Voyager Chronology |
Voyager Chronology |
Jun 19 2008, 08:38 PM
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#16
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
I recall being very nervous about the Voyager 1 Jupiter flyby as the interesting satellite passes occurred after closest Jovian approach and I was extremely worried about radiation messing up the craft before they happened.
I managed to be in the Huntley Lodge in Montana, as I recall, for the great 1979 solar eclipse. It was a sufficient distraction to make my Voyager anxiety tolerable. Time magazine managed to cover both events in the same issue. |
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Jun 21 2008, 06:12 PM
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#17
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Junior Member Group: Members Posts: 45 Joined: 18-July 05 Member No.: 439 |
I can offer the following, need to do more research to verify timezones and SCET/ERT: 12 Nov 1980 (05:41) Titan: Titan flyby (targetted) 12 Nov 1980 (22:17) Tethys: Tethys flyby (distant) 12 Nov 1980 (23:46) Saturn: Saturn Fly-By 13 Nov 1980 (01:43) Mimas: Mimas flyby 13 Nov 1980 (01:51) Enceladus: Enceladus flyby (distant) 13 Nov 1980 (03:39) Dione: Dione flyby (distant) 13 Nov 1980 (06:22) Rhea: Rhea flyby 13 Nov 1980 (16:45) Hyperion: Hyperion flyby (distant) Well, I was able to extract the sequence of Voyager 1 Saturn flyby from Voyager 1 and Voyager 2 Saturn encounter orbit determination Campbell J.K., Jacobson R.A., Riedel J.E., Synnott S.P., Taylor A.H. AIAA-1982-419 20th Aerospace Sciences Meeting, Orlando, FL, Jan 11-14, 1982, 17 p. At http://www.aiaa.org/content.cfm?pageid=406...r&gID=90384 the report is not available without payment but with a carefull googling all the encounter table may be extracted. Event - Date and time, UTC - Time relative to CA, hours - Distance Titan CA. 11/12/80 05:40:41 -18.09 6969 Enter Titan Sun-occ. 05:46:22 -17.99 Enter Titan Earth-occ. 05:47:33 -17.97 [Exit] Titan Sun-occ. 05:57:06 -17.81 Descending node 05:58:09 -17.79 1184575 Exit Titan Earth-occ. 05:59:45 -17.77 Tethys CA 22:15:52 -1.50 415855 Saturn CA* 23:45:50 0. 184497 Closest Mimas in light 11/13/80 00:37:41 +0.86 108432 Mimas CA** 01:42:32 +1.95 88996 Enter Saturn Earth-occ. 01:43:16 +1.96 Enceladus CA 01:50:36. +2.08 202796 Enter Saturn Sun-occ. 01:56:54 +2.18 Exit Saturn sun-occ. 02:37:24 +2.86 Exit Saturn Earth-occ. 03:10:35 +3.41 Enter Ring Earth-occ. 03:19:40 +3.56 Closest Dione in light 03:28:13 +3.71 161543 [Exit] Ring Earth-occ. 03:35:09 +3.82 Dione CA*** 03:39:00 +3.89 161285 Ascending node 04:20:06 +4.57 377902 Rhea CA 06:21:13 +6.59 72797 Hyperion CA 16:44:01 +16.97 897277 CA = closest approach *One-way light time = 01 24 47 **Mimas is in darkness at CA ***Dione is in darkness at CA |
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Jun 24 2008, 08:37 PM
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#18
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Junior Member Group: Members Posts: 45 Joined: 18-July 05 Member No.: 439 |
Voyager 2 25 Aug 1981 (09:24) 665,960 km Titan: Titan flyby (distant) 26 Aug 1981 (01:04) 502,250 km Dione: Dione flyby (distant) 26 Aug 1981 (02:34) 309,990 km Mimas: Mimas flyby (distant) 26 Aug 1981 (03:24) 161,081 km Saturn: Saturn 26 Aug 1981 (03:45) 87,140 km Enceladus: Enceladus flyby 26 Aug 1981 (06:12) 93,000 km Tethys: Tethys flyby 26 Aug 1981 (06:29) 645,280 km Rhea: Rhea flyby (distant) Again I was able to extract Voyager 2 Saturn visit times from the article by Campbell, Jacobson et al. Date and time, UTC SCET -- Time from Saturn CA -- Event -- Distance, km 1981.08.23 01:26:56.5 -03 01:57:11 Iapetus 909070 1981.08.25 01:25:25.8 -01 01:58:42 Hyperion 470840 1981.08.25 09:37:46.3 -00 17:46:21 Titan 665960 1981.08.25 22:57:33.2 -00 04:26:35 SXII Helene (1980 S6) 318200 1981.08.26 01:04:31.8 -00 02:19:36 Dione 502250 1981.08.26 02:22:16.8 -00 01:01:51 SXIV Calypso (1980 S25) 153518 1981.08.26 02:34:26.X -00 00:49:41 Mimas 309990 1981.08.26 03:08:29.4 -00 00:15:38 SXVII Prometheus (1980 S28) 287170 1981.08.26 03:19:17.5 -00 00:04:50 SXV Pandora (1980 S26) 107000 1981.08.26 03:24:07.8 00 00:00:00 Saturn 1981.08.26 03:33:02.4 +00 00:08:55 SXVI Atlas (1980 S27) 246590 1981.08.26 03:45:16.1 +00 00:21:08 Enceladus 87140 1981.08.26 03:50:03.6 +00 00:25:56 SX Janus (1980 S1) 222760 1981.08.26 04:00:24.6 +00 00:36:17 Earth occult enter Saturn? 166133 1981.08.26 04:05:55.8 +00 00:41:48 SXI Epimetheus (1980 S3) 147010 1981.08.26 04:08:12.1 +00 00:44:04 Sun (umbra) occult enter Saturn 1981.08.26 05:34:36.9 +00 02:10:29 Earth occult leave Saturn 215762 1981.08.26 05:44:56.s +00 02:20:21 Sun (umbra) occult leave Saturn 223334 1981.08.26 06:02:46.7 +00 02:38:39 SXIII Telesto (1980 S13) 284400 1981.08.26 06:12:30.2 +00 02:48:22 Tethys 93000 1981.08.26 06:28:48.4 +00 03:04:41 Rhea 645280 1981.09.05 01:22:33.5 +09 21:58:26 Phoebe 2073640 Notes: 1. Two or more lines for rings crossing were not discernible. 2. Numbers cross-checked against the Saturn CA time. 3. Current names an designations for small satellite discovered in 1979-1980 are used. 4. Don't know why this distance to Phoebe was there in the table. 5. Current estimate for Saturn CA seems to be 03:24:05. |
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Jun 26 2008, 09:34 PM
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#19
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Member Group: Members Posts: 655 Joined: 22-January 06 Member No.: 655 |
I never cease to be amazed at the quality of the initial reconnaisance of the Saturn system by the two Voyagers. The amount of data gathered by the two craft, which between them spent less than two weeks within Iapetus' orbit is nothing short of astonishing.
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Aug 20 2008, 11:12 PM
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#20
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Senior Member Group: Admin Posts: 3108 Joined: 21-December 05 From: Canberra, Australia Member No.: 615 |
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May 15 2009, 11:36 AM
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#21
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Junior Member Group: Members Posts: 39 Joined: 26-March 09 From: Cornwall Member No.: 4697 |
A few more Voyager 2 dates, source is a diagram in Spaceflight, Nov 81:
1979-07-23 TCM6 1981-07-31 Start Far Encounter 1 1981-08-11 Start Far Encounter 2 1981-08-25 Start Near Encounter (CA-16 h) 1981-08-27 End Near Encounter (CA+28 h) 1981-09-28 End Post Encounter 1981-09-29 TCM10 |
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Jul 22 2009, 01:21 PM
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#22
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Junior Member Group: Members Posts: 45 Joined: 18-July 05 Member No.: 439 |
--- Unnecessary quoting removed! Mod. ---
Thank you very much, qwiz. |
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Aug 22 2012, 10:53 PM
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#23
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Member Group: Members Posts: 241 Joined: 16-May 06 From: Geneva, Switzerland Member No.: 773 |
35 years of flight !! Happy Anniversary Voyager 2 !
http://voyager.jpl.nasa.gov/news/voyager_35.html |
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Jan 22 2014, 11:45 PM
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#24
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
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Jan 23 2014, 12:45 AM
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#25
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Yeah, orbital motion & points of reference will mess you up every time.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Feb 8 2014, 03:39 PM
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#26
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Member Group: Members Posts: 102 Joined: 8-August 12 Member No.: 6511 |
That raises a question: has anyone worked out exactly when Voyager will hit the mark of 20 billion kilometers from Earth? (It's currently 19.033 billion.) A quick BOTE calculation gives December 2015, but Earth's orbital motion makes that a very rough estimate.
I know 20 billion is just a number. But, dang, it's a big number. Doug M. |
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Feb 10 2014, 09:09 AM
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#27
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Senior Member Group: Moderator Posts: 2262 Joined: 9-February 04 From: Melbourne - Oz Member No.: 16 |
According to Horizons it will be on 4th November 2015, at 05:22 UTC in the Eastern US, 05:23 in the UK and Western US, three minutes later still in Australia.
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Feb 12 2014, 09:42 AM
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#28
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Member Group: Members Posts: 102 Joined: 8-August 12 Member No.: 6511 |
Well, mark our calendars! Thank you, James.
Doug M. |
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Dec 30 2014, 03:25 PM
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#29
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Member Group: Members Posts: 102 Joined: 8-August 12 Member No.: 6511 |
So the official NASA extended mission plan for Voyager 1, last updated in June 2014, tells us that this is the year its gyroscope will be shut down: "Discontinue gyro operations (+14.4 W steady state, +3.6 W turn on transient and maneuver) - 2015; TBD. This power load reduction step is currently sequenced to occur on DOY 350, 2015 but could be changed if the RTG output is better than predicted."
I assume DOY 350 would be ooa December 16, 2015... Okay, so does anyone know anything more? Is the RTG output about as expected? And what consequences will there be from turning off the gyroscope? Doug M. |
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Dec 31 2014, 10:59 PM
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#30
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Junior Member Group: Members Posts: 95 Joined: 5-September 07 Member No.: 3662 |
So the official NASA extended mission plan for Voyager 1, last updated in June 2014, tells us that this is the year its gyroscope will be shut down: "Discontinue gyro operations (+14.4 W steady state, +3.6 W turn on transient and maneuver) - 2015; TBD. This power load reduction step is currently sequenced to occur on DOY 350, 2015 but could be changed if the RTG output is better than predicted." I assume DOY 350 would be ooa December 16, 2015... Okay, so does anyone know anything more? Is the RTG output about as expected? And what consequences will there be from turning off the gyroscope? Doug M. AFAIK, the RTG output hasn't really changed from predictions. The exponential decay of the plutonium and degradation of the thermocouples are both well understood. Unless something in the power system fails, the wattage should be accurately predictable for the duration of the mission. But two things come immediately to mind with shutting down the gyros. First, the periodic antenna repointings will require hydrazine when the gyros are powered down. Voyager 1 had 18 kg of hydrazine left as of September 19, and typical consumption is about 5-6 grams per week. I don't know how much a repointing will cost, or how often it needs to be done (I looked at the weekly 2014 reports, which are current up to September 19, and no repointings were obvious for either V1 or V2 during the year). Science observations on V1 (rolling the spacecraft for particles/fields) take 100-400 grams, it seems, so I'd guesstimate that much for a repointing. But if it's done annually or less frequently, there should be enough hydrazine until the RTGs finally run too low to keep the spacecraft operating. Second, the gyros make heat. It's amazing that the spacecraft are able to function in the cold. Without heaters and insulation, they'd probably be down to 30-40K by now. It wouldn't be a terrible surprise to me if at some point, an important piece just got too cold to work. (E.g., the hydrazine freezes in the fuel lines, or a piece of electronics fails or something.) I remember listening to Jay Barbree report the launch of one of the Voyagers in 1977, and was glued to the TV during the flybys. I sure hope to see Voyager 2 break through into interstellar space before either it or I shut down. That both V1 and V2 are still working is virtually miraculous, and a testament to the dedication and talent of the people who designed, built, and operate them. |
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