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Voyager Status, What is it?
tasp
post May 1 2007, 04:42 AM
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I am aware of the futility of examining 'do overs' but just for old times sake, here's one:

IIRC, the 'window' for possible Uranus flyby dates was roughly a week long, and the nav team selected one that gave a nice close up of Miranda, good resolution on Ariel and Titania, and so-so for Umbriel and Oberon.

It seems a good satellite configuration existed just before the opening of the Uranus window (although I have no information on the specific satellite config at that time).

Would the surplus manuvering fuel on Voyager II have allowed this encounter, and would it have been sufficient to put Voyager II back on the the exquisite Neptune 'polar crown' trajectory 3 years later ??


(I realize the mission team had specific requirements for fuel margins and the line needed to be drawn somewhere, but I can dream, can't I?)
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Paolo
post May 1 2007, 06:58 AM
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QUOTE (Dominik @ May 1 2007, 01:42 AM) *
May be, it's a little bit off topic but would it be possible to power on the voyager camera again with the remaining power? Unnecessarily to say that they couldn't see much, because it's distance to the sun.


Having been at sub-freezing temperatures for years since their heaters were turned off I think the cameras are now damaged and unusable
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AndyG
post May 1 2007, 10:09 AM
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QUOTE (Paolo @ Apr 30 2007, 09:41 AM) *
The cameras have long since been powered off. They were last used in 1990. Their software has been erased, and the imaging team has dispersed.

Surely that's: "are no longer focussed." biggrin.gif

Andy
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Pando
post Jun 14 2007, 05:17 AM
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During my recent explorations into the bowels of Nasa's web servers, I came across this recent mishap of Voyager 2:

QUOTE
Notes on Voyager 2 Quick Look Data: Data after Nov 29, 2006

On November 30, 2006, a spacecraft systems command was incorrectly decoded by the spacecraft as a command to turn on the heaters associated with the mechanical flipper mechanism for the outboard magnetometer on Voyager 2. The heaters on remained until Dec 4, 2006, resulting in extremely high temperatures (> 130C). The sensors rotated away from the orientation in which they were designed to operate, and the characteristics of the instrument were changed in ways that are not yet fully understood. The result is seen in the quick look data as extremely high magnetic fields. It has not been possible to fully diagnose and correct for the damage to the Voyager 2 magnetometer, although efforts to do so are ongoing. Data from the spacecraft roll scheduled for March 15, 2007 and special coil orientations before and after, will provide crucial information needed to design a process to recover scientific data from the modified instrument.


ftp://vgrmag.gsfc.nasa.gov/pub/voyager/quicklook/v2-warning

Since I couldn't find any info about it on this forum nor any news anywhere else, I'd like to see if anyone knows a bit more what the heck happened there and whether the magnetometer was successfully recharacterized after the recent roll. Also, did this have any long term impact to the health of the spacecraft?
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dilo
post Jun 14 2007, 06:21 AM
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Thanks for the info, Pando. Let's hope magnetometer will fully recover!

PS: In the meanwhile, last data from cosmic ray detector confirm that a still increasing regime of low-energy particles and turbulence, compared to 1 year ago... smile.gif


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Guest_Analyst_*
post Jun 14 2007, 06:25 PM
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QUOTE (Pando @ Jun 14 2007, 05:17 AM) *
Since I couldn't find any info about it on this forum nor any news anywhere else, I'd like to see if anyone knows a bit more what the heck happened there and whether the magnetometer was successfully recharacterized after the recent roll. Also, did this have any long term impact to the health of the spacecraft?


The reason for this is the HYBIC swap test. The test itself has been successful, but it changed the status of the MAG and turned on IRIS (turned off since then). The permanent HYBIC swap is on hold because of this. I have no information about the MAG status. I also do not know if all four MAG instruments are involved or not.

Analyst
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monitorlizard
post Jun 14 2007, 06:53 PM
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This is old news from the January 18, 2007, JURAP meeting, but it expands on the news Pando gave:

HYBIC SWAP TEST RESULTS

REDUNDANT HYBIC TEST & TEMPORARY SWAP

-PURPOSE OF THE TEST
. Validate operability of HYBIC 1 and health of celestial sensors
. Refine sun sensor bias offsets between HYBIC 2 and 1
. Gather information in preparation for a permanent swap and calibration or futher study

--The HYBIC test was performed on 11/30/2006, DOY 335/02:32:37 UTC (6:32 PM PST). All events executed as planned. HYBIC 1 functioned properly and the pointing offset data were obtained.

--At the time of the swap, the available power dropped to an unexpected level.

--The MAG instrument status indicated that the Out-Board flipper status had changed and that the flipper is now ON. The instrument temperature increased significantly.

--Our investigation revealed that one of the commands issued to reinstate HYBIC 1 also caused the Out-Board Flipper ON command to be issued. This caused an additional 10.2 watt of power consumption. This similar anomaly happened once before in 1998. The cause was thought to be contamination of the 2N222A transistors in the Power System (power command decoder).

--It's believed that the excessive heat caused the wax pellet actuators that move the flipper back and forth from the "forward" to "reverse" position to melt. Data indicate that the flipper position is "reverse", near O degrees.

--Early indications are that the Out-Board MAG is still functioning. We are awaiting more feedback from the PI's.

--We have formed a team of consultants to investigate the cause of this anomaly.

--The permanent swap has been delayed until this investigation is complete.
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dilo
post Jun 14 2007, 07:58 PM
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I tried to plot the measured magnetic field components reported on the same link where Pando took the warning (note that I sampled only some interesting time windows):
Attached Image

The anomaly associated to HYBIC test is clearly visible at the center, while on the right side the values recorded at the beginning of January appear 2/3 times the levels at beginning of November (left)... I do not know if this can be normal or is an indication of damaged magnetometer, however...


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Guido
post Aug 11 2007, 08:28 AM
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Voyager reports for weeks 03-16-2007 to 07-06-2007 Available

http://voyager.jpl.nasa.gov/mission/weekly-reports/index.htm

http://voyager.jpl.nasa.gov/mission/weekly...2007-03-16.html
to
http://voyager.jpl.nasa.gov/mission/weekly...2007-07-06.html
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abalone
post Aug 21 2007, 12:47 PM
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Fantastic birthday.The Voyagers will outlive them all
biggrin.gif biggrin.gif biggrin.gif biggrin.gif

http://www.space-travel.com/reports/Pionee...Flight_999.html
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jasedm
post Nov 22 2007, 08:59 AM
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QUOTE (Guido @ Aug 11 2007, 08:28 AM) *


I'm very surprised that V2 has more remaining propellant than V1 after double the planetary encounters (see report for 2007-07-06)
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brellis
post Nov 22 2007, 11:13 AM
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QUOTE (jasedm @ Nov 22 2007, 01:59 AM) *
I'm very surprised that V2 has more remaining propellant than V1 after double the planetary encounters (see report for 2007-07-06)


If I understand correctly, the planetary encounters added velocity, so V2's extra encounters mean it would have needed less propellant.
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djellison
post Nov 22 2007, 11:52 AM
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"needed less propellant"

For what? V1 hasn't been consuming prop in an attempt to catch up. One could imagine that with 4 required targetting points, V2 would have required more prop for TCM's etc.

However - perhaps V1's trajectory was slightly less optimal than V2's and thus it required more Delta-V for targetting.

Doug
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ugordan
post Nov 22 2007, 12:24 PM
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Or maybe one of the spacecraft is inherently more "stable" and hence does less RCS thrusting?


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brellis
post Nov 22 2007, 12:32 PM
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"needed less propellant - for what?"

The extra planetary encounters would also help point the craft to its next destination, thus saving propellant on trajectory changes.
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