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Thread: Voyager course correction

  1. #1
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    Thumbs up Voyager course correction

    Voyager 1 Just Fired Up its Backup Thrusters for the 1st Time in 37 Years

    Voyager 1 hadn't used its four "trajectory correction maneuver" (TCM) thrusters since November 1980, during the spacecraft's last planetary flyby — an epic encounter with Saturn. But mission team members fired them up again Tuesday (Nov. 28), to see whether the TCM thrusters were still ready for primetime.
    [...]
    "The Voyager team got more excited each time with each milestone in the thruster test," Todd Barber, a propulsion engineer at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, said in a statement. "The mood was one of relief, joy and incredulity after witnessing these well-rested thrusters pick up the baton as if no time had passed at all."
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    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

  2. #2
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    Whoa, impressive. I'd be ecstatic if some of the things I build today would still be operational in 37 years.
    Conserve energy. Commute with the Hamiltonian.

  3. #3
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    I get excited (and relieved) each morning when the car starts. I can't imagine what it would be like firing something up after 37 years in a deep space environment and having it perform flawlessly. Seriously, hats off!

  4. #4
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    Are there any KBO's along Voyagers course? If they could squeeze one more flyby out of her, now that would be impressive. I suppose that would be too much to expect. Do we know if the scan platform even works anymore?

  5. #5
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    It sounds like they are going to use the TCM thrusters to adjust attitude to maintain communication with Voyager 1. There are attitude-control thrusters but they have a limited life. Using the TCM thrusters will allow extend the lifetime of stable attitude and thus communication for 2 or 3 years.

  6. #6
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    Quote Originally Posted by Superluminal View Post
    Are there any KBO's along Voyagers course? If they could squeeze one more flyby out of her, now that would be impressive. I suppose that would be too much to expect. Do we know if the scan platform even works anymore?
    I suspect there are no KBOs along either crafts' course (space is big) and there is no way to course correct enough to fly by one.

    The cameras and the spectrometers are no longer working, so it wouldn't be much of a flyby (working instruments and status).
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  7. #7
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    Quote Originally Posted by Reality Check View Post
    It sounds like they are going to use the TCM thrusters to adjust attitude to maintain communication with Voyager 1. There are attitude-control thrusters but they have a limited life. Using the TCM thrusters will allow extend the lifetime of stable attitude and thus communication for 2 or 3 years.
    That sounds correct.

  8. #8
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    I was amazed at this story. Just how many gallons of thruster fuel was on the craft over 40 years ago. And the electronics! Did the computer have a core store? It was designed and put together in the early seventies. If the engineers responcible are still around they should take a bow and explain how they got it so right. I suspect a nuclear powered thermoelectric generator provides a nice stable power source without glitches! And the semiconductors have escaped cosmic rays apparently. Fantastic!

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    Quote Originally Posted by peteshimmon View Post
    And the electronics! Did the computer have a core store?
    Good question. Apparently it used plated wire memory, which is not a technology I was aware of.
    https://www.allaboutcircuits.com/new...itude-control/
    (see the links at the bottom of that article for more detailed info)

  10. #10
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    Quote Originally Posted by peteshimmon View Post
    <snip> I suspect a nuclear powered thermoelectric generator provides a nice stable power source without glitches!
    Depends on what you mean by stable. It isn't subject to spikes and power fluctuations. But as the radioactive material decays, the heat generation, and thus the power generation, will decrease over time.

    https://en.wikipedia.org/wiki/Voyager_1#Power
    Voyager 1 has three radioisotope thermoelectric generators (RTGs) mounted on a boom. Each MHW-RTG contains 24 pressed plutonium-238 oxide spheres.[19] The RTGs generated about 470 W of electric power at the time of launch, with the remainder being dissipated as waste heat.[20] The power output of the RTGs declines over time (due to the 87.7-year half-life of the fuel and degradation of the thermocouples), but the craft's RTGs will continue to support some of its operations until 2025.

    As of April 4, 2018, Voyager 1 has 72.56% of the plutonium-238 that it had at launch. By 2050, it will have 56.5% left.
    https://voyager.jpl.nasa.gov/mission...rty-year-plan/
    Radioisotope Thermoelectric Generators (RTGs) provide electrical power to the Voyager spacecraft. Due to the natural radioactive decay of the plutonium dioxide heat source, the electrical power provided by the RTGs is continually declining, as expected. The current rate of decay is approximately 4 watts per year. Because of the continual decline in the amount of power that is available, it is necessary to periodically reduce power consumption in order to maintain an adequate power margin. This is accomplished by turning off spacecraft power loads.
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