The Pioneer Anomaly Options

[remcook]

http://www.planetary.org/news/2005/pioneer_anomaly_faq.html

The planetary society may be checking it out...

The Planetary Society has committed to raise the funds to preserve the priceless Pioneer data from destruction.


After years of analysis, but without a final conclusion, NASA, astonishingly, gave up trying to solve the "Pioneer Anomaly" and provided no funds to analyze the data. The Pioneer data exists on a few hundred ancient 7- and 9-track magnetic tapes, which can only be read on "antique" outdated computers. The agency is going to scrap, literally demolish, the only computers able to access and process that data in the next few months!

[edstrick]

I'd have to check, but I think the Apollo 17 instrument's name included the term "Tidal". They were looking at freequencies below those the seismometer would detect, at least in part... looking for whole-moon "ringing" frequencies, like the ringing of the whole earth after a Richter 8+ quake.

The instrument failed because it was balanced in 1 G with the aid of a loading mass or spring which was unloaded on the moon. The problem was an arithmetic booboo in the calculation of the design for lunar gravity.. the instrument had a "bias" range that was adjustable for a range of lunar gravities, or really more accurately, for a range of instrument sensitivities... The adjustable range of the instrument was such that actual lunar gravity (very well known) was outside the adjustment range. This is similar to the focus failure on Deep Impact's hi rez camera.. The camera was "focussed" from pre-launch out of focus conditions by heating the carbon-composite truss to drive out water vapor in vaccuum, intending to slow down and stop when the instrument approached and achieved perfect focus..... it never got there due to a ground base calibration problem. The actual focus point was outside of the adjustment range.

[dvandorn]

I'd have to check, but I think the Apollo 17 instrument's name included the term "Tidal".

Not in the experiment title, no -- Apollo 17 carried two gravimeters, the Lunar Surface Gravimeter (LSG) and the Lunar Portable Gravimeter (LPG). The tidal reference may have been in the detailed description of the LSG, but it was not part of the instrument's name.

The LPG was the same type of instrument used by oil companies to find salt domes underneath otherwise flat land -- oil and gas are often entrained in salt domes. It detected negative anomalies on the slopes of the massifs and positive anomalies on the valley floor, indicating just how much more massive the basaltic valley fill is when compared to the massifs. IIRC, the anomalies were on the order of 10 to 30 milligals.

So, the LSG was an ultra-sensitive seismometer that hoped to use the entire mass of the Moon to detect gravity waves? Interesting... even if we now think that gravity waves would have been undetectable with such an instrument.

-the other Doug