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Galileo Highlights of Jupiter Orbital Tour 92-14a


Galileo's orbital tour consists of 11 different elliptical orbits around Jupiter. Each orbit (except one) includes a close flyby and gravity assist at Ganymede, Callisto or Europa, near the inner (Jupiter) end of the orbit. The outer end of the orbit will vary from 5 to almost 20 million kilometers (3.2 to more than 12 million miles). No close flyby is planned for Orbit 5, when Galileo is out of communication due to solar conjunction when the Sun will be between Jupiter and Earth. Distant scientific encounters with additional satellites are scheduled for a number of orbits, and the spacecraft will observe Io at medium range on every orbit.

Spacecraft flight path through 2-year, 
11-orbit mission49K

Galileo's Eleven Orbit Trek Around Jupiter

Often referred to as a "petal plot" because of its resemblance to a drawing of a flower, this figure shows the orientation of Galileo's eleven orbits.

The Ganymede encounter on May 7, 1997 is the eighth of these satellite swingbys. Each time the orbiter flies closely past one of the major inner moons, Galileo's course will be changed due to the satellite's gravitational effects. Careful targeting allows each flyby to direct the spacecraft on to its next satellite encounter and the spacecraft's next orbit around Jupiter. Galileo will fly by Ganymede four times, Callisto three, and Europa three. Io gets only the one close pass, on arrival day, because Galileo cannot linger long in the hazardous radiation environment in which Io resides without damaging the spacecraft's electronics.


The Galilean Satellites
Ganymede, Callisto, Io and Europa

These satellite encounters will be at altitudes as close as 262 kilometers (163 miles) above the surfaces of the moons, and typically 100 to 300 times closer than the Voyager satellite flybys. These encounters will help determine surface chemical composition, geological features and geophysical history of the satellies. Galileo's scanning instruments will scrutinize the surface and features of each targeted moon. After a week or so of satellite observation, with its tape recorder full of data, the spacecraft will spend the next months in orbit playing out the information to Earth. Throughout the 23-month orbital tour, Galileo will continuously gather data on the Jovian magnetospheric and dust environment.

Also, be sure to check out the Tour Summary by Orbit and Tour Summary by Target setup by the Galileo imaging team.

After completing the orbital tour in December 1997, Galileo will then proceed with the Galileo Europa Mission.

Galileo's Orbital Tour

            Date                Inbound/  Altitude  Lat
Encounter  (UTC)    Satellite   Outbound    (km)   (deg)  Objective

G1       27 Jun 96   Ganymede   In         844      25    Wake, Alfven wings,
                                                          UVS, gravity,
                                                          reduce period

G2        6 Sep 96   Ganymede   In         262      85    Alfven wing,
                                                          gravity, reduce

C3        4 Nov 96   Callisto   In       1,100      13    Wake, Alven
                                                          wing, UVS 
                                                          rotate, Jupiter

E3A       6 Nov 96   Europa     Out     31,947       0    Coverage (232
                                                          deg. W. Long.,
                                                          Phase = 34 deg.)

E4       19 Dec 96   Europa     Out        695       0    Wake, Europa 
                                                          occs., Jupiter

(E5A)    20 Jan 97   Europa     Out     27,419       1    Occurs during 

E6       20 Feb 97   Europa     In         588      17    Europa occs., 
                                                          Jupiter occs.,
                                                          Io occ.

E7A       4 Apr 97   Europa     In      23,244       2    Coverage (133
                                                          degrees W. 
                                                          Long., Phase =
                                                          51 degrees), 
                                                          distant wake

G7        5 Apr 97   Ganymede   Out      3,065      56    Alfven wing

C8A       6 May 97   Callisto   In      33,499     -42    Coverage (72 
                                                          deg. W. Long.,
                                                          Phase = 44 deg.)

G8        7 May 97   Ganymede   In       1,584      29    Ganymede occs.,
                                                          Jupiter occ., 
                                                          distant UVS

C9       25 Jun 97   Callisto   In         416       2    Callisto occs.,
                                                          Jupiter occ.,
                                                          tail petal

G9A      26 Jun 97   Ganymede   In       79,961      0    Coverage (98
                                                          deg. W. Long.,
                                                          Phase = 20 deg),
                                                          distant wake

Tail petal apojove: 8 Aug 97, 143 RJ, Phase = 175 degrees, 
                    Inclination = 0.2 degrees 

C10      17 Sep 97   Callisto   In          524      5    Wake, Alfven 
                                                          wing, Jupiter 
                                                          occ., rotate,
                                                          UVS, reduce 

E11       6 Nov 97   Europa     In        1,119     66    Alfven wing, 
                                                          Earth occ.

    Deterministic Delta-V:     Jupiter Orbit Insertion = 643 m/s
                               Perifove Raise = 375 m/s
                               Tour = 23 m/s

    Total Radiation = 123 Krad


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