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Subject: SPACE Digest V10 #252

SPACE Digest                                     Volume 10 : Issue 252

Today's Topics:
        Re: Technology and space colonization
              Re: Space Elevator
        STS 33 Visual Observation Guide (long)
----------------------------------------------------------------------

Date: 15 Nov 89 19:07:00 GMT
From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Technology and space colonization

In article <[e-mail]> [e-mail] (John Roberts) writes:
>...It is
>true that migration from Europe to North America did not require any major
>advances in technology. However, our current level of technology *is*
>rapidly increasing, and it is not rediculous to assume that it will soon
>reach a level that will make extraterrestrial colonies practical from a
>technical viewpoint. Economic attractiveness is a separate matter...

The economic problem is 95% of the problem, actually.  There are people
who would happily colonize space today if they could possibly afford it.
The technical problems of the colonies proper look manageable, and have
been explored in some detail.  The big obstacle is the enormous cost of
transportation.  Solve that one well, and all else is trivia.

It is not really true that we need "major advances in technology" to
bring transport costs down.  There are a good many well-informed people
who say that at least one order of magnitude, and possibly two, could
be achieved with current technology.  The big problem is that almost
nobody is trying.  (In particular, NASA, which is supposed to do this
sort of thing, stopped doing it almost two decades ago.)  Many of the
people best-equipped to try have vested interests in not trying.

Colonization does not have to be dirt cheap to be practical.  Freeman
Dyson has observed that the Plymouth Rock colonists spent every cent
they had and were deep in debt for twenty years thereafter.  Early
stages of the migration from Europe to North America did not require
new technology, but they *were* enormously expensive by the standards
of the time.  It took a long time for travel costs to fall, and living
standards to rise, to the point where intercontinental travel no longer
entailed massive financial hardship for the average person.  Nobody but
the rich (or the employees of the rich) is going to commute to and from
early space colonies.  It would suffice to bring the cost of one-way
cattleboat-class travel, plus a bare minimum of ongoing logistics support,
down to the barely-affordable-with-great-hardship point.
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 15 Nov 89 05:58:05 GMT
From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo![e-mail]  (Henry Spencer)
Subject: Re: Space Elevator

In article <[e-mail]> [e-mail] (John Hogg) writes:
>``Pinwheel'' or rotating tether proposals generally require that
>payload up ~= payload down, so that a minimal amount of propellant
>is used to keep the tether CG in the desired orbit...

Actually this isn't a requirement, although it does simplify life.
Orbit maintenance for a pinwheel can be done with low-thrust high-
exhaust-velocity engines, e.g. ion rockets, that burn much less fuel
than chemical engines.  (That is, yes, shipping fuel up for that
purpose is indeed a sensible thing to do.)
--
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry [e-mail]

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

Date: 15 Nov 89 12:02:47 GMT
From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu![e-mail]  (Ted Molczan)
Subject: STS 33 Visual Observation Guide (long)


                      STS 33 Visual Observation Guide
                      -------------------------------

                     by  T.J. Molczan, Toronto, Canada

                               12 Nov 1989
                           rev 13 Nov 1989 (mainly Sec. 1.2.1)
                           rev 14 Nov 1989 (Sec. 3.0)

   The following information is intended to assist those who wish to attempt
visual observations of STS 33.  This is a DOD mission, and therefore, most
aspects of the mission have been classified.  However, it is possible to make
an accurate assessment of the prospects for visual observation using the
information that is in the public domain.  All that is required is a basic
knowledge of orbital mechanics, shuttle orbit constraints and some leaked
information made available by various news media.

To make use of the information in this report you will require an orbit
prediction program, compatible with NORAD "2-line" orbital elements.  Programs
for this purpose can be downloaded, free, from the Celestial RCP/M BBS, based
in Ohio.  See Section 5.0 for details on accessing this board.


1.0  STS 33 Mission
     --------------

1.1  AVIATION WEEK & SPACE TECHNOLOGY - 6 NOV 89
     -------------------------------------------

According to AV WEEK, STS 33 will launch a secret, military signal
intelligence-gathering satellite, identical to the one launched by STS 51-C in
Jan 85.

The shuttle will initially enter a 204 km x 519 km orbit at an inclination of
28.45 deg to the equator. There will be three OMS (orbital manoeuvering
system) burns, the last on rev #4. (Presumably, the first burn would
circularize the orbit at 519 km. Will the remaining two take it even higher?)

The satellite will be deployed on the 7th orbit and will ignite its IUS rocket
at the ascending node of the 8th orbit, to place it in a geo-synchronous
transfer orbit.  (Presumably the orbits are counted using NASA's method,
whereby the first ascending node is the start of rev #2.  NORAD would call
this rev #1.)

The launch has been scheduled for 20 Nov. The 4 h launch period begins at
18:30 EST. The actual launch window is 70 min long. (Several media sources
have said that the launch is scheduled for 19:34 EST.)

The mission will last 4d 2h 13m, with landing at Edwards AFB on rev 64.


1.2 The Rumour Mill
    ---------------

AV WEEK's past DoD shuttle exposes have generally proved to be reliable, so
there is good reason to be confident of their STS 33 story. However, the
possibility of a disinformation campaign cannot be ruled out. A friend has
learned from a usually reliable source that the launch azimuth will be to the
north-east and not due east as the AV WEEK article implies. This would suggest
a high inclination mission, perhaps 57 deg, as on STS 27 and STS 28. The
source confirms the 19:34 EST launch time. The following are some possible
57 deg inclination missions, based on rumours and interesting coincidences.

1.2.1  Re-fueling Mission
       ------------------

There has been a rumour that either STS 33 or STS 36 (9 Feb 1990) will be a
re-fueling mission in a 57 deg inclination orbit.  A possible candidate for
such a mission is USA 40 (89061B / 20167), launched in August by STS 28.  This
satellite was reported by AV WEEK to have been a new generation of photo recon
sat.  Past such satellites were launched into sun-synchronous (approx 97 deg
inclination) orbits from Vandenberg AFB, using ELV's.  Plans to launch
shuttles on similar missions from Vandenberg were dropped after the Challenger
accident.

A photo recon sat in a 57 deg inc orbit loses the nearly constant shadows on
the ground, and pole to pole coverage afforded by sun-synchronous orbits.
Therefore, some observers have suggested that USA 40 might increase its
inclination.  Orbital plane changes are very costly in terms of fuel, so a
sun-synch orbit is probably not feasible, however a 70 deg inclination might
be within reach.  USA 40 was deployed into a 57 deg inc, 300 km orbit and
then manoeuvered into a 432 km x 487 km orbit. It is conceivable that it is
awaiting re-fueling so that it can move to a higher inclination. Another,
possibility is that it could be a fuel tank awaiting the launch of the photo-
recon sat.

Until a few days ago, the main problem with a rendezvous involving USA 40 was
that it was not manoeuvering and had a rapid spin, an indication that it might
have failed.  When the object was first seen in its present orbit, in mid-
August, the spin was 30.7 RPM.  Natural forces have gradually reduced the spin
rate, and as of 8 Nov it was 28.6 RPM. However, based on observations over the
past few days, it has been determined that the object manoeuvered on 8 Nov. It
is now in a 409 km x 510 km orbit. This is 5.5 km higher and somewhat more
eccentric than prior to the manoeuver. Is it only a coincidence that the burn
took place one day after the completion of the STS 33 flight readiness review?
Also, recall that in the previous section, AV WEEK claimed that the shuttle
would enter a 204 km x 519 km orbit and then complete four OMS burns up to
rev #4. Could those be part of a rendezvous?

In the event that STS 33 is intended to rendezvous with USA 40, then the
launch would be expected at about 18:48 EST on 20 Nov, and 21 min earlier each
day thereafter.  It would have to head north east into a 57 deg orbital
inclination, instead of the expected due east into a 28.45 deg inclination.
This would be very obvious to those at the launch site.  Television viewers
would notice that the vehicle would roll through a much greater angle than
usual, though this might be difficult to judge from certain camera angles.


1.2.2  Lacrosse 2 Deployment
       ---------------------

Will STS 33 deploy the second satellite in the Lacrosse series?  It is
interesting to note that the expected launch time, 19:34 EST on 20 Nov, would
enable a Lacrosse 2 to be deployed in a plane 45 degrees east of Lacrosse 1.
(The initial separation would be 47.9 deg east, but this would decrease to
45 deg east by the time Lacrosse 2 reached its final altitude, assuming the
same timing of mission events as for Lacrosse 1.)

This sounds interesting, however, no one knows the planned spacing for the
Lacrosse series.  Furthermore, a launch at 13:59 EST would enable the plane
of Lacrosse 2 to be placed 45 deg WEST of Lacrosse 1.  This would be the same
net result as putting it 45 deg EAST, without the need for a night launch.

The launch window for missions involving Lacrosse would be 19 min earlier
each day.


2.0  Orbital Elements
     ----------------

The following is a simplified procedure to estimate the orbital elements of
STS 33 :


2.1  Inclination
     -----------

It is assumed that the inclination will be 28.45 deg as reported by AV WEEK.
(In case the inclination is 57 deg, as some people suspect, then refer to
section 2.7)

2.2  Mean Motion and Rate of Decay
     -----------------------------

Based on the AV WEEK story, the shuttle will be at least 519 km high until
rev #4, when it may go even higher.  The mean motion corresponding to a 519 km
altitude is 15.18 rev/day.  In case AV WEEK has got the height wrong, it would
be prudent to use several mean motions in the range between, say, 15.0 and
15.9 rev/day.

If the shuttle goes into a 57 deg inclination to rendezvous with 89061B or
deploy a Lacrosse, then the most likely mean motion would be about
15.39 rev/day. Still, it would be a good idea to use 15.0 rev/d to 15.9 rev/d
to play it safe.

The great uncertainty in the mean motion makes it useless to make estimates of
the rate of orbital decay, therefore set any drag or decay elements in your
orbit prediction model to zero.


2.3  Eccentricity, Argument of Perigee and Mean Anomaly
     --------------------------------------------------

Shuttle orbits are close enough to circular that a zero eccentricity, argument
of perigee and mean anomaly can be assumed.


2.4  Epoch
     -----

For a 28.45 deg inclination mission, the first complete revolution about the
Earth begins when the shuttle reaches its first ascending node (north-bound
equator crossing), which occurs about 1 h 13 m after liftoff.  This is a
reasonable time to use for the epoch.

The launch time and date must be expressed in UTC (Universal Time).  If the
shuttle is launched as expected on 20 Nov at 19:34 EST, then this would be
21 Nov 00:34 UTC.  The time of day of the epoch would be :

                           00:34 UTC
                         + 01:13
                           -----
                           01:47 UTC

The day of the year is also part of the epoch and is commonly combined with
the time of day of the epoch as follows :

    EPOCH = YYDDD.dddddd

    where:       YY = last 2 digits of year i.e. 89 for 1989

                DDD = day of year, i.e. 21 Nov 1989 is day 325

            .dddddd = fraction of day, i.e. 01:47 UTC = (1 + 47 / 60) / 24

                                                      = 0.074306

Putting the above pieces together yields :

    EPOCH = 89325.074306


2.5  Right Ascension of the Ascending Node (RAAN)
     --------------------------------------------

The RAAN is a function of the longitude and the time and date of the ascending
node. For the above EPOCH, which corresponds with the ascending node of the
first revolution of a 28.45 deg orbit, the longitude of the ascending node is
-173.2 deg W.

The first step is to calculate the Greenwich mean sidereal time at the epoch.
An accurate formula for 1989 is :

    GMST = (6.6424 + 0.06571 * DDD + 24.06571 * 0.dddddd) mod 24

         where DDD and 0.dddddd are as defined above

For the epoch calculated earlier the GMST is :

    GMST = (6.6424 + 0.06571 * 325 + 24.06571 * 0.074306) mod 24

         = 29.7864 mod 24

         =  5.7864 h

The final step is to calculate RAAN :

    RAAN = (15 * GMST - WEST LONGITUDE) mod 360

         = (15 * 5.7864 - (-173.2)) mod 360

         = 260.0 deg


2.6  For 57 DEG Inclination Orbits
     -----------------------------
In case the shuttle goes into a 57 deg inclination orbit, the above formulas
for EPOCH and RAAN still apply, however the following values change.  The
first ascending node begins 01:27 after lift-off, and the ascending node is
+122.0 deg W.  Therefore, assuming the same launch date and time as above :

     EPOCH =  89325.084028

     GMST  =  6.0203

     RAAN  = (15 * 6.0203 - (+122.0)) mod 360

           = 328.3 deg


2.7 Summary
    -------

The above estimates are summarized below in a pseudo NORAD 2-line format :

Launch on 21 Nov 89 at 00:34 UTC into 28.45 deg inclination :
-------------------------------------------------------------

89325.074306   00000000   00000+00   00000+00
28.45  260.0   0   0   0   15.0 to 15.9   00001


Launch on 21 Nov 89 at 00:34 UTC into 57 deg inclination :
----------------------------------------------------------

89325.084028   00000000   00000+00   00000+00
57.0   328.3   0   0   0   15.0 to 15.9   00001


3.0  Visibility Window Analysis
     --------------------------

The tables below show the range of dates of visibility (visibility window) of
the shuttle during the upcoming mission.  There are individual tables for
evening and morning for 28.45 deg and 57 deg inclination missions.  Visibility
windows are a function of time/date of launch and observer's latitude.  The
windows have been computed for 5 launch times over the announced launch
period of 20 NOV 18:30 EST - 22:30 EST, however all times and dates have been
expressed in Universal Time.  In many cases the windows begin several days
prior to the the launch date.  This merely indicates when the window would
have begun, had the orbit pre-existed the launch date.

The windows were based on a circular orbit, 519 km high, as indicated by the
AV WEEK story.  If the shuttle goes lower, then the windows generally will be
narrower, and some windows will "disappear".  For this project, a window was
defined as passes which culminate at least 5 deg above the horizon, and which
are illuminated for more than half of the pass.

The visibility windows will not be greatly affected by a delay in the date of
launch, as long as the launch window does not change greatly.  In that case,
add the number of days of the delay to the launch and visibility window dates
in the tables. If there is to be a rendezvous, then the launch window will be
about 20 min earlier for each day of delay, however the visibility window
dates will tend to remain constant.


                 28.45 DEG INCLINATION - EVENING VISIBILTY WINDOWS
     -------------------------------------------------------------------------
     LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)
---  -------------  -------------  -------------  -------------  -------------
LAT  20 NOV  23:30  21 NOV  00:30  21 NOV  01:30  21 NOV  02:30  21 NOV  03:30
---  -------------  -------------  -------------  -------------  -------------
45N  15/11 - 25/11  17/11 - 27/11  19/11 - 29/11  21/11 - 01/12  23/11 - 03/12

35N  11/11 - 29/11  13/11 - 01/12  15/11 - 03/12  17/11 - 05/12  19/11 - 07/12

25N  08/11 - 02/12  10/11 - 03/12  12/11 - 05/12  14/11 - 07/12  16/11 - 09/12

15N  05/11 - 03/12  07/11 - 05/12  09/11 - 07/12  11/11 - 09/12  13/11 - 11/12

05N  23/11 - 05/12                                08/11 - 21/11  10/11 - 23/11


                 28.45 DEG INCLINATION - MORNING VISIBILTY WINDOWS
     -------------------------------------------------------------------------
     LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)
---  -------------  -------------  -------------  -------------  -------------
LAT  20 NOV  23:30  21 NOV  00:30  21 NOV  01:30  21 NOV  02:30  21 NOV  03:30
---  -------------  -------------  -------------  -------------  -------------
15N                                                              25/10 - 20/11

05N                                               10/11 - 21/11  12/11 - 23/11

05S  08/11 - 20/11  10/11 - 22/11  12/11 - 24/11  14/11 - 26/11  16/11 - 28/11

15S  11/11 - 06/12  13/11 - 08/12  15/11 - 10/12  17/11 - 12/12  19/11 - 14/12

25S  14/11 - 04/12  16/11 - 06/12  18/11 - 08/12  20/11 - 10/12  22/11 - 12/12

35S  18/11 - 02/12  20/11 - 04/12  22/11 - 06/12  24/11 - 08/12

45S  24/11 - 29/11


                   57 DEG INCLINATION - EVENING VISIBILTY WINDOWS
     -------------------------------------------------------------------------
     LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)
---  -------------  -------------  -------------  -------------  -------------
LAT  20 NOV  23:30  21 NOV  00:30  21 NOV  01:30  21 NOV  02:30  21 NOV  03:30
---  -------------  -------------  -------------  -------------  -------------
60N  22/11 - 21/12  25/11 - 24/12

50N  19/11 - 22/12  22/11 - 25/12  25/11 - 28/12

40N  17/11 - 22/12  20/11 - 25/12  23/11 - 28/12

30N  15/11 - 27/11  18/11 - 30/11  21/11 - 03/12  24/11 - 06/12

20N  14/11 - 24/11  17/11 - 27/11  19/11 - 30/11  22/11 - 03/12

10N  12/11 - 21/11  15/11 - 24/11  17/11 - 27/11  20/11 - 30/11  23/11 - 03/12

00                  12/11 - 22/11  15/11 - 25/11  18/11 - 28/11  21/11 - 01/12

10S                 09/11 - 20/11  12/11 - 23/11  15/11 - 26/11  18/11 - 29/11

20S                                08/11 - 21/11  11/11 - 24/11  13/11 - 27/11

30S                                               03/11 - 22/11  05/11 - 25/11

40S                                                              22/10 - 22/11



                  57 DEG INCLINATION - MORNING VISIBILTY WINDOWS
     -------------------------------------------------------------------------
     LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)  LAUNCH  (UTC)
---  -------------  -------------  -------------  -------------  -------------
LAT  20 NOV  23:30  21 NOV  00:30  21 NOV  01:30  21 NOV  02:30  21 NOV  03:30
---  -------------  -------------  -------------  -------------  -------------
60N                                                              30/10 - 22/11

50N                                               26/10 - 22/11  28/10 - 24/11

40N                                22/10 - 21/11  24/10 - 24/11  27/10 - 27/11

30N                 11/11 - 20/11  14/11 - 23/11  17/11 - 26/11  20/11 - 29/11

20N                 14/11 - 22/11  17/11 - 25/11  20/11 - 28/11  23/11 - 01/12

10N  14/11 - 21/11  17/11 - 24/11  20/11 - 27/11  23/11 - 30/11

00   16/11 - 23/11  19/11 - 26/11  22/11 - 29/11  25/11 - 02/12

10S  18/11 - 26/11  21/11 - 29/11  24/11 - 02/12

20S  20/11 - 29/11  23/11 - 02/12

30S  23/11 - 06/12


4.0  Observation Tips
     ----------------

The shuttle is easy to spot with the naked eye.  When favourably illuminated,
nearly overhead and in a dark sky, it has a visual magnitude between
-1 and -2, about as bright as Jupiter.  The shuttle has been observed as early
as 15 minutes after sunset or before sunrise, however that is probably too
difficult for the inexperienced observer.

The uncertainty in the mean motion makes the search for the shuttle a
challenge, but far from impossible.  The best search strategy is to produce
several different orbital element sets covering mean motions in the range
between about 15.0 rev/day and 15.9 rev/day and run predictions for each
elset. In this way the predictions will "bracket" the shuttle's actual time of
passage and path across the sky.

This procedure takes advantage of the fact that the orientation of the
shuttle's orbital plane with respect to the Earth can be predicted with much
greater accuracy than the position of the shuttle within its orbit.  The idea
is to "stare" at the imaginary ring in the sky which is the shuttle's orbit.
As we wait for the shuttle to appear, the Earth rotates, which makes the orbit
ring move across the sky.  The shuttle must occupy each point along the orbit
once per revolution, so eventually it must be seen.

If the shuttle makes a near overhead pass, even the small uncertainty in the
orientation of the plane can result in large errors in its predicted path
across the sky, especially at maximum elevation.  Therefore, take care to scan
a wide section of the sky.  It would be unfortunate to be looking for a 65
degree high pass in the south only to have the shuttle pass 70 degrees high in
the north.


5.0  Observation Network
     -------------------

During the STS 27 and STS 28 DoD missions there was an informal network of
amateur observers who shared their observations.  This made it possible for
more people to see the shuttle because we were able to quickly refine our
orbital estimates and pass on the information.

If you observe the shuttle during the first day of the mission, please, if
possible, phone your observation in to me at one of the numbers given below.
That will enable me to update the elements and distribute them to other
observers as quickly as possible.  Observations on subsequent days can be sent
by slower means, such as BBS, e-mail and fax.

The best observations are positions related to the stars along with the time
accurate to 1 second or better. For example,

         "passed between Castor and Pollux, 1/3 distance from Castor to
          Pollux, 08:34:21 UTC 9 AUG 89"

                            or

         "passed 3 degrees below Vega, 09:12:10 UTC 9 AUG 89"

In addition, estimates of visual magnitude and colour would be useful. If the
magnitude is varying regularly, measure the period of variation.  If two
objects are seen, then state the separation between them.  For example, "the
brighter object lead the fainter by 10 seconds of time", or "the red object
was about 4 degrees behind the other at maximum elevation of 50 degrees" would
be useful.

Make certain to provide your latitude and longitude as accurately as possible.


Observations of the payload(s) would also be of great interest.

If you have information to share, try the following communications channels :

      1) Leave a message on the Celestial RCP/M BBS for Ted Molczan.
         This is a free, 24 h/day board, 2400 8N1, [phone].
         This board has available several orbit prediction programs,
         one of the more popular of which is SEESAT.

      2) Leave a message on the CSS (Canadian Space Society) BBS
         for Ted Molczan. This is a free, 24 h/day board, 2400 8N1,
         [phone].

      3) Phone me at [phone] (H) or 926-2085 (W)

      4) Fax me at [phone]

      5) Send e-mail to [e-mail]

Please pass this on to other BBS's or interested individuals.

                   *     *     *     *

--
Ted [e-mail]

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

End of SPACE Digest V10 #252
*******************