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 The Pioneer data exists on a few hundred ancient 7- and 9-track magnetic tapes, which can only be read on "antique" outdated computers.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!

[dvandorn]

Once again, I'm asking a question that I probably ought to just Google up for myself, but it does go along with the thread...

One of the experiments in the Apollo 17 ALSEP was the Lunar Surface Gravimeter. As I recall, it was designed to detect gravity waves. (It failed because it was balanced in 1G and was entirely out of balance, and hence useless, in 1/6G.)

Does anyone know what types of waves the LSG was designed to detect? Would it have been more in the LISA range or the LIGO range?

I guess I'm wondering what kinds of things we might have been gathering data on for more than 30 years if the instrument had just been designed properly...

-the other Doug

[Guest_Richard Trigaux_*]

Does anyone know what types of waves the LSG was designed to detect?  Would it have been more in the LISA range or the LIGO range?

I guess I'm wondering what kinds of things we might have been gathering data on for more than 30 years if the instrument had just been designed properly...

-the other Doug

I think that, even if such an instrument was properly designed, it had far from enough sensitivity to detect expected gravitationnal waves. Gravimeters are very sensitive indeed, they can detect such "low" masses as mountains, and even less (remember the historical Cavendish experiment which measured the effect of a some kilograms mass). But this is very far from enough to detect gravitationnal waves, which are many orders of magnitude under this level of sensitivity. Otherwise it would not be necessary to build such complicated experiments as LIGO, it would be enough to send a gravimeter in the ISS.

Perhaps the most powerfull recent gravitationnal event was the supernova in 1978, but who knows what happens in the gravitationnal field.

[The Messenger]

...
Perhaps the most powerfull recent gravitationnal event was the supernova in 1978, but who knows what happens in the gravitationnal field.

The failure to observe any evidence of SN1987A by any gravity wave detectors is not a good omen. True, the GW spectrum of a supernova is up-in-the-air, but an explosion of that magnitude, that close, should have created enough broad spectrum transients we should have found something, especially since the timing of the event is well known.

I wouldn't pin my life's savings on Advanced LIGO - which seems to be progressing slightly ahead of schedule. Every generation of gravity wave detectors from Weber's work in the '70's on, have been built with the expectation that a GW event was just one pixal below the horizon.

Advanced LIGO:
http://www.ligo.caltech.edu/docs/G/G050364-00.pdf

Eventually, with 1-year of data at design sensitivity, the LIGO detectors will be sensitive at a level several times below the nucleosynthesis bound.

http://arxiv.org/PS_cache/astro-ph/pdf/0507/0507254.pdf

FWI worth, there is still a great deal of contraversy in the supernova community about just what the gamma rays, and expansion RINGs associated with 1987A mean. John Middleditch amoung others, is convinced both the rings and rays reveal a binary event, and he argues most supernovae involve binary systems. This grates against SN Ia theory, but his arguments, (including the 'double humped' light curves observed in many SN Ia spectra.) are strong.

http://arxiv.org/abs/astro-ph/0310671

http://arxiv.org/abs/astro-ph/0311484

[Guest_Richard Trigaux_*]

I wouldn't pin my life's savings on Advanced LIGO - which seems to be progressing slightly ahead of schedule. Every generation of gravity wave detectors from Weber's work in the '70's on, have been built with the expectation that a GW event was just one pixal below the horizon.

Advanced LIGO:
http://www.ligo.caltech.edu/docs/G/G050364-00.pdf
http://arxiv.org/PS_cache/astro-ph/pdf/0507/0507254.pdf

Very interesting article, although arduous to read. To summarize, the purpose of LIGO is to detect the cosmic background gravitationnal noise caused by very early cosmological events, far before the electromagnetic background. Today LIGO has not yet achieved this goal, but it made only short runs of data sampling which were rather aimed at improving sensitivity and eliminating instrument noise. With a long run at expected maximum sensitivity they expect to detect the level of gravitationnal waves predicted by the most recent theories of inflation. If they really achieve this design sensitivity and still not fing a gravitationnal background noise, the theories of inflation are at risk. Still only some years of work to let us know...

Every generation of gravity wave detectors from Weber's work in the '70's on, have been built with the expectation that a GW event was just one pixal below the horizon.

This is often like this in difficult scientifical achievements. Look for instance at the tokamac, the quantum computer, superconduction at ambient temperature... This is also due to the fact that the first researchers were really optimistic. Today evaluations of gravitationnal waves are, alas, much more pessimistic, and if they were know in 1970 Weber would not have started his experiment. Weber simply did what was best possible to do at his epoch, knowing what we knew.

FWI worth, there is still a great deal of contraversy in the supernova community about just what the gamma rays, and expansion RINGs associated with 1987A mean.

Please remember that the curious set of three non-coplanar rings around SN1987A were already here before the explosion. They were discovered after, with close examination of the place, but such rings are more likely of the planetary nebula family. It was said at this epoch that there will be new hubbub here when the expanding fireball would reach the first ring, 20 years later (2007). Also we are still to detect the predicted blinking of the central object indicating the presence of a pulsar.

[The Messenger]

Please remember that the curious set of three non-coplanar rings around SN1987A were already here before the explosion. They were discovered after, with close examination of the place, but such rings are more likely of the planetary nebula family. It was said at this epoch that there will be new hubbub here when the expanding fireball would reach the first ring, 20 years later (2007). Also we are still to detect the predicted blinking of the central object indicating the presence of a pulsar.

News to me - can you provide a source? Middleditch based his models on fast rotating binary systems, and the resulting Gamma Rays, so I don't think prior rings cause a conundrum (prior rings being a product of the orbital dog-and-cat fight (?)).

[Guest_Richard Trigaux_*]

News to me - can you provide a source? Middleditch based his models on fast rotating binary systems, and the resulting Gamma Rays, so I don't think prior rings cause a conundrum (prior rings being a product of the orbital dog-and-cat fight (?)).

This set of three non-coplanar rings was photographied just after the blast was extinct, some months after the supernova, when astronomers began to examine the place. I remember well that it was in all the science reviews (Here in France "Science et Avenir", "Science et Vie", "Pour la science" , and also in amateur astronomy reviews. At that time the fireball from the explosion was just an unresolved point at the centre of the well resolved three rings. Previous photos of the same place showed the parent star, but were not large enough to show the rings. These rings much puzzled the astronomers, and they played a role in the planetary nebula theory (since it was found one or several planetary nebula looking like hour glasses, ressembling the rings of 1987A). They are now expected to form from binary systems. But I never heard of a companion star of SN1987A, with my opinion if it exists it must be a very weak star, white dwarf, neutron star or black hole. Anyway it puzzles me that today some people (and even scientists) seem to think that the three rings resulted from the explosion. Today the fireball of the explosion is just catching the innermost ring.


Another curious thing is that, while the fireball was still very bright, days of weeks after the explosion,I heard mentioned that just nearby there was a huge transcient infrared source, most powerfull than the entire Magellanic cloud. But I never heard of this again, perhaps it was just an observation error. Often unexplained facts are considered as mistakes and forgotten. But there may be some new thing about. Today people may think that it was the effect of a focused gamma ray beam like those predicted by some supernova theories.

Sorry, I have no other sources than my memories of the scientific press at this epoch. If you want more precise sources, I think you should look in the archives of science and astronomy reviews (like the "scientific American" in the months following the supernova, I think you cannot miss the images of the three rings.