The McFly-by Anomalies

Added: 2026-05-19

[00:00:05]Hello, I'm Mike McCulloch.

[00:00:08]Today, I'd like to talk to you about the the flyby anomalies.

[00:00:13]So, I first heard about the flyby anomalies back in 2008 when John Anderson published a paper on them.

[00:00:23]So, what these are is that um NASA tends to save fuel on spacecraft by sending them out into the solar system and then flying them past the Earth in their orbit. So, in a clever way, the Earth pulls them along for a certain amount of time, increasing their speed. And so and then they they fire them off or slingshot them out towards Jupiter or Saturn or the the outer solar system or other places. [clears throat] So, a guy called John Anderson had noticed that several of these spacecraft, as they flew by the Earth, showed unexpected velocity increases of only a few millimeters per second, but it was significant given the error bars on the data.

[00:01:19]So, this paper published in 2008 excited me very much because it pointed out that the the larger anomaly for these flybys occurred when the spacecraft came in at the equator and left further towards the pole.

[00:01:37]So, the the anomaly depended on the difference between the incident latitude and the exit latitude.

[00:01:44]And at the time, so I was I was working at the Met Office at the time and I I read the paper. I I got extremely extremely excited about this, but then I but I I couldn't explain it. So, I got I got very upset.

[00:02:01]Um and I I went off to a to a lecture room to to think about it. And so, I I realized something in that lecture room.

[00:02:14]>> [clears throat] >> In that when the spacecraft come in at the equator, their acceleration relative to all the particles of mass inside the Earth is relatively large because they see some parts of the Earth accelerating away from the spacecraft and some parts of the Earth accelerating towards it on different sides.

[00:02:38]So, the mutual acceleration is large in that case.

[00:02:41]But when the spacecraft leaves at the poles, it's looking down on the spin axis of the Earth and so, the mutual acceleration between the spacecraft and all the bits, particles in the Earth is much lower.

[00:02:54]And quantize inertia predicts that when you have a low acceleration and as I realized when thinking about this, a low mutual acceleration, then the inertial mass drops.

[00:03:08]And by the conservation momentum, the spacecraft has to speed up.

[00:03:13]And it turned out what the when I I considered this uh using maths, I I integrated um over the sphere of the Earth, things like that.

[00:03:24]I managed to show that the predicted anomalies matched to some extent the the observed the observed anomalies.

[00:03:35]Uh so, this was quite quite encouraging.

[00:03:40]So, um so, I published a paper on this in in 2008.

[00:03:46]And so, the the agreement between the the six then observed flybys flybys was pretty good, but it wasn't perfect.

[00:03:59]And when I'm thinking about it now, I realize that I missed missed an extra effect.

[00:04:07]Because although the the change of inertial mass of the spacecraft as it passed by the earth causes them to speed up by conservation of momentum.

[00:04:19]It will also affect the gravitational interaction between them and the planet.

[00:04:23]So if they lose inertial mass, for example, and and and NEAR, the the spacecraft called NEAR, Near Earth Asteroid Rendezvous is a prime example.

[00:04:35]If they come in at the equator like that one did and leave at the pole, then they lose inertial mass so they speed up, but they are also attracted back towards the earth more than they would otherwise have been. And I I didn't factor that in.

[00:04:50]That might be a a significant thing to try next. It'd be nice It'd be nice to model this.

[00:04:57]This this also in in the paper I also made a prediction that the earth has a relatively fast spin, but some objects in the universe like galaxies have a much lower spin. And for them, the flyby boost the at the pole is predicted to be much greater.

[00:05:15]So we should see a lot of things leaving a galactic along the galactic axis. So indeed we do see galactic jets. So this could account for that.

[00:05:26]So that will be interesting to look at as well.

[00:05:29]Okay, so I hope you've enjoyed this short.

[00:05:32]If you like this this sort of thing, please do subscribe to my my Patreon and the link will be shown at the end of this video.

[00:05:41]Okay, so I look forward to seeing you next time. Goodbye.