Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V13_5/V13_548.TXT

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Subject: SPACE Digest V13 #548

SPACE Digest                                     Volume 13 : Issue 548

Today's Topics:
            SPACE Digest V13 #533
            SPACE Digest V13 #529
         MAJOR SOLAR FLARE ALERT - PROTON FLARE ALERT
              Re: Why the space station?

Administrivia:

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ReSent-Message-ID: <Added.cc=[e-mail]>
Resent-Date:  Mon, 13 May 91 20:38:38 EDT
Resent-From: Tom McWilliams <[e-mail]>
Resent-To: [e-mail]
Date:         Sun, 12 May 91 03:00:00 EDT
Reply-To: [e-mail]
From: [e-mail]
Subject:      SPACE Digest V13 #533
Comments: To: [e-mail]
To: david polito <[e-mail]>, Tom McWilliams <[e-mail]>

Subject: Re: SPACE Digest V13 #486

>In article <[e-mail]>
> [e-mail] (someone who hides his name behind
> a gateway) apologizes for Coffman's errors:

What's a gateway?  If you mean calling myself Tommy Mac, it's a nickname many
of my friends call me.  My name is Tom McWilliams, if it's important to you.
Forgive me for being on an old E-mail system that doesn't let me program cool
sigs like y'all got.

>>I'm reaching into some very dark memeories at this point, but if I remember
>>correctly, efficiency is <100% whenever the exhaust velocity is < c, and the
>mass conversion is less than 100% in the fule system.  So what's your point?

>You are suddenly re-defining "efficiency".  (Also mis-spelling "fuel".)
>here is the definition again, for your edification:             ^^^^^^^^
                                                          [typos are reel
>       eff = energy_output/energy_input                  [reluvent

Hey, I said I was reaching!  P.S> Efficiency means MUCH more, as long as nit-
picking is an acceptable part of this.  Example:  Work done : time spent on
the job.

If you are referring to a heat engine, than you really mean that efficieny
is a function of the difference in temperature of the exhaust and the ambient
air.  (heat sink).  Traditional rocket efficieny is derived from this, with
insignificant terms dropped.  It seems you have redefined efficieny too! :)

>In the case of a rocket, the output is the final kinetic energy of
>the payload, and the input is the energy in the fuel (chemical
>energy in the case of chemical fuels).

>Mr. Tommie Mac, your knowledge does not impress me in the slightest.

My goal was not to impress you.  I could have easily found my 'rocketry made
easy' handbook and found the figures to spread around like rice at a wedding.
My point was that you were being unnecessarily rude in your post, as well as
your counter-post.

>>Pulse-width doesn't change the power level (Energy per second), nor do the
>>optics on the ground.

>True.  I am frankly amazed that you understand this, given that
>you spend so many bytes defending someone who does not.

Again, I'm not defending what he said, I am in contention with your lack of
professionalism and common courtesy.  That you missed this point shows YOUR
ignorance.  But the compliment still means a lot to me.

>>So, since you are such a wealth of useful info;  spread it around!
>>HOW DO IT WORK?

>Since you insist, I'll give you a thumbnail sketch of what has
>already been posted to this group many times:

>A payload is placed on top of a block of ice (propellant).  It
>is blown out of an air cannon (to get it moving); as it rises
>into the air, the mirrors for an array of drive lasers track it.
>They deliver precisely shaped pulses of light to the propellant,
>which vaporizes a thin layer off the back and then flashes it
>into plasma with a high-power burst.  The plasma expands and
>propels the payload.  When the plasma has dissipated enough to
>permit laser light to penetrate once more, the process is repeated.
>One does this until the payload has achieved orbit.

>Note:  this is a THUMBNAIL SKETCH.  It is not intended to be a
>reference work, nor address all the physical and engineering
>problems of laser-launch systems.  If you demand that I do,
>I will politely tell you to get lost.

You are doing much better here!  You actually gave some useful information!
Good.
Unfortunatley, I did not stress that the information I was seeking was the
solution to the blooming problem.  This was one of the things you originally
blasted me (and coffman) for suggesting exists.  The answer had NOT been posted
to this group many times (I've never seem it anyway.)

That you so easily brush it off (get lost?) suggests that your initial
assertion that it's easily solvable or non-existent is either too obvious to
mention (doubtable) or you don't know.  Should I blast YOU for being ignorant?

>>Pointing it out is one thing (Which is done quite a bit), but blasting people
>>for it shows, not ignorance, but plain old lameness and immaturity.

>Or exasperation with willful ignorance.  You show ability to learn,
>but lack of tact, scholarship, and reading ability.  You could be
>educated easily, had I the patience.  I doubt Coffman can be, not
>because he is unable, but because he is UNWILLING.

 'Willful ignorance'?  Like "I'm stupid by choice"?   You sound like a social
engineer.  Are you a Liberal?

You teach someone?  I train people on routine computer software.  Had you
shown up, with your 'exasperation' with ignorance, and tried to train these
people, you would have a fat lip right now, and deserved it.

My point, AGAIN, is that YOU are lacking tact.  The fact that you missed the
point shows how useless tactlessness is in 'educating' someone.  I'm sure that
your snide comments to Coffman brought him no closer to learning about either
rocketry or laser-launch (which, it seems to me, you would like people to
learn about, since it seems promising).  Similalry, my snide comments to you
will probably bring you no closer to a professional manner, though your
previous paragraph containing actual math suggests that you have the ability
to learn, though I wouldn't have the patience, either.

But THIS shows a basic good-heartedness on your part;

>Terminology:    Vexh = Exhaust velocity
>                Vfin = Final payload velocity
>
>Assume:         Payload mass = 1 (units irrelevant).
>                Efficiency of conversion of energy to
>                propellant exhaust energy is 1.
>
>        Mass_ratio = loaded_mass / payload_mass = e^(Vfin/Vexh)
>        Fuel mass = payload * (Mass_ratio - 1) = e^(Vfin/Vexh) - 1
>
>        Total energy required    = (energy/unit_fuel) * (fuel_mass)
>(1)                              = 1/2 (Vexh)^2 * (e^(Vfin/Vexh) - 1)

>From formula 1 above, show that the mass-ratio which results in
>the least energy required to achieve a given Vfin is approximately 4.
>(You are not getting any points for ignoring the question the first time.
>You get 2 points if you read this far.  You get MUCHO points if you
>actually work the problem and learn something.)

Can I have my gold star now?  And I'll value it so much more than the
actual knowledge.

Back to the original point regarding rocketry and 'efficiency':  When Coffman
suggested that the advantage to a rocket is that more of it's fuel goes into
lifting payload, rather than fuel, as time goes on, why didn't you point out
that a Laser Launcher gets the same advantage, since more of it's energy goes
into lifting payload rather than reaction mass as the flight progresses?

That you chose to blast him, rather than point this out suggested to me that
you would rather blast than discuss/disseminate info/share ideas, etc.

Hence, my original blasting of you.

That you blasted me for it suggests that my original conclusion was correct.

That you responded as you did today shows you are getting the idea, though
if you find it hard to explain something to someone without pointing out
their (perceived) ignorance, you  will also find that not many people will
learn from you.
This suggests that you CANNOT percieve anything but ignorance in your
'students'.

No wonder you don't have the patience.  Neither do they.

Tom
Acknowledge-To: <18084TM@MSU>

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

ReSent-Message-ID: <Added.wc=ozlS00UkTF=[e-mail]>
Resent-Date:  Mon, 13 May 91 22:40:25 EDT
Resent-From: Tom McWilliams <[e-mail]>
Resent-To: [e-mail]
Date:         Sun, 12 May 91 02:13:13 EDT
Reply-To: [e-mail]
From: [e-mail]
Subject:      SPACE Digest V13 #529
Comments: To: [e-mail]
To: david polito <[e-mail]>, Tom McWilliams <[e-mail]>

Subject: Gravity Waves
>
>>>During the making of the show, I got into a long discussion with one of
>>>the consultants regarding the ins and outs of inescapable gravity
>>>fields, gravity propagation possibly exceeding the speed of light, etc. I
>>>wound up making a rather large cash bet that, once we are able to detect
>>>gravity waves, we would discover that they make a far less cluttered
>>>means of interplanatary communications ( and that we are more likely to
>>>detect another civilization using gravity wave communications than radio).

I'd bet that too, but I'm not sure why.  Pure intuition.  I can just imagine
the Intelligent Aliens involved in SETI on other Planets:
"The most logical medium for any intelligent species would be gravity waves,
so we have saved funding $$ by restrivting ourselves to that bandwidth ..."

>>
>>One question...does the ability to *detect* gravity waves imply the ability
>>to *generate* gravity waves?  From what little I know of the field, gravity

>That depends, here at Caltech, in the room next door is a portable
>gravitational wave (gravity waves conventionally refer to surface
>waves in fluids) generator!!! It is a standard exercise for the GR
>courses here to calculate the flux ;-) It is rather small.
>(Hint, I feel in imminent danger of being shredded by the tidal
>forces so generated)

>>waves are thought to be generated primarily by supernovas...am I correct

>The favoured sources at the moment are hard binaries spiralling in,
>generating "chirps" of gravitational waves, estimates of detectable
>signals are from one per year to one per day, depending some
>assumptions made. The supernovae rate is more like 1 per 10 years
>or maybe a bit better. See Thorne in "300 years of Gravitation"
>for details.

Uh, maybe this is a bad time to bring this up, but isn't true that the actual
existence of these 'waves' is still in question?  I.e, they haven't been
detected (yet).

I beleive the same is true of 'gravitons' the photon-like particle that
carries gravity (in theory).

Tom McWilliams
Acknowledge-To: <18084TM@MSU>

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

Date: Mon, 13 May 91 01:18:50 MDT
From: oler <@BITNET.CC.CMU.EDU:[e-mail]> (CARY OLER)
Subject: MAJOR SOLAR FLARE ALERT - PROTON FLARE ALERT
X-St-Vmsmail-To: st%"[e-mail]"

                        --  MAJOR SOLAR FLARE ALERT  --

                                 MAY 13, 1991

                              Flare Event Summary
                          Potential Impact Assessment


                                    --------



MAJOR ENERGETIC EVENT SUMMARY

     A major solar flare erupted early in the UT day of 13 May.  The flare,
rated a class M8.2 x-ray flare, was optically uncorrelated.  Region 6615,
which crossed beyond the west limb about a day ago, spawned this event which
produced a loop complex above the western limb.  The flare began at 01:03 UT,
peaked at 01:44 UT and ended at 02:22 UT on 13 May.  A weak Type II and a
weak Type IV sweep were observed from this flare.  The intensity of the
sweeps were probably diminished somewhat due to the distance of this region
beyond the west limb.

     A satellite proton event and a polar cap disturbance are IN PROGRESS.
The satellite proton event began near 03:00 UT on 13 May.  Proton levels were
at 190 p.f.u. (particle flux units) at 05:30 UT on 13 May.  The event is
expected to continue.

     A polar cap disturbance is also in progress.  Radio communicators are
warned of increased absorption levels over the polar regions and probable
errors in navigational beacons near the polar regions.

     Region 6615 left the west limb in a continued complex configuration.  It
appears as though it has retained its complexity.  This region may return in
a potentially flare-prone configuration in late May.  This will be determined
to a more accurate extent later.


POTENTIAL TERRESTRIAL IMPACT ASSESSMENT

     Todays major energetic event is not expected to have a terrestrial
impact on Earth, aside from the proton and polar cap activity.  No
geomagnetic storming is expected from this event.

     Satellite proton levels will begin to decay over the next several days.
However, proton levels are expected to remain above event thresholds for
the next 24 to 48 hours at least.  Polar cap effects will likely remain
present for the next 3 to 5 days at least.

     HF radio propagation conditions have become degraded over the polar
regions due to the proton activity.  Absorption levels have increased.
Errors in navigational beacons are likely over the polar regions.  Navigators
are warned to be cautious when using polar paths for navigational purposes.

     M-class flaring with a slight chance for a major flare exists from
several regions currently on the solar disk: 6619 (N29W16), 6621 (N09W08),
and 6624 (S16E17).  As a result, the Potential Major Solar Flare Warning
will remain in progress until otherwise noted.

     Region 6619 spawned a long-duration class M2.1 flare yesterday (11 May).
The event was observed over a period of 243 minutes.  No major effects are
anticipated from that event, although slightly elevated geomagnetic activity
may be possible.  Region 6619 remains a large, although somewhat dormant spot
system.  It is maintaining a delta configuration and is expected to continue
to produce M-class flares with a slight risk for a major flare (a proton
flare is not out of the question, although it is deemed somewhat unlikely).
No significant growth or decay has been observed in Region 6619.

     Region 6624 has grown very rapidly over the past 24 hours.  The region
now contains a Beta-Gamma magnetic configuration with 28 visible spots within
the region.  The area of this region has more than doubled over the past 24
hours and plage fluctuations have been observed in conjunction with this
rapid growth.

     At the present time (13 May), all of the major centers of activity
contain moderate amounts of magnetic complexity.  Regions 6621 and 6624 are
Beta-Gamma groups, while Region 6619 is a Beta-Delta group.  Moderate amounts
of shear also exist in these regions, leading support to the conclusion that
M-class flaring will continue into the near-future.


**  End of Alert  **

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

Date: 13 May 91 19:14:14 GMT
From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!wa4mei!ke4zv![e-mail]  (Gary Coffman)
Subject: Re: Why the space station?

In article <[e-mail]> [e-mail] writes:
>
>"If you assume we will never want a gazebo, then we don't need
>to build the gazebo this summer." If we ever want to do these fun
>things, the only alternative is to rush out do them right now?  Sheesh.

A better analogy would be "If you ever want a gazebo, you'd better make
sure the house you are buying has a big enough yard." A space station
offers the possiblility of doing the basic things necessary in a stepping
stone fashion to ultimately allow you to do the things you really want
to do in a more efficient way.

If we really want to understand the Jovian system, we want more than a
few fuzzy snapshots as we whiz by. If we want something as good as
SPOT images or Landsat images over an extended time so that we can
really understand what is happening, then we need a transportation
system better than a slingshot firing from the Earth's surface.
A space station gives us the capability to assemble a probe that
doesn't need to be designed to ever pass through atmosphere. A
large enough probe to hold capable instruments and communications
systems. A probe that can be fully checked out in orbit with
niggling things like a balky antenna fixed on the spot. With a
true HLV seeming to receed farther and farther away every day,
the only alternative is to assemble systems in orbit unless we
are content with tiny probes gathering fragmentary information
in brief glimpses.

Gary

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

End of SPACE Digest V13 #548
*******************