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.
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 in June 1996 is the first of these satellite swingbys, and will shorten and change the shape of Galileo's ensuing orbit. 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.
These satellite encounters will be at altitudes as close as 200 kilometers (125 miles) above the surfaces of the moons, and typically 100 to 300 times closer than the Voyager satellite flybys, to determine surface chemical composition, geological features and geophysical history. Galileo's scanning instruments will scrutinize the surface and features of each. 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.
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 255 85 Alfven wing,
gravity, reduce
inclination
C3 4 Nov 96 Callisto In 1,100 13 Wake, Alven
wing, UVS
counter-
rotate, Jupiter
occs.
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
occs.
(E5A) 20 Jan 97 Europa Out 27,419 1 Occurs during
solar
conjunction
interval
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
period
E11 6 Nov 97 Europa In 1,119 66 Alfven wing,
Earth occ.
Io encounter: 7 Dec 95 (10:38 a.m. PST/ERT); Inbound,
altitude 1000 km; latitude -2 degrees
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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