Gravitational Waves Search Options

[dilo]

I recall that one of the science objectives of Cassini mission during the trip to Saturn was detection of long wavelenght radiation through two-way radio link...
However, in the past I often searched informations on the results without success.
It is easy argue that search didn't showed clear evidence of this radiation, but I do not know if something was going wrong with experiment or was established an upper limit on intensity based on this...
Can anyone could give some info/link on this item?
Thanks...

[cIclops]

I recall that one of the science objectives of Cassini mission during the trip to Saturn was detection of long wavelenght radiation through two-way radio link...
However, in the past I often searched informations on the results without success.
It is easy argue that search didn't showed clear evidence of this radiation, but I do not know if something was going wrong with experiment or was established an upper limit on intensity based on this...
Can anyone could give some info/link on this item?
Thanks...

Yes it is not easy to find details about this work. Cassini and several other spacecraft have been used to search for very low frequency gravity waves by looking for changes in spacecraft speed. A brief survey of the results can be seen here (section 4.4) http://www.ligo.org/pdf_public/techpapers_camp.pdf which says the experiment worked and, as you said, established an upper limit. There is a more readable description of the experiment with Cassini here http://www.jpl.nasa.gov/releases/2001/release_2001_227.html

Cassini was also used to make a more precise measurement of the bending of electromagnetic waves as predicted by general relativity. Results here: http://www.jpl.nasa.gov/releases/2003/133.cfml

[dilo]

Thank you very mich, Ciclops! (hey, based on your nickname, you should work in the Cassini Imaging Science Team...?!? ).
Regards.

[The Messenger]

Yes it is not easy to find details about this work. Cassini and several other spacecraft have been used to search for very low frequency gravity waves by looking for changes in spacecraft speed. A brief survey of the results can be seen here (section 4.4) http://www.ligo.org/pdf_public/techpapers_camp.pdf which says the experiment worked and, as you said, established an upper limit. There is a more readable description of the experiment with Cassini here http://www.jpl.nasa.gov/releases/2001/release_2001_227.html

Cassini was also used to make a more precise measurement of the bending of electromagnetic waves as predicted by general relativity. Results here:  http://www.jpl.nasa.gov/releases/2003/133.cfml

Good references, but the bottom line is unchanged by the Cassini experiment:

We have yet to observe ANY local galactic or cosmic evidence of gravity waves. If nothing shows up in LIGO science run 4 - I think it is being crunched as we speak -and if the expected sensitivity is achieve, the current theory for how gravity waves propagate is in serious jepoardy. Watch and see.

(G-Wave theory is well-supported by energy budget studies in binary pulsars.)

[ljk4-1]

General Relativity and Quantum Cosmology, abstract
gr-qc/0510105

From: Lorenzo Iorio [view email]

Date (v1): Tue, 25 Oct 2005 12:58:07 GMT (8kb)

Date (revised v2): Mon, 5 Jun 2006 14:50:00 GMT (84kb)

On the perspectives of testing the Dvali-Gabadadze-Porrati gravity model with the outer planets of the Solar System

Authors: Lorenzo Iorio, Giuseppe Giudice

Comments: LaTex, 21 pages, 2 tables, 10 figures, 26 references. Changes in authorship, references added, numerical simulations included

Subj-class: General Relativity and Quantum Cosmology; Space Physics

The multidimensional braneworld gravity model by Dvali, Gabadadze and Porrati was primarily put forth to explain the observed acceleration of the expansion of the Universe without resorting to dark energy.

One of the most intriguing features of such a model is that it also predicts small effects on the orbital motion of test particles which could be tested in such a way that local measurements at Solar System scales would allow to get information on the global properties of the Universe. Lue and Starkman derived a secular extra-perihelion \omega precession of 5\times 10^-4 arcseconds per century, while Iorio showed that the mean longitude \lambda is affected by a secular precession of about 10^-3 arcseconds per century. Such effects depend only on the eccentricities e of the orbits via second-order terms: they are, instead, independent of their semimajor axes a. Up to now, the observational efforts focused on the dynamics of the inner planets of the Solar System whose orbits are the best known via radar ranging. Since the competing Newtonian and Einsteinian effects like the precessions due to the solar quadrupole mass moment J2, the gravitoelectric and gravitomagnetic part of the equations of motion reduce with increasing distances, it would be possible to argue that an analysis of the orbital dynamics of the outer planets of the Solar System, with particular emphasis on Saturn because of the ongoing Cassini mission with its precision ranging instrumentation, could be helpful in evidencing the predicted new features of motion. In this note we investigate this possibility in view of the latest results in the planetary ephemeris field. Unfortunately, the current level of accuracy rules out this appealing possibility and it appears unlikely that Cassini and GAIA will ameliorate the situation.

http://arxiv.org/abs/gr-qc/0510105

[Guest_Richard Trigaux_*]

Could the Pioneer effect be caused by very low frequency gravity waves?

[ljk4-1]

If that were the case, why would we need such ultra-sensitive
instruments to detect them, and why aren't all deep spacecraft
affected in a similar way?

[djellison]

Because the effect is so small it's impossible to seperate it from the small forces that result from RCS's on more modern vehicles.

Doug

[Guest_Richard Trigaux_*]

If that were the case, why would we need such ultra-sensitive
instruments to detect them, and why aren't all deep spacecraft
affected in a similar way?

Very low frequencies, with periods of several years, would affect different spaceships, launched at different times, in a different direction or intensity.

More, it seems that, in cosmological gravitationnal waves, the low frequency spectrum is in 1/f, meaning the lower the frequency the greater the amplitude.

But as says Doug, it is unlikely that this amplitude would be so large as the measured Pioneer effect. But I am not sure.

By the way, hello Doug.