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Posted by: dmuller Mar 22 2009, 01:37 AM

Whilst extracting data for the "notional DSN coverage" of my realtime simulations, I stumbled over (the probably widely known) fact that from around April 2010, only the Canberra DSN station will be able to communicate with Voyager 2 as it is that far south of the ecliptic by then. At least they will get 24 hours coverage of Voyager 2! Might be a selling point to maintain and upgrade the antennas there ...

http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=399&vbody=-32&month=3&day=21&year=2009&hour=00&minute=00&rfov=45&fovmul=-1&bfov=30&porbs=1&showsc=1
http://space.jpl.nasa.gov/cgi-bin/wspace?tbody=399&vbody=-32&month=9&day=30&year=2011&hour=12&minute=00&rfov=45&fovmul=-1&bfov=30&porbs=1&showsc=1

Posted by: Astro0 Mar 22 2009, 02:42 AM

We may have some news on that last point soon. Fingers crossed

Posted by: jasedm May 7 2010, 06:20 PM

Emily has recently posted a blog entry at The Planetary Society website, which suggests that Voyager 2 is experiencing problems with it's flight data system - I hope the issue can be resolved satisfactorily - V2 is by far my favourite spacecraft, and probably the most groundbreaking piece of space hardware ever.
Long may she prevail.

Posted by: Astro0 May 8 2010, 03:58 AM

It's safe to say that we are in 2-way comms with Voyager 2 after a busy week or so.
For the moment we're down to a 40-bit data rate, about a quarter of the regular rate.
Don't worry, we haven't heard the last of this amazing spacecraft.

Posted by: nprev May 8 2010, 04:09 AM

Glad you guys are keeping your ear out for her, Astro0...thanks for taking good care of our baby!

Posted by: JohnVV May 8 2010, 06:36 AM

that's good to hear .

on a slightly diff note .That 40 bit rate ( 160 bit norm)

I seam to remember hearing someplace that a very OLD 1970's computer was being kept alive to be able to read the data

new computers were not able to slow down so much . and that grad students are sent out to search for parts .
true or not ?

Posted by: Paolo May 8 2010, 08:23 AM

There is a JPL release on the Voyager 2 problem: http://www.jpl.nasa.gov/news/news.cfm?release=2010-151

Posted by: dtolman May 10 2010, 08:03 PM

If the flight data system ends up being unusable (no longer able to send correctly formatted data), is the craft useful for any science anymore?

Posted by: Hungry4info May 10 2010, 09:15 PM

Maybe they can conjure up some way to use tracking of the spacecraft to probe the density of the interstellar medium.
But other than that, I can't see how it would be useful.

Posted by: nprev May 10 2010, 09:56 PM

I would imagine just being able to receive a signal for as long as possible from her might be valuable from a strictly engineering standpoint (i.e., as a testbed for advanced signal processing).

Posted by: cbcnasa May 11 2010, 04:28 PM

The engineering value is there for as far as the spacecraft keeps going. Maybe with future technology data received now which might just be a signal could become useful .

Posted by: jgoldader May 12 2010, 01:27 PM

This could be something relatively simple--a stuck bit, for example, which might be programmed around. And IIRC, the FDS has A and B sides, so perhaps ops could be switched to the other side? But of course, due to loss of expertise and limited resources, either of those could be such major operations that they'd not be done.

Let's cross our fingers and send good thoughts to the old girl.

Jeff

Posted by: climber May 12 2010, 02:59 PM

You may be right Jeff: http://www.spaceflightnow.com/news/n1005/11voyager2/

Posted by: Roby72 May 12 2010, 09:22 PM

I remember that a few days before the Uranus encounter of Voyager-2 such a bit flip occured in the imaging subsystem, characterising as streaks in the images. The error was quickly identified and corrected. It appeared over big areas over the frames, because (IMHO) of compressing the digital information a simple bit flip could destroy more data. I remember further the bit flip was permanent and corrected mathematically in the processing.

Robert

Posted by: tasp May 13 2010, 12:08 AM

Yes, I recall the 'stuck bit' problem from the Uranus flyby. We have also had cosmic ray bit flips cause problems too, and perhaps a simple replay of the current software load uplinked from Canberra (nice to know about that constraint) might be all it takes to fix the problem. The expertise at this end is also significant too. If the science data coming down can be 'unscrambled' like the Galileo pics, or the compressed Uranus pictures, then maybe the problem isn't worth fixing due to the risk of introducing another problem.

I have considerable affection for the "old girl" and hate to see her cut loose, but we must be mindful the craft has been out there for 33 years and there is a certain inevitability to the situation.

I am fascinated though with the almost complimentary flight paths of V1 and V2 moving away from the ecliptic, and wonder if this enhances the analysis and significance of the the data from both sufficiently to make a better case for keeping V2 working for as long as V1 is working too. Regarding the desirability of having an engineering model that far out, I am not sure you get as much concatenation with 2 craft as you do with the science data, but maybe you do.

Posted by: nprev May 14 2010, 04:12 AM

Kudos to the stuck-bit adherents; does appear to be the most likely cause. Excellent (as usual) http://www.planetary.org/blog/article/00002485/ from Emily.

Posted by: MarcF May 26 2010, 09:30 PM

Great news : the Voyager 2 problem seems to be fixed !!
http://www.jpl.nasa.gov/news/news.cfm?release=2010-151
Marc.