Order of Kilopi
Mean radius is 2,576 vs 2,634km. 'Quite a bit larger'? It's 2.3% Jerry. It's so close that before we really got up close with Titan, we thought IT was larger because of the size of its atmosphere.Originally Posted by Jerry
This part is true.closer to the sun,
Because Saturn's tiny, right?and close to a larger planet,
Yeah - That would be good. As would be answering the manifold questions I've asked you, as the rules of ATM dictate you should.Once again, I need .........discard the premise.
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How is this an answer? throwing a shot a few yards on earth is the same as travelling 429 million kilometers over 174 days to reach a target only about 7km across?
IF Gravity doesn't work like we think how did it get there on the button? How is Deep Impact able to continue it's mission out to 2020 to visit several other objects if the theory is wrong?
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Order of Kilopi
Fair question. The single most provocative data are the gravitational fields of Mars. Mars has positive Bougner gravitational anomalies that correspond with mountainous and elevated regions; and chasma indicate negative anomalies. Remember, Bougner gravitational anomalies are corrected for altitude, so the elevated regions appear to be more dense, and the cavities less dense that the surrounding terrain, and physically this is very difficult to model - for example, there should be greater stress features near the mountains. Why is this so important? If Big G is not constant, flyby measurements of gravity fields and the moment of inertia should appear to vary with variation in altitude above Mars; and this is indeed the case - Each gravity field mapping mission has returned slightly different Love numbers - and calculations of the Love numbers from fixed sites does not mesh well with fly-by calculations. So there has either been greater experimental error than expected, or the underlying physics should be suspect.
Notice that we have had a similar problem with discrepant gravity field data from the lunar missions, and this is why we have two identical gravity satellites chasing down the gravity field of the moon. I expect the close orbit mission of Messinger about Mercury will yield a different set of numbers than the more ellipical survey (if they do a gravity study at the lower altitude.)
Order of Kilopi
There is a little trick called the mid coarse corrections. Hitting a target requires corrections for gravity, but it also requires correction factors for the solar wind, stabilization rockets and so on. The exact mass of the moon and planet, and the distribution of the mass within the body, only become critical in the final moments of orbital insertion or during the descent. Most, if not all of our Martian probes have over-shot targets by somewhere between two and three sigma. Likewise, we were only close on the estimates of the gravity fields of Luna during the Apollo program.
Order of Kilopi
Because water has so much lower of a melting point than refractory minerals, like sand. Water ice and CO2 ice do not have near the compression strength of sand. Craters should be much deeper in bodies made from water ice, or they should melt and level-out on the floor - we should not expect the peak to form in the middle the way it does when stuff plows into the Earth and Mars. Hyperions craters are water-ice craters; Phoebo and Janis craters are not.
Established Member
No they should not. Look at the water phase diagram and it is pretty obvious why this is not going to happen on most satellites. As has been pointed out before. And Hyperion's craters are filled with a reddish material loaded with carbon and oxygen - which is not characteristic of pure water.Craters should be much deeper in bodies made from water ice, or they should melt and level-out on the floor
Senior Member
That has NOTHING to do with gravity, and EVERYTHING to do with mass concentrations (mascons) beneath the surface of the Moon.
Seriously, you didn't know that??
Senior Member
What happens when this doesn't occur?
In other words, if the failure of your "predictions" does not cause you to abandon this "variable gravity" idea of yours, what will???
Order of Kilopi
The mass of the Sun has a huge impact for the entire cruise. The mass of the Earth has a huge impact post launch. The mass of many bodies have a huge impact during the manifold gravity assists we have conducted over the years. Your assertion is utterly false
This is a utterly false JerryMost, if not all of our Martian probes have over-shot targets by somewhere between two and three sigma.
http://www.cs.odu.edu/~mln/ltrs-pdfs...aa-97-3663.pdf
Mars Pathfinder - 0.5km downrange and 5km cross range.
Spirit and Opportunity were downrange - their ellipses were 70km long.
http://ntrs.nasa.gov/archive/nasa/ca...2008012840.pdf
"The landing locations for both “Spirit” and “Opportunity” were within the pre-entry
predicted footprint ellipses. “Spirit” landed 13.4 km downrange from its predicted
landing location, while “Opportunity landed 14.9 km downrange from its predicted
landing location [11]. These downrange landing locations from their desired targets
are consistent with experiencing less dense atmospheres during both entries"
The reduction in drag does tie in with post landing data from the rovers (warmer than expected) and orbital data - plus - the accelerometer data during atmospheric entry. An excellent peer reviewed analysis of this is here : http://sirius.bu.edu/aeronomy/withersmericarus2006.pdf and here : http://www.ssdl.gatech.edu/papers/co...-3-2008-16.pdf
Phoenix landed long because they decided against a final TCM to re-aim for the center..
http://trs-new.jpl.nasa.gov/dspace/b.../1/11-0051.pdf
"Why did Phoenix land long?—Due to cancellation of
the sixth trajectory correction maneuver (TCM-6)
during the Cruise phase, the predicted landing location
was updated and re-centered 17 km uptrack of the
original target landing location (Figure 3). However,
the vehicle landed 21 km downtrack and 5 km
crosstrack from the newly predicted site, or a straightline distance of 21.6 km. The primary cause was the
higher-than-predicted angle of attack during hypersonic
entry. When this error is combined with the
reconstructed atmospheric density and high-altitude
winds, and with the very small navigation entry state
error (i.e., error in knowledge of position, velocity or
entry time) the propagated landing site is within 2 km
of the newly predicted landing site (and well below the
1σ uncertainty)."
All mars landings long by at least 2 or 3 sigma? Totally false Jerry. It took me 5 minutes to find the actual data to refute that. Why would you make a claim without doing the research first?
Jerry - please tell me that you're joking with the part I've put in bold. I explained, very clearly - these bodies have no atmospheres. Water DOES.NOT.MELT in a vacuum. It sublimates. Have you heard of a phase diagram? http://en.wikipedia.org/wiki/File:Ph...m_of_water.svg Please - learn about this then retract this catastrophcially missinfomred claim.
Order of Kilopi
Your definition of a spike, not mine. If you are looking at two weeks worth of flight data, a flyby is a spike on the chart. I'm trying to find concise way to state that the slope of a gravitational well is a function of how broadly the mass is distributed within a sphere: Standing on the earth, we are in a gravitational plane. In spacecraft flyby (or broad elliptical orbit), a moon transitions from a point to a planer well. It is the slope during this transition period that helps us define the center-of-mass, Love numbers, and the inertial moment.
Order of Kilopi
Not false - but again, over simplified.
Yes, the mass of the sun is critical, but the force can be transformed into a linear visual flight path. We can us Big G to calculate this linearization, because we used Big G to determine the mass of the sun. It does not matter if the this Big G assumption is false and the mass of the sun is not what we predict - we could empirically derive the relationship without a controlling theory, which is really what Newton did. However, Newton's derivation does not rule out an inertial component that also follows the inverse square geometry.
This is a utterly false Jerry
http://www.cs.odu.edu/~mln/ltrs-pdfs...aa-97-3663.pdf
Mars Pathfinder - 0.5km downrange and 5km cross range.
Spirit and Opportunity were downrange - their ellipses were 70km long.
http://ntrs.nasa.gov/archive/nasa/ca...2008012840.pdf
"The landing locations for both “Spirit” and “Opportunity” were within the pre-entry
predicted footprint ellipses. “Spirit” landed 13.4 km downrange from its predicted
landing location, while “Opportunity landed 14.9 km downrange from its predicted
landing location [11]. These downrange landing locations from their desired targets
are consistent with experiencing less dense atmospheres during both entries"
The reduction in drag does tie in with post landing data from the rovers (warmer than expected) and orbital data - plus - the accelerometer data during atmospheric entry. An excellent peer reviewed analysis of this is here : http://sirius.bu.edu/aeronomy/withersmericarus2006.pdf and here : http://www.ssdl.gatech.edu/papers/co...-3-2008-16.pdf
Phoenix landed long because they decided against a final TCM to re-aim for the center..
All mars landings long by at least 2 or 3 sigma? Totally false Jerry. It took me 5 minutes to find the actual data to refute that. Why would you make a claim without doing the research first?
The ellipses I have seen included one, two and three sigma, and I think both Spirit and Oppertunity were near two sigma and Pathfinder close to three. Very acceptable navigation, buy the way, but they all overshot.
Spirit and Opportunity descent analyses were incomplete at the time of Pathfinder because they could not find a model that took them all the way to the ground.
The atmospheric pressure would be off if either the temperture gradient or the Martian inertial parametrics are wrong. We have watched this over and over: Why is the upper atmosphere always thinner than we predict? I think we have a poor physical model of Martian gravitational dynamics.
Why was Phoenix coming in long before the final scheduled correction? Certainly not because of atmospheric effects! The trajectory should be slightly long if there is an unexpected inertial budget relative to the sun.
One word: Pressure gradient. Ok, that is two words. In any extremely aggressive collision there is a compression that will drive everything into critic pressure states - the human body essentially liquifies when a test pilot drives a plane into the desert, and so does some of the metal. These rapid phase transitions may or may not include large scale boiling and sublimation, but they certainly do include transition through a liqufication process. I don't think the crater of a rock exploding into ice should look like a crater made by a rock impacting another rock. The craters of Janus are not right for a watery world.Jerry - please tell me that you're joking with the part I've put in bold. I explained, very clearly - these bodies have no atmospheres. Water DOES.NOT.MELT in a vacuum. It sublimates. Have you heard of a phase diagram? http://en.wikipedia.org/wiki/File:Ph...m_of_water.svg Please - learn about this then retract this catastrophcially missinfomred claim.
Order of Kilopi
Mascons are the current explanation - likely a mostly correct one, from the featureless crater floors that we see - they are consistent with a molten melt, post impact.
We should have a better feel for whether or not the Mascon theory is complete after the current pair of twins complete new, high resolution gravity field maps.
We do see features in the floors of the craters of Mimas and Janus that are not consistent with mascons, or 'water ice cons'.
Order of Kilopi
And I've cited papers that refute that.
What are you talking about Jerry? Pathfinder was launched in 1996. Spirit and opportunity launched 7 years AFTER that. Infact, Spirit and Opportunity were not even selected until the decade AFTER PathfinderSpirit and Opportunity descent analyses were incomplete at the time of Pathfinder because they could not find a model that took them all the way to the ground.
This model lets us guide spacecraft astonishingly accurately. Odyssey, MRO, MEX are all flown with remarkable accuracy - such that a vehicle from 300km altitude can put a object the size of a golf cart slap bang in the middle of a color image 1km across.I think we have a poor physical model of Martian gravitational dynamics.
Go read the papers I cited please Jerry. I'm going to quite significant effort to refute you false claims with DATA and SCIENCE. Please at least show us all the respect of reading it. You'll see exactly why in those papers.Why was Phoenix coming in long before the final scheduled correction?
The fact that Pathfinder landed on the night-side of Mars - thus the net gravitational field would have been Mars + Sun - whereas others have landed on the day side ( Mars - Sun ) seems to have escaped your attention. Again - this was in the papers I cited and you've elected to ignore.Certainly not because of atmospheric effects! The trajectory should be slightly long if there is an unexpected inertial budget relative to the sun.
Explain why not. Ice at the temperatures of the solarsystem has the characteristics of rock. Why WOULDN'T it behave like a rock Jerry?I don't think the crater of a rock exploding into ice should look like a crater made by a rock impacting another rock. The craters of Janus are not right for a watery world.
Senior Member
Mascons are the accepted mainstream explanation. If you have evidence to dispute this, please present that evidence.
How is this relevant?...we're talking about Earth's Moon.We do see features in the floors of the craters of Mimas and Janus that are not consistent with mascons, or 'water ice cons'.
Established Member
Even if the material does pass through a liquid phase - how long will that last? The area on a phase diagram for liquid water is really small. You are postulating that somehow each impact somehow drives the material into this phase and keeps it there long enough to make a significant difference to the final crater morphology. Can you provide any links to work that shows anything like this? You are far more likely to get a supercritical phase than liquid, and even then it would be short lived.One word: Pressure gradient. Ok, that is two words. In any extremely aggressive collision there is a compression that will drive everything into critic pressure states - the human body essentially liquifies when a test pilot drives a plane into the desert, and so does some of the metal. These rapid phase transitions may or may not include large scale boiling and sublimation, but they certainly do include transition through a liqufication process. I don't think the crater of a rock exploding into ice should look like a crater made by a rock impacting another rock. The craters of Janus are not right for a watery world.
Your example of the human body is totally bogus too. There is no phase change there - merely a demonstration of plasticity of the material.
Established Member
Jerry, I'm repeating this request. Please consider it a direct question, per the rules of the ATM sub-forum. Please provide citations--not your personal opinions and interpretations!--for the claims you are making.
Also, please provide a link to your original predictions, so that they may be evaluated independently of your claims about them.
Thanks!
Order of Kilopi
Wrong. There are other ways of measuring the mass of the sun.
Moreover that mass of the sun works from 0.3AU to thousands of AU. 4 orders of magnitude or more - it's impact remains accurate.
Is this just word gravy? 'Intertial budget' is not one a cursory search finds in much use. Infact, the only other uses I can find are regarding actual fiscal budgets - not physics. Yours is the first use that talks to physics.unexpected inertial budget relative to the sun.
Perhaps you should use real physical phraseology and not your own word gravy?
Just to repeat this one - Janus is not a 'watery' world. It has high ice content, and that ice, out at those distances, has rock like physical properties.The craters of Janus are not right for a watery world.
I'll once again ask - do you intended to answer all the outstanding questions in this thread?
And once again - I ask you for your single best piece of evidence that there is something wrong in modern physics. Your last attempt was a total dud.
Senior Member
I know this is before your time, here, but Jerry has been "promoting" his variable gravity idea on this board since December 2004* when he started a thread "predicting" the crash of the Huygens probe.
7 and a half years later, and Jerry is no closer to proving himself correct than he was then.
Just a little "background" to put things into perspective.
*that is the first occurance I can find.
Order of Kilopi
Oh - I'm well aware of, and debated him on the issue regarding Huygens. I remember him trying to argue that the heatshield was still attached long after every possible piece of data showed it was gone.
I live in hope that he'll retract some of the more ludicrous claims when shown facts and evidence.
Order of Kilopi
Suppose for the sake of argument that Jerry's inferences of masses that are different from the results of Newtonian calculations from the orbital motions have some merit. Then the burden is on him to show a revised mathematical theory of gravitation that will resolve those issues, while remaining in good agreement with numerous well-observed orbital motions that already are known to be in good agreement with Newtonian calculations (Einsteinian GR if we are really splitting hairs). So far he has shown nothing of the sort. All we have are a lot of words that may look impressive to a novice with no background in physics.
If Jerry thinks he has a good idea but lacks the mathematical knowhow to elaborate on it, then he should emulate Einstein and do the necessary mathematical study and grunt work. If that takes ten years, so be it.
Order of Kilopi
What if you could do it in a month but he can't do it even
in fifty years?
-- Jeff, in Minneapolis
http://www.FreeMars.org/jeff/
"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"
"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves
Established Member
That would mean that he would not have actually been able to follow the papers that have been used to support his idea, rending it a guess. You cannot have it both ways - if you are capable of analysing and understanding papers well enough to come up with the theory then you are capable of putting it on at least a partially sound mathematical footing.
Order of Kilopi
A guess is the most important step in the development
of every new theory.
-- Jeff, in Minneapolis
http://www.FreeMars.org/jeff/
"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"
"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves
Established Member
Actually, no. A guess is just that - a shot in the dark. Asking someone else to assess your guesses for you is a ridiculous expectation. I can make up dozens of guesses a day, I certainly could not assess these guesses fully at the same rate.A guess is the most important step in the development of every new theory.
And it is irrelevant - Jerry is presenting predictions and papers/results that apparently support them. My point was that if he is competent to assess evidence like this then he is competent enough to at least make a stab at formalising his theory and presenting it.
Established Member
Er well. The fact that most guesses have no great value hardly affects the possible importance of a guess in a successful theory. It is a separate question whether that guess is the most important step.
However, I would regard it implausible (and have seen nothing to support it) that the Newtonian approximation to the Einsteinian theory of gravity is substantially falsifiable.
Order of Kilopi
Exactly! The deep holes are what one would expect if the water-ice portion of the moon was melted and sublimed away in the impact with an iron rich comet or asteroid. If the other icy moons are truly icy, they should look the same way. They don't. They have a relatively thin ice coat on a very hard, dense shell. The leading surface of Iapetus is black: Precisely what one would expect to see if a thin ice coating of the moon has been sublimed away by collisions with meteorites. Why only Iapetus? The current mainstream explanation is that 'dark stuff' from Phoebe has painted a new face on Iapetus. Why would Phoebe only deposit dark stuff on a single moon? It is just as rational to assume Iapetus has a very thin ice layer to start with that has melted away and exposed the chocolate on the inside. Eventually Hyperion will look more like Iapetus. So will Janis and Mimas, but they will not go through an Iapetus phase because their ice layers are not that thick.
Last edited by Jerry; 2012-May-28 at 12:09 PM.
Order of Kilopi
Huygens was an amazing mission. What we have in the data base is a mess - doppler signatures that diverge broadly from expectations for about fifteen minutes; and then about two hours of...nothing - likewise the descent imagery consists of a small fraction of the expected number of images taken during decent; even if only one channel of data was recovered.
Every piece of date is consistent with more than one interpretation because of a critical programming failure: The Ultrastable timing function was not switched on. The fact remains: Engineers tracking the descent of Huygens were amazed by how fast the probe appeared to be descending on the doppler images; and the fact that just as suddenly (and only fifteen minutes after entry) the doppler images stablized and matched the linearized motions of the moon relative to the Earth. To model these patterns as a long descent, modelers had to change the wind directions in Titans atmosphere 180 degrees, then set a wind cadence that decreased in an exactly linear rate right to Huygens landing at the predicted time with the probe rotating in the opposite direction from which it was designed to rotate! Nope. I still don't buy that - All of the data is still consistent with a very rapid descent and landing within seconds of when the large parachute was cut. Absolutely amazing.
Order of Kilopi
I don't have a working theory, but I have tried. Inverse - squared physics are very simple; but do not directly demonstrate causality - Newton even apologised for having no reasoning behind his instantanous action at a distance.
Gravitational tensors are a little more difficult to model, but GR is not the only workable field theory.
Einstein was curve fitting. When his curves diverged from the Newtonian mechanics correctly, everyone declared victory.If Jerry thinks he has a good idea but lacks the mathematical knowhow to elaborate on it, then he should emulate Einstein and do the necessary mathematical study and grunt work. If that takes ten years, so be it.
For decades, it was ironic to me that Einstein essentially returned us from Newtonians 'action at a distance' to what is similar to Aristotle's "it is the nature of rocks to be drawn to the ground" - "it is the nature of matter to curve space-time".
A century after he made the predictions, we are running into snags: No gravitational waves; and the evidence-to-date of frame-dragging is iffy-at-best; Null results must drive new theories, (not to mention the difficult constraints derived from relativity on the creation of hard gamma and cosmic rays). There are a lot of ways to nudge Mercury and the other planets about that can cause the observed orbital procession. Inductive models work; and at the same time, inductive models provide straightforward derivatives for generating gamma rays. So I think there are theorems already on-the-shelf that are plug-and-play. We have to decide when null results should lead to a theories abandonment. I think it is time.
Order of Kilopi
I agree. Educated guesses are the mainstay of mediums and mentalists. I think there are many physical observations - many good reasons to suspect that the densities and moment-of-inertia determinations of moons and planets are way off-beam. I think that a back-to-the-basics space-based Cavendish experiment will demonstrate this.
Order of Kilopi
Some of the math is very simple. If the Newtonian assumption that inertial mass is constant is wrong, it is not by much; and further, any variation must follow an inverse square rule or something very close to it. Mars is much smaller than the Earth, so it should have a slightly greater inerta-to-mass ratio. Therefore, when we try to land a probe with a known mass, we always overshoot the target - but only slightly. I can't pin down the exact ratio for the same reason I can't prove it: The atmosphere is an unpredictable variable. But I can ask the question: Why have the modelers always been forced to use a thinner upper atmosphere than predicted?
To me, one of the most interesting tests in all of science are the inertial wheel tests regularly performed during the Cassini mission. These are tests of the spin down, the amount of friction these wheels encounter in their nearly friction-free housings. In theory, the friction should remain constant, or increase slightly due to loss of lubricant. These tests are chronicled in the Cassini logs and it appears that sometimes the wheels perform better or worse than others. I would love to have the opportunity to try to correlate these tests with the orbital distance of Cassini from Saturn.
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