THE FLYBY-SLINGSHOT ANOMALY AND A NEW/OLD EXPLANATION
When Mr. T.M. sent along this one, I knew I had to blog about it. In fact, he sent it as I was sifting and sorting through the week's emails and articles, and, as it arrived at "the last minute" so to speak, it actually "bumped" another article off my "finals list" that I was going to blog about. This one, while written in the typical bland sort of style typical of reports about science, is a "whopper doozie", and I hope I'll be able to explain why.
So the background here - laid out very well in the article - is the "Flyby anomaly." Most people are aware that when deep space probes are sent out into deep space, they use a "fllyby" or "slingshot" effect of planets to hurl them further out into space. This is done by plotting trajectories that take the probe into the gravity well of a planet, which increases their velocity, and then hurls them away from the planet. It's sort of like those moments during a golf tournament when a golfer has to sink a very important putt, everyone gets very quiet, he or she putts, and the ball whips around the outer rim of the hole without going in.
The problem, however, is that over the past few years, scientists have noticed that their use of this "gravity well-slingshot" effect isn't working quite as calculated; generally speaking, probes acquire rather more acceleration than there calculations, based on general relativity and so on, predicted.
So with that in mind, here's the article (and see if you can spot what leapt out to my attention):
Now, as one can imagine, what caught my eye here was this statement concerning what the real source of this anomaly was:
Their model took into account the tidal forces exerted by the Sun and by Jupiter’s larger satellites – Io, Europa, Ganymede and Callisto – and also the contributions of the known zonal harmonics. They also accounted for Jupiter’s multipolar fields, which are the result of the planet oblate shape, since these play a far more important role than tidal forces as Juno reaches perijove.
In the end, they determined that an anomaly could also be present during the Juno flybys of Jupiter. They also noted a significant radial component in this anomaly, one which decayed the farther the probe got from the center of Jupiter. As Acebo explained:
“Our conclusion is that an anomalous acceleration is also acting upon the Juno spacecraft in the vicinity of the perijove (in this case, the asymptotic velocity is not a useful concept because the trajectory is closed). This acceleration is almost one hundred times larger than the typical anomalous accelerations responsible for the anomaly in the case of the Earth flybys. This was already expected in connection with Anderson et al.’s initial intuition that the effect increases with the angular rotational velocity of the planet (a period of 9.8 hours for Jupiter vs the 24 hours of the Earth), the radius of the planet and probably its mass.”
They also determined that this anomaly appears to be dependent on the ratio between the spacecraft’s radial velocity and the speed of light, and that this decreases very fast as the craft’s altitude over Jupiter’s clouds changes. These issues were not predicted by General Relativity, so there is a chance that flyby anomalies are the result of novel gravitational phenomena – or perhaps, a more conventional effect that has been overlooked. (Bold & italics emphasis added)
Now, why is this significant? Because in the basic assumptions typically used, the only real phenomenon taken into consideration was mass, not rotating mass, but just mass. Think of it as being a heavy bowling ball on a trampoline, and you're shooting a golf ball so that it uses that gravity well created by the bowling ball to whip around the bowling ball and further out onto the trampoline, checking its trajectory in the process.
But now what happens if one places a rapidly rotating ball on the trampoline? The fabric around the ball will be twisted in the direction of the ball's rotation(the heavier the ball and the faster its rotation, the more the "twist"), and that in effect will add a function of the ball's angular momentum to the golf ball when you shoot it by the bowling ball.
This effect is called torsion, and the combination of several such rotating masses in a medium is called dynamic torsion, indicating the interplay of all these "effects of rotation" with in a particular region.
Now, all this took me back to the revolution that occurred in physics, and the all-too-quick response of scientists to jump on the relativity bandwagon. In the late nineteenth century, scientists proposed the idea of an "Aether lumeniferous," a super-fine matter, permeating empty space and all objects in it, and undetectable. It was, so to speak, the "Dark Matter" of the day. The reason they posited this substance was that in all wave phenomena known to physics, the waves had to have something upon which to "wave." Two American physicists named Michelson and Morley reasoned that the best way to detect the presence of this "aether" would be to detect the very subtle dragging or "wind" of this aether as it "blew past the Earth", and the best way to detect this slight drag would be to use light. They set up an apparatus where a beam of light was split, and one beam run in the direction of the Earth's rotation, and another perpendicular to it. They reasons that if the "aether" was there, it would cause the beam of light traveling in the direction of the Earth's rotation to shift in the phase of its waves, and that this shift would be detectable by an interference pattern when the two split beams were merged on a plate.
Unfortunately, try as they might, Michelson and Morley could detect no such phase shift, and that meant, by the assumptions of the day, that there was no aether. Physics was deeply shaken until Albert Einstein came along and stood everything on its head by accepting the results of the experiment, and saying that there was no aether detection because the speed of light was constant to all frames of reference. And thus the relativistic age was born.
"Now wait just a minute," said a French physicist by the name of Georges Sagnac in 1913, a few years after Einstein's relativity revolution was already well under way. Sagnac criticized the whole Michelson-Morley experiment by pointing out that if one wanted to detect the presence of an "aether drag", then the measuring apparatus itself needed to be in a rotating system. Michelson and Morley's was not (other than the rotating earth itself). Sagnac actually set up a beam-splitting experiment on a large rotating platform (using a grammophone for the purpose), and split the beams, making one run in the direction of the rotation of the platform, and another counter to it, and voila, on this occasion when the beams were re-interferred, there was a detectable interference pattern, and a detectable phase shift. In effect, Sagnac was saying that Michelson and Morley were looking for the right thing, but in the wrong way.
In effect, what Sagnac was saying was that there is some sort of "aether drag" effect, but this required rotating systems, and these rotating systems were twisting the warped structure of space around them. To put it country simple: mass not only had to be considered, but rotation - the angular momentum of a system - had also to be considered. Both can serve to stress the lattice work of the medium, and to warp and/or twist it.
And this is where we run into some trouble, not only with today' article, but with respect to an earlier phenomenon I noted in my book The SS Brotherhood of the Bell: in the days of the early space race between the Soviet Union and the USA, both nations lost space probes that they were sending to the Moon to this "flyby anomaly" effect: some probes would go crashing into the planet, and others would be whipped out into deep space and lost. There are only three ways to explain this: (1) the calculations of the Moon's mass were off (perhaps significantly so), and (2) no reckoning of this torsion effect was being including in trajectory calculations, or (3) some combination of both. In yet another version of the anomaly, an early US military rocket carrying an American satellite into orbit ended up being much higher up than calculated, causing Von Braun's rocket team to find out why, and the "why" turned out to be very simple: the rocket was spinning.
After these "false starts," scientists were able to calculate things accurately.
In other words, by parity of reasoning the anomaly had to have been noticed at the dawn of the space age, and its indicators had to be made part of equations. Yet, now, here we are again apparently, recognizing the same "anomaly", with the same indicators being given for its solution as Sagnac guessed at something ago. In fact, as I pointed out in SS Brotherhood of the Bell, Walther Gerlach was carrying on a correspondence with Austrian physicists Lense and Thirring, over precisely such dragging effects on artificial satellites, and for that matter, satellites and the companies who own them, know all about this effect, otherwise, this global network would break down, and break down in a hurry.
So the question of the day is, are we looking at simple incompetence of a sort, of the graduate student relying on the "knowledge" contained in textbooks of satellite and space engineering that have not been adequately updated? Or are we perhaps looking at a bit of knowledge that is more closely and deliberately held? And if the latter, why?
Perhaps, just perhaps, the answer lies in the connection between rotating systems and DARPA's 100-year "make America warp capable" project. Torus-shaped engines, anyone?
See you on the flip side...
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