Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Thu, 16 Nov 89 01:36:30 -0500 (EST) Message-ID: <8ZMZJ6S00VcJMhqE4r@andrew.cmu.edu> Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 16 Nov 89 01:35:52 -0500 (EST) 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!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Technology and space colonization In article <8911140156.AA02098@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (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 henry@zoo.toronto.edu ------------------------------ Date: 15 Nov 89 05:58:05 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@purdue.edu (Henry Spencer) Subject: Re: Space Elevator In article <1989Nov14.130347.1124@jarvis.csri.toronto.edu> hogg@db.toronto.edu (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 henry@zoo.toronto.edu ------------------------------ Date: 15 Nov 89 12:02:47 GMT From: cs.utexas.edu!mailrus!jarvis.csri.toronto.edu!utgpu!molczan@tut.cis.ohio-state.edu (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, (513) 427-0674. 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, (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 to Molczan@gpu.utcs.utoronto.ca Please pass this on to other BBS's or interested individuals. * * * * -- Ted Molczan@gpu.utcs.utoronto.ca ------------------------------ End of SPACE Digest V10 #252 *******************