Galileo Ganymede 1 Flyby Navigation Results

On June 27, 1996, the Galileo probe flew by Ganymede at a distance of 835 km. Not only did this close flyby enable Galileo to collect excellent science data of the solar system's largest moon, but it provided a planned gravity assist to change Galileo's orbit for the next encounter on September 6, 1996. Below are the times and navigation results of the Ganymede 1 flyby.

Acronyms

C/A  - Closest Approach
ERT  - Earth Receive Time
JMED - Jupiter Mean Equator of Date
JOI  - Jupiter Orbit Insertion
OD   - Orbit Determination
OTM  - Orbital Trim Maneuver
PM   - Propellant Margin
S/C  - Spacecraft
SCET - Spacecraft Event Time

Ganymede 1 Flyby

C/A Time (SCET): 6/27 06:29:07 UTC, 6/26 23:29:07 PDT, 6/27 02:29:07 EDT
C/A Time (ERT): 6/27 07:03:57 UTC, 6/27 00:03:57 PDT, 6/27 03:03:57 EDT
Radius: 3469.0 km (2155.8 miles)
Altitude: 835.0 km (518.9 miles)
Latitude (JMED): 30.62 deg
Speed at C/A: 7.800 km/s (17,450 mph)
Approach Speed: 7.426 km/s (16,610 mph)

Speed Increase to C/A: 374 m/s (837 mph)

Ganymede 1 Gravity Assist

Total Gravity-Assist Delta-V: 728.1 m/s (1,629 mph)
Orbiter Speed Change: -433 m/s (-969 mph)
Equivalent S/C Propellant:

13% larger than JOI
3.7 times Delta-V remaining
47% of total Delta-V at launch

Before Flyby After Flyby Orbiter Speed 14.944 km/s (33,430 mph) 14.511 km/s (32,460 mph) Orbit Period 209.9 days 72.1 days Orbit Inclination (JMED) 5.81 deg 4.42 deg

Ganymede 1 Flyby Navigation

Target Achieved Miss Time (6/27, UTC/SCET) 06:29:04.0 06:29:06.7 +2.7 sec Altitude 843.8 km 835.0 km -8.8 km Latitude (JMED) 30.38 deg 30.62 deg +0.24 deg

OTM-7: 0.6 m/s (1.3 mph)
PM Savings: ~8 kg
(Courtesy Galileo Navigation Team)

Ganymede 1 Doppler Plot

Ganymede 1 Quick-Look Orbit Facts

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