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