December 5, 2017 Zimmerman/Batchelor podcast


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Embedded below the fold, in two parts.

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2 comments

  • wayne

    “The Changeling” (short version)
    ST: Original series
    https://youtu.be/egyd0cnmpPo
    (2:51)

  • J Fincannon

    Always glad to hear you on Batchelor.

    I don’t want to be picky, but something seemed “off” or “odd” when you said Pioneer is “dead” in a recent John Batchelor program. It came when you were talking about communications with various deep space probes.

    Assuming you were talking about Pioneer 10 and 11, I do not think it can be conclusively stated. they are “dead”. Dead implies destroyed or turned off or with no power. Pioneer with its radioisotope power system will have the potential for power for a long time. I am not aware that they purposefully chose to turn it off as they do recent spacecraft. I am not aware of any information stating it was destroyed (indeed how could they?).

    Pioneer 10 last received signal at Earth on 2006. For Pioneer 11 was 1995. But in both cases, this does not really mean it is “dead”. The power level maybe low, too low to send a signal back to Earth that can be heard. At least for Pioneer 10, it cannot point at Earth. So, just because it cannot communicate with Earth does not mean it is dead. I have read at https://nssdc.gsfc.nasa.gov/planetary/text/pioneer_10-11_status_971201.txt that “The Mission of Pioneer 11 has ended. Its RTG power source is exhausted.” That is actually a logical fallacy. If the power source was exhausted, the spacecraft could not report that this was the case since you need power to send such telemetry. What I think they meant was there was not enough power to support communications with Earth, so this means as far as the mission controllers are concerned, the power supply was exhausted. In reality it still provides power, although likely too low to do much and if it is broadcasting a signal, it can only be heard nearby.

    So, I think it best to say, both have ended their respective missions and their status is unknown (as it must be since they cannot send telemetry to Earth letting us know their status).

    Since the Pioneer power is radioisotope, you still get heat even today to keep the spacecraft warm, but you may not get enough power converted by the thermoelectric elements to power anything beyond simple circuits. Without telemetry/communications we do not know the status.

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