Galileo Ganymede 1 Flyby Entry Timeline

Ganymede 1 Flyby was 27 June 1996

Galileo's first flyby of Ganymede on 27 June was the first of the satellite flybys to have all the instruments taking observations. (During the Io flyby in December 1995, no images were taken to ensure that all the probe data were captured.) During this encounter, the Energetic Particles Detector (EPD) went into a safe mode and did not make any observations close to Ganymede. In addition, following the flyby, the Near Infrared Mapping Spectrometer (NIMS) experienced some difficulties in playing back some of its data. Both problems have been fixed by ground engineers and are not expected to reoccur.

At the same time the NIMS experienced its anomalous behaviour, the Photopolarimeter-Radiometer (PPR) experienced a problem with its filter wheel, which engineers discovered after the encounter had become stuck. Attempts to free the stuck filter wheel will not occur until after the Ganymede 2 encounter, therefore no observations will be made with the PPR during that encounter.

The flyby of Ganymede made by Galileo was the first of several close encounters of the Galilean satellites and the second closest flyby Galileo will make to Ganymede. The distance Galileo came to Ganymede during this flyby was about 835 km altitude above the satellite (or about 1.3 Ganymede radii from Ganymede's center), some 17 times closer than Voyager 2. Some tentative science results from some of the instruments are available in a JPL press release dated 10 July 1996.

The following timeline is a list of different events which occurred beginning with the official start of the Ganymede encounter and proceding until the last data from the encounter were played back. The times are given in Universal Time (UTC) of the event at the spacecraft.

Date/Time             Instrument    Event
________              __________    _____
23 June 16:00                       Start of Ganymede encounter
        16:02         F&P           Real-time survey (Ganymede-1)

24 June 02:54         UVS           Jupiter auroral map, Io footprint
        18:30                       Orbital Trim Maneuver (OTM) 6

25 June 17:36         SSI           First Io monitoring observation (See NSSDCA Photo Gallery.)

26 June 08:45         SSI           Ganymede Global color image
        12:40         NIMS          Callisto Global composition map
        20:29         RS            Ganymede gravity field measurement
        21:23         UVS           Io torus observation
        21:30         NIMS/UVS      Ganymede global surface map

27 June 03:24         PPR           Ganymede dayside thermal map
        04:18         SSI           First Great Red Spot (GRS) observation (See NSSDCA Photo Gallery.)
        06:07         F&P           Ganymede wake crossing recording
        06:08         SSI           Mosaic of Uruk Sulcus (Ganymede) (See NSSDCA Photo Gallery.)
        06:09         SSI           Mosaic of Galileo Regio (Ganymede) (See NSSDCA Photo Gallery.)
        06:29                       Ganymede closest approach (3,480 km)
        13:13                       Callisto closest approach (1,040,000 km) 

28 June 00:01         NIMS          Europa north high-latitude observation (See NSSDCA Photo Gallery.)
        00:31                       Jupiter closest approach (789,000 km)
        01:22                       Europa closest approach (156,000 km)
        01:43         NIMS/SSI      Europa global observation
        18:22         PPR           Io full disk map (See NSSDCA Photo Gallery.)
        18:28                       Io closest approach (697,000 km)
        22:30                       Science turn (high-phase Io, Jupiter)

29 June 03:37         PPR
        03:46         SSI
        06:38                       Science turn (high-phase Io, Jupiter)
        11:32         NIMS          Last Io monitoring observation
        14:45         NIMS          Last GRS observation

30 June 02:00         F&P           Plasma sheet crossing recording
        04:30                       Start of data playback (Ganymede-1)
        07:42                       Orbital Trim Maneuver (OTM) 7

01 July 00:45                       Turn to return to Earth point

03 July 00:00         F&P           End of real-time survey (Ganymede-1)

05 Aug  08:00                       Orbital Trim Maneuver (OTM) 8

10 Aug  01:49                       Ganymede OPNAV (for Ganymede-2)

15 Aug  00:00         F&P           Start of first magnetosphere mini-tour

19 Aug  01:49                       Turn for attitude maintenance

27 Aug  06:36         EUV/UVS       First Io torus observation (Ganymede-2)
        17:30                       Orbital Trim Maneuver (OTM) 8

01 Sep  16:00                       End of data playback (Ganymede-1)

Other Event Related News

| NSSDCA Galileo page | NSSDCA Planetary page |

Dr. Edwin V. Bell, II
Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771

NASA Official: Dr. David R. Williams V1.0, 29 August 1996
Last Updated: Monday, 02-Mar-2015 13:38:01 EST, EVB II