Continuation The Electric Comet Theory Boogaloo (Part 2)

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Gravity. Something else for RC to add to his list of things that Sol doesn't understand about basic science. If we'd actually let EUers plan this mission, I wonder where it would have ended up? Proxima, in about 40 000 years? It would probably never have got off the ground, given that the shielding would have been too heavy, due to taking account of all the squillions of electrons flowing into/ out of their electric sun. Invisible electrons, that is, with built in Romulan cloaking devices.
 
Sol88 said:
Well then I must be a neo-Velikovskyian!
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The idiocy of comparing images of balls of ice and dust to images of the Earth should be obvious to you, Sol88 - even as a believer in the neo-Velikovsky delusions :p!.

If you have not read the fantasies of Velikovsky then I suggest that you do not rot your brain by doing so. You have already seen the effects of Velikovsky on David Talbott and Wal Thornhill. Their intellectual facilities have been so badly corrupted that they can entertain the delusions that I listed previously and the delusion that comets are rocks.
 
Sol88 said:
and not so sure about the set in stone (no pun intended) figure of 470 kg/m^3
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That is a thing called science, Sol88:
  1. Measure the mass of a comet with one method of several explained in the blog you linked to Determining the mass of comet 67P/C-G !
  2. Measure the volume of a comet
  3. Divide mass by volume to get the density of the comet!
For 67P: Comet vital statistics (as at 22/01/2015) has 0.47 g/cc.

Note that before 67P's strange shape was discovered, the mass was measured from 67P's orbit and its volume from its light curve (modeled as a ellipsoid) and was estimated as 0.1 g/cc.
ETA: Hopefully we will not see the delusion that a change from 0.1 to 0.47 means that a jump to 1.0 or greater is possible! 0.47 is a more accurate result than the previous 0.1. With more observations the mass and volume may change by a few % leading to a few % change in the density. We are not going to see the mass double or the volume halve!

Note that 67P is not the only comet that exists :jaw-dropp! The densities of many comets have been measured and average out to ~0.6 g/cc as you have now n for 6 years now and continue to deny.

Dave Higgins question is reasonable and answered
Luke says: 22/08/2014 at 10:45
The new estimated density is higher than expected, not lower. Uncompacted snow can be well under 100 kg/m^3, see http://www.sciencelearn.org.nz/Contexts/Icy-Ecosystems/Looking-closer/Snow-and-ice-density and with no gravity or freeze/tham cycle to compact it, snow + dust at an average density of about 100 kg/m^3 was the guess. What Rosetta has found is either much dirtier (rock at density 3000-5000 vs ice at 1000) or much more compacted than expected.
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Sol88 said:
Do you assume the gravity is the same as on Earth??? :rolleyes:
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Luckily you have the :rolleyes: there Sol88 :rolleyes:!
67P is massively lighter than the Earth so "the gravity" is not the same.
But the same law of gravity applies as to any massive body. That is not an assumption. That is a observationally confirmed fact because we can predict the motions of massive bodies such as spacecraft, planets, moons, asteroids and even comets using the laws of gravity. It was the observations of the orbits of the planets that lead to Kepler's laws and then to Newton's law of gravitation.
 
Dancing David said:
Wow a whole new layer of Conspiracy Theory!

So the Rosetta probe got there with calculations based upon standard celestial mechanics:

Yes or No Sol88 ?


I can't wait for the explanation!
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From the Rosetta blog

Big Burn 2 complete



Last night's orbit correction manoeuvre ran as expected, with nominal completion at 23:00 CEST (21:00 UTC).
The thruster burn got underway as scheduled at 16:21:58 CEST (14:21:58 UTC) and ran for 6hrs:39mins, about 2 minutes less than planned but well within margins. About 190 kg of fuel was used.
The manoeuvre was triggered automatically by a command stack that had been uploaded on Tuesday. Engineers were able to monitor the event in real time via ESA's 35m deep-space antenna at New Norcia, Australia.
The Rosetta flight control team can't say what the precise results were in terms of actual delta-v delivered until Flight Dynamics here at ESOC do a review and orbit determination, which takes a day or so, but if a burn runs for anywhere close to the planned time, then we know it went more or less OK – as it did (see note below).
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So if you have fuel to do orbit correction manoeuvres, then your maths only has to be ballpark :rolleyes:

and it (gravity) has a few anomalies, so... again fudge factor = fuel

here are some observations that are not adequately accounted for, which may point to the need for better theories of gravity or perhaps be explained in other ways.
Rotation curve of a typical spiral galaxy: predicted (A) and observed (B). The discrepancy between the curves is attributed to dark matter.

Extra-fast stars: Stars in galaxies follow a distribution of velocities where stars on the outskirts are moving faster than they should according to the observed distributions of normal matter. Galaxies within galaxy clusters show a similar pattern. Dark matter, which would interact gravitationally but not electromagnetically, would account for the discrepancy. Various modifications to Newtonian dynamics have also been proposed.

Flyby anomaly: Various spacecraft have experienced greater acceleration than expected during gravity assist maneuvers.

Accelerating expansion: The metric expansion of space seems to be speeding up. Dark energy has been proposed to explain this. A recent alternative explanation is that the geometry of space is not homogeneous (due to clusters of galaxies) and that when the data are reinterpreted to take this into account, the expansion is not speeding up after all,[28] however this conclusion is disputed.[29]

Anomalous increase of the astronomical unit: Recent measurements indicate that planetary orbits are widening faster than if this were solely through the sun losing mass by radiating energy.

Extra energetic photons: Photons travelling through galaxy clusters should gain energy and then lose it again on the way out. The accelerating expansion of the universe should stop the photons returning all the energy, but even taking this into account photons from the cosmic microwave background radiation gain twice as much energy as expected. This may indicate that gravity falls off faster than inverse-squared at certain distance scales.[30]

Extra massive hydrogen clouds: The spectral lines of the Lyman-alpha forest suggest that hydrogen clouds are more clumped together at certain scales than expected and, like dark flow, may indicate that gravity falls off slower than inverse-squared at certain distance scales.[30]
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Hows the maths going for the Pioneer anomaly??

Just let it go thru to the keeper i spose, like anything too hard or will not fit with the very elegant maths.

Gravity!!!!! The weakest force in the universe :blush:

In fact so weak that a black hole is a mathematically defined region of spacetime and never observed.
 
Reality Check said:
Luckily you have the :rolleyes: there Sol88 :rolleyes:!
67P is massively lighter than the Earth so "the gravity" is not the same.
But the same law of gravity applies as to any massive body. That is not an assumption. That is a observationally confirmed fact because we can predict the motions of massive bodies such as spacecraft, planets, moons, asteroids and even comets using the laws of gravity. It was the observations of the orbits of the planets that lead to Kepler's laws and then to Newton's law of gravitation.
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BUT mass and gravity are not interchangeable! you have no idea of the gravity of 67P therefore you have underGUESSED the mass... :rolleyes:

you assumed there would be water, you assumed there would be ice, you assumed they would be weaker than a powdered snow bank.....time to not make assumptions, me thinks.
 
Reality Check said:
That is a thing called science, Sol88:
  1. Measure the mass of a comet with one method of several explained in the blog you linked to Determining the mass of comet 67P/C-G !
  2. Measure the volume of a comet
  3. Divide mass by volume to get the density of the comet!
For 67P: Comet vital statistics (as at 22/01/2015) has 0.47 g/cc.

Note that before 67P's strange shape was discovered, the mass was measured from 67P's orbit and its volume from its light curve (modeled as a ellipsoid) and was estimated as 0.1 g/cc.
ETA: Hopefully we will not see the delusion that a change from 0.1 to 0.47 means that a jump to 1.0 or greater is possible! 0.47 is a more accurate result than the previous 0.1. With more observations the mass and volume may change by a few % leading to a few % change in the density. We are not going to see the mass double or the volume halve!

Note that 67P is not the only comet that exists :jaw-dropp! The densities of many comets have been measured and average out to ~0.6 g/cc as you have now n for 6 years now and continue to deny.

Dave Higgins question is reasonable and answered
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Why strange?? mainstream did not expect the shape of ANY comet yet visited...SURPRISE! (again)
 
Sol88 said:
BUT mass and gravity are not interchangeable!
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BUT you have the delusion that people think that gravity and mass are interchangeable when anyone with two brain cells knows that they are two different things (e.g. different units of measurement) :p!

Lying about us not knowing the gravity of 67P is wrong, Sol88. We have measured it over decades by looking at its orbit. The trajectory of the Rosetta spacecraft was designed with the gravity of 67P included. We measured it by looking at how it affected the Rosetta spacecraft. We have had the Rosetta spacecraft orbiting 67P under the influence of the gravity of 67P :eek:!
Of course 67P has mass (no mass and it would not orbit the Sun) and so has gravity - this is a fundamental property of mass!

67P/Churyumov-Gerasimenko mass determination based on a new method for modeling non-gravitiational forces and accelerations (2012)
Moreover, we obtained the nucleus mass of: 3.14⨯1012±0.21⨯1012kg. This mass corresponds to a density equal to 102±9 kg m-3. This determination is consistent with those obtained by other authors ([3],[4]).
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The densities of comets were measured. Based on that they have to be made of ices (including water) and dust. The estimated strengths of comet material never was "weaker than a powdered snow bank". They were estimated using science.
 
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Sol88 said:
Hows the maths going for the Pioneer anomaly??
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Your own source says how it's going:

"once the thermal recoil force is properly accounted for, no anomalous acceleration remains."

Really, Sol, you should read your own links now and then.

But the real kicker is that it wouldn't even matter if this anomaly was some new physics (it's not). The anomaly is so small that, even applied to the comet density problem, it would be lost in the noise. So it wouldn't make any real difference to the fact that comets and asteroids have radically different densities.
 
Sol88 said:
Why strange?? mainstream did not expect the shape of ANY comet yet visited...SURPRISE! (again)
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A reply based on your ignorance as expected, Sol88.
Any body forming in space tends to form a sphere which is the shape that scientist expected comets to be 60 years ago - "dirty snowball" :p.
But add spin and the sphere gets deformed. That is why asteroids and comets are modeled as ellipsoids if we do not know their actual shape.

Then add some more reality
* comets are made of ice and dust and may sublimate in strange ways
* comets can collide
So we know that modeling as ellipsoids is an approximation. 67P looks like a contact binary.
 
Funnily enough, Sol,the thrusters are not firing continuously. If you look at the Rosetta blog you'll see the strange orbital paths that Rosetta has been following. You need to fire thrusters to change your orbit. Once in that orbit (like a satellite orbiting Earth), you pretty much stay there until the next change. If the mission planners put this thing on a course to take it within 6 km of the nucleus (which, from memory, they have done), and they are relying on their measured gravity based on 470 kg/m^3 to get it to 6 km, then what do you think happens if the measured density is wrong by a factor of 5 or 6? That's right, gravity is increased, all their calculations are wrong, and crash, bang, wallop, no more Rosetta. Can't suddenly fire the thrusters when it takes light and radio waves ~15 minutes to reach it. By the time data reaches them saying it's going to crash, that data is already 15 minutes old. Then it will take another 15 minutes to send a signal back, plus the time to do the new calculations. It's a no go, they need to know the density and gravity to a high degree of accuracy. And they do. And many other space missions have been flown using exactly the same theory. And they keep getting it right, despite ignoring everything ever written by the high priests of EU.

ETA

And of course Philae was landed on the comet using these same estimates. If they were badly off in their estimate we wouldn't be waiting for Philae to wake up. We'd be scouring the surface for the debris.
 
I *have* to comment to Sol88's ballpark remark about the fuel corrections.
Dear Sol88, have you ever even TRIED to do the maths that are needed to get a probe the size of the rosetta to a comet?
We are talking about a several year journey using the gravity of several planets (repeatedly) to reach an end in a volume of space that is utterly mindboggling.
An error margin on that journey of 0.001% (which most of us consider utterly precise) would send that probe off into interstellar space without ever getting close.
All of this calculated and predicted by mainstream astronomy.
And it worked.
If your delusions about gravity being variable were right that probe would never have gotten there.
If your delusions about an electric universe were anywhere near right that probe would also never have gotten there as induced magnetism would have altered its course by whole percentage points.

You can zoom in on pixels all you want and claim that proves something, but the fact that the probe is there at all invalidates all EU fantasy by it's very orbit.
Of course so did the voyagers.
And the pioneers.
And the sputnik.
And the apollo missions.
And everything else we've sent into outer space.
That's the beauty of science right there. No matter whether you believe it or not, the results are there.
 
Lukraak_Sisser said:
I *have* to comment to Sol88's ballpark remark about the fuel corrections.
Dear Sol88, have you ever even TRIED to do the maths that are needed to get a probe the size of the rosetta to a comet?
We are talking about a several year journey using the gravity of several planets (repeatedly) to reach an end in a volume of space that is utterly mindboggling.
An error margin on that journey of 0.001% (which most of us consider utterly precise) would send that probe off into interstellar space without ever getting close.
All of this calculated and predicted by mainstream astronomy.
And it worked.
If your delusions about gravity being variable were right that probe would never have gotten there.
If your delusions about an electric universe were anywhere near right that probe would also never have gotten there as induced magnetism would have altered its course by whole percentage points.

You can zoom in on pixels all you want and claim that proves something, but the fact that the probe is there at all invalidates all EU fantasy by it's very orbit.
Of course so did the voyagers.
And the pioneers.
And the sputnik.
And the apollo missions.
And everything else we've sent into outer space.
That's the beauty of science right there. No matter whether you believe it or not, the results are there.
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Yeah well done!! :rolleyes:


but Rosetta's orbit to 67P was a catch up one and why would they not use the Go-Onto-Target system using off the shelf military system, the Target tracker (67P) Missile tracker (Rosetta Probe) Guidance computer( using the star tracker)

Get the probe to near enough the the target, 67P, then let the tracking computer make adjustments in real time. No radio lag from earth to probe return comms, just one way to let u know how it went, for instance jonesdave116,

Lukraak_Sisser Or are you implying they did (the flight planners) one calculation and sent it on its way??? No OCM's
 
Sol88 said:
but Rosetta's orbit to 67P was a catch up one and why would they not use the Go-Onto-Target system using off the shelf military system, the Target tracker (67P) Missile tracker (Rosetta Probe) Guidance computer( using the star tracker)

Get the probe to near enough the the target, 67P, then let the tracking computer make adjustments in real time. No radio lag from earth to probe return comms, just one way to let u know how it went, for instance jonesdave116,

Lukraak_Sisser Or are you implying they did (the flight planners) one calculation and sent it on its way??? No OCM's
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First, why the hell would they use terrestrial guidance programs for extra-terrestrial navigation? And why would you use algorithms designed to hit a target when your goal is to orbit around a target? That makes no sense.

Second, do you know why orbital correction maneuvers are necessary? It's not because the orbital calculations are insufficiently accurate, it's that the launch into orbit process is inaccurate. Getting just the right thrust, at just the right angle, is not easy to do. At a certain point, it's easier to make the process correct during flight rather than try to improve initial accuracy further. But you still need to be pretty darn accurate to start with, because there's a rather limited supply of fuel available to do such corrections, space is awfully big, and these orbits take a long time.

Third, how do you get "close enough" if your model of gravity is not just a tiny bit off, but radically wrong? Well, you don't. You can't. It's only possible to get this close to the comet because our model of gravity is incredibly accurate.
 
As for the dust. Interstellar Olivine

Mg-rich olivine has also been discovered falling into infant stars.

The spectral signature of olivine has been seen in the dust disks around young stars. Comet-like (magnesium-rich) olivine has also been detected in the planetesimal belt around the star Beta Pictoris.

http://en.wikipedia.org/wiki/Olivine
 
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Sol88 said:
From the Rosetta blog



So if you have fuel to do orbit correction manoeuvres, then your maths only has to be ballpark :rolleyes:

and it (gravity) has a few anomalies, so... again fudge factor = fuel



Hows the maths going for the Pioneer anomaly??

Just let it go thru to the keeper i spose, like anything too hard or will not fit with the very elegant maths.

Gravity!!!!! The weakest force in the universe :blush:

In fact so weak that a black hole is a mathematically defined region of spacetime and never observed.
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Uh huh, so when you drive you never adjust your course, I see Sol88, the world you live in must be very special. Your car gets to it's destination without any steering by you.

Burning fuels does not equal anomaly, this really make you seem to be a Conspiracy Theorist and getting to produce stranger arguments every day.

the fact that you even mention the Pioneer Anomaly just shows you cut and paste, or you would have found it is explained.

So instead of spamming us, how about you actually explain this alleged gravitational anomaly?

BTW what is the course error of .0001% over 6.4 billion kilometers?
 
Sol88 said:
BUT mass and gravity are not interchangeable!
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Excuse me, but what is the formula for calculating gravitational force?

Your statement is certainly a Conspiracy Theory level statement. I may have to suggest that is where this thread is headed.

You have zero concept of orbital mechanics or you would now the mass of an object can be derived from its orbital interactions. The interaction of Rosetta (known mass) and its interaction with the comet gives a very precise measure of the mass of the comet.
 
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