Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/spacedig/v13_0/v13_084.txt

Internet Message Format | 1991-06-28 | 17KB

Return-path: <[e-mail]>
X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson
Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/[e-mail] (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests)
          ID </afs/andrew.cmu.edu/usr1/ota/Mailbox/MbcweoC00WBw02704U>;
          Mon, 28 Jan 91 01:54:44 -0500 (EST)
Message-ID: <[e-mail]>
Precedence: junk
Reply-To: [e-mail]
From: [e-mail]
To: [e-mail]
Date: Mon, 28 Jan 91 01:54:40 -0500 (EST)
Subject: SPACE Digest V13 #084

SPACE Digest                                      Volume 13 : Issue 84

Today's Topics:
              Re: SPACE Digest V13 #041
          Re: What is cosmological constant?
                 Ulysses SRM
         MAJOR SOLAR FLARE ALERT - 21 JANUARY
              Origin of Word "Anomaly" ?
                Thanx!
      Re: Metrics (was Re: Rotating Joints for Habitat)
           new space-investors mailing list

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: 25 Jan 91 04:41:54 GMT
From: zephyr.ens.tek.com!tektronix!sequent!crg5![e-mail]  (Nick Szabo)
Subject: Re: SPACE Digest V13 #041

In article <[e-mail]> [e-mail] (George William Herbert) writes:
>In article <[e-mail]> [e-mail] (Nick Szabo) writes:
[Why Jupiter may be among the first space settlements: energy costs 3
orders of magnitude lower]

>...
>    First, if you want to get down near the planet, you need a delta-V that
>can only be described as 'impossible' to get down and back again.  The del-V
>to surface-synchronous orbit and back to (one of the middle moons, i can't
>remember which offhand) was something like 72 km/sec.  We had to talk the
>student out of some very neat ideas because of this.

Going down to Metis is easy (electromagnetic brake and gravity maneuvers
with the larger moons to elongate orbit, then aerobrake at Jupiter).
Going up requires transmitting energy from the generator at Metis to the
spacecraft, or having a very powerful mass driver based at Metis.


>    Second, it's radiation belts are very, very nasty.  You can shield,
> esp with magnetic shields, but it's not a very hospitable place.

As discussed previously, an outpost at Callisto with a small amount
of ice and rock shielding would be fine.  Radiation levels at Metis pose a
problem for some kinds of machinery and the few on-site operators that
might be needed.  These can be housed in small captured asteroids, in
tunnels underneath Metis, or shielded by Metis-powered electromagnets.


>    I will admit it has possibility.  But only in Forwardian scales.

The only way space can be economically settled is in Forwardian scales.
Simply moving earth-scale industries into space will not work.

Some of the major economic factors that will shape human
settlement of the solar system:

* the time value of money (2.35 for Hohmann Jupiter round-trip at 18%)
* energy costs (Jupiter/Metis generator 1/1000 cost of SPS at Earth)
* location of significantly differentiated precious metals and
  isotopes (unknown, requires more solar system exploration)
* comet/asteroid collision opportunities (cometary aerobraking for
  moving asteroids; function of the number of asteroids and comets
  we have discovered and tracked).
* potential of microgravity industry (unknown, require research and
  cheaper source of raw materials).
* Earth launch as a bottleneck ($/delta-V from Earth->LEO
  over 10^6 times the $/delta-V in Jupiter system, due to
  environment/atmosphere (10^3) and energy (10^3) costs.
* technology (factory automation, high-temp superconductors, laser
    communications, teleoperations, electric propulsion, etc.)
    will help considerably.

Note that surprisingly few of these economic factors are being
addressed by contemporary space programs.  The most valuable projects
today for settling the solar system tommorrow are those that increase
our knowledge of the solar system (solar system astronomy) and that
progress technology in general.  Specifically, work on chemical rockets
and small, extremely expensive manned spacecraft does very little to bring
us closer to space settlement.


--
Nick Szabo            [e-mail]
Embrace Change...  Keep the Values...  Hold Dear the Laughter...

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

Date: 20 Jan 91 10:06:50 GMT
From: att!news.cs.indiana.edu!ariel.unm.edu!pprg.unm.edu!topgun!mustang!nntp-server.caltech.edu![e-mail]  (Steinn Sigurdsson)
Subject: Re: What is cosmological constant?

[e-mail] (Todd A. Brun) writes:

>In article <[e-mail]> [e-mail] (joefish) writes:
>>    It is difficult for me to understand why Einstein's Cosmological
>>constant is discussed other than in the interest of the history of
>>the General Theory of Relativity.
>>
>Reportedly, Einstein called the cosmological constant "the biggest blunder of
>my life".  However, it is a mistake to dismiss it as only an historical
>footnote.  I'm not an astrophysicist, but they hang out right down the hall
>from me; and most of them believe that a non-zero cosmological constant
>is quite plausible, and least at one time.  One of them even went so far as
>to say that "most" cosmologists believe that at one time the cosmological
>constant was non-zero.
Hi Todd!
>they posit that at one time the universe was in a rapidly-expanding
>'inflationary' state, which caused it to expand enormously in a very short
>time.  As there isn't any known reason why this should happen, it is common
>to invoke a non-zero cosmological constant in the early universe.

>Why bother to do this?  Because, until recently anyway, the inflationary
>models were the most successful at explaining what we actually see.  Nowadays,
>almost all cosmological models are in very bad shape, being attacked from
>both ends.  On the one had, recent discoveries of very large scale structure
>in the universe (the 'Great Wall' and 'Great Voids') has made it clear that
>the present universe is much more inhomogenous that was originally though;
>on the other hand, measurements of the cosmic background radiation by COBE
>have made it clear the early universe was very much more homogenous than
>originally thought.  Under this twin strain, about 90% (it may be more by now)
>of all cosmological models have quietly expired.  If COBE manages to push its
>accuracy to about 1 part in 10^7, it will pretty much have scotched the lot.

>Anyway, if the cosmological constant was at one time non-zero, the real puzzle
>is why the heck it's so small now.  Having a non-zero cosmological constant
>is essentially the same as saying that completely empty spacetime isn't
>flat, which would imply that special relativity isn't actually right.  Since,
>as has been often pointed out in this august newsgroup, SR is the most
>well-tested physical theory of all time, the corrections due to the constant
>must be truly minute.  Considering the shakiness of all these models in the
>light of current experiments, your guess is probably as good as anyone
>else's.

In fact the situation is getting so tight, that a finite cosmological
constant has been invoked as being necessary to save cosmological models.
Of course you may believe the computer modelling about as far as you can
throw the printouts.
 The jury is still out, but the cosmological constant
is currently very much alive.
--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
|Steinn Sigurdsson            | standard disclaimer     |
|Physics, Caltech            |             |
|[e-mail]        |             |

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

Date: Sun, 20 Jan 91 14:52:56 EST
From: John Roberts <[e-mail]>
Disclaimer: Opinions expressed are those of the sender
    and do not reflect NIST policy or agreement.
Subject: Ulysses SRM


>From: swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!Wales.Larrison@u\
>csd.edu  (Wales Larrison)
>Subject: Drat!

>Henry Spencer replies:
>>>[Ulysses] The Delta-VEGA maneuver used was a god-
>>>send to them.
>>
>>Again, ???  Unless I am badly mistaken, Ulysses is going direct to
>>Jupiter, no delta-VEGA involved.  Only Galileo gets to bat around
>>the inner system for a while first.
>>
>   Hmmm - you may also be right on this.  I can't find confirming or
>denying data. Considering my batting average on this posting, you're
>probably right.  Although that's a whole lot of energy to get out of
>that IUS.

Looking at old postings:

Ulysses was launched toward Jupiter with the equivalent of three solid
booster stages - initially by a two-stage IUS, then after IUS separation
by a Payload Assist Module (PAM-S).

The velocities relative to earth were listed as follows:
  Initial - 17300 mph
  After 1st stage of IUS (SRM1) - 22550 mph
  After 2nd stage of IUS (SRM2) - 25580 mph
  After PAM-S - 34130 mph

Magellan used another version of the PAM.

>Wales Larrison
>Internet: [e-mail]
>Compuserve: >internet:[e-mail]
           John Roberts
           [e-mail]

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

X-Delivery-Notice:  SMTP MAIL FROM does not correspond to sender.
Date:    Sun, 20 Jan 91 23:53:00 MST
From: [e-mail] (Cary Oler)
Subject: MAJOR SOLAR FLARE ALERT - 21 JANUARY
X-St-Vmsmail-To: st%"[e-mail]"

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

Please Note:  In order to analyze the data from the recent major flare,
compilation of the Solar Terrestrial Forecast and Review for 20 January has
been postponed.  It will be posted as soon as possible.

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


                        --  MAJOR SOLAR FLARE ALERT  --

                               JANUARY 21, 1991

                              Flare Event Summary
                           Potential Impact Forecast

                                    --------


MAJOR ENERGETIC EVENT SUMMARY

     Another major energetic flare occurred from Region 6455 today, located
at S14W47.  The flare peaked at 00:28 UT and was rather impulsive.  The
duration of this event was only 20 minutes.  It attained an x-ray and optical
classification of M6.2/2N but was not associated with any sweep frequency
events.  The only significant radio event associated with this flare was a
burst at 245 MHz of 2100 s.f.u.  This region has grown in spot area and
complexity and now exhibits a magnetic Beta-Gamma configuration.  This flare
did not produce any proton enhancements (yet) and is not expected to enhance
protons at satellite altitudes.  IPS at Sydney, Australia did register a
short-wave fade which was associated with this event.  The SWF occurred at
00:18 UT and ended at 00:50 UT on 21 January.

     This region is not expected to produce any further major flaring.
However it should be noted that it does possess the magnetic complexity
to spawn further major flares.  Predictions, therefore, could be wrong.
Hence, those who require advanced warning of major flaring should be on
the alert for possible flaring activity from this region, since it does
possess the magnetic complexity to produce further major flaring even
though we are not expecting further major flares from this region (at
the present time, anyway).

     Region 6444 is now rotating off the west limb.  Limb surging is now
visible from this region.  It is, however, decaying and is expected to
exit the west limb quietly.  Region 6458 (N23E12) showed some growth over
the past 24 hours and managed to spawn two C-class flares, despite its
simple magnetic configuration.

     Limb surging is also visible now on the east limb, at latitudes
North 10, South 10 and South 24.  There currently are no significant optical
regions visible on the east limb.  The regions responsible for the surging
should become visible over the next 24 to 48 hours.


POTENTIAL TERRESTRIAL IMPACT FORECAST

     This flare is not expected to produce any terrestrial impacts.  Models
currently indicate only a 16% probability that any terrestrial shocks will
be observed.  The window for any possible terrestrial effects begins at
06:00 UT on 24 January and runs until about 12:00 UT on 25 January.  Any
terrestrial effects are expected to be small.

     As an additional side-note, the major flare of 17 January has not yet
produced a terrestrial impact.  The window for impacts from this flare has
now passed, so no effects from that flare are currently anticipated.

     Additional notes:  There have been several disappearing filaments over
the passed 48 hours (since 19 January) which may have been associated with
coronal mass ejections.  Any effects from these events are currently expected
to be small. Geomagnetic activity might increase slightly in response
to possible effects near 21/22 January.  At the present time, no significant
terrestrial impacts are anticipated.

     A small coronal hole is now rotating into the western hemisphere.
It may have a very slight terrestrial impact on or near 22/23 January.
Currently, any impacts are expected to be small, if not negligable.


**  End of Report **

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

Date:        Tue, 22 Jan 91 14:09:21 AST
To: "Space Digest" <[e-mail]>
From: Richard Langley <[e-mail]>
Subject:     Origin of Word "Anomaly" ?

Does anyone know how the word "anomaly" as in "true anomaly" came into
use to describe the angular position of an orbiting body?  I imagine
that it could have something to do with the pre-Keplerian astronomers'
expectations that orbits would be circular rather than elliptical, but
I would like to get some specific references.  For example, who first
used the term "true anomaly"?  Was it Kepler or someone else?

================================================================================
 Richard B. Langley, Assoc. Prof.              BITnet: [e-mail] or [e-mail]
 Geodetic Research Laboratory                  Phone:  [phone]
 Dept. of Surveying Engineering                Telex:  014-46202
 University of New Brunswick                   FAX:    [phone]
 Fredericton, N.B., Canada  E3B 5A3
================================================================================

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

Date: 22 Jan 91 22:58:30 GMT
From: olivea!samsung!zaphod.mps.ohio-state.edu!magnus.ircc.ohio-state.edu![e-mail]  (Earl W Phillips)
Subject: Thanx!


Than you everyone who responded to my plea for conversion
to hex from decimal! I will be wading thru the responses
for the easiest way for  while, but the response was terrific!
I'm glad thtere are still people willing to offer advise!

*****************************************************************
*                                    | ====@====      ///////// *
* [e-mail]|     ``________//         *
*                                    |       `------'           *
*                 -JR-               | Space;........the final  *
*                                    | frontier...............  *
*****************************************************************

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

Date: 23 Jan 91 16:03:54 GMT
From: mcsun!ukc!acorn!ixi![e-mail]  (Clive Feather)
Subject: Re: Metrics (was Re: Rotating Joints for Habitat)

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

>_All_ civil aviation is conducted in feet (altitude) and knots (speed),
>with the possible exception of _internal_ Aeroflot operations.  All
>air traffic control is conducted in English, too.

Actually, all air traffic control within the Soviet Union is done in
metres. I have been on the flight deck of a 747 over the SU, and the
crew carry conversion tables for this situation.
--
Clive D.W. Feather     | IXI Limited         | If you lie to the compiler,
[e-mail]          | 62-74 Burleigh St.  | it will get its revenge.
Phone: [phone] | Cambridge   CB1 1OJ |   - Henry Spencer
(USA: 1 800 XDESK 57)  | United Kingdom      |

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

Date: 23 Jan 91 23:48:04 GMT
From: o.gp.cs.cmu.edu![e-mail]  (Vincent Cate)
Subject: new space-investors mailing list


I am starting a new mailing list called "space-investors".
This list is for information relevant to investing in space
related companies.  Reasonable topics include:

*  Results of tests of new space related products

*  New product announcements

*  Contracts won or lost by space related companies

*  Sudden stock price swings

*  Space related startups needing venture capital or going public

*  Earnings reports

In general any space related investment opportunities or any events
affecting these potential investments are fair game.

If you would like to be on this list send me mail at [e-mail].
If you sent me mail after my post about OSC then you do not need to
send additional mail.

   -- Vince

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

End of SPACE Digest V13 #084
*******************