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Conference 7.286::space

Title:Space Exploration
Notice:Shuttle launch schedules, see Note 6
Moderator:PRAGMA::GRIFFIN
Created:Mon Feb 17 1986
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:974
Total number of notes:18843

549.0. "STS-28 Visual Observation" by HYDRA::BIRO () Mon Jul 31 1989 11:05

 
                     STS 28 Visual Observation Guide
                     -------------------------------
 
                           by  T.J. Molczan
 
 
   The following information is intended to assist those who wish to attempt
visual observations of STS 28. 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 a minimum of
leaked information courtesy AV WEEK (known as AV LEAK by friend and foe
alike).
 
 
1.0  STS 28 Mission
     --------------
 
It is widely believed that this mission will deploy a new generation of photo
reconnaissance satellite in the KH (Key Hole) series, the long awaited KH-12.
As with the old KH-9 and current KH-11 series, KH-12 is expected to be large,
in low orbit and highly maneuverable.
 
Two payloads are expected. The first will be KH-12 with a mass of 9.3 tonnes
which will be deployed on the 5th revolution. The second object, believed to
be an SDI experiment, has a mass of 129 kg and will be deployed on rev 18.
 
AV WEEK reported that the shuttle will enter a 300 km high, 57 deg inclination
orbit. This is a reasonable assumption for a recon sat deployment, which would
require the greatest orbital inclination that the shuttle can attain from
Kennedy to provide coverage of the northern USSR. The maximum inclination for
launches from Kennedy has long been limited to 57 deg to provide a reasonable
margin of safety for the East Coast of N. America. However, some recent new
information from a reliable NASA source has to be considered. After a lengthy
study, it has been decided that shuttle missions can now be launched into
63 deg inclinations from Kennedy. This option is available NOW. This
information is not classified, but has not yet been made public (officially).
 
Almost any increase in inclination over 57 deg would be of benefit to a recon
sat. For example, the Plesetsk launch complex, the Soviet's busiest, is just
below 63 deg N. Thus, it makes sense to consider 63 deg as well as 57 deg
inclination orbits for STS 28.
 
On 26 July, NASA scheduled the launch of STS 28 for 8 August, during a launch
window between 11:30 UTC and 15:30 UTC.
 
 
2.0  Orbital Elements
     ----------------
 
The following is a simplified procedure to estimate the orbital elements of
STS 28 :
 
 
2.1  INCLINATION
     -----------
 
As stated earlier, the shuttle can be expected to enter either a 57 deg or 63
deg inclination orbit.
 
 
2.2  MEAN MOTION and RATE OF DECAY
     -----------------------------
 
Past shuttle missions have had a mean motion between 15.2 and 15.9 rev/day,
with the majority between 15.8 and 15.9 rev/day. It would be prudent to make
orbital predictions using several different mean motions between 15.2 and 15.9
rev/day.
 
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
     -----
 
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 27 m after liftoff. This is a reasonable time of day to use for the epoch.
 
If the shuttle is launched on 8 August at 11:30 UTC then the time of day of
the epoch would be :
 
                           11:30 UTC   (MUST USE UTC !)
                         + 01:27
                           -----
                           12:57 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. 8 AUG 1989 is day 220
 
            .dddddd = fraction of day, i.e. 12:57 UTC = (12 + 57 / 60) / 24
 
                                                      = 0.539583
 
Putting the above pieces together yields :
 
    EPOCH = 89220.539583
 
 
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, the longitude of the ascending node is 122 deg W for 57 deg
inclination orbits and 117.5 deg W for 63 deg inclination orbits.
 
The first step is to calculate the Greenwich mean sidereal time at the epoch.
An accurate formula for 1989 is :
 
    GMST = (6.65831 + 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 = (6.65831 + 0.06571 * 220 + 24.06571 * 0.539583) mod 24
 
         = 34.099958 mod 24
 
         = 10.099958 h
 
The final step is calculate RAAN :
 
    RAAN = (15 * GMST - WEST LONGITUDE) mod 360
 
         = (15 * 10.099958 - 122) mod 360   (for 57 deg inclination)
 
         = 29.5 deg
 
For a 63 deg inclination, WEST LONGITUDE of the ascending node is 117.5 deg
and RAAN is :
 
     RAAN = (15 * 10.099958 -117.5) mod 360
 
          = 34.0 deg
 
 
2.6 SUMMARY
    -------
 
The above estimates are summarized below in a pseudo NORAD 2-line format :
 
Launch on 8 Aug 89 at 11:30 UTC into 57 deg inclination :
 
89220.539583   00000000   00000+00   00000+00
57.0  29.5   0   0   0   15.2 to 15.9   00001
 
Launch on 8 Aug 89 at 11:30 UTC into 63 deg inclination :
 
89220.539583   00000000   00000+00   00000+00
63.0  34.0   0   0   0   15.2 to 15.9   00001
 
 
3.0  VISIBILITY WINDOW ANALYSIS
     --------------------------
 
The table below shows the range of latitude on Earth for which there will be
evening or morning visibility of the shuttle during some portion of a 4 day
mission. Observers at the extremes of these ranges can expect very poor
passes. A mean motion of 15.85 rev/day was used in this analysis. If the orbit
is higher, as was STS 27 / LACROSSE wich had a mean motion of 15.39 rev/day,
then the visibilty window latitude ranges will be a little wider than shown
below. These windows will be reasonably accurate even if the mission is
delayed for a few days.
 
 
LIFT-OFF           VISIBILITY WINDOW
8 AUG 89    ----------------------------------
  UTC          EVENING             MORNING
--------    --------------      --------------
 11:30      10 S  to  60 S      45 N  to  10 S
 
 12:30      10 N  to  55 S      35 N  to  30 S
 
 13:30      20 N  to  45 S      20 N  to  40 S
 
 14:30      35 N  to  35 S       5 N  to  55 S
 
 15:30      45 N  to  15 S      10 S  to  60 S
 
 
4.0  OBSERVING 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 15.2 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 / LACROSSE mission there was an informal network of amateur
observers who shared their observations. This made it possible for more people
to see the shuttle (and LACROSSE) because we were able to quickly refine our
orbital estimates and pass on the information. STS 28 will be more difficult
because the visibility in the northern hemisphere will be limited at best.
However, if you are at a latitude with some chance of visibility (consult
Section 3.0) you may be able to participate.
 
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.
 
If you are able to observe either of the payloads after the shuttle lands,
that information would also be of interest.
 
If you have information to share, try the following communications channels :
 
 
      1) leave a message on this BBS for Ted Molczan
 
      2) leave a message on the CSS (Canadian Space Society) BBS
         for Ted Molczan. This is a 24 h/day free board, 2400 8N1.
         (416) 458-5907.
 
      3) phone me at (416) 928-3046 (H) or 926-2085 (W)
 
      4) fax me at (416) 926-2218
 
      5) send e-mail message via [email protected]
         This is on NETNORTH, which is connected to BITNET and
         other academic/research networks.
 
Please pass this on to other BBS's or interested individuals.
 
                   *     *     *     *
 
========================================================================

T.RTitleUserPersonal
Name
DateLines
549.1UHF RADIO observaionHYDRA::BIROMon Jul 31 1989 11:1436
    I did the element set a little different, runing them did not give
    any good visual times for the Boston Mass area, however there
    is a good radio window starting about 2 min after launch for
    about 10 min.  NASA safty rules require even DOD mission to
    use the UHF radio untill actual insersion orbit and on the
    last orbit for wx info etc... Also watch Fleetsat 261-262 MHZ
    25 KHz steps for uplink of FAX information during the mission.
    
    If you have any informatio to share on either visual or radio
    contacts please post them here, If you like I will pass them 
    on to Ted....
    
    
    john
    

	STS-28-57_DEG           (Launch 89-99-  A)   Set:    1, 
          Epoch Year: 1989  Day: 220.539583000    Orbit #       1
          Inclination  =  57.00000000     R.A.A.N      =  29.50000000
          Eccentricity =   0.00079390     Arg of Per   =   0.00000000
          Mean Anomaly =   0.00000000     Mean Motion  =  15.39997000
          Drag         =  0.99990E-04     Frequency    =        0.000
          S.M.A.       =    6824.2122     Anom Period  =      93.5067
          Apogee Ht    =     451.4699     Perigee Ht   =     440.6344

	STS-28-63_DEG           (Launch 89-99-  A)   Set:    1, 
          Epoch Year: 1989  Day: 220.539583000    Orbit #       1
          Inclination  =  63.00000000     R.A.A.N      =  34.00000000
          Eccentricity =   0.00079390     Arg of Per   =   0.00000000
          Mean Anomaly =   0.00000000     Mean Motion  =  15.39997000
          Drag         =  0.99990E-04     Frequency    =        0.000
          S.M.A.       =    6824.2122     Anom Period  =      93.5067
          Apogee Ht    =     451.4699     Perigee Ht   =     440.6344

    
    
549.2STAR::HUGHESTue Aug 08 1989 10:0110
    Liftoff was at 8:37am (EDT, unofficial).
    
    FWIW, the ascent did not look like the Lacrosse mission. I guessed that
    the inclination was lower, but upon rereading .0 I'd now just say that
    it was different.
    
    As with other DoD missions, voice communcations were not relayed over
    NASA Select.
    
    gary
549.3STAR::HUGHESTue Aug 08 1989 10:254
    Orbit insertion occurred at 41m 30s MET. Form the timing, I'd say this
    was the OMS-2 burn.
    
    gary
549.4? OHMs one ?PARITY::BIROTue Aug 08 1989 10:398
    ???? did they say they had OHMs one,
    if it was a 57 deg insertion they would have said
    'Roger, no OHMs one'    this is the giveaway
    I will check my tapes at lunch time
    
    John
    
    
549.5STAR::HUGHESTue Aug 08 1989 10:5610
    As I mentioned in .2, they do not carry the communications from either
    the orbiter or MSC Houston. Only the 'voice of mission control' and it
    says very little on a DoD mission.
    
    OMS-1 is nominally around 10 mins MET, OMS-2 nominally at 40 min for a
    high inclination mission.
    
    If you were taping shuttle UHF you may have heard more.
    
    gary
549.6PAXVAX::MAIEWSKITue Aug 08 1989 11:035
  So is this the long awaited KH-12? Can anyone tell from the orbit what
the payload is? The fact that Columbia has a smaller weight capacity may
also be a clue as to the cargo. Anyone know how much a KH-12 weighs?

  George
549.714 tonsWONDER::STRANGEOu est le Soleil?Tue Aug 08 1989 11:316
    I believe they said KH-12 weighs 28,000 lbs. on CNN this morning.
    It's capable of resolution to a few inches!  I assume that's ideal
    atmospheric conditions, of course.  There is also supposedly an
    SDI test satellite, on the order of a couple hundred pounds.
    
    			Steve
549.8STAR::HUGHESTue Aug 08 1989 12:3313
Don't know if it is a KH-12 or not.

I had gotten the impression earlier that KH-12 was at the limit for shuttle 
launches from VAFB, and Atlantis would have to be used. I don't know how that
translates into launch capability from Kennedy with different operational limits
on SSME thrust.

I'd guess that KH-12 is likely, given the state of other recsats. The use of
the Hubble Space Telescope for 'tests' recently also supports a KH-12 flight
real soon now. The next DoD flight would be STS-33, and I don't when that is
scheduled now.

gary
549.9my 2 centsHYDRA::BIROTue Aug 08 1989 13:5412
    from all indication of the insersion orbit, I dont think this
    is a KH-12 .  I think it is an Optical Spy-Sat, I did not get
    anything on UHF but I will check tonight with other monitors.
    NASA rules use to require that the UHF link stayed open until OHM2 -
     even for DOD missions for safty reasons...
    
    When I get more reports this evening I will have a good indication
    of the insersion orbit and will post an estimated element set.
    
    
    john
    
549.10STAR::HUGHESTue Aug 08 1989 14:397
re .9

But the KH-12 is an optical reconnaissance satellite, isn't it?

There was talk of encrypting the UHF. I don't know if they ever did.

gary
549.111st guess for STS-28HYDRA::BIROTue Aug 08 1989 15:0624
my guess for the orbit
    re. -1
    
    I not sure anymore, LA-Cross is the radar if that is not a KH-12
    then the KH-12 is an optical,, it is possible that the inc will
    changed so that it can be part of the other constalation of
    optical reconnaissance satellite, it 90 deg spaceing etc.
    
    as for the UHF encrypting, no idea, it was not encrypted on the
    La-Cross mission ( I think it was STS-27 ) and I had good coverage
    up to OHMS-1 on STS-27 then DOD blackout, then UHF again for the last orbit.
    
    
    STS-28                                              Set:    1, Obj:      1
          Epoch Year: 1989  Day: 220.586111110    Orbit #       1
          Inclination  =  56.98550000     R.A.A.N      =  46.05670000
          Eccentricity =   0.00050600     Arg of Per   =   0.00000000
          Mean Anomaly =   0.00000000     Mean Motion  =  15.39557338
          Drag         =  0.33983E-02     Frequency    =        0.000
          S.M.A.       =    6825.5113     Anom Period  =      93.5334
          Apogee Ht    =     450.8050     Perigee Ht   =     443.8976

    
                                                    
549.12STAR::HUGHESTue Aug 08 1989 16:048
Lacrosse is the synthetic aperture radar imaging spysat. KH-12 is optical,
visual and infrared.

BTW, predicted deployment of the primary payload was orbit #5, over the Indian
Ocean. Does DoD make use of the ARIA planes? If so, I'd guess that there is
one loitering above the Indian Ocean as was the case for the Magellan deploy.

gary
549.13photo recon for sureHYDRA::BIROWed Aug 09 1989 09:0326
    
    ok, others did get UHF reports, so NASA safty rules still
    require UHF on take-offs and landings and it is not 
    encyrpted.  Not much just something link ' we have MECO on
    speed' reports however indicated that the signal was weaker 
    then normal....
    
    from visual observation, it looks like the STS-28 is about
    150 km lower in orbit then the La-Cross Mission thus indicating
    that it is a photo recon bird...
    
    updated elements best guess are:
    

    
    STS-28                                              Set:    1, Obj:      1
          Epoch Year: 1989  Day: 220.579000000    Orbit #       1
          Inclination  =  56.98550000     R.A.A.N      =  46.05670000
          Eccentricity =   0.00050600     Arg of Per   =   0.00000000
          Mean Anomaly =   0.00000000     Mean Motion  =  15.91400000
          Drag         =  0.33983E-02     Frequency    =        0.000
          S.M.A.       =    6676.4592     Anom Period  =      90.4864
          Apogee Ht    =     301.6775     Perigee Ht   =     294.9209

    
                                                              
549.14This launch forced me to whine!!BALMER::MUDGETTdid you say FREE food?Thu Aug 10 1989 23:3934
    
    Hello again fellow space adventurers,
    
    Would you guys mind if I whine for a minute...
    
    1. I looked forward for the last couple of months to being at the
    Shuttle was launched. Well I got down there and pretty much knew
    it was going to fly on the 8th of August the last day of my vacation.
    Add to that bleak thought my wife is pregant and didn't want to
    hang around Florida waiting for the shuttle to fly. So we came back
    early and I watched the launch on TV like everyone else.
    
    2. While I was watching the launch CBS seemed to want to make a
    issue of how little the Columbia has flown. They seemed to be
    desparately trying to make a case for the calling the Columbia a
    failure and having it grounded permanently. Of course its the Hanger
    Queen of the fleet, of couse its heavier than all the other shuttles
    but it still has flown as many flights as Discovery. 
    
    The thing that made me steamed about this "investigation" was that
    all the "allegations" that Columbia is a failure was that the
    information they "uncovered" is common knowledge to anyone who has
    read AW+ST in the last 3 years. To me the reason the shuttles aren't
    flying more often is a lack of support facilities to prepare the
    shuttles. 
    
    So now I'm in a foul mood at the media because they only know how
    to yell fire all the time (or is it that the sky is falling?) And
    I'm steamed at my ungrateful family that couldn't hang around Central
    Florida for 5 extra days so I could see a shuttle launch.
    
    And now I'm back at work!
    
    Fred Mudgett
549.15100% isn't enough?CLIPR::KLAESN = R*fgfpneflfifaLFri Aug 11 1989 12:415
    	Could someone please explain to me how the Space Shuttle could
    go at 104% throttle up?
    
    	Thanks.
    
549.16STAR::HUGHESFri Aug 11 1989 12:508
    The engines are rated at a nominal performance (100%) which allows them
    to operate within all constraints of reliability, operational life etc.
    However, they can operate at higher thrust levels, with a decrease in
    reliability and, more importantly, a decrease in operational lifetime.
    They may also be less efficient at higher thrust levels, so 104% thrust
    may require, say, 110% propellant rates.
    
    gary
549.17Re .15MAYDAY::ANDRADEThe sentinel (.)(.)Fri Aug 11 1989 12:535
    Re .15
    
    104% of first planned thrust. I guess they could rename this 100%
    except that by keeping it as it is they save themselves a lot of
    doc and spec re-writes.
549.18Who is Frank?HYDRA::BIROMon Aug 14 1989 08:5421
    
    
    UHF conversation came back on, most likly the last 2 or 3 orbits,
    they were talking to a person name Frank about fule tank ISO
    and about great compacts??? at least the word sounded like 
    compacts and proper vent must have been done or they would
    not have got the great compacts...
    
    
    Orbit aos/los indicates that the visual observation guide is
    a good first pass element set, with a few visual/radio contacts
    the element set can predict orbits  within 5 min or so.. at
    best and worst case I have about 12 min error... not bad
    for rolling your own,   I am sure the Russian can correct this
    the the fraction of a second and tell you the cross section area
    of the two birds the shuttle launched...
    
    john
    
    
    
549.19Have we landed yet?WONDER::STRANGEOu est le Soleil?Mon Aug 14 1989 11:071
    
549.20KAOA04::KLEINSusan H. Klein @TROMon Aug 14 1989 11:1210
>                            -< Have we landed yet? >-

Yes! On Sunday morning at Edwards Air Force Base. I have a general observation
that is interesting. After they landed, the crew was shown leaving Columbia 
without the partial pressure suits on, they were wearing the blue flight suits.
Do they get changed before they come out? I can remember other missions were
they were wearing the suits after they landed. Or do they not need to wear the
suits on reentry? 

Looked like a real smooth landing. Not much dust.
549.21Another questionSTAR::KOHLSNo comment.Mon Aug 14 1989 11:239
    
    I've heard the Columbia called the "Hangar Queen" in this notes file,
    and similar things on TV.  Just how many times has it flown?  It seems
    like even before the Challenger accident the Columbia was used less
    frequently than the other orbiters.
    
    
    						-SK
    
549.22STS-28 NASA ELEMENT SETsHYDRA::BIROMon Aug 14 1989 12:2420
    just got my NASA mail and I found the element set for STS-28
    it is not classified  I bet DOD is happy....
    
    here are a few element set so you can grade your home brew ones
    
sts-28 89 61 A
1 20164U          89220.55325463 0.00084253           25599-3 0    15
2 20164  57.0005  46.3102 0012736 291.1181 241.7481 15.91332185    05
sts-28 89 61 A
1 20164U          89220.79027750 0.00079075           25599-3 0    26
2 20164  57.0015  45.2137 0009385 304.2600 146.5357 15.90176904    53
sts-28 89 61 A
1 20164U          89221.08986465 0.00026967           88476-4 0    44
2 20164  57.0002  43.8308 0009249 309.4077  56.8652 15.90058720    97
sts-28 89 61 A
1 20164U          89221.10520486 0.00078617           25599-3 0    50
2 20164  56.9981  43.7612 0008896 307.8287 146.2817 15.90071905    97

    
    
549.23PAXVAX::MAIEWSKIMon Aug 14 1989 14:149
  After flying the 1st four flights and being regularly used for the 1st few
years, Columbia was sent back to the factory to be moderinized. It had just
returned and had flown one mission when Challanger blew up (broke up actually).
As a result, it's only flown something like once in the past 5 years. 

  Also, because it weighs more than the other orbiters, it is limited as to
what payloads it can fly.

  George
549.24More Info on ColumbiaKAOA04::KLEINSusan H. Klein @TROMon Aug 14 1989 14:3920
The following list is the flights of Columbia and the launch date. STS 1 thru 4
were orbital test flights. STS 5 was the first operational flight. STS 9 was 
the first flight of Spacelab.

	STS 1	- 12 April 1981

	STS 2	- 12 November 1981

	STS 3	- 22 March 1982 

	STS 4	- 27 June 1982 

	STS 5	- 11 November 1982 

	STS 9  	- 28 November 1983 

	STS 61C	- 12 January 1986 

	STS 28	- 8 August 1989 

549.25ModsLANDO::STONETue Aug 15 1989 13:329
    Just to add one point re: Columbia's remodification.  New aerosensors
    were placed on various parts of the orbiter (wings and vertical
    stabilizer) for re-entry studies (the data will probably be used for
    the Aerospace Plane as well as orbiter improvements).  If you look at
    the top of the vertical stabilizer there is now a pod mounted there.
    I had read somewhere that there were cameras located there to record
    the airflow and thermal characteristics during re-entry.  This
    capability existed on Columbia's last mission before 51L, but I've
    never seen any of the info published.
549.26Guide to STS 28 PayloadsHYDRA::BIROWed Aug 16 1989 09:13281
    
                   Guide to Searching for STS 28 Payloads
                   --------------------------------------

                              by  T.J. Molczan

Shuttle Columbia has returned safely to Earth, and STS 28 is over. Southern
Hemisphere observers had good visibility, but in the Northern Hemisphere we
had daylight passes. However, the STS 28 payloads' orbits are now beginning to
precess into morning twilight which will enable them to be observed. These
military payloads' orbital elements are classified, therefore observing them
is a challenging proposition for the hobbyist. The objects must first be
located and then observed with sufficient accuracy for their orbits to be
determined. This is a guide for those who would like to assist in this effort.


1.0 Payloads
    --------

It is believed that STS 28 deployed two payloads. The first is thought to be a
member of the KH (Key Hole) series of photographic reconnaissance satellites
and probably will be designated 89061B. It may be an advanced KH-11 or
possibly the long awaited KH-12. According to Aviation Week magazine, the
payload has a mass of 9.3 tonnes.

Recent KH's, such as the KH-9 and KH-10, are believed to be about 15 m long
and 3 m in diameter. Hobbyists who have observed the current KH-11, 84122A,
have reported that it is often as bright as a star with a visual magnitude of
zero. (There are only about ten stars that are as bright.)

The second payload, 89061C, is believed to be a 129 kg SDI experiment.


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

It is probable that the STS 28 payloads are in a somewhat similar orbit to
that of Columbia, whose elements are no longer classified and are now in the
public domain. As of this writing, my most recent Columbia elements are :

20164  89061A  89223.02569416  .00078926  00000+00  25599-3  013
56.9982  34.8993  0008868  311.3318  339.9367  15.90148092 00039

It is reasonable to assume that the secondary payload, 89061C, is in the same
orbit as Columbia because it was probably too small to have carried a rocket
motor.

If the primary payload, 89061B, belongs to the KH series, then it is highly
maneuverable and it is reasonable to assume that it is now in a different
orbit than that of Columbia. The current KH-11 in orbit, 84122A, is somewhat
higher than Columbia, and has a mean motion of about 15.78 (based on accurate
observations made by hobbyists). In the absence of height data for 89061B, it
is reasonable to assume that it has maneuvered to a 15.78 mean motion. In view
of its maneuverability, 89061B's decay can be assumed to be zero.

84122A has been observed to have an eccentricity as great as 0.037, however it
is best to assume that 89061B has the same eccentricity as Columbia for the
purpose of the search because we have no idea of its argument of perigee.

Based on the preceeding discussion, the following elset can be assumed for
89061B :

?????  89061B  89223.02569416 .00000000  00000+00  00000+00  001
56.9982  34.8993  0008868  311.3318  339.9367  15.78000000 00039

3.0 Visibility Windows for AUG/SEP 89
    ---------------------------------

The table below lists the morning and evening visibility windows of 89061B
between 60 N and 60 S latitude. The basis for the predictions was the orbit
estimated in Section 2.0. 89061C would have very similar windows.


                Morning                Evening
      ---------------------------    ------------
      North-bound    South-bound     North-bound
      ------------   ------------    ------------
      START   END    START   END     START   END
LAT   dd/mm  dd/mm   dd/mm  dd/mm    dd/mm  dd/mm
----  -----  -----   -----  -----    -----  -----
60 N  25/08  31/08   31/08  06/09    12/09  30/09

50 N  20/08  30/08   30/08  08/09    10/09  05/10

40 N  16/08  22/08   04/09  09/09    09/09  15/09

30 N  14/08  18/08   06/09  10/09    08/09  13/09

20 N  12/08  15/08   08/09  11/09    07/09  11/09

10 N  -----  -----   09/09  12/09    06/09  10/09

00 N  -----  -----   10/09  13/09    05/09  09/09

10 S  -----  -----   11/09  14/09    04/09  08/09

20 S  -----  -----   12/09  16/09    02/09  07/09

30 S  -----  -----   13/09  18/09    31/08  06/09

40 S  -----  -----   15/09  21/09    27/08  04/09

50 S  -----  -----   18/09  11/10    11/08  02/09

60 S  -----  -----   23/9   09/10    14/08  30/08


4.0 Search Strategy
    ---------------

4.1 "Stare" at the Orbit
    --------------------

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

To facilitate the type of search described above, it is useful to compute a
set of theoretical satellite passes for different times on each morning or
evening of the search.

Consider the ephemeris below for 89061B, at Cape Cod on the morning of
19 August. It was computed using the elements given in Section 2.0 and shows
that if the satellite passes on time at 04:16 EDT, then it should pass about
24 deg above the horizon in the south east :


19/ 8/89  EDT  J2000.0  CAPE COD
---------------------------------------------------------------------

  TIME      %I   MAG    AZ  EL    R.A.   DEC   FE   VANG  RANGE   ALT
--------    --  ----   ---  --   -----  -----  --   ----  -----  -----
04:15:46 LS 61   0.4   152  21   03:16  -21.8   3   0.52    805    337
04:16:01    56   0.4   144  23   03:43  -17.5   3   0.56    770    338
04:16:14    50   0.5   136  23   04:07  -13.3   3   0.58    751    338
04:16:27    44   0.6   128  24   04:32   -8.9   3   0.59    744    338
04:16:40    38   0.7   120  24   04:56   -4.4   3   0.58    748    338
04:16:53    32   1.0   112  23   05:19   -0.1   3   0.56    765    338
04:17:06    27   1.2   105  22   05:42    3.8   3   0.52    792    339
04:17:20    22   1.5    98  20   06:05    7.7   2   0.47    832    339
04:17:36    18   1.9    91  18   06:28   11.4   2   0.41    891    339
04:17:54    14   2.4    84  16   06:53   14.8   2   0.35    969    339


The position of the satellite within its orbit is not known, therefore, there
is no reason to expect it to arrive at the time shown above. If it arrives
say, 15 minutes early, then it will pass only about 16 deg in the south east,
as shown in the ephemeris below. That ephemeris was computed by subtracting
15 minutes from the epoch. In Section 2.0, the epoch for 89061B was
89223.02569416 days. The 15 minute early epoch was calculated as follows :

89223.02569416 days - 15 min / 1440 min/day = 89223.01527749


19/ 8/89  EDT  J2000.0  CAPE COD  (Assuming 15.0 min early arrival)
---------------------------------------------------------------------
  TIME      %I   MAG    AZ  EL    R.A.   DEC   FE   VANG  RANGE   ALT
--------    --  ----   ---  --   -----  -----  --   ----  -----  -----
04:00:46 LS 47   1.1   132  16   04:23  -17.6   3   0.45    987    337
04:01:03    42   1.2   125  16   04:47  -13.1   3   0.45    980    338
04:01:20    36   1.4   117  15   05:11   -8.5   3   0.44    988    338


The ephemeris below is for a pass that is 25 minutes late. It was computed by
adding 25/1440 to the epoch given in Section 2.0.


19/ 8/89  EDT  J2000.0  CAPE COD  (Assuming 25.0 min late arrival)
----------------------------------------------------------------------
  TIME      %I   MAG    AZ  EL    R.A.   DEC   FE   VANG  RANGE   ALT
--------    --  ----   ---  --   -----  -----  --   ----  -----  -----
04:40:47 LS 89  -0.1   200  23   00:30  -22.6   5   0.34    772    337
04:41:09    85  -0.5   194  29   01:00  -17.6   4   0.48    642    338
04:41:25    81  -0.7   187  35   01:27  -12.7   4   0.62    560    338
04:41:37    76  -0.9   180  40   01:53   -8.0   4   0.74    507    338
04:41:47    71  -0.9   171  44   02:17   -3.3   4   0.85    471    338
04:41:56    65  -1.0   161  48   02:42    1.4   4   0.95    446    339
04:42:04    59  -0.9   150  50   03:06    6.0   3   1.01    431    339
04:42:11    53  -0.9   139  52   03:29   10.1   3   1.04    424    339
04:42:18    48  -0.7   128  52   03:52   14.1   3   1.04    423    339
04:42:25    42  -0.6   116  51   04:17   17.9   3   1.02    428    339
04:42:32    37  -0.4   106  49   04:42   21.4   2   0.96    439    339
04:42:40    31  -0.1    96  46   05:09   24.8   2   0.89    458    339
04:42:48    26   0.2    88  43   05:36   27.6   2   0.80    483    339
04:42:57    22   0.5    81  39   06:04   30.0   2   0.69    518    340
04:43:08    17   1.0    75  34   06:35   32.1   1   0.58    568    340

The above examples show how easy it is to compute a set of theoretical passes
to assist in searching for a satellite. For naked eye objects, such as 89061B,
it is recommended that such a set include passes beginning at say 10 deg
elevation in the east, moving  westward at increments of about 20 deg of
elevation for succeeding passes. For satellites which are not believed to be
naked eye, such as 89061C, the theoretical passes need to be much more closely
spaced, to facilitate searching through binoculars. (It is suggested that
observers practise on bright, naked eye objects before trying faint ones.)

It is important to observe on every clear day to ensure that the object is
found. If you do not see it on a given occasion do not give up. It may have
made too low a pass, or arrived too close to twilight. On the next day you may
get a better pass. If you want to search for missing or secret objects, then
patience is not only a virtue, it is a must.


4.2 Special Considerations for 89061B
    ---------------------------------

As stated earlier, 89061B may be in a fairly eccentric orbit, yet we assumed
a near circular orbit because there was no way to make an educated guess at
the argument of perigee. This means that the satellite may not follow the
exact theoretical path for a given time of arrival. The path across the sky
may be lower or higher, depending on its actual eccentricity and argument of
perigee. Also, it may have a different mean motion than the assumed 15.78,
which would change the rate of precession of the ascending node, and hence its
path across the sky. Therefore, it is a good idea to scan at least 10 deg
either side of the theoretical path.


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

During the STS 27 / LACROSSE mission there was an informal network of amateur
observers who shared their observations. This made it possible for more people
to see the shuttle (and LACROSSE) because we were able to quickly refine our
orbital estimates and pass on the information. Within a few days after the
Shuttle Atlantis had landed, amateur observers managed to find Lacrosse and
determine its orbital elements. This was achieved despite the fact that it was
boosted into an orbit 230 km higher than when it had been deployed !

If you find either of the two payloads please make as accurate an observation
as you can.

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 20 AUG 89"

                            or

         "passed 3 degrees below Vega, 09:12:10 UTC 20 AUG 89"


If you are not familiar with the stars, then give the time, azimuth and
elevation at the point of maximum elevation.

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.

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


      1) leave a message on this BBS for Ted Molczan

      2) leave a message on the CSS (Canadian Space Society) BBS
         for Ted Molczan. This is a 24 h/day free board, 2400 8N1.
         (416) 458-5907.

      3) phone me at (416) 928-3046 (H) or 926-2085 (W)

      4) fax me at (416) 926-2218

      5) send e-mail message via [email protected]
         This is on NETNORTH, which is connected to BITNET and
         other academic/research networks.

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

                   *     *     *     *