Printable Version of Topic

Click here to view this topic in its original format

Unmanned Spaceflight.com _ Voyager and Pioneer _ Voyager Status

Posted by: tuvas Dec 6 2006, 05:48 AM

Anyone know the latest Voyager status? I've hear rumors, but I'm wondering if anyone has anything more concrete (I won't share the rumors, as I really don't know much about it, so...)

Posted by: dilo Dec 6 2006, 06:31 AM

Curious, http://voyager.jpl.nasa.gov/mission/weekly-reports/index.htm was published in August, exactly when V1 hit 100au milestone... sad.gif
Anyway, the two spacecrafts still alive, as confirmed by http://voycrs.gsfc.nasa.gov/heliopause/heliopause/recenthist.html updated to one week ago and V2 ftp://space.mit.edu/pub/plasma/vgr/v2/ha/key/ updated yesterday... smile.gif

Posted by: Analyst Dec 6 2006, 08:45 AM

The Voyager status reports are always late: very small team in an extended, extended, extended smile.gif mission. But the DSN tracking schedules are up to date, and they show normal activity. There has been the standard once per year memory readout recently. So there is no hint of a spacecraft issue I can see right now.

But Voyager 2 should cross the termination shock about now, Voyager 1 did this a couple of years ago. I have no insight and understanding of the science data. They should show this. And Voyager 1 should cross the next "shock" (I can never remember these solar system bondaries) in the not so far future.

Analyst

Posted by: Myran Dec 6 2006, 10:37 PM

You might be thinking of the Heliopause Analyst. Voyager 1 should be in the Heliosheath where the solar wind begins to mix with the Interstellar medium. The bow shock could be a bit further away than this image shows. It might be some time before Voyager 1 reach the bowshock, but it would be wonderful if it did. There wont be any TAU mission in the forseeable future so the two Voyagers will be the best shot we have of studying this region.

 

Posted by: Littlebit Dec 7 2006, 06:15 PM

QUOTE (Myran @ Dec 6 2006, 03:37 PM) *
You might be thinking of the Heliopause Analyst. Voyager 1 should be in the Heliosheath where the solar wind begins to mix with the Interstellar medium. The bow shock could be a bit further away than this image shows. It might be some time before Voyager 1 reach the bowshock, but it would be wonderful if it did. There wont be any TAU mission in the forseeable future so the two Voyagers will be the best shot we have of studying this region.

The 'Soft' cosmic ray rate has been increasing since September and is up to ~30ips. It last peaked about Nov 2005. I have to wonder if this is correlated - with an appropriate time lag, with the increase in solar activity. It is a roller coaster out there.

Posted by: tasp Dec 8 2006, 12:26 AM

. . . BEEP . . .

cold and dark


. . . BEEP . . .


still cold and dark


. . . BEEP . . .

yep, it's really cold, and really dark


. . . BEEP . . .

yawn



. . . BEEP . . .

really, really cold, and still dark




blink.gif

Posted by: edstrick Dec 8 2006, 06:49 AM

Space is Big.
Space is Dark.
It's hard to find
a place to park.
. burma shave.

Posted by: lyford Dec 8 2006, 07:21 AM

http://en.wikipedia.org/wiki/Marco_Polo_%28game%29

.......


......


......

Posted by: AndyG Dec 8 2006, 11:47 AM

Shame it's too late to get http://en.wikipedia.org/wiki/Hawkwind's 1973 recording of http://www.youtube.com/watch?v=ugTLEkPi1Jc added to the Voyagers' records...twelve string guitar, psychaedelic synths and memorably cheesy lyrics... Yep, that'd do me as I drifted off into the endless AUs...

The path goes onward through the night
Beyond the realms of ancient light


rolleyes.gif

Andy

Posted by: mchan Dec 9 2006, 03:55 AM

On that note, my bit of wistfulness for the Voyager music as it travels thru interstellar space would be the song from John Carpenter's early film Dark Star...

Benson, Arizona,
Warm wind thru your hair,
My body roams the galaxy,
My heart longs to be there.

Benson, Arizona,
Same stars in the sky,
But they look so much better,
When we watch them, you and I.


Coincidentally, Benson is less than an hour down the road from LPL.

smile.gif

Posted by: tuvas Dec 9 2006, 07:54 AM

QUOTE (mchan @ Dec 8 2006, 08:55 PM) *
Coincidentally, Benson is less than an hour down the road from LPL.

smile.gif


I never knew there was a song about Benson, such a little town in Arizona, but it has it's own song... Sigh.

Posted by: dvandorn Dec 9 2006, 09:06 AM

It's not merely a song about Benson, AZ. It's the somewhat improbable theme song of the John Carpenter student film-cum-cult-classic, Dark Star. It's a country-and-western song in format, but the lyric is about a lonely guy, flying through interstellar space at relativistic speeds, and thinking of everything -- and one special person -- he left behind.

If I can recall the words...

A million suns shine down,
But I see only one.
When I think I'm over you,
I find I've just begun.
The years move faster than the days,
There's no warmth in the light.
How I miss those desert skies,
Your cool touch in the night.

CHORUS:
Benson, Arizona, blew warm wind through your hair.
My body flies the galaxy, my heart longs to be there.
Benson, Arizona, the same stars in the sky,
But they seemed so much kinder when we watched them, you and I.

Now the years pull us apart,
I'm young and now you're old.
But you're still in my heart,
And the memory won't grow cold.
I dream of times and spaces
I left far behind,
Where we spent our last few days,
Benson's on my mind.

(CHORUS)


smile.gif

-the other Doug

Posted by: alan Dec 9 2006, 06:26 PM

QUOTE (lyford @ Dec 8 2006, 01:21 AM) *
http://en.wikipedia.org/wiki/Marco_Polo_%28game%29

.......
......
......


.......


.......



.......



".......Polo"

Posted by: edstrick Dec 10 2006, 10:08 AM

"Why do I always have to feed the alien?"

"Cause you brought the stupid thing on board in the first place!"

Posted by: tasp Dec 10 2006, 03:10 PM

How could it be alive it was just a bag of gas?

blink.gif

Posted by: Myran Dec 10 2006, 07:04 PM

"......and dont dare play that record one more time!"

Posted by: mchan Dec 11 2006, 09:12 AM

QUOTE (dvandorn @ Dec 9 2006, 01:06 AM) *
It's not merely a song about Benson, AZ. It's the somewhat improbable theme song of the John Carpenter student film-cum-cult-classic, Dark Star. It's a country-and-western song in format, but the lyric is about a lonely guy, flying through interstellar space at relativistic speeds, and thinking of everything -- and one special person -- he left behind.

If I can recall the words...

Thanks for posting the lyrics. Your memory is much better than mine. I could only recall the chorus and even missed some of the words there, but remembered the feeling of flying thru space alone and leaving someone behind. Over-anthromorphising Voyager here. Crikey, maybe that's where ST:TMP came from. smile.gif

Posted by: nprev Dec 11 2006, 05:43 PM

We have to be careful not to teach the Voyagers phenomenology... blink.gif

Posted by: edstrick Dec 12 2006, 10:17 AM

"How could it be alive it was just a bag of gas?"

Yeah.. but I'm still convinced it was smarter than the entire crew put together.

Posted by: monitorlizard Jan 1 2007, 07:19 PM

QUOTE (tuvas @ Dec 5 2006, 11:48 PM) *
Anyone know the latest Voyager status? I've hear rumors, but I'm wondering if anyone has anything more concrete (I won't share the rumors, as I really don't know much about it, so...)

Tuvas, this is probably what you're referring to, and it's not a rumor. There hasn't any press on this to my knowledge, but the JPL JURAP site describes a problem with Voyager 2 in its November meeting minutes. There is a problem with a part of the AACS (attitude and articulation control system) called HYBIC, which has something to do with an analog-to-digital converter not working properly some of the time. This apparently has affected the sun sensor and star tracker on the spacecraft. The part that grabbed my attention was where it said "Impact: Possible loss of spacecraft".

This is not a trivial problem, but the minutes described a swap procedure to a backup HYBIC. The process runs from November, 2006, through February, 2007, but it should result in a healthy spacecraft again. I'm sure the Voyager folks didn't want to make this too public until they know more of how well the swap is succeeding (although JURAP is a publicly-accessible website).

The whole Voyager presentation runs 13 pages, and I'm sure many of you will understand the technical details better than I. It's a complicated web address, so I'll break it down a bit:

(1) go to: rapweb.jpl.nasa.gov

(2) in the right-hand column, click on "Joint Users Allocation and Planning Committee (JURAP) Minutes

(3) click on "Voyager 2 November 2006" (probably in Acrobat format)

This reminds us that the Voyager spacecraft are slowly degrading and unfortunately won't last forever (though it sometimes seemed that they would).

Posted by: Analyst Jan 5 2007, 07:54 AM

This is the same switch they did on Voyager 1 in early 2002. Switching HYBIC means you have to use the redundant star tracker (roll) and sun sensor (pitch and yaw) as well, even if the current used ones are just fine. On the other hand, the scan platform pointing information (azimuth and elevation) is no longer needed. So there is some risk because you use other sensors with different and not completely known biases. And there is the possibility HYBIC 1 is not working and you have to switch back to the dedraded HYBIC 2. The AACS computer in charge remains the same, there is no switch planned.

Interesting note: One branch of attitude control trusters for pitch and yaw failed in 1999. But they are not critical on that because they can use the (larger) TCM trusters if the second branch fails.

Analyst

Posted by: edstrick Jan 5 2007, 10:06 AM

"...because they can use the (larger) TCM trusters if the second branch fails."

Might mean a much higher rate of use of attitude control propellant, leading to eventual end-of-mission before other expected problems <like low voltage or inadequate suntracker sensitivity> ends mission.

Posted by: ljk4-1 Jan 5 2007, 02:57 PM

Since the main receiver failed on Voyager 2 shortly after launch back in 1977,
and they had to rely on the backup receiver which is apparently tone deaf, for
lack of a better technical phrase, how is that rather critical piece of equipment
holding up? And how are they keeping it so finely in tune after all this time?

Posted by: tuvas Jan 5 2007, 03:45 PM

Thanks for the info. The only thing I knew was that we lost one of our 70m passes due to some kind of emergancy with one of the Voyagers. This seems to fit quite well with the details included here, so... Thanks for your help!

Posted by: Analyst Jan 5 2007, 05:11 PM

QUOTE (ljk4-1 @ Jan 5 2007, 03:57 PM) *
Since the main receiver failed on Voyager 2 shortly after launch back in 1977,
and they had to rely on the backup receiver which is apparently tone deaf, for
lack of a better technical phrase, how is that rather critical piece of equipment
holding up? And how are they keeping it so finely in tune after all this time?


The only working receiver (there are two) is unable to change its receiving frequency, so it can only listen in a very, very narrow frequency spectrum. It can't stay in lock if the incomming frequency shifts.

There are at least two problems resulting:

- The receiving frequency can't be changed by the spacecraft to stay in lock, but it can change because of temperture variations. A one degree temperature change means a frequency shift of x Hz. So you have to look very carefully at the receiver temperature when the signal arrives (Ten hours or so after being sent). If there is an attitude change (MAGROL etc.) of the spacecraft, the temperature and therefore the frequency can't be predicted good enough. Then they declare a command moratorium and no commands are sent for some days.

- But even if you know the receiving frequency you have to take into acount the doppler effect: Voyager is moving away from the sun, but the earth moves arround the sun and so the distance between earth and spacecraft sometimes rises, sometimes falls. Earth itself rotates, this complicates things too. And the atmosphere changes the signal too.

So you must predict the receiver frequency and then sent a command at a frequency, that adjusted for the doppler effect and atmospheric changes matches this predicted frequency within a few Hz. Because of the uncertainty commands are sent more than once at different frequencies nearby (brackated) so that at least some get through. They do since 1978!

If this last receiver fails, the Voyager 2 command loss routine will configure the spacecraft for longterm science return even without further commanding from earth. Of course you lose the capability to react to science events and failures of other subsystem components, but you get (limited) science as long as nothing happens the spacecraft can't handle by itself (by switching to redundant subsystems etc.).

Analyst

Posted by: Analyst Jan 7 2007, 05:06 PM

http://www.nasm.si.edu/research/dsh/artifacts/GC-Voyager.htm is another spare HYBIC, flight-qualified, but not quite on location. smile.gif

Analyst

Posted by: Paolo Feb 11 2007, 08:48 PM

QUOTE (monitorlizard @ Jan 1 2007, 08:19 PM) *
This is not a trivial problem, but the minutes described a swap procedure to a backup HYBIC. The process runs from November, 2006, through February, 2007, but it should result in a healthy spacecraft again. I'm sure the Voyager folks didn't want to make this too public until they know more of how well the swap is succeeding (although JURAP is a publicly-accessible website).


Any update on this?

Posted by: monitorlizard Feb 12 2007, 01:37 PM

The January JURAP meeting did discuss the status of the HYBIC swap, but the report of that meeting hasn't been released yet. JURAP minutes are released on a somewhat irregular basis, so it's hard to say when we ordinary people will get to see them.

Posted by: PhilCo126 Feb 12 2007, 06:44 PM

Last things I've read on the Grand Tour spacecraft:
Voyager 1 crossed the termination shock at 94 AU in December 2004, 100 AU in December 2006 and estimates show it will pass the Heliopause by 2015.
Voyager 2 is now at ~82 AU and is likely to cross the shock sometime this year.
Fingers crossed both will still have some electrical power to keep operating.
By The Way: this year is the 30th anniversary of the summer 1977 launches!

Posted by: Steffen Feb 14 2007, 07:53 PM

That's 3 AU per year. Will these overtake the Pioneers?

Posted by: PhilCo126 Feb 14 2007, 08:31 PM

Indeed, both voyagers will overtake the Pioneer 10 and 11 as the Voayager 1 & 2 have a significant speed advantage. I didnít calculate when they will out-distance the Pioneers but here are the formulas for the distances traveled by both Voyagers:

Voyager 1: 76.34 + 3.50 ( future year Ė 2000 ) = distance in AU
Voyager 2: 59.75 + 3.13 ( future year Ė 2000 ) = distance in AU

( 1 AU = Astronomical Unit is the average distance between Sun & Earth : approx 150 million kilometers )

Posted by: remcook Feb 14 2007, 09:08 PM

ehm...I thought they already did??

Posted by: Analyst Feb 15 2007, 01:16 PM

Voyager 1 already did in 1998, Voyager 2 will in about 2022.

http://www.heavens-above.com/solar-escape.asp?lat=0&lng=0&alt=0&loc=&TZ=CET

Analyst

Posted by: Analyst Mar 5 2007, 08:12 PM

The tracking schedules on the Voyager http://voyager.jpl.nasa.gov/mission/soe-sfos/sfos_2007.html from February/March 2007 donít show the permanent HYBIC switch as planned in November last year. Maybe some unexpected results from the short test swap in early December.

Analyst

Posted by: PhilHorzempa Mar 9 2007, 07:51 PM

Has anyone tried to determine if Voyager 1 or 2 will fly
anywhere near a Kuiper Blet Object?
Is there enough fuel on the Voyagers to conduct
a Mid-Course Maneuver to enable a close flyby of a KBO?
Assuming all of that, what is the status of each camera
on the Voyagers? When were they last used?

I bring this up because the Voyagers are now in the Kuiper
Belt, whose components were discovered after the launches
of the Voyagers, and because "new" KBO's are being detected
all the time. Perhaps one of those ice balls will be in the right
place at the right time.


Another Phil

Posted by: djellison Mar 9 2007, 08:09 PM

The scan platforms have been switched off for many years, and there would not be the power to operate enough systems to make this a feasable exercise.

Doug

Posted by: Analyst Mar 9 2007, 08:30 PM

Aren't the majority of the Kuiper belt objects more or less (+/- 10 or so degrees) in the plane of the ecliptic? The Voyagers are going north and south by 25 or 30 degrees and are therefore in a region with not so many Kuiper belt objects, if I am correct with my assumption. The last time a Voyager camera was used was in February 1990. The heaters on the scan platforms are turned off and even if there is power to spare it is doubtful the cameras would work again.

Analyst

Posted by: edstrick Mar 10 2007, 09:50 AM

Not only have the scan platform instruments been switched off.. the scan platform HEATERS have been switched off. Hardware on the platforms is probably at pretty seriously cryogenic temperatures.

And while the majority of KB objects are near the ecliptic, that is increasingly seeming to be an artifact of where we're searching. a *LOT* of them have higher inclinations and spend much of their time outside the near-ecliptic search zones and have been found by accident as they crossed the zone.

Isn't Eris, the biggest KB Planet/Dward-whatever in a 45 deg orbit?

Posted by: Gsnorgathon Mar 11 2007, 12:40 AM

Eris's orbit is indeed inclined nearly 45 degrees, though that doesn't necessarily mean it was 45 degrees away from the ecliptic when it was discovered. Your point about the artifact of where astronomers look for objects is a very good one. The Minor Planet Center's http://www.cfa.harvard.edu/iau/lists/OuterPlot.html is a great illustration of this. There's a big hole! And - surprise! - it's in the direction of the center of galaxy, where finding really dim objects is not so easy. (I suppose the fact that New Horizons is flying right into that big hole is great reason for optimism that some nice juicy targets will be found for post-Pluto encounters.)

I'd guess we should expect large numbers of TNOs at high inclinations, based on what I've read about planetary migration driving up TNO inclinations.

As always, this kind of discussion reminds me of the joke about the drunk who's looking for his car keys under the streetlight, not because that's where he thought he lost them, but because it's easier to look for them there. tongue.gif

Posted by: Analyst Mar 11 2007, 08:58 AM

QUOTE
Voyager Mission Operations Status Report # 2006-12-01, Week Ending December 01, 2006

Voyager 2 performance was nominal during this report period. Activity consisted of the Attitude Control System Hybrid Buffer Interface Circuit swap test on 11/30 (DOY 335). The test executed as planned; however, extraneous commands were issued to turn on the out-board Magnetometer flipper and the IRIS instrument. Spacecraft operations have been returned to normal and the investigation into the anomaly continues.


There we have the reason why the permanent HYBIC switch has not occured yet. The MAG flipper (A mechanical device to reorientate the MAG sensor, it did put some torque on the spacecraft.) and the IRIS instrument (Unsued for years, on the scan platform.) turned on during the swap test. So the permanent HYBIC switch won't come before this is understood. Meanwhile, normal operation goes on.

Analyst

Posted by: John Flushing Mar 22 2007, 09:48 PM

http://www.tucsoncitizen.com/daily/local/43056.php

I noticed some false information in this article.

QUOTE
Voyager 2 was turned off in 1998 and is presumably coasting through space without a power source. Before the spacecraft was abandoned, it became the only spacecraft to have flown by the sun's most distant planet, Neptune, and its moons, Holberg said. (Pluto once was thought to be the planet farthest from the sun, but most scientists no longer consider it a planet.)

Posted by: brellis Apr 30 2007, 06:17 AM

Regarding KBO's, which were undiscovered prior to Voyagers' launch: do the spacecraft have any way to scan ahead to see if they might run into or near anything, as unlikely as it would be? Even if they couldn't image anything, it would be a great feather in the cap of the Voyager team to detect a new object more than 30 years into the mission!

Posted by: Paolo Apr 30 2007, 08:41 AM

QUOTE (brellis @ Apr 30 2007, 08:17 AM) *
Regarding KBO's, which were undiscovered prior to Voyagers' launch: do the spacecraft have any way to scan ahead to see if they might run into or near anything, as unlikely as it would be? Even if they couldn't image anything, it would be a great feather in the cap of the Voyager team to detect a new object more than 30 years into the mission!


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.

Posted by: Dominik Apr 30 2007, 11:42 PM

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.

Posted by: brellis May 1 2007, 12:50 AM

My earlier question pertained to whether any of Voyagers' operating instruments might pick up an indication of a distant KBO or even some wandering interstellar object of significant proportions. Pioneer may have already captured the prize, having possibly been deflected by an undiscovered KBO at around 8Bn km. It was affected by the object in 1992, and it took 7 years to figure out what might have happened.

I realize my original question is just a speculative exercise in a fantastic "what if", but here's what I've found in a quick search:

I read through the VIM proposal for the 2005 NASA funding review. As mentioned above and in other Voyager threads, the only devices left on are for measuring helioshperic and extraheliospheric features.

"The entire Voyager 2 scan platform, including all
of the platform instruments, was powered down in
1998. All platform instruments on Voyager 1, except
UVS, have been powered down. The Voyager 1 scan
platform was scheduled to go off-line in late 2000, but
has been left on at the request of the UVS investigator
(with the concurrence of the Science Steering Group)
to investigate excess in UV from the upwind direction.
The PLS experiment on Voyager 1 which had been
turned off in 2000 to provide power to extend UVS
lifetime, was turned on again in 2004 when there was
evidence that the spacecraft was in the vicinity of the
26
termination shock. UVS data are still captured, but
scans are no longer possible."


While it seems unlikely for the Voyagers at 100 AU to closely encounter any KBO's, they'll be in the KBO neighborhood for a long time -- Sedna's 10,000 year orbit takes it out to 900AU!

As to whether either Voyager craft could maneuver towards a newly-discovered object:

"The thrusters currently in use are expected to
last the rest of any mission projection. Nearly 1/3 of the
original propellant remains available."


While they're only using thrusters to keep the craft in optimal contact with earth, it is kind of amazing how much fuel is left. They sure saved a lot of juice using the "Grand Alignment" of the outer planets for gravity-assists to sling-shot the Voyagers out of the solar system!

Real world note: One of the many compelling reasons to keep the program alive is that the Voyager craft are making the first beyond-the-shock measurements of Radio Wave events generated during the declining phases of solar cycles. I have the mental image of the Voyager craft being the first to measure waves lapping at the shore of the "lake" that is the solar system.

Posted by: tasp May 1 2007, 04:42 AM

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?)

Posted by: Paolo May 1 2007, 06:58 AM

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

Posted by: AndyG May 1 2007, 10:09 AM

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

Posted by: Pando Jun 14 2007, 05:17 AM

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?

Posted by: dilo Jun 14 2007, 06:21 AM

Thanks for the info, Pando. Let's hope magnetometer will fully recover!

PS: In the meanwhile, http://voycrs.gsfc.nasa.gov/heliopause/heliopause/recenthist.html confirm that a still increasing regime of low-energy particles and turbulence, compared to 1 year ago... smile.gif

Posted by: Analyst Jun 14 2007, 06:25 PM

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

Posted by: monitorlizard Jun 14 2007, 06:53 PM

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.

Posted by: dilo Jun 14 2007, 07:58 PM

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):


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...

Posted by: Guido Aug 11 2007, 08:28 AM

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-reports/2007-03-16.html
to
http://voyager.jpl.nasa.gov/mission/weekly-reports/2007-07-06.html

Posted by: abalone Aug 21 2007, 12:47 PM

Fantastic birthday.The Voyagers will outlive them all
biggrin.gif biggrin.gif biggrin.gif biggrin.gif

http://www.space-travel.com/reports/Pioneering_NASA_Spacecraft_Mark_Thirty_Years_Of_Flight_999.html

Posted by: jasedm Nov 22 2007, 08:59 AM

QUOTE (Guido @ Aug 11 2007, 08:28 AM) *
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-reports/2007-03-16.html
to
http://voyager.jpl.nasa.gov/mission/weekly-reports/2007-07-06.html


I'm very surprised that V2 has more remaining propellant than V1 after double the planetary encounters (see report for 2007-07-06)

Posted by: brellis Nov 22 2007, 11:13 AM

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.

Posted by: djellison Nov 22 2007, 11:52 AM

"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

Posted by: ugordan Nov 22 2007, 12:24 PM

Or maybe one of the spacecraft is inherently more "stable" and hence does less RCS thrusting?

Posted by: brellis Nov 22 2007, 12:32 PM

"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.

Posted by: ngunn Nov 22 2007, 12:49 PM

V1 had no 'next destination' after Saturn and therefore needed no trajectory changes. It's been in freefall since Saturn.

Posted by: jasedm Nov 22 2007, 01:00 PM

Thinking about it, perhaps the answer is a combination of several factors:

1) Maybe voyager operators were more sparing of the propellant for V2 knowing that Uranus (and beyond) were at least 'on the cards' from the off.
2). Different trajectories and speeds of the two spacecraft
3) V1 I think had to make a huge (many minutes) burn to set up for the Titan close encounter.

Posted by: ugordan Nov 22 2007, 01:07 PM

QUOTE (jasedm @ Nov 22 2007, 02:00 PM) *
1) Maybe voyager operators were more sparing of the propellant for V2 knowing that Uranus (and beyond) were at least 'on the cards' from the off.

You can't spare propellant, saving it for Uranus because if you didn't do the necessary burn now there would not be any Uranus encounter, but a huge miss instead.
Rule of thumb: fewer targetted encounters = less fuel consumed.

I seem to remember it was V2 that performed a big burn to set up a trajectory to the Uranus aimpoint and cleanup all the perturbations after passage through the Saturnian system .

Posted by: jasedm Nov 22 2007, 01:41 PM

QUOTE (ugordan @ Nov 22 2007, 01:07 PM) *
Rule of thumb: fewer targetted encounters = less fuel consumed.


That's just the reason for my surprise in post 56 above:
Voyager 1 - housekeeping attitude control since November 1980 (except for the family portrait shot)
Propellant left: 27.7kg on July 6th 2007
Voyager 2 - observations of an additional two planets/ring systems and at least 10 moons since Saturn encounter
I understand the amount of spacecraft slewing at Uranus was huge due to the number of targets at C/A coupled with the planet's axial tilt
Propellant left: 29.41kg on July 6th 2007 smile.gif

Posted by: djellison Nov 22 2007, 02:03 PM

What I was suggesting is that perhaps V1's trajectory inherantly required significantly more Delta V for..

Post launch TCM
Targetting at Jupiter
Clean up after Jupiter
Targetting for Saturn.

Didn't someone say here a while back that one of the two had an LV underperform a little?

Doug

Posted by: ugordan Nov 22 2007, 02:07 PM

QUOTE (djellison @ Nov 22 2007, 03:03 PM) *
Didn't someone say here a while back that one of the two had an LV underperform a little?

Yep, something like the Titan IV booster undeperformed and the Centaur was barely able to compensate (IIRC with only 3 seconds of burn time left). The difference is most likely due to the TCMs in the end.

Posted by: Bernard1963 Jun 20 2019, 09:06 AM

I was wondering if anyone else had noticed / had any info on what appears to be a mystery about the low and varying signal from Voyager 1? For well over a month now the signal from Voyager 1 (as shown on https://eyes.nasa.gov/dsn/dsn.html) has been varying by approx 3db over the course of an hour or so and its at best about 2db lower than it should be, at worst 5db or 6db lower. With DSS63 out for long term maintenance its currently often being tracked on 2 x 34m dishes at Madrid which are unable to obtain data lock for much of the time. Only DSS14 now seems able to hold data lock.

Tweeting one of the Canberra DSN controllers he confirms this is the case, its not a website anomaly. The mystery is that he tells me the Voyager project apparently are not seeing any problem with the spacecraft?

Posted by: stevesliva Jun 20 2019, 12:51 PM

A month ago, Voyager 2 notes this sort of activity:

QUOTE
@NSFVoyager2 May 14 Changing my data transmission rate back from Engineering Low to Science Cruise (40 to 160 bps) FDS:MRO XB CR-5T (2019:135:002845:2ECa)

@NSFVoyager2 May 14 Starting Command & Control Subsystem timing test, measuring difference btw CCS timing chain & FDS frame start CCSTIM(COARSE) (2019:135:001813:2T)

@NSFVoyager2 May 14 Starting Command & Control Subsystem timing test, measuring difference btw CCS timing chain & FDS frame start CCSTIM(FINE) (2019:135:000013:2T)

@NSFVoyager2 May 14 Flight Data System clock reset! FDS CLOCK RESET BML (2019:134:214300:2EC)

‏ @NSFVoyager2 May 14 Changed my data transmission rate from Science Cruise to Engineering Low (160 to 40 bps) FDS:MRO XB EL-40 (2019:133:205741:2ECa)


... There is no equivalent data source for V1. I note it more as a form of "what's it (maybe) been up to" than an explanation.

I take that back... there might be more to be gleaned here: https://voyager.jpl.nasa.gov/pdf/sfos2019pdf/19_06_13-19_07_08.sfos.pdf

Posted by: Bernard1963 Jul 5 2019, 08:51 PM

Thank you stevesliva. Even though I've only just joined the forum I'm a long time fan of the Voyagers and follow all posts available. The problem was, there was no answer that could be derived online. The condition of Voyager 1 has deteriorated with the signal variations increasing. Personally I was expecting the spacecraft to be lost before too long. I gather today the Voyager team have finally admitted a problem with the Earth pointing of the spacecraft. In a way of confirmation for the first time today I noticed the tracking schedule was not followed as per https://voyager.jpl.nasa.gov/pdf/sfos2019pdf/19_06_27-19_07_22.sfos.pdf with Voyager 1 taking the slot of Voyager 2 on DSS43 and arrayed with DSS34 & DSS35. I understand the team are investigating a yaw error and hope to make corrections shortly. My only fear now is that Voyager 1 is so far off point it may be difficult to upload commands.

Posted by: Bernard1963 Jul 5 2019, 08:56 PM

On the subject of Voyager 2 I notice from https://voyager.jpl.nasa.gov/pdf/sfos2019pdf/19_06_27-19_07_22.sfos.pdf it looks like Voyager 2 will be swapping attitude control trusters to its TCM thrusters on July 9th, as was done with Voyager 1 in Jan 18.

Posted by: Xcalibrator Jul 6 2019, 02:35 PM

QUOTE (Bernard1963 @ Jun 20 2019, 04:06 AM) *
I was wondering if anyone else had noticed...


Looking back, the https://voyager.gsfc.nasa.gov/_recent/v1la1.html started showing noticeable gaps around June 6.

Posted by: Bernard1963 Jul 9 2019, 10:38 AM

They've fixed it pretty quickly once they admitted the problem, but it had got very bad. The signal is now stable and the strength is as expected :-) https://eyes.nasa.gov/dsn/dsn.html

Posted by: stevesliva Jul 9 2019, 01:24 PM

Coincidentally posted yesterday:
https://voyager.jpl.nasa.gov/news/details.php?article_id=114

I haven't see anything other than this thread mentioning an anomaly... in any event, amazing what they're still doing with these two.

Posted by: JRehling Jul 10 2019, 05:08 AM

I don't nitpick often (do I?) but while the Voyagers are perhaps the oldest spacecraft still operating, Vanguard 1 (launched March 17, 1958) is the oldest spacecraft still flying, though it's been dead and inert since 1965.

Posted by: Bernard1963 Aug 17 2019, 12:24 AM

I've noticed the past couple of days Voyager 1's signal is low again into the DSN, presumably off point again. Tracking times available here https://voyager.jpl.nasa.gov/pdf/sfos2019pdf/19_08_15-19_09_02.sfos.pdf the levels received here https://eyes.nasa.gov/dsn/dsn.html you should see roughly -155db on a 70m and -157db on a 34m dish.

Posted by: Bernard1963 Sep 24 2019, 11:25 AM

I should have noted that around the 7th September there was a sun sensor calibration and ASCAL which does appear to have fixed the pointing issue and the signal into the DSN has been as expected since then. However as this was the 2nd such incident in the past 6 months I wonder if the sun sensor is having trouble keeping a lock on the sun, now at 147AU.

Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)