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Subject: SPACE Digest V13 #480

SPACE Digest                                     Volume 13 : Issue 480

Today's Topics:
           Re: Transportation Tethers (Beanstalks)
        Re: Alexander Abian wants to blow up the moon?
              ESA Press Release No.12/91
             Re:  Saturn V vs ALS
      GEOMAGNETIC STORM UPDATE - STORM UPGRADED TO MAJOR
               Re: Saturn V and the ALS
        Re: Alexander Abian wants to blow up the moon?
                   Re: NASP
          Re: Energia (was Re: Saturn V blueprints)
                   IRIDIUM

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: 29 Apr 91 08:22:57 GMT
From: emperor![e-mail]  (Dave Rickel)
Subject: Re: Transportation Tethers (Beanstalks)

In article <[e-mail]>, [e-mail] (William Lewis) writes:
>(btw, what are
> the differences between beanstalks, skyhooks, tethers, etc.?

Yep, there seems to be quite a bit of ambiguity here.  How about the following:

Beanstalk--a tether with a stationary end.  One end of the tether is rooted to
    the planet.

Skyhook--an orbiting, rotating tether, in such an orbit that an end
    occassionally has 0 (or low) velocity with respect to the surface of
    the planet.


david rickel
uunet!emperor!daver

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

Date: 29 Apr 91 22:36:31 GMT
From: bu.edu!buast5![e-mail]  (Alan Lohof)
Subject: Re: Alexander Abian wants to blow up the moon?

In article <[e-mail]> [e-mail] (Lloyd E Vancil) writes:
>In article <[e-mail]> [e-mail] (Robert Duff) writes:
>>
>>If the Earth were tilted to 0 degrees and the Moon obliterated,
>> what would be the impact on
>>life on Earth?  Sure, it would be Springtime all
>> year round
>>devestating for plant life whose life cycles are base
>> on the seasons.  Also, no more tides!
>>
>>Could life continue without the moon?
>>
>Yes say good by to Apples.. and many other fruits.
>Not to mention,
>     What does this guy propose to mitigate the effects of this one impact?
>Does he suppose that this thing will splash down like a tennis ball in a bath-
>tub?



YO!!!  did everyone forget something called conservation of momentum????
If the moon blew up, all the little pieces would stay in the original
orbit.  some parts would (after time) start to spread out in the orbit
and form a nice ring about the earth.  everyone remember jupiters rings??
notice the similarities??  how about the asteroid belts around the sun??
same thing.

Someone mentioned that  all the crops would die because its always Spring?
recall that seasons are due to the tilt of the earth with respect to the
Sun. the north pole points to Polaris.  loss of the moons mass all at
one point would have virtually no effect on the earths tilt. angular
momentum must be conserved.  there would be a minor change in the
precession of the earths axis when the moons mass spread into a even ring,
but that wouldn't change the tilt by much and it would take A VERY long
time.

Tides: yes these would be gone. but the loss would be as gradual as the
        spreading of the moons mass.

Earth - moon fragment collisions:  remember that all previous collisions
that we know of were from meteors, asteroid stuff.  the moon fragments
would come in as decaying orbits, spiraling in, like the space shuttle.
lots of time spent burning in the atmosphere. and it would take a very
large chunk to make it thru the atmosphere and hit surface.

Comments??

alan
[e-mail]

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

Date: Mon, 29 Apr 91 16:02:19 SET
From: [e-mail]
Comment: CROSSNET mail via MAILER@CMUCCVMA
Subject: ESA Press Release No.12/91

Date: 29 April 1991, 16:01:07 SET
From: Mike M. SKALA             ++39-6-941801-293    MSKALA   at ESRIN
To:   [e-mail]



ESA Press Release no.12; Paris, 91/04/26

Launch of ERS-1 Satellite on hold

Arianespace announced on 91/04/26 that the Launch of Ariane V44
carrying ERS-1 (European Remote Sensing Satellite) (scheduled for
91/05/03) would be postponed for a few days to allow additional
time for complementary work on the margins related to the third
stage engine operation.

The ERS-1 mission is in no way compromised by this delay.
Following the arrival in French-Guyana on 91/03/08, the spacecraft
has already been integrated, undergone extensive testing, and
been filled with hydrazine.

ESA decided to mate the satellite with the launcher and proceed
to T-4 days, where it is possible to hold the camapign.
A new launch is still to be announced.

As with the launch of every satellite, putting ERS-1 into orbit
involves risk. ESA endorses Arianespace's policy of minimising
this risk, and making safety and reliability its top priorities.

compiled by Mike M. Skala ([e-mail])

PS: waiting for comments (e-mail|), if I should continue
    to post this press releases (next time it should be more up to date)

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

Date: 29 Apr 91 15:39:12 GMT
From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re:  Saturn V vs ALS

In article <[e-mail]> [e-mail] (Brett Vansteenwyk) writes:
>...what would the Saturn V
>based cargo booster configuration look like?  I could see a case for only
>keeping the first two stages since they are sufficient by themselves for
>getting into orbit.  Unfortunately, if memory serves me, all the smarts of
>this rocket are in the third stage.  Would there be a problem in putting them
>in a section of the payload canister?

You'd have to put the Instrument Unit somewhere; normally it rode on top
of the third stage.  Launching entirely without a third stage was never
really tried, as Skylab was a converted third stage (including a functional
IU).  However, the IU is not large and could be tucked in somewhere.

You might or might not want to skip the third stage.  You do get more payload
to orbit with three stages than with two.

>Would a third stage the size of the
>original Saturn V third stage be justified even for geosynchronous orbit
>delivery?

Depends on what you're delivering.
--
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  [e-mail]  utzoo!henry

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

Date: Mon, 29 Apr 91 13:24:02 MDT
From: oler <@BITNET.CC.CMU.EDU:[e-mail]> (CARY OLER)
Subject: GEOMAGNETIC STORM UPDATE - STORM UPGRADED TO MAJOR
X-St-Vmsmail-To: st%"[e-mail]"

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

                            GEOMAGNETIC STORM UPDATE

                                Upgraded to MAJOR

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

                               19:00 UT, 29 April

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


STORM UPDATE INFORMATION:

     Geomagnetic activity intensified early in the UT day of 29 April.  Major
to severe storming was observed over some northerly middle to high latitude
areas.  The storm has been upgraded to a major-category storm.

     Geomagnetic activity is expected to remain at very active to major storm
levels throughout 29 and most of 30 April.  Some improvements are possible
either later in the day on 30 April or on 01 May.

     Auroral activity has been moderate to high over the middle and high
latitudes.  If the luminosity of the moon wasn't so high, some southerly
middle to low latitude areas may have spotted auroral activity.  However,
lunar phase is severely hampering attempts to view auroral activity.

     HF propagation conditions have been degraded over the past 24 to 48
hours.  Degradation is expected to continue, particularly during the local
evening and early morning hours.  Storming should begin to let up somewhat
either later in the UT day of 30 April or on 01 May.  At that time, some
improvements in HF propagation are likely.

     Several reports of VHF auroral backscatter have been received over the
past 24 hours, so conditions have been favorable for VHF auroral backscatter.
Expect similar conditions during the local evening hours of 29 April, with a
slightly reduced risk (but a fair possibility) for favorable conditions in
the local evening hours of 30 April.  For best chances at auroral backscatter
communications, use very low elevation angles for transmissions.

Alerts currently in progress:

  - MAJOR GEOMAGNETIC STORM ALERT

Warnings currently in progress:

  - POTENTIAL GIC ANOMALY WARNING


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

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

Date: 29 Apr 91 15:58:16 GMT
From: agate!bionet!uwm.edu!rpi!news-server.csri.toronto.edu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Saturn V and the ALS

In article <[e-mail]> [e-mail] writes:
>It is my understanding that the SSME and the F-1 are two different beasts
>a   main difference being fuels. Isn't there alsoa difference in the
>method of fuel delivery/combustion in which the SSME opted for the
>more risky/tempermental approach (sort o like the difference in a
>rotary vs piston engine?)...

Actually, there was a fundamental difference in philosophy that had all
kinds of implications.  The F-1 was, apart from its sheer size, very
carefully and deliberately built as a very plain, ordinary, unambitious
engine.  Considerable effort was made to produce a robust and reliable
engine that did not push technology in any way.  The huge size was expected
to (and did) cause enough problems without throwing in new technology.
Whereas the SSME pushed technology in almost every direction you can
think of, and nobody should be too surprised that the result is cranky,
temperamental, and short-lived.

Apart from the different fuels (kerosene vs. hydrogen), the major technical
difference is that the SSME uses a very high chamber pressure and has to
run a large fraction of its propellants through its gas generator and pump
turbine to get adequate pump power.  This "staged combustion" cycle gives
a higher exhaust velocity (the basic measure of rocket performance) but
seems to be trouble-prone.  The Japanese decided to use it for the main
engine of their H-2 booster, and are having just as much fun trying to
make it work as NASA did.

>...could the F-1 be improved easily, either
>performance or manufacturability, or is it fine the way it is?

Manufacturability was, as far as I know, not a big problem for the F-1.
It was a pretty ordinary engine apart from its size.  Performance could
undoubtedly be improved if the engine had a long-term future to provide
some incentive.  Robust and simple engines that are in use for a long
time typically have a history of steady improvement in performance as
the engineers fine-tune the parameters and learn which margins can be
reduced somewhat.  The same goes for vehicles as a whole; the Saturn V
for the last lunar landing carried about 30% more payload than the first.

>would a big booster by itself more expensive (but cheaper/kg) reduce
>overall launch costs by eliminating the need for expensive miniaturi-
>zation of the payload?

To some extent, yes, although you have to convince the payload builders
that it is worth changing some deeply-rooted mindsets.  They're very
strongly locked into a vicious circle of cost-is-no-object payloads where
any increase in available mass is used for more performance rather than
cost reduction.  The idea of actually reducing costs is quite foreign to
them.
--
And the bean-counter replied,           | Henry Spencer @ U of Toronto Zoology
"beans are more important".             |  [e-mail]  utzoo!henry

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

Date: 30 Apr 91 02:08:26 GMT
From: mnemosyne.cs.du.edu!isis.cs.du.edu![e-mail]  (Eric Bergman-Terrell)
Subject: Re: Alexander Abian wants to blow up the moon?


I read an article about him about 1 wk ago in the WSJ, which referenced an
article in OMNI.

The reason for exploding the moon is to reduce the obliquity of the ecliptic,
resulting in milder weather (less difference between summer and winter).

Did anyone read what the value of the obliquity of the ecliptic would be
after the moon was destroyed?


Terrell

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

Date: 29 Apr 91 14:37:04 GMT
From: sun-barr!olivea!samsung!umich!ox.com!hela![e-mail]  (Allen W. Sherzer)
Subject: Re: NASP

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

>Any chance anyone out there working on the NASP can post regular updates
>on progress with the NASP?

Well, I don't work on it but one of my congressional sources is very
interested in it.  I'll ask him now and then and post what I can.

One very interesting thing has happened recently on the political front.
In recent testimony military whitnesses have been very enthusiastic about
NASP. This is a far cry from past years when they saw no need for it. They
now see lost of missions for it now and are interested in funding it. This
is a far cry from years past where they zeroed out their part of the funding.

If this continues, the large hurdle which NASP needs to cross to get a
vehicle built will be a lot easier.

  Allen
--
+-----------------------------------------------------------------------------+
|Allen W. Sherzer | If you love something, let it go. If it doesn't come back |
|   [e-mail]   | to you, hunt it down and kill it.                         |
+-----------------------------------------------------------------------------+

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

Date: 29 Apr 91 15:06:02 GMT
From: zaphod.mps.ohio-state.edu!caen!ox.com!hela![e-mail]  (Allen W. Sherzer)
Subject: Re: Energia (was Re: Saturn V blueprints)

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

>What is launched from the payload bay is not the only payload, even if
>Henry sometimes says so.    On most flights, more space science is done
>in the cabin than on most satellites launched on unmanned launchers.

Granted. However, this stuff used for space science is sent up at horrendous
cost. For less money we could build a simple space station, put Spacelab
up there and get far more utilizaiton out of it.

  Allen
--
+-----------------------------------------------------------------------------+
|Allen W. Sherzer | If you love something, let it go. If it doesn't come back |
|   [e-mail]   | to you, hunt it down and kill it.                         |
+-----------------------------------------------------------------------------+

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

Date: 29 Apr 91 16:45:09 GMT
From: sdd.hp.com!news.cs.indiana.edu!noose.ecn.purdue.edu!en.ecn.purdue.edu![e-mail]  (/dev/null)
Subject: IRIDIUM


I read an ancient article from AvWeek about Motorola's new
IRIDIUM proposal, putting a bunch of light-sats in orbit
(77 is the number the article said) to make a world wide
network.

They said if they get only 500K subscribers in the world
they would make a profit.

I guess to build it would requre a 'space industrial revolution'
with assembly lines - high automation - cheap small launchers
(pegasus and others to launch 'bunches' of them) - and
a willingness to risk and think big.  kind of refreshing
when the press constantly claims that American buisnesses can't think
past the next quarter (I disagree with the press on this, making
a mountain of a molehill, but I digress ... :) )

Well, anyone know more than this or cares to comment
on feasability, etc?

I'd like to know

Brent
.

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

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

End of SPACE Digest V13 #480
*******************