilities.  I do think that investment in automation/teleoperation/AI R&D
>would be more beneficial at this point in history than the type of manned space
>presence we could develop with the same amount of money.

While general automation/robotics/teleoperation/AI *may* be useful in
space, it would also be very useful here on earth. As such, the primary
funding should not be from NASA. NASA's primary role at this time should
be in developing access to space and support systems in the space enviornment,
not primarily in developing equipment for end users of space. That should be
left primarily to space users in the commercial and scientific realm. If users
deem manned presence necessary, then NASA needs to support those users
through launch systems and space support systems. If users only want to
chunk some machinery in orbit, NASA should have the transportation systems
available to do that as well. If the best transport system turns out to
do both, then a great economy is achieved. If not, then separate systems
need to be developed.

NASA should be primarily a developer of transportation and service systems
that support *users* of space. Users of these services should get their
funding elsewhere. NSF should fund "pure" research like Hubble, Astro,
Voyager and Gallieo, while agencies like the EPA and NOAA should fund things
like EOS. NASA should concentrate on advanced shuttles, advanced heavy lift
vehicles, and general purpose space platforms designed to supply user support
utilities.

Gary

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

End of SPACE Digest V13 #658
*******************