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Could anyone furnish me the orbital elements of the Galileo spacecraft now   (i.e. valid until Earth encounter Dec 8) and those after the Earth encounter?   If there are any known midcourse corrections between now and then, what I   really want is the elements in the few days pre-and-post-encounter. Thanks! Martin Connors Space Research University of Alberta

Could anyone furnish me the orbital elements of the Galileo spacecraft now   (i.e. valid until Earth encounter Dec 8) and those after the Earth encounter?   If there are any known midcourse corrections between now and then, what I   really want is the elements in the few days pre-and-post-encounter. If anyone has such, please post. What's the brightness of Galileo at Earth encounter?  Better than, say, mag. 15? Peter Monta   This e-mail address is being protected from spam bots, you need JavaScript enabled to view it MIT Advanced Television Research Program

I have had a couple of replies about this. There seems to be interest in   optically viewing Galileo...apparently there was a sighting last time around. I   do not know too much about this. There was also an allegation that Galileo's orbital elements are secret   because JPL does not want publicity or interference due to its RTG's coming   back . Either the elements or further comments on their secrecy would be   interesting to get... Martin Connors Space Research University of Alberta

What's the brightness of Galileo at Earth encounter?  Better than, say, mag. 15? A probe several meters across, enshrouded in gold foil, passing 300 km overhead?  Intuition tells me that it will be much brighter than that, possibly a naked-eye _object_, especially if the high-gain antenna pops open.  But I don't know how to make an estimate with any accuracy.      O~~*           /_) ' / /   /_/ '  ,   ,  ' ,_  _           |/    - ~ -~~~~~~~~~~~/_) / / /   / / / (_) (_) / / / _~~~~~~~~~~~zap!  /                                (_) (_)                    / |  |       |     Bill Higgins   Fermi National Accelerator Laboratory         /     Bitnet:     This e-mail address is being protected from spam bots, you need JavaScript enabled to view it    -   -       Internet:   This e-mail address is being protected from spam bots, you need JavaScript enabled to view it      ~         SPAN/Hepnet:      43011::HIGGINS

There was also an allegation that Galileo's orbital elements are secret   because JPL does not want publicity or interference due to its RTG's coming   back . Never heard this, and I find it implausible.  Given that the arrival dates at Gaspra, Earth, and Jupiter are public, it's hard to see how they could do more than introduce a little uncertainty into the figures.   Anyway, a friend at JPL has provided the official story. If you're looking for proof of a coverup, I guess you can check for yourself on December 8th.  (-: Here you go: ==============[begin JPL official announcement]================= INTERPLANETARY ORBITAL ELEMENTS FOR GALILEO Galileo was launched on October 18, 1989, on a six-year trajectory that will take it to Jupiter.  On the way, Galileo's flight path takes it on a flyby of Venus, then of Earth, then by the asteroid Gaspra, followed by another Earth flyby and an encounter with the asteroid Ida.  Several months before Jupiter arrival, Galileo will release a probe which will descend into the Jovian atmosphere.  The main Galileo orbiter will undertake a complex oribtal tour at Jupiter including flybys of all of the giant planet's major moons.   The following are classic orbital elements for the Galileo spacecraft, as provided in December 1990 by the Galileo Navigational Team at the Jet Propulsion Laboratory.  The coordinate system is Earth Mean Ecliptic, 1950 Equinox.   Dates (in year/month/day format) and times (in 24-hour format) are both in Universal Time (UTC), also known as Greenwich Mean Time (GMT).   All elements apply to the mated Galileo orbiter and probe, with the exception of the final three sets of elements which are marked as being for the probe only.  The elements for the orbiter after probe separation (July 17, 1995) are not listed but will be posted when available from the Galileo Project.                                      _____ LAUNCH Valid from                    89/10/19 01:29   to                          89/10/26 01:55 Epoch                         89/10/19 01:29 Central body                        Earth Semi-major axis (km)                -2.584E4 Eccentricity                         1.26 Inclination (deg)                   54.9 Longitude of ascending node (deg)  157.2 Argument of periapsis (deg)         -1.1 Mean anomaly                        36.4 EARTH-VENUS Valid from                    89/10/26 01:55   to                          90/02/05 15:20 Epoch                         89/10/26 01:55 Central body                         Sun Semi-major axis (km)                 1.245E8 Eccentricity                         0.20 Inclination (deg)                    4.3 Longitude of ascending node (deg)   24.7 Argument of periapsis (deg)       -175.3 Mean anomaly                      -177.3 VENUS FLYBY Valid from                    90/02/05 15:20   to                          90/02/14 20:56 Epoch                         90/02/10 05:59 Central body                        Venus Semi-major axis (km)                -8.555E3 Eccentricity                         3.59 Inclination (deg)                  134.9 Longitude of ascending node (deg)  -70.6 Argument of periapsis (deg)       -109.1 Mean anomaly                         0.0 VENUS-EARTH Valid from                    90/02/14 20:56   to                          90/12/05 15:47 Epoch                         90/02/14 20:56 Central body                         Sun Semi-major axis (km)                 1.479E8 Eccentricity                         0.29 Inclination (deg)                    3.4 Longitude of ascending node (deg)   76.0 Argument of periapsis (deg)        106.3 Mean anomaly                       -10.3 EARTH 1 FLYBY Valid from                    90/12/05 15:47   to                          90/12/12 01:24 Epoch                         90/12/08 20:35 Central body                        Earth Semi-major axis (km)                -4.977E3 Eccentricity                         2.47 Inclination (deg)                  142.2 Longitude of ascending node (deg)   71.8 Argument of periapsis (deg)         95.9 Mean anomaly                         0.0 EARTH-GASPRA Valid from                    90/12/12 01:24   to                          91/10/29 22:49 Epoch                         90/12/12 01:24 Central body                         Sun Semi-major axis (km)                 2.375E8 Eccentricity                         0.43 Inclination (deg)                    4.5 Longitude of ascending node (deg) -104.1 Argument of periapsis (deg)       -136.8 Mean anomaly                       -14.9 GASPRA-EARTH Valid from                    91/10/29 22:49   to                          92/12/05 10:09 Epoch                         91/10/29 22:49 Central body                         Sun Semi-major axis (km)                 2.376E8 Eccentricity                         0.43 Inclination (deg)                    4.6 Longitude of ascending node (deg) -103.9 Argument of periapsis (deg)       -137.1 Mean anomaly                       143.8 EARTH 2 FLYBY Valid from                    92/12/05 10:09   to                          92/12/11 21:03 Epoch                         92/12/08 15:35 Central body                        Earth Semi-major axis (km)                -5.059E3 Eccentricity                         2.32 Inclination (deg)                  161.1 Longitude of ascending node (deg)  155.9 Argument of periapsis (deg)       -136.7 Mean anomaly                         0.0 EARTH-IDA Valid from                    92/12/11 21:03   to                          93/08/28 16:35 Epoch                         92/12/11 21:03 Central body                         Sun Semi-major axis (km)                 4.683E8 Eccentricity                         0.69 Inclination (deg)                    1.5 Longitude of ascending node (deg) -104.1 Argument of periapsis (deg)       -173.5 Mean anomaly                        -0.3 IDA-JUPITER (PROBE ONLY) Valid from                    93/08/28 16:35   to                          95/09/14 03:12 Epoch                         93/08/28 16:35 Central body                         Sun Semi-major axis (km)                 4.693E8 Eccentricity                         0.69 Inclination (deg)                    1.6 Longitude of ascending node (deg) -105.3 Argument of periapsis (deg)       -172.5 Mean anomaly                        45.7 JUPITER APPROACH (PROBE ONLY) Valid from                    95/09/14 03:12   to                          95/12/07 22:04 Epoch                         95/09/14 03:12 Central body                       Jupiter Semi-major axis (km)                -4.136E6 Eccentricity                         1.02 Inclination (deg)                    8.0 Longitude of ascending node (deg)   27.4 Argument of periapsis (deg)        132.3 Mean anomaly                      -561.7 PROBE ENTRY Valid from                    95/12/07 22:04   to                          95/12/07 22:04 Epoch                         95/12/07 22:04 Central body                       Jupiter Semi-major axis (km)                -2.274E6 Eccentricity                         1.03 Inclination (deg)                    8.2 Longitude of ascending node (deg)   25.5 Argument of periapsis (deg)        134.8 Mean anomaly                         0.0 ==============[end JPL official announcement]================= Note that Galileo has not committed to the Ida encounter yet.  That decision will be made next July. What Fermi did under a stadium           Bill Higgins   Da deuteron, ron, ron, da deuteron ron   Fermi National Accelerator Laboratory She did with heavy water and palladium   Bitnet:     This e-mail address is being protected from spam bots, you need JavaScript enabled to view it Da deuteron, ron, ron, da deuteron ron   SPAN/Hepnet: 43011::HIGGINS    

There was also an allegation that Galileo's orbital elements are secret   because JPL does not want publicity or interference due to its RTG's coming   back . Either the elements or further comments on their secrecy would be   interesting to get... Martin Connors Space Research University of Alberta There has been some discussion on this newsgroup regarding the orbital elements for Galileo's second Earth flyby.  Mention was made of the 'secrecy' of some information.  As a member of the Galileo Navigation Team, allow me to respond to this: (Note:  This is only my interpretation of the policy, since I do not speak offically for the Galileo Project....) Interplanetary (i.e. heliocentric) information regarding Galileo's orbit is avaliable to anyone without restriction.  Detailed orbital information specifically dealing with geocentric coordinates around the time of the Earth encounter requires a written request to the Galileo Project office here at JPL, and can only be given after Project approval of such a request. The reason for this restriction is simple:  Galileo's use of RTG's and the fact it is flying near Earth has caused great concern from enviromental groups.  You'll recall that days before the launch of Galileo a few such groups tried to force a court order to prohibit the launch. The limitations of discussing the orbital information is to prohibit any attempt to disable Galileo via an unauthorized up_link_.