Cassini Saturn Orbit Insertion Timeline

On July 30, Cassini will pass through its most critical mission milestone since launch, as the Saturn-bound spacecraft attempts to slow-down sufficiently for orbital capture. This slowing down is achieved first by flying close enough to Saturn and then in a reverse facing direction, by firing its engine (the ‘insertion burn’). To get close enough to the ringed planet, the spacecraft will have to fly through the wispy outer ring and thus collide with ring residue.

The following timeline and color key show the times and events as the mission unfolds– Colors: orange = maneuvers; blue = geometry; purple = SOI-related; green = data playbacks

UTC GroundUTC Pacific TimeTime wrt SOIActivityDescription
175T00:00 Jun 23 01:23Tue Jun 22 06:23 PMSOI-08d01hActivate SOI critical sequence and begin quiet period8-day period of minimal spacecraft activity begins; Solid State Recorders (SSRs) set to SOI configuration
181T19:00 Jun 29 20:24Tue Jun 29 01:24PM SOI-01d06hOrbiter transitions to SOI telemetry modeDual record of engineering on both Solid State Recorders (SSRs) begins; only real-time engineering at 1896 bps downlinked
181T20:00 Jun 29 21:24Tue Jun 29 02:24 PMSOI-01d05hBegin critical commanding for SOICritical sequence begins issuing commands for SOI (burn start – 29 hours)
182T23:27 Jul 01 00:51Wed Jun 30 05:51 PMSOI-01h45mTransition to Low-Gain Antenna 1 (LGA-1) communicationTelemetry is turned off; carrier only for SOI communication
182T23:47 Jul 01 01:11Wed Jun 30 06:11 PMSOI-01h25mTurn to protective attitude for ascending ring-plane crossingProtects spacecraft from dust encounter in ring plane; turn takes 10 min
183T00:47 Jul 01 02:11Wed Jun 30 07:11 PMSOI-00h25mAscending ring-plane crossing Distance = 158,500 km (98,500 miles);High-Gain Antenna (HGA) is oriented to dust ram direction
183T00:57 Jul 01 02:21Wed Jun 30 07:21 PMSOI-00h15mTurn to burn attitudeTurn takes 10 min; 6 min spare time after turn completion before burn start
183T01:11 Jul 01 02:35Wed Jun 30 07:35 PMSOI-00h01mOpen latch valvesValves opened in preparation for pressurized burn
183T01:12 Jul 01 02:36Wed Jun 30 07:36 PMSOI-00h00mSaturn Orbit Insertion burn startMain engine maneuver, velocity change = 626 m/s (1400 mph); 96 minute burn
183T01:35 Jul 01 02:59Wed Jun 30 07:59 PMSOI+00h23mCassini passes behind Saturn’s F ring as seen from EarthCommunication still likely
183T01:42 Jul 01 03:06Wed Jun 30 08:06 PMSOI+00h30mCassini passes behind Saturn’s A ring as seen from EarthCommunication unlikely for 25 minutes
183T02:07 Jul 01 03:31Wed Jun 30 08:31 PMSOI+00h55mCassini passes behind Cassini division as seen from EarthBrief communication possible for 6 minutes
183T02:13 Jul 01 03:37Wed Jun 30 08:37 PMSOI+01h01mCassini passes behind Saturn’s B ring as seen from EarthCommunication unlikely for 28 minutes
183T02:30 Jul 01 03:54Wed Jun 30 08:54 PMSOI+01h18mSaturn orbit achievedSpacecraft has slowed enough to be capture by Saturn’s gravity and is no longer in escaping orbit (78 min into burn)
183T02:39 Jul 01 04:03Wed Jun 30 09:03 PMSOI+01h27mClosest approach to Saturn in entire missionDistance = 80,230 km (49,850 miles) from center of Saturn, 19,980 km (12,400 miles) from cloud tops
183T02:41 Jul 01 04:05Wed Jun 30 09:05 PMSOI+01h29mCassini passes behind Saturn’s C ring as seen from EarthCommunication restore until science turns (C ring is less opaque to Cassini radio freqs than A or B ring)
183T02:48 Jul 01 04:12Wed Jun 30 09:12 PMSOI+01h36mSaturn Orbit Insertionnominal burn end
183T02:51 Jul 01 04:15Wed Jun 30 09:15 PMSOI+01h39mReconfigure radio comm, close main engine cover, begin turn toEarth-pointMain engine cover is closed to protect engine nozzles during descending ring plane crossing; will shift if burn ends late
183T02:54 Jul 01 04:18Wed Jun 30 09:18 PMSOI+01h42mSpaceraft on Earth-pointWill shift if burn ends late
183T02:57 Jul 01 04:21Wed Jun 30 09:21 PMSOI+01h45mNominal end of critical sequence; main engine cover fully closedWill shift if burn ends late
183T02:58 Jul 01 04:22Wed Jun 30 09:22 PMSOI+01h46mSaturn Orbit Insertionmax burn end
183T03:00 Jul 01 04:24Wed Jun 30 09:24 PMSOI+01h48mCassini passes behind Saturn’s D ring as seen from EarthCommunication remains likely (D ring is less opaque to Cassini radio frequencies than A or B ring)
183T03:06 Jul 01 04:30Wed Jun 30 09:30 PMSOI+01h54mMax end of critical sequenceBackground sequence takes over spacecraft control
183T03:06 Jul 01 04:30Wed Jun 30 09:30 PMSOI+01h54mSwitch to High-Gain Antenna (HGA) communicationTelemetry resumes; 1896 bits per second real-time engineering data transmitted
183T03:07 Jul 01 04:31Wed Jun 30 09:31 PMSOI+01h55mTurn off Earth-line for post-burn science observationsBackground sequence turns spacecraft to view rings and magnetosphere; communication not possible
183T03:15 Jul 01 04:39Wed Jun 30 09:39 PMSOI+02h03mJettison INMS coverIon & Neutral Mass Spectrometer (INMS) cover is removed for post-SOI observations
183T03:30 Jul 01 04:54Wed Jun 30 09:54 PMSOI+02h18mCassini passes behind Saturn’s C ring as seen from EarthCassini should be in science attitudes and will not be communicating with Earth; otherwise communication possible
183T03:33 Jul 01 04:57Wed Jun 30 09:57 PMSOI+02h21mCassini passes behind Saturn as seen from EarthCassini should be in science attitudes and will not be communicating with Earth; otherwise communication not possible
183T04:08 Jul 01 05:32Wed Jun 30 10:32 PMSOI+02h56mTurn to protective attitude for descending ring-plane crossingCassini descending crossing turn
183T04:09 Jul 01 05:33Wed Jun 30 10:33 PMSOI+02h57mCassini emerges from behind Saturn (and is behind A ring)Cassini should be in science attitudes and will not be communicating with Earth; otherwise communication not likely
183T04:20 Jul 01 05:44Wed Jun 30 10:44 PMSOI+03h08mCassini emerges from behind A ring as seen from EarthCassini should be in science attitudes and will not be communicating with Earth; otherwise communication possible
183T04:34 Jul 01 05:58Wed Jun 30 10:58 PMSOI+03h22mDescending ring-plane crossingDistance = 158,500 km (98,500 miles); HGA is oriented to dust ram as directed by background sequence
183T05:36 Jul 01 07:00Thu Jul 01 12:00 AMSOI+04h24mSpacecraft returns to Earth-point; SOI data playback beginsDouble playback of SOI science & engineering data for 19.5 hours; data played back over Madrid, then Goldstone
183T05:48 Jul 01 07:12Thu Jul 01 12:12 AMSOI+04h36mOpen main engine coverMain engine cover is opened for upcoming post-SOI maneuver
183T09:25 Jul 01 10:49Thu Jul 01 03:49 AMSOI+08h13mSwitch to reaction wheel controlSpacecraft has been controlled with thrusters since before SOI; now reaction wheel control is appropriate
183T11:15 Jul 01 12:39Thu Jul 01 05:39 AMSOI+10h03mFirst SOI images returnedPost-SOI images of Saturn and rings are retrieved from recorders

The Cassini-Huygens mission is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Office of Space Science, Washington, D.C.

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