PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = " Original Author/Date Unknown; Richard Simpson, 1994 - Primary author; Steven Joy, 1998-06 - Changed text to past tense, added table 1; Carol Polanskey, 1998-06 - Updated orbital phase date/times and corrected other errors and omissions; Lyle Huber, 1998-08 - Add Probe info; Steven Joy, 1998-10 - Removed 'Spacecraft Operations Type' throughout, updated LAUNCH info; Carol Polanskey, 1998-10 - Added FSW Phase descriptions; " OBJECT = MISSION MISSION_NAME = "GALILEO" OBJECT = MISSION_INFORMATION MISSION_START_DATE = 1977-10-01 MISSION_STOP_DATE = 1997-12-15 MISSION_ALIAS_NAME = "JUPITER ORBITER-PROBE (JOP)" MISSION_DESC = " Mission Overview ================ The Galileo mission utilized a single launch of a combined Orbiter and Probe using the space shuttle Atlantis and an inertial upper stage (IUS) to inject the Galileo spacecraft on its interplanetary trajectory to Jupiter. The launch occurred October 18, 1989. Since the IUS does not have the energy to inject Galileo on a direct trajectory to Jupiter, the spacecraft was launched first towards Venus for the first leg of its Venus-Earth-Earth gravity assist (VEEGA) trajectory. Target-of-opportunity science observations were made at Venus (closest approach February 10, 1990), the first Earth encounter (closest approach to Earth and Moon December 8 and 9, 1990), the asteroid Gaspra (closest approach October 29, 1991), the second Earth encounter (closest approach to Earth and Moon December 8, 1992), the asteroid Ida (closest approach August 28, 1993), and distant observations of the impact of comet Shoemaker-Levy 9 into Jupiter's atmosphere from July 16-22, 1994. The Probe separated from the Orbiter on July 13, 1995. After this time, the Probe proceeded on a ballistic trajectory to its entry point (6.54 deg north latitude, 4.46 west longitude) into the atmosphere of Jupiter. The Orbiter used its 400 Newton engine on July 27, 1995 to perform a deflection maneuver to keep from following the Probe into the atmosphere of Jupiter, and to retarget the Orbiter to the proper encounter conditions required for the Jupiter Orbit Insertion phase of the mission. A close flyby (892 kilometer altitude) of the Jovian satellite Io occurred at 17:45:58 UT on Dec 7, 1995, during the Jupiter Orbit Insertion phase. This flyby allowed fields and particles science observations to be made and slowed the Orbiter down relative to Jupiter by nearly 200 meters/second in order to reduce the propellant required during the Jupiter Orbit Insertion (JOI). Remote sensing observations of Io were not made at this time due to an anomaly with the onboard tape recorder associated with high speed recording that was not well understood at the time of the flyby. Perijove at 4.00 Jupiter radii occurred at 21:53:44 UT on the same day. A few minutes after perijove passage, the Probe entered the Jovian atmosphere and began relaying data back to the Orbiter. The Probe mission and data relay lasted 58.6 minutes, after which JOI was performed, slowing the Orbiter down relative to Jupiter by about 630 meters/second. The initial orbit period is about 200 days. A large 400 Newton engine burn is performed at the first apojove in order to raise perijove from 4 Jupiter radii to about 9 Jupiter radii, thus allowing the mission to complete 10 targeted satellite encounters without exceeding the allowed total accumulated radiation exposure at the spacecraft. This limit would have been exceeded after three orbits if perijove had been allowed to stay at 4 Jupiter radii, where the radiation environment is very severe. Orbital operations consisted of 10 targeted satellite encounters over 24 months. During the course of the satellite tour, the orientation, shape and size of the spacecraft orbits around the Jovian system, referred to as petals because of how the spacecraft orbits appear on an equatorial projection of the Jovian satellite tour trajectory, were controlled almost exclusively by gravity assists of the satellites themselves. The orbit periods were pumped down by successive encounters with the satellites from the initial 200 days to approximately 35-40 days between encounters. During the 9th orbit, when the orbit petal orientation was approximately in the anti-sun direction, the period was again pumped up to about 100 days which allowed one of the primary objectives, probing the Jovian magnetotail, to be accomplished. After this magnetotail orbit, the period was again pumped down, by gravity assist encounters with the Jovian satellites, to 35-40 days for the final targeted encounters. (Refer to GLLMS1991, GLLSRD1989, and GLLIOM1992). The Galileo orbits were named by concatenating the first letter of the name of the primary target in each orbit with the orbit number. Thus, the fourth Jupiter orbit, in which Europa is the primary target, is called E4. The project defined orbits according to spacecraft command load boundaries rather than the normal convention of apoapsis to apoapsis. The navigation team did not always adhere to this convention, causing some confusion. The PDS organized the data and data delivery schedule around the project defined orbit boundaries. Table 1 contains information about the orbital tour: _______________________________________________________________ Table 1 Orbital Facts _______________________________________________________________ Periapsis Periapsis Satellite Satellite Orbit Range* (Rj) Date/Time Closest Approach Flyby (Rj=71492km) (UT) Date/Time (UT) Alt** (km) _______________________________________________________________ J0 4.00 95-341 21:53:44 95-341 17:45:58 896 G1 11.03 96-180 00:31:26 96-179 06:29:07 838 G2 10.65 96-251 13:37:54 96-250 18:59:34 264 C3 9.21 96-311 13:31:07 96-309 13:34:28 1138 E4 9.16 96-354 03:21:58 96-354 06:52:58 688 J5 9.05 97-020 00:26:57 N/A N/A E6 9.12 97-051 20:54:15 97-051 17:06:10 582 G7 9.12 97-094 11:03:38 97-095 07:09:58 3104 G8 9.27 97-128 11:41:46 97-127 15:56:10 1606 C9 10.77 97-178 11:52:22 97-176 13:47:50 421 C10 9.17 97-261 23:10:00 97-260 00:18:55 538 E11 8.97 97-311 00:42:01 97-310 20:31:44 2039 * Range is measured from center of mass ** Altitude is computed by subtracting a satellite radius from a measured range. Variations in reported values may be attributed to differences in the radius value value subtracted (estimates improve). The failed deployment of the Galileo High Gain Antenna necessitated fundamental changes in how the spacecraft acquired and transmitted data back to Earth if more than a fraction of the science objectives were to be met. Changes were required to both the spacecraft software (Command Data System (CDS) and Attitude and Articulation Command System (AACS)) and many of the science instruments software. The mission can be described in terms of three distinct set of flight software (FSW) which are commonly called Phase 0 FSW, Phase 1 FSW, and Phase 2A FSW. The Galileo flight software phases should not be confused with Mission Phases which will be describe later. Phase 0: Initial spacecraft flight software configuration at launch. Telemetry was sent in a Time-Division-Multiplex (TDM) or Fixed-format mode. The data rates in this phase were designed to be supported by the high gain antenna and had very limited capability to return science data at telemetry rates below 7.68 kbps. The Phase 0 flight software was patched on June 15, 1993 to increase the memory readout block size from 32 bytes to 80 bytes. Phase 1: The Phase 1 flight software consisted of minor modifications of Phase 0 to improve the data return from the Galileo probe. It was loaded onto the spacecraft January 30 through February 12, 1995. The changes provided for: the capability to write edited Probe symbol data and Doppler wind data to the extended memory of the primary onboard computer, new downlink telemetry rates at 8 bps and 16 bps, a new 7.68 kbps Probe data record format, 80 byte memory readouts to decrease data return time, and more robust fault protection during the time of Relay/JOI. Phase 2A: The Phase 2 flight software is fundamentally different from the Phase 0 flight software. The purpose of the changes was to utilize the low gain antenna more effectively to return science data. There were two major categories of change: 1) to return data from the tape recorder in a more efficient and autonomous fashion, and 2) to provide a real time capability for the fields and particles science instruments. More than 58% of the onboard computer memory was loaded with new code. The new capabilities included packetized telemetry with advanced Reed-Solomon encoding, 8 downlink rates from 8 to 160 bps, new tape recorder record formats, automated and adaptive playback modes, science data selection, sampling, summation and compression, and 9 low rate real-time science downlink formats. Real time editing of optical navigation images was also provided. Eight of the science instruments also developed new flight software in support of the changing spacecraft capabilities in Phase 2. Select science instruments were provided with automated loading of their onboard stored, mode dependent software. While the Phase 2 flight software was in testing, problems were discovered with the tape recorder. Additional features were added to the flight software to manage the tape recorder to avoid the known failure mechanisms and to avoid unwrapping the tape which had been damaged in the spacecraft anomaly of October 11, 1995. The final flight software delivery which included the tape recorder modifications was called Phase 2A. The Phase 2A flight software was loaded onto the spacecraft from May 18-22, 1996. The instrument Phase 2 software loads were completed by May 26, 1996. Numerous anomalies occurred on the Orbiter during this mission that impacted data return but did not fundamentally change the mission. Please check the Galileo Orbiter instrument host catalog for additional information on spacecraft anomalies. The end of mission occurred on December 15, 1997 with a viable spacecraft in orbit around Jupiter. A new mission called the 'Galileo Europa Mission (GEM)' was proposed to NASA and approved. This new mission has new science objectives and is truly a new mission using an old spacecraft. The GEM mission is expected to include seven more flybys of Europa, four more flybys of Callisto, and 2 passes by Io that include remote sensing. Please see the GEM mission template for more details. Mission Phases ============== LAUNCH AND DEPLOYMENT --------------------- Galileo was launched on October 18, 1989 at 16:53:39 GMT aboard the Space Shuttle Atlantis (OV-104), flight STS-34. An Inertial Upper Stage (IUS-19) placed Galileo on its Earth- to-Venus trajectory. Following the IUS burn, Galileo configured itself for solo flight and separated from the IUS on October 19, 1989 at 01:06:53 GMT. (Refer to GLLMS1991). After IUS separation, the spacecraft underwent an outgassing period prior to powering on the science instruments. The instruments were turned on later and data were acquired to verify that each instrument was operational. The commanding of this process was more complicated than most command sequences since the exact launch date and time were not known in advance. The launch and deployment mission phase covers the same time period as was covered by the command sequences LAUNCH and EV0 (Earth-Venus 0). Spacecraft Id : GO Target Name : VENUS Mission Phase Start Time : 1989-10-17T00:00:00 Mission Phase Stop Time : 1989-10-26T16:00:00 INTERPLANETARY CRUISE --------------------- The trajectory of the spacecraft from Earth to Jupiter was dictated by the limited propulsion capability allowed within the Space Shuttle to boost the spacecraft from Earth orbit to an interplanetary trajectory. This limit prevented a direct trajectory from Earth to Jupiter; instead a 'VEEGA' trajectory was used to achieve the energy necessary to send Galileo to Jupiter. The acronym VEEGA is from the trajectory description: Venus-Earth-Earth Gravity Assist. In this trajectory, Galileo passes Venus once, then flies by Earth twice, thus obtaining three gravity assists before heading toward Jupiter. (Refer to SSR1992.) The Earth-Jupiter Cruise phase includes the following phases: Earth-Venus Cruise, Venus Encounter, Venus-Earth Cruise, Earth1 Encounter, Earth-Earth Cruise, Gaspra Encounter, Earth2 Encounter, Earth-Jupiter Cruise, Ida Encounter, Shoemaker-Levy 9 Encounter, Probe Release. Spacecraft Id : GO Target Name : JUPITER Target Name : VENUS Target Name : EARTH Target Name : IDA Target Name : GASPRA Target Name : SL9 Mission Phase Start Time : 1989-10-26T16:00:00 Mission Phase Stop Time : 1995-10-08T00:00:00 EARTH-VENUS CRUISE ------------------ The Earth-Venus Cruise phase occurred during the Interplanetary Cruise phase. It lasted from the end of the Launch sequence to February 19, 1990. This phase included the encounter with the planet Venus. Spacecraft Id : GO Target Name : VENUS Mission Phase Start Time : 1989-10-26T16:00:00 Mission Phase Stop Time : 1990-02-19T00:00:00 4-DAY CHECKOUT -------------- The 4-Day Checkout phase occurred during the Earth-Venus portion of Interplanetary Cruise phase. This was the first time the science instruments were turned on and permitted to check their health after launch. Calibration data exists for all instruments from this period. Spacecraft Id : GO Target Name : N/A Mission Phase Start Time : 1989-12-27T00:00:00 Mission Phase Stop Time : 1989-12-31T00:00:00 VENUS ENCOUNTER --------------- The Venus Encounter phase occurred during the Interplanetary Cruise phase. A 12-day single load sequence provided the sequencing resources for the Venus encounter. Most of the data gathered were put onto the onboard tape recorder, since the high gain antenna had to remain furled behind its sunshade during this near-sun activity, and the low gain antenna did not have the performance for real-time science data transmission to Earth during the Venus encounter. The Venus encounter data were played back to Earth in November 1990, when Galileo was close enough to Earth that science data rates could be achieved over the low gain antenna. Upstream energetic particles were detected, bowshock crossings were indicated, and the plasma wave instrument saw evidence of lightning discharges. Eighty-one images by the Solid State Imaging experiment were taken, which proved useful in atmospheric motion studies. In addition, the Venus encounter yielded radio tracking data which have been analyzed by the Radio Science (Celestial Mechanics) Team to obtain a mass estimate for Venus. In contrast to the other experiments, the Radio Science data were not stored on the spacecraft recorder, but were available in real time on Earth for analysis. (Refer to GLLMS1991). Closest approach to Venus occurred February 10, 1990 at an altitude of 16,123 km. at 05:58:48 UTC. Spacecraft Id : GO Target Name : VENUS Time of closest approach : 1990-02-10T05:58:48 Mission Phase Start Time : 1990-02-07T00:00:00 Mission Phase Stop Time : 1990-02-19T00:00:00 VENUS-EARTH CRUISE ------------------ The Venus-Earth Cruise phase occurred during the Interplanetary Cruise phase. It included the interplanetary cruise from Venus, around the sun, and back to and past the Earth. This phase also included the first Earth encounter. The primary science gathering during this period was performed through EUV, DDS, MAG and the USO Redshift experiments. In November 1990, as the spacecraft approached the first Earth encounter, the three DMS tracks of Venus data were successfully played back. The High-Gain Antenna Deployment planned for April 11, 1991 was unsuccessful, most likely due to an incomplete release of three HGA ribs. Future attempts for rib release were then scheduled for Earth-Earth Cruise. Spacecraft Id : GO Target Name : EARTH Target Name : MOON Mission Phase Start Time : 1990-02-19T00:00:00 Mission Phase Stop Time : 1991-04-29T00:00:00 EARTH1 ENCOUNTER ---------------- The first Earth gravity assist occurred on December 8, 1990 at a flyby altitude of 960 km at 20:34:35 UTC. The Moon encounter occurred on December 9, 1990 at a flyby altitude of 346,608 km at 2:28:21 UTC. The spacecraft trajectory took Galileo virtually up the Earth's magnetotail, providing unprecedented opportunity for fields and particles measurements. The plasma science experiment results brought into question the validity of the previous assumption that the bulk flows of the ion and electron plasmas in the distant magnetotail are identical. Spectral mapping observations of Australia and Antarctica were made by the near infrared mapping spectrometer. A first ever time-lapse movie, in six colors, of the rotating Earth over a period slightly greater than one day was made by the Solid State Imaging experiment. Multispectral imaging of the western nearside and eastern farside of the Moon were obtained by the SSI. These data showed that Orientale Basin ejecta deposits are similar to typical highlands deposits such as the soils at the Apollo 16 site, while observations of the South Pole-Aitken basin interior contain characteristics that appear distinctively different from that of nearside maria, thus providing new information on mare deposits on the limb and farside of the Moon. Spacecraft Id : GO Target Name : EARTH Time of closest approach : 1990-12-08T20:34:35 Target Name : MOON Time of closest approach : 1990-12-09T02:28:21 Mission Phase Start Time : 1990-11-08T00:00:00 Mission Phase Stop Time : 1990-12-16T00:00:00 EARTH-EARTH CRUISE ------------------ The Earth-Earth cruise phase occurred during the Interplanetary Cruise phase. It included the interplanetary cruise from Earth, around the sun, and back to and past the Earth a second time. Key activities included the on-going HGA Recovery effort, which proved unsuccessful, encounters with the asteroid Gaspra as well as with Earth, collection of cruise science data, SSI cover and EPD shade deployments and opportunities for radio science experiments at spacecraft conjunction and opposition. Spacecraft Id : GO Target Name : EARTH Target Name : MOON Target Name : GASPRA Mission Phase Start Time : 1991-04-29T00:00:00 Mission Phase Stop Time : 1993-04-12T00:00:00 GASPRA ENCOUNTER ---------------- The Gaspra Encounter phase occurred during the Interplanetary Cruise phase and the Earth-Earth Cruise phase. On 29 October 1991 Galileo passed Gaspra at a distance of approximately 1,600 km and a speed of approximately 30,000 km per hour. Color and black and white images were taken of Gaspra as well as measurements to indicate composition and physical properties. The data were stored on the spacecraft tape recorder and later played back to Earth. Spacecraft Id : GO Target Name : GASPRA Time of closest approach : 1991-10-29T22:36:46 EARTH2 ENCOUNTER ---------------- The Earth2 Encounter phase occurred during the Interplanetary Cruise phase and the Earth-Earth Cruise phase. The second Earth encounter provided an opportunity to gather Earth and Lunar science and perform instrument calibrations. Additionally, during this period Galileo participated in the GOPEX deep space laser communication experiment. The flyby altitude of Moon 2 was 110,267 km on December 8, 1990 at 3:57:45 UTC. The flyby altitude of the Earth 2 was approximately 304 km at 15:09:25 UTC. Spacecraft Id : GO Target Name : EARTH Time of closest approach : 1992-12-08T15:09:25 Target Name : MOON Time of closest approach : 1992-12-08T03:57:45 Mission Phase Start Time : 1992-11-08T00:00:00 Mission Phase Stop Time : 1992-12-20T00:00:00 EARTH-JUPITER CRUISE -------------------- The Earth-Jupiter Cruise phase occurred during the Interplanetary Cruise phase. It covered the period from April 12, 1993 to October 8, 1995. The second Earth encounter places the spacecraft on a direct trajectory to Jupiter. Again, the spacecraft passed through the Asteroid Belt. This transit included an August 1993 encounter with the 32-km.-diameter, S-type, main-belt asteroid, Ida. The Earth-Jupiter Cruise phase included the following phases: Ida Encounter, Shoemaker-Levy 9 Encounter, Probe Release and ODM. Spacecraft Id : GO Target Name : JUPITER Target Name : IDA Target Name : SL9 Mission Phase Start Time : 1993-04-12T00:00:00 Mission Phase Stop Time : 1995-10-09T00:00:00 IDA ENCOUNTER ------------- The Ida Encounter phase occurred during the Interplanetary Cruise phase and the Earth-Jupiter Cruise phase. Galileo flew by Ida in the southern hemisphere (75 degrees south ecliptic latitude) on the asteroid's dark side, passing approximately 2400 km (1500 mi) from the center of the asteroid while traveling at a speed relative to the asteroid of 12.4 km/sec (27,700 mph). During closet approach, Ida appeared from Earth to be located at Right Ascension: 196.7 degrees; Declination: -8.0 degrees toward the constellation Virgo. Ida is 3-4 degrees northwest of Spica, Virgo's brightest star. Spacecraft Id : GO Target Name : IDA Time of closest approach : 1993-08-28T16:52:05 SHOEMAKER-LEVY 9 ENCOUNTER -------------------------- The Shoemaker-Levy 9 Encounter phase occurred during the Interplanetary Cruise phase and the Earth-Jupiter Cruise phase. Shoemaker-Levy 9 was a comet that broke into multiple pieces during its passage by Jupiter in July 1992. On July 16,1994 these fragments began to impact Jupiter. It is estimated that between 20 and 25 struck the planet. Observations were made by the following instruments: NIMS, SSI, PPR, PWS, EUV/UVS. MAG and DDS conducted observations over a longer period of time. Spacecraft Id : GO Target Name : SL9 Mission Phase Start Time : 1994-07-16T00:00:00 Mission Phase Stop Time : 1994-07-22T00:00:00 PROBE RELEASE AND ODM --------------------- The Probe Release Encounter phase occurred during the Interplanetary Cruise phase and the Earth-Jupiter Cruise phase. The Probe was released on July 13, 1995 at 05:30:00 UTC, which was ~150 days before Jupiter Orbit Insertion (JOI). Fourteen days after release, July 27th, the Orbiter performed an Orbit Deflection Maneuver (ODM) of about 60 m/sec to place it on a trajectory which overflew the Probe during its entry and descent. The ODM was the first use of the 400 N engine. Spacecraft Id : GP Spacecraft Id : GO Target Name : JUPITER Mission Phase Start Time : 1995-07-05T00:00:00 Mission Phase Stop Time : 1995-07-31T00:00:00 JUPITER ORBIT OPERATIONS ------------------------ Jupiter arrival occurred on December 7, 1995. Arrival day at Jupiter was characterized by a rapid series of high-priority engineering and science events. Much of the science that was unique to this orbit (science requiring remote sensing data) was lost due to an anomaly with the onboard tape recorder. No science data were acquired during the 32,000 km non-targeted encounter of Europa. About 4 1/2 hours after the Europa fly-by, the spacecraft then flies within about 1000 km of Io. Fields and particles data were recorded for approximately 3 hours in the vicinity of Io. The flyby was also designed to provide a gravity assist which reduced the delta-V necessary to achieve orbit around Jupiter. The probe entry occurred a little over 4 hours after the Io encounter. During the descent of the Probe its data were relayed to the Orbiter. Probe Relay lasted 58.6 minutes and was followed about one hour later by the JOI burn. Probe data were played back from the tape recorder on the orbiter twice over the next several months to ensure that no Probe data were lost. Another hour of fields and particles science data were recorded after probe relay in conjunction with the JOI maneuver. At apojove of the insertion orbit, a large Perijove Raise Maneuver (PJR) increased the perijove altitude of the orbit and targeted the spacecraft for its first encounter. After this time, the trajectory was primarily shaped by close encounters with Ganymede, Callisto, and Europa. Ten such close encounters, one per orbit, plus a one-month 'phasing orbit' which occurred between the Europa 4 encounter and the Europa 6 encounter were planned over the 24 months of the orbital mission. There was no targeted encounter during the phasing orbit. There were several non-targeted encounters (at ranges of tens to hundreds of thousands of kilometers) of the Galilean satellites, Jovian atmospheric and magnetospheric measurements throughout the tour, and a large 'tail petal' orbit designed to explore the Jovian magnetotail. Spacecraft Id : GO Target Name : JUPITER Target Name : IO Target Name : CALLISTO Target Name : GANYMEDE Target Name : EUROPA Mission Phase Start Time : 1995-10-09T00:00:00 Mission Phase Stop Time : 1997-12-15T00:00:00 JUPITER APPROACH ---------------- The Jupiter Approach phase occurred during the Jupiter Orbit Operations phase. An image of Jupiter was taken on approach; however, shortly afterwards there was an anomaly with the onboard tape recorder which prohibited the return of that image. The only science data acquired on approach was from DDS, EUV and MAG. Spacecraft Id : GO Target Name : JUPITER Mission Phase Start Time : 1995-10-09T00:00:00 Mission Phase Stop Time : 1995-12-03T00:00:00 JUPITER 0 ORBIT --------------- The Jupiter 0 Orbit phase occurred during the Jupiter Orbit Operations phase. Jupiter arrival occurred on December 7, 1995. Arrival day at Jupiter was characterized by a rapid series of high-priority engineering and science events. Much of the science that was unique to this orbit (science requiring remote sensing data) was lost due to an anomaly with the onboard tape recorder. No science data were acquired during the 32,000 km non-targeted encounter of Europa. About 4 1/2 hours after the Europa fly-by, the spacecraft then flies within about 1000 km of Io. Fields and particles data were recorded for approximately 3 hours in the vicinity of Io. The flyby was also designed to provide a gravity assist which reduced the delta-V necessary to achieve orbit around Jupiter. The probe entry occurred a little over 4 hours after the Io encounter. During the descent of the Probe its data were relayed to the Orbiter. Probe Relay lasted 58.6 minutes and was followed about one hour later by the JOI burn. Probe data were played back from the tape recorder on the orbiter twice over the next several months to ensure that no Probe data were lost. Another hour of fields and particles science data were recorded after probe relay in conjunction with the JOI maneuver. At apojove of the insertion orbit, a large Perijove Raise Maneuver (PJR) increased the perijove altitude of the orbit and targeted the spacecraft for its first encounter. Spacecraft Id : GO Target Name : JUPITER Target Name : IO Mission Phase Start Time : 1995-12-03T00:00:00 Mission Phase Stop Time : 1996-06-23T00:00:00 IO 0 ENCOUNTER ---------- The Io 0 encounter phase occurred during the Jupiter 0 Orbit operations phase. The spacecraft flew past Io at an altitude of less than 900 km. Much of the science that was unique to this orbit (science requiring remote sensing data) was lost due to an anomaly with the onboard tape recorder. This was the only close flyby of Io during the mission. Fields and particles data were recorded for approximately 3 hours in the vicinity of Io. Another hour of fields and particles science data were recorded after probe relay while still in the Io torus. In addition to providing science data, the flyby was designed to provide a gravity assist which reduced the delta-V necessary to achieve orbit around Jupiter. Spacecraft Id : GO Target Name : IO Time of closest approach : 1995-12-07T17:45:58 Mission Phase Start Time : 1995-12-03T00:00:00 Mission Phase Stop Time : 1996-01-03T00:00:00 PROBE ----- The Probe phase occurred during the Jupiter Orbit Operations phase. The probe entry occurred a little over 4 hours after the Io encounter. During the descent of the Probe its data were relayed to the Orbiter where is was stored on tape. The data were later replayed and transmitted to Earth. The Probe Relay lasted 58.6 minutes and was followed about one hour later by the JOI burn. For a more complete description of the Galileo Probe mission, please refer to [YOUNGETAL1996]. Spacecraft Id : GP Spacecraft Id : GO Target Name : JUPITER Mission Phase Start Time : 1995-12-07T22:01:00 Mission Phase Stop Time : 1995-12-07T23:22:00 GANYMEDE 1 ORBIT ---------------- Spacecraft Id : GO Target Name : GANYMEDE Mission Phase Start Time : 1996-06-23T00:00:00 Mission Phase Stop Time : 1996-09-01T00:00:00 GANYMEDE 1 ENCOUNTER -------------------- Objectives: Wake, Alfven Wing, start of first magnetospheric mini-tour, remote Io torus observations, plasma sheet crossing at 25 Rj, Ganymede and Europa geology and atmospheric properties, Io monitoring, distant Callisto observations, gravity, Great Red Spot, Jupiter northern and southern aurora, Io footprint, reduce period. Altitude: 838 km, Latitude: 30.39 degrees Spacecraft Id : GO Target Name : GANYMEDE Time of closest approach : 1996-06-27T06:29:07 Mission Phase Start Time : 1996-06-23T00:00:00 Mission Phase Stop Time : 1996-06-30T00:00:00 GANYMEDE 2 ORBIT ---------------- Spacecraft Id : GO Target Name : GANYMEDE Mission Phase Start Time : 1996-09-01T00:00:00 Mission Phase Stop Time : 1996-11-02T00:00:00 GANYMEDE 2 ENCOUNTER -------------------- Objectives: North Alfven wing, Jovian radio emissions, first mini-tour of Jovian magnetosphere continues, remote Io torus, plasma sheet crossing at 40 Rj, unique Ganymede north polar pass, Europa low- phase global images, Io monitoring, Callisto, Amalthea, stratospheric circulation, Jupiter southern aurora, Shoemaker-Levy 9 remnant material images, gravity, reduce inclination Altitude: 264 km, Latitude: 79.29 degrees Spacecraft Id : GO Target Name : GANYMEDE Time of closest approach : 1996-09-06T18:59:34 Mission Phase Start Time : 1996-09-01T00:00:00 Mission Phase Stop Time : 1996-09-08T00:00:00 CALLISTO 3 ORBIT ---------------- Spacecraft Id : GO Target Name : CALLISTO Mission Phase Start Time : 1996-11-02T00:00:00 Mission Phase Stop Time : 1996-12-15T00:00:00 CALLISTO 3 ENCOUNTER -------------------- Objectives: Wake and Alfven Wing, completion of first mini-tour of Jovian magnetosphere, Jupiter aurora, remote Io torus, Callisto Asgard Basin, Europa non-targeted encounter - volcanism observations, closest Io approach of tour, gravity, UVS counter-rotate, white oval observations, Jupiter northern aurora, Jupiter atmosphere during solar occultation. Altitude: 1138 km, Latitude: 13.19 degrees Spacecraft Id : GO Target Name : CALLISTO Time of closest approach : 1996-11-04T13:34:28 Mission Phase Start Time : 1996-11-02T00:00:00 Mission Phase Stop Time : 1996-11-11T00:00:00 EUROPA 4 ORBIT -------------- Spacecraft Id : GO Target Name : EUROPA Mission Phase Start Time : 1996-12-15T00:00:00 Mission Phase Stop Time : 1997-02-16T00:00:00 EUROPA 4 ENCOUNTER ------------------ Objectives: Wake and northern Alfven wing, north to south plasma sheet crossing, remote Io torus, excellent Europa dayside and nightside coverage, Io partial eclipse, Jupiter rings, Amalthea, Thebe, Adrastea, northern equatorial belt hot spot, Europa & Jupiter occultations, Jupiter northern aurora. Altitude: 688 km, Latitude: -1.65 degrees Spacecraft Id : GO Target Name : EUROPA Time of closest approach : 1996-12-19T06:52:58 Mission Phase Start Time : 1996-12-15T00:00:00 Mission Phase Stop Time : 1996-12-22T00:00:00 EUROPA 6 ORBIT -------------- Spacecraft Id : GO Target Name : EUROPA Mission Phase Start Time : 1997-02-16T00:00:00 Mission Phase Stop Time : 1997-03-30T00:00:00 EUROPA 6 ENCOUNTER ------------------ Objectives: South Alfven wing, Jupiter magnetic equator crossing, Europa Argiope Linea and other lineated regions, Io plume monitoring, Jupiter rings, Thebe, Amalthea, south equatorial belt-zone region, Jupiter northern aurora, Europa, Io, and Jupiter occultations Altitude: 582 km, Latitude: -17.02 degrees Spacecraft Id : GO Target Name : EUROPA Time of closest approach : 1997-02-20T17:06:10 Mission Phase Start Time : 1997-02-16T00:00:00 Mission Phase Stop Time : 1997-02-23T00:00:00 GANYMEDE 7 ORBIT ---------------- Spacecraft Id : GO Target Name : GANYMEDE Mission Phase Start Time : 1997-03-30T00:00:00 Mission Phase Stop Time : 1997-05-04T00:00:00 GANYMEDE 7 ENCOUNTER -------------------- Objectives: North Alfven Wing, first dawn-side plasma sheet at 46 Rj, start of second mini-tour of Jovian magnetosphere, Ganymede high-energy impact regions (Kittu, etc.), Europa non-targeted encounter, Callisto full-color mosaic, visually clear or Brown Barge regions, Jupiter northern aurora. Altitude: 3104 km, Latitude: 55.80 degrees Spacecraft Id : GO Target Name : GANYMEDE Time of closest approach : 1997-04-05T07:09:58 Mission Phase Start Time : 1997-03-30T00:00:00 Mission Phase Stop Time : 1997-04-06T00:00:00 GANYMEDE 8 ORBIT ---------------- Spacecraft Id : GO Target Name : GANYMEDE Mission Phase Start Time : 1997-05-04T00:00:00 Mission Phase Stop Time : 1997-06-22T00:00:00 GANYMEDE 8 ENCOUNTER -------------------- Objectives: Upstream wake crossing, continue second mini-tour of Jovian magnetosphere, plasma sheet/Jupiter aurora at 20 Rj, Ganymede surface morphology: Osiris, Tiamat Sulcus, etc., Callisto non-targeted encounter south pole, Metis, Elara, south polar haze zone, Jupiter northern and southern aurora, Io footprint, Ganymede & Jupiter occultations. Altitude: 1606 km, Latitude: 28.27 degrees Spacecraft Id : GO Target Name : GANYMEDE Time of closest approach : 1997-05-07T15:56:10 Mission Phase Start Time : 1997-05-04T00:00:00 Mission Phase Stop Time : 1997-05-11T00:00:00 CALLISTO 9 ORBIT ---------------- Spacecraft Id : GO Target Name : CALLISTO Mission Phase Start Time : 1997-06-22T00:00:00 Mission Phase Stop Time : 1997-09-14T00:00:00 CALLISTO 9 ENCOUNTER -------------------- Objectives: Unique deep magnetotail passage of 143 Rj, continue second mini-tour of Jovian magnetosphere, Jupiter aurora, Callisto Valhalla multi-ringed structure, Ganymede non-targeted encounter, Metis, Adrastea, Amalthea, Thebe, Great Red Spot, equatorial plume head, Io footprint, high solar phase angle of Jovian atmosphere, Callisto & Jupiter occultations. Altitude: 421 km, Latitude: 1.96 degrees Spacecraft Id : GO Target Name : CALLISTO Time of closest approach : 1997-06-25T13:47:50 Mission Phase Start Time : 1997-06-22T00:00:00 Mission Phase Stop Time : 1997-06-29T00:00:00 CALLISTO 10 ORBIT ----------------- Spacecraft Id : GO Target Name : CALLISTO Mission Phase Start Time : 1997-09-14T00:00:00 Mission Phase Stop Time : 1997-11-02T00:00:00 CALLISTO 10 ENCOUNTER --------------------- Objectives: Wake and Alfven Wing, continue second mini-tour of Jovian magnetosphere, Jupiter magnetic equator crossing, Callisto global and bright limb observations, Io aurora and Jupiter rings during solar occultation, Europa volcanism survey, Amalthea, Thebe, Adrastea, Metis, north polar haze region, Jupiter aurora and lightning during solar occultation. Altitude: 538 km, Latitude: 4.60 degrees Spacecraft Id : GO Target Name : CALLISTO Time of closest approach : 1997-09-17T00:18:55 Mission Phase Start Time : 1997-09-14T00:00:00 Mission Phase Stop Time : 1997-09-20T00:00:00 EUROPA 11 ORBIT --------------- Spacecraft Id : GO Target Name : EUROPA Mission Phase Start Time : 1997-11-02T00:00:00 Mission Phase Stop Time : 1997-12-15T00:00:00 EUROPA 11 ENCOUNTER ------------------- Objectives: Combined Europa fly-by and magnetic equator crossing for fields & particles instruments, end of second mini-tour of Jovian magnetosphere, Jupiter auroral map campaign, Brown Barge campaign, northern aurora oval, lightning detection campaign, ring observations, Io monitoring, Europa Pwyll, Mannann'an wedge and bright planes, Earth occultation. Altitude: 2039 km, Latitude: 25.73 degrees N Spacecraft Id : GO Target Name : EUROPA Time of closest approach : 1997-11-06T20:31:44 Mission Phase Start Time : 1997-11-02T00:00:00 Mission Phase Stop Time : 1997-11-09T00:00:00 " MISSION_OBJECTIVES_SUMMARY = " Mission Objectives Summary ========================== The Galileo mission was designed to make long-term investigations of the Jovian system using a spacecraft consisting of a Probe and an Orbiter. The Probe, after being released on the initial approach to Jupiter, entered the Jovian atmosphere and made in-situ measurements. The Probe data were relayed to Earth by the Orbiter. The Orbiter then entered orbit around Jupiter for a 23-month, 10-satellite encounter tour of the Jovian system. Specific science objectives of the Galileo mission were: Jovian Atmosphere: Determine and investigate the chemical composition; structure to at least 10 bars; radiative heat balance; circulation and dynamics; nature of cloud particles. Gaspra, Ida, and Galilean Satellites: Characterize the morphology, geology and physical state; investigate the surface mineralogy and surface distribution of minerals. Galilean Satellites: Determine the gravitational and magnetic fields and dynamic properties; study the atmospheres, ionospheres and extended gas clouds; study the magnetospheric interactions of the satellites. Jovian Magnetosphere: Characterize the vector magnetic fields and the energy spectra, composition and angular distribution of plasma and energetic particles, including plasma wave phenomena, out to 150 Rj." 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