Cassini Saturn Orbit Insertion Timeline

Summary (Jun 29, 2004): Over the next few days, if the Cassini spacecraft achieves its next critical milestone, Saturn will capture it for at least a four-year mission. But if the orbital insertion doesn't succeed, the spacecraft flies past Saturn towards deep space.

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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 Ground	UTC Pacific Time	Time wrt SOI	Activity	Description
175T00:00 Jun 23 01:23	Tue Jun 22 06:23 PM	SOI-08d01h	Activate SOI critical sequence and begin quiet period	8-day period of minimal spacecraft activity begins; Solid State Recorders (SSRs) set to SOI configuration
181T19:00 Jun 29 20:24	Tue Jun 29 01:24	PM SOI-01d06h	Orbiter transitions to SOI telemetry mode	Dual record of engineering on both Solid State Recorders (SSRs) begins; only real-time engineering at 1896 bps downlinked
181T20:00 Jun 29 21:24	Tue Jun 29 02:24 PM	SOI-01d05h	Begin critical commanding for SOI	Critical sequence begins issuing commands for SOI (burn start - 29 hours)
182T23:27 Jul 01 00:51	Wed Jun 30 05:51 PM	SOI-01h45m	Transition to Low-Gain Antenna 1 (LGA-1) communication	Telemetry is turned off; carrier only for SOI communication
182T23:47 Jul 01 01:11	Wed Jun 30 06:11 PM	SOI-01h25m	Turn to protective attitude for ascending ring-plane crossing	Protects spacecraft from dust encounter in ring plane; turn takes 10 min
183T00:47 Jul 01 02:11	Wed Jun 30 07:11 PM	SOI-00h25m	Ascending ring-plane crossing Distance = 158,500 km (98,500 miles);	High-Gain Antenna (HGA) is oriented to dust ram direction
183T00:57 Jul 01 02:21	Wed Jun 30 07:21 PM	SOI-00h15m	Turn to burn attitude	Turn takes 10 min; 6 min spare time after turn completion before burn start
183T01:11 Jul 01 02:35	Wed Jun 30 07:35 PM	SOI-00h01m	Open latch valves	Valves opened in preparation for pressurized burn
183T01:12 Jul 01 02:36	Wed Jun 30 07:36 PM	SOI-00h00m	Saturn Orbit Insertion burn start	Main engine maneuver, velocity change = 626 m/s (1400 mph); 96 minute burn
183T01:35 Jul 01 02:59	Wed Jun 30 07:59 PM	SOI+00h23m	Cassini passes behind Saturn's F ring as seen from Earth	Communication still likely
183T01:42 Jul 01 03:06	Wed Jun 30 08:06 PM	SOI+00h30m	Cassini passes behind Saturn's A ring as seen from Earth	Communication unlikely for 25 minutes
183T02:07 Jul 01 03:31	Wed Jun 30 08:31 PM	SOI+00h55m	Cassini passes behind Cassini division as seen from Earth	Brief communication possible for 6 minutes
183T02:13 Jul 01 03:37	Wed Jun 30 08:37 PM	SOI+01h01m	Cassini passes behind Saturn's B ring as seen from Earth	Communication unlikely for 28 minutes
183T02:30 Jul 01 03:54	Wed Jun 30 08:54 PM	SOI+01h18m	Saturn orbit achieved	Spacecraft 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 04:03	Wed Jun 30 09:03 PM	SOI+01h27m	Closest approach to Saturn in entire mission	Distance = 80,230 km (49,850 miles) from center of Saturn, 19,980 km (12,400 miles) from cloud tops
183T02:41 Jul 01 04:05	Wed Jun 30 09:05 PM	SOI+01h29m	Cassini passes behind Saturn's C ring as seen from Earth	Communication restore until science turns (C ring is less opaque to Cassini radio freqs than A or B ring)
183T02:48 Jul 01 04:12	Wed Jun 30 09:12 PM	SOI+01h36m	Saturn Orbit Insertion	nominal burn end
183T02:51 Jul 01 04:15	Wed Jun 30 09:15 PM	SOI+01h39m	Reconfigure radio comm, close main engine cover, begin turn toEarth-point	Main engine cover is closed to protect engine nozzles during descending ring plane crossing; will shift if burn ends late
183T02:54 Jul 01 04:18	Wed Jun 30 09:18 PM	SOI+01h42m	Spaceraft on Earth-point	Will shift if burn ends late
183T02:57 Jul 01 04:21	Wed Jun 30 09:21 PM	SOI+01h45m	Nominal end of critical sequence; main engine cover fully closed	Will shift if burn ends late
183T02:58 Jul 01 04:22	Wed Jun 30 09:22 PM	SOI+01h46m	Saturn Orbit Insertion	max burn end
183T03:00 Jul 01 04:24	Wed Jun 30 09:24 PM	SOI+01h48m	Cassini passes behind Saturn's D ring as seen from Earth	Communication remains likely (D ring is less opaque to Cassini radio frequencies than A or B ring)
183T03:06 Jul 01 04:30	Wed Jun 30 09:30 PM	SOI+01h54m	Max end of critical sequence	Background sequence takes over spacecraft control
183T03:06 Jul 01 04:30	Wed Jun 30 09:30 PM	SOI+01h54m	Switch to High-Gain Antenna (HGA) communication	Telemetry resumes; 1896 bits per second real-time engineering data transmitted
183T03:07 Jul 01 04:31	Wed Jun 30 09:31 PM	SOI+01h55m	Turn off Earth-line for post-burn science observations	Background sequence turns spacecraft to view rings and magnetosphere; communication not possible
183T03:15 Jul 01 04:39	Wed Jun 30 09:39 PM	SOI+02h03m	Jettison INMS cover	Ion & Neutral Mass Spectrometer (INMS) cover is removed for post-SOI observations
183T03:30 Jul 01 04:54	Wed Jun 30 09:54 PM	SOI+02h18m	Cassini passes behind Saturn's C ring as seen from Earth	Cassini should be in science attitudes and will not be communicating with Earth; otherwise communication possible
183T03:33 Jul 01 04:57	Wed Jun 30 09:57 PM	SOI+02h21m	Cassini passes behind Saturn as seen from Earth	Cassini should be in science attitudes and will not be communicating with Earth; otherwise communication not possible
183T04:08 Jul 01 05:32	Wed Jun 30 10:32 PM	SOI+02h56m	Turn to protective attitude for descending ring-plane crossing	Cassini descending crossing turn
183T04:09 Jul 01 05:33	Wed Jun 30 10:33 PM	SOI+02h57m	Cassini 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 05:44	Wed Jun 30 10:44 PM	SOI+03h08m	Cassini emerges from behind A ring as seen from Earth	Cassini should be in science attitudes and will not be communicating with Earth; otherwise communication possible
183T04:34 Jul 01 05:58	Wed Jun 30 10:58 PM	SOI+03h22m	Descending ring-plane crossing	Distance = 158,500 km (98,500 miles); HGA is oriented to dust ram as directed by background sequence
183T05:36 Jul 01 07:00	Thu Jul 01 12:00 AM	SOI+04h24m	Spacecraft returns to Earth-point; SOI data playback begins	Double playback of SOI science & engineering data for 19.5 hours; data played back over Madrid, then Goldstone
183T05:48 Jul 01 07:12	Thu Jul 01 12:12 AM	SOI+04h36m	Open main engine cover	Main engine cover is opened for upcoming post-SOI maneuver
183T09:25 Jul 01 10:49	Thu Jul 01 03:49 AM	SOI+08h13m	Switch to reaction wheel control	Spacecraft has been controlled with thrusters since before SOI; now reaction wheel control is appropriate
183T11:15 Jul 01 12:39	Thu Jul 01 05:39 AM	SOI+10h03m	First SOI images returned	Post-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.

Related Web Pages

Chronology of a Scientific Safari
Ring Recycling
Lord of the Rings
Long, Strange Trips
Titan's Icy Bedrock
Saturn-- JPL Cassini Main Page
Alien Landers: Extreme Explorers Hall of Fame

Note: Life and Giant Planets

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Tuesday, June 29, 2004