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/usr1/ota/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests) ID ; Fri, 29 Sep 89 05:22:47 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 29 Sep 89 05:22:25 -0400 (EDT) Subject: SPACE Digest V10 #89 SPACE Digest Volume 10 : Issue 89 Today's Topics: Frequently Asked Questions, Higgins version Re: NASA Headline News for 09/20/89 (Forwarded) Re: ...hospital radiation machine... Erich von Daniken (was Re: Analysis of Martian "Face" Announced) NEW SUBSCRIBER C orbital prediction subroutines, and a query ---------------------------------------------------------------------- Date: Thu, 21 Sep 89 13:11 CDT From: Bill Higgins-- Beam Jockey Subject: Frequently Asked Questions, Higgins version Original_To: Orig_To! SPACE,SPENCER,EUGENE@AMELIA.NAS.NASA.GOV I have been irritated every time Eugene posts something about Frequently Asked Questions, for two reasons: A lot of F.A.Q.'s don't seem to be on his list, and some of the things he's answering don't seem to be Asked all that Frequently. At last, after reviewing a few months' worth of traffic (and reading the Digest for a few years), I drew up my own list of F.A.Q.'s. You are free to consider this just as eccentric as Eugene's. Maybe we can kick this around a bit... I notice the absence of questions about the Soviet programs. I guess these get dealt with pretty well by such people as Henry Spencer and Glenn Chapman as they come up; I don't feel that there are a lot of recurring ones. "HOW DO I GET'S" [Canned answers to these would be good to have around, and maybe reposting them infrequently would be helpful. Note that many good definitive answers to them have been posted in the recent or distant past. Maybe we should collect such answers someplace. Mike Smithwick once did a good job on NASA Select, Eugene wrote about astronaut selection, Ken Jenks catalogued aerospace employers, etc. Some answers are just a bit of library work.] --How do I get access to the International Astronomical Union bulletins? --Where can I get free material about NASA/ESA/other space programs? --How do I apply to be an astronaut? How do I get 'em to select me? --Will there be any launches while I'm visiting Florida? --Where is the best place to watch a Shuttle launch from? --Tell me about NASA Select, the satellite channel. --How do I get Voyager/Viking/etc. images in machine-readable form? --How do I receive and interpret weather satellite pictures? --Where can I get software to simulate the entire Solar System? --I am writing software to simulate the entire Solar System. Where can I get positions and velocities of all the planets and satellites? --How do I contact L5/NSS/SSI/PlanSoc/World Space Foundation/SEDS et al? --Is there an astronomy newsgroup on Internet/Bitnet/etc.? PRETTY SPECIFIC QUESTIONS [These keep recurring.] --Can we just resurrect the Saturn V? --What is the orbital debris hazard? How can it be cleaned up? --Where do Shuttle names come from? --Can Hubble Space Telescope look at the ground? --What is the current status of private launch companies? (Amroc, Space Services, Third Millenium, Pacific American, OTRAG) --Why don't those idiots at NASA put external tanks in orbit? --How would you terraform Mars? Venus? --What does a Shuttle cost? Will private operators ever run one? --Why didn't they send Voyager to Pluto? Or back to Earth? "TELL ME'S" [Some subjects keep coming up, and there is broad interest in them, rather than more narrowly focused specifics. Perhaps our best defense is to have a list of readily available references for each subject. Not possible in all these cases.] --Tell me about spy satellites. (Optical, signal intelligence, radar) --Tell me about the Global Positioning System. --Tell me about amateur radio satellites. --Tell me about scramjets. --Tell me about laser launching. --Tell me about electric rockets. --Tell me about solar sails. --Tell me about electromagnetic catapults (railguns, mass drivers). --Tell me about mass extinctions, asteroid/comet bombardment, and the Nemesis (hidden companion of Sun) theory. ============================================================================= So. What have I left out? What should we do next? ______meson Bill Higgins _-~ ____________-~______neutrino Fermi National Accelerator Laboratory - - ~-_ / \ ~----- proton Bitnet: HIGGINS@FNALB.BITNET | | \ / SPAN/Hepnet/Physnet: 43011::HIGGINS - - ~ Internet: HIGGINS%FNAL.BITNET@UICVM.uic.edu ------------------------------ Date: 21 Sep 89 20:13:59 GMT From: sjsca4!news@uunet.uu.net (Greg Wageman) Subject: Re: NASA Headline News for 09/20/89 (Forwarded) Opinions expressed are the responsibility of the author. In article <32247@ames.arc.nasa.gov> yee@trident.arc.nasa.gov (Peter E. Yee) writes: > >This is NASA Headline News for Wednesday, September 20..... > > >As Hurricane Hugo continues to move in a northwesterly direction >towards the U.S. East Coast, Kennedy Space Center launch >officials have decided not to make a decision yet on moving the ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >Space Shuttle Atlantis back to the Vehicle Assembly Building. >Meanwhile, launch officials have made a tentative decision not to ^^^^^^^^^^^^^^^^^^ >demate the FltSatCom satellite from the Atlas-Centaur booster at >the Cape. The launch has been slipped to no earlier than Sunday >at 4:13 A.m., Eastern time. It's a good thing the managers at NASA are so *decisive*. Wow. :-) Copyright 1989 Greg Wageman DOMAIN: greg@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!greg San Jose, CA 95110-1397 BIX: gwage CIS: 74016,352 GEnie: G.WAGEMAN Permission granted for not-for-profit reproduction only. ------------------------------ Date: 21 Sep 89 22:48:46 GMT From: vsi1!daver!lynx!neal@apple.com (Neal Woodall) Subject: Re: ...hospital radiation machine... In article Gregory E. Gilbert writes: >Neal Woodall mentioned in V10 #58 some unfortunate individuals who came >across an old Cobalt Therapy machine and started playing with the source. >Does anyone have a full account of this incident? I wish i could give you more info, however it was about a year or two ago and I read a lot of newspapers and magazine. I did happen in Brazil, several exposed people died, a few city blocks had to be decontaminated. I remember a followup story that said the bodies of the victims had to be buried in lead boxes, and the graves were checked regularly for leakage. Must have been some pretty nasty stuff. >Bye the way, I am new to this digest what's an RTG? Radioisotope Theromoelectric Generator. Not a nuclear reactor....the isotope of Pu used is radioactive, but not fissionable. It produces energy from its decay (heat) that is converted to electricity, but it does not support sustained chain reactions. Less power, but safer. Neal ------------------------------ Date: 20 Sep 89 20:17:53 GMT From: mcsun!ukc!reading!cf-cm!cybaswan!iiitsh@uunet.uu.net (Steve Hosgood) Subject: Erich von Daniken (was Re: Analysis of Martian "Face" Announced) In article <9189@june.cs.washington.edu> dfkling@cs.washington.edu (Dean F. Kling) writes: > A few months ago PBS in Seattle had a British TV show that discussed >these kinds of ad-hoc correlations. As an examle they took Stonehenge, >the Salisbury Cathedral, and several local farms and drew dozens of striking >conclusions based on their geographical realtionships, sight lines, and >long distance relationships to other English monuments, and to solstice lines, >etc. The obvious conclusion they drew was that the whole complex *must* >have been part of an overall coherent design, by a single culture. >There were just *too* many "coincidences" to be explained by mere chance! >The lesson was that if you look hard enough for post-facto relationships, >you will find them. > About 15 years ago, the BBC's 'Horizon' science programme did a hatchet-job on the then-popular theories of Erich Von Daniken (author of 'Chariots of the Gods?' and other titles). The bit of this program that sticks in my mind was where they rubbished the 'Nazca UFO Landing Strip' pictures. They did a good job of this... setting the camera up to replicate the still photo in the book. Sure, it looked just like a runway, complete with little bays for hard-standing at the sides. Then the narrator walked into the shot. Either very small aliens built the landing strip, or the BBC have a 250 ft high narrator! The whole design was evidently no more than 10ft from end to end. Erich Von Daniken admitted in the following interview that he didn't take the picture, but someone sent it to him and that he published it without any checks. -----------------------------------------------+------------------------------ Steve Hosgood BSc, | Phone (+44) 792 295213 Image Processing and Systems Engineer, | Fax (+44) 792 295532 Institute for Industrial Information Techology,| Telex 48149 Innovation Centre, University of Wales, | JANET: iiitsh@uk.ac.swan.pyr Swansea SA2 8PP | UUCP: ..!ukc!cybaswan!iiitsh -----------------------------------------------+------------------------------ My views are not necessarily those of my employers! Please note the change in my username as of 1 Aug '89 ------------------------------ Date: Thu, 21 Sep 89 10:09:30 EDT From: Michael Ryan (FSF) Cc: MRYAN@PICA.ARMY.MIL Subject: NEW SUBSCRIBER Request to be put on distribution ------------------------------ Date: 21 Sep 89 12:33:26 GMT From: ecsvax.uncecs.edu!dukeac!tcamp@mcnc.org (Ted A. Campbell) Subject: C orbital prediction subroutines, and a query Some readers of sci.astro and sci.space may have seen the Space Flight Simulator, version 0.02, which was posted to comp.binaries.ibm.pc. If I ever make up my mind just how to do it, I may release the source code for the whole thing. In the meantime, I'm going to post the following subroutines to sci.astro and sci.space for two reasons (a) someone might actually find them useful, and (b) someone might want to advise me on a technical point that is apparently beyond the abilities of this bear-of-very-little-brain. The following code contains three critical subroutines (in C). or_init() sets up orbital parameters based on an apoapsis and periapsis (in kilometers). It presumes that the following globals have already been set: (double) fo_mass the mass of the orbital focus in grams (earth = 5.98e27) (double) fo_radius the radius of the orbital focus in kilometers (double) fo_siday the sidereal period of the orbital focus in seconds The include file "sfsm.h" defines a structure for orbits, the elements of which should be obvious. sfs_orbits[ n ] is an array of pointers to orbit structures, so that sfs_orbits[ 0 ]->period would give the orbital period in seconds for orbit 0, etc. The subroutine or_ssp() calculates the subsatellite point for an orbit, given the time (in seconds). It also calculates the current altitude. It, in turn, calls or_kep(), which solves Kepler's equation. These routines may be useful for anyone wanting to build C applications with orbital calculations. The subroutines are based on pseudocode given in Martin Davidoff's Satellite Experimenters Handbook (published by ARRL for Radio Amateurs using the OSCAR and other Amateur satellites), but the C implementation is my own. PROBLEM: These routines seem to work well enough for orbits with inclinations near 0 and near 180 degrees (by the way -- all angles in these routines are in radians). But for orbits with inclinations near 90 degrees, there is a grotesque skewing that occurs (at the highest/lowest points in the orbit). As of yet, I haven't been able to figure what causes this skewing. Of course, it's possible that the algorithms are correct, and that the skewing occurs in other routines that manipulate their output in various ways. On the other hand, the skewing occurs so frequently that I suspect the culprit is here somewhere. email: tcamp@dukeac.ac.duke.edu /**************************************************************** SFS_OR.C Orbital calculation routines for SFS Copyright (c) 1989, Ted A. Campbell ****************************************************************/ #include "math.h" #include "time.h" #include "vdi.h" #include "sfsm.h" extern double or_lfix(); /**************************************************************** or_init() Set up an orbit ****************************************************************/ or_init( orbit, ap, aa ) int orbit; double aa, ap; { /*** Calculate semimajor axis */ sfs_orbits[ orbit ]->semimajor = ( aa + ap + ( 2 * fo_radius )) / 2; /*** Calculate orbital center - focus distance */ sfs_orbits[ orbit ]->dist = sfs_orbits[ orbit ]->semimajor - ( fo_radius + ap ); /*** Calculate semiminor axis */ sfs_orbits[ orbit ]->semiminor = sqrt( (double) ( sfs_orbits[ orbit ]->semimajor * sfs_orbits[ orbit ]->semimajor ) - (double) ( sfs_orbits[ orbit ]->dist * sfs_orbits[ orbit ]->dist )); /*** Calculate orbital eccentricity */ sfs_orbits[ orbit ]->eccentricity = sqrt( 1.0 - (( sfs_orbits[ orbit ]->semiminor / (double) sfs_orbits[ orbit ]->semimajor ) * ( sfs_orbits[ orbit ]->semiminor / (double) sfs_orbits[ orbit ]->semimajor )) ); /*** Calculate orbital period */ sfs_orbits[ orbit ]->period = sqrt ( ( ( 4.0 * ( PI * (double) PI ) ) / ( UGC * fo_mass ) ) * ( sfs_orbits[ orbit ]->semimajor * sfs_orbits[ orbit ]->semimajor * sfs_orbits[ orbit ]->semimajor ) ); /*** Calculate the increment factor of longitude of the ascending node. This factor must be multiplied by a time factor (orbital period or time into orbit, in seconds. See Davidoff, pp. 8-9 and 8-10, and formula 8.14. */ if ( fo_siday == 0.0 ) { sfs_orbits[ orbit ]->lif = 0; } else { sfs_orbits[ orbit ]->lif = (2 * PI) / (double) fo_siday; } } /**************************************************************** or_kep() Solve Kepler's equation Globals utilized: sfs_orbits[ orbit ]->eccentricity Eccentricity of the orbital ellipse sfs_orbits[ orbit ]->semimajor Semimajor axis of the orbital ellipse (km) sfs_orbits[ orbit ]->period Orbital period (seconds) Inputs: t Time from periapsis in seconds ( 0 < t < sfs_orbits[ orbit ]->period ) Output: theta Angle between periapsis, geocenter, and current position (theta). r Distance from satellite to focal center, in kilometers ****************************************************************/ or_kep( orbit, t, theta, r ) int orbit; long t; double *theta; long *r; { double z, z3, E; z = 2.0 * PI * ( (double) t / (double) sfs_orbits[ orbit ]->period ); E = z; do { z3 = ( E - ( sfs_orbits[ orbit ]->eccentricity * sin( E )) - z ) / ( 1 - ( sfs_orbits[ orbit ]->eccentricity * cos( E ))); E = E - z3; } while ( fabs( z3 ) > 0.000000001 ); *theta = PI; if ( E != PI ) { *theta = 2.0 * atan( sqrt( ( 1 - sfs_orbits[ orbit ]->eccentricity ) / ( 1 + sfs_orbits[ orbit ]->eccentricity )) * tan( E / 2.0 )); if ( E > PI ) { *theta = ( (double) 2.0 * PI ) + *theta; } } *r = sfs_orbits[ orbit ]->semimajor * ( 1 - sfs_orbits[ orbit ]->eccentricity * sfs_orbits[ orbit ]->eccentricity ) / ( 1 + sfs_orbits[ orbit ]->eccentricity * cos( *theta )); return 1; } /**************************************************************** or_ssp() Calculate Subsatellite Point This function utilizes available data on the satellite to return the subsatellite point, that is, the point on the surface of the orbital focus directly under the satellite at a given moment. ****************************************************************/ or_ssp( orbit, t, latitude, longitude, r, n ) int orbit; long t, *r, *n; double *longitude, *latitude; { static long _r, tp; static double theta; double n1, n2, n4, E, lan; long t1; *n = t / sfs_orbits[ orbit ]->period; /* return number of current orbit */ t1 = t - ( sfs_orbits[ orbit ]->period * ( *n ) ); /* get seconds into this orbit */ if ( t1 == 0 ) { t1 = 1; } or_kep( orbit, t1, &theta, &_r ); *r = _r; /*** Calculate the longitude of the ascending node at the beginning of this orbit. See Davidoff, p. 8-9 and 8-10, and equations 8.13a, 8.13b, and 8.14. */ lan = sfs_orbits[ orbit ]->lon_an - ( sfs_orbits[ orbit ]->lif * sfs_orbits[ orbit ]->period * *n ); /*** Calculate the latitude of the SSP. See Davidoff, pp. 8-13 - 8-15, esp. equation 8.20. */ *latitude = asin( sin( sfs_orbits[ orbit ]->inclination ) * sin( theta + sfs_orbits[ orbit ]->arg_per )); if ( ( sfs_orbits[ orbit ]->inclination * RAD_DEG >= 0 ) && ( sfs_orbits[ orbit ]->inclination * RAD_DEG < 90 ) ) { n2 = 1; } else { n2 = 0; } if ( ( ( *latitude ) * RAD_DEG ) < 0.0 ) { n4 = 1; } else { n4 = 0; } if ( ( sfs_orbits[ orbit ]->arg_per * RAD_DEG > 180 ) && ( sfs_orbits[ orbit ]->arg_per * RAD_DEG <= 540 ) ) { n1 = 1; } else { n1 = 0; } E = 2 * atan( (double) pow( ( 1 - sfs_orbits[ orbit ]->eccentricity ) / ( 1 + sfs_orbits[ orbit ]->eccentricity ), (double) 0.5 ) * tan( sfs_orbits[ orbit ]->arg_per / 2.0 )) + ( 2.0 * PI * n1); tp = ( sfs_orbits[ orbit ]->period / ( 2.0 * PI ) ) * ( E - sin( E ) ); *longitude = or_lfix( lan - pow( (double) -1.0, n2 + n4 ) * acos( cos( theta + sfs_orbits[ orbit ]->arg_per ) / cos( *latitude ) ) - sfs_orbits[ orbit ]->lif * (double) t1 - sfs_orbits[ orbit ]->lif * (double) tp ); } double or_lfix( l ) double l; { double l1; l1 = l; while ( l1 < ( 0 - PI ) ) { l1 += ( 2.0 * PI ); } while ( l1 > PI ) { l1 -= ( 2.0 * PI ); } return l1; } ------------------------------ End of SPACE Digest V10 #89 *******************