Lots of perceptive comments in response to yesterday’s proposed Esthwaite Experiment to determine the curvature (or lack of it) of the surface of the the Earth. I think that the experiment is good in principle, but needs some more careful design.
I’d also hope to be able to keep it simple (and cheap). If that could be done, you might find that it becomes a science experiment that lots of people perform, and whose results they compare with each other – with no universities or Royal Societies or Big Science involved at all. And also it might stimulate an interest in currents and wave motion and tides in lakes. Does Esthwaite Water have a tide? Does the water slosh from one end to the other every day, or twice a day?
I’m currently building a new version of my orbital simulation model that I hope will allow things like tides to be studied. The tides are, after all, largely the product of gravitational forces of the Sun and Moon. These are small forces, but they act on large masses (bodies of water) for long periods of time. It might be possible to find out how the tide in Esthwaite Water should be expected to behave as the mass of the water in it is drawn first in one direction, and then another. Heck, you might even see 0.5 mm high tides.
And as part of the construction of this new model, I got hold of the state vectors (positions and speeds) from NASA of Apollo 11’s journey to the Moon in July 1969. In fact I don’t have the state vectors of the Apollo 11 Lunar Module, but only of the Apollo 11 S-IVB booster rocket that was used to inject the Lunar Module into a trans-lunar orbit. The Lunar Module actually separated from the S-IVB shortly after leaving Earth, and they pursued slightly different paths to the Moon, with the S-IVB missing the Moon and entering a solar orbit.
Anywhere, here’s my own reconstruction of the Apollo 11 journey to the Moon:
The Earth is in the centre and the arc below it shows the path of a geostationary satellite that I built into my map of the Earth, only half of whose orbit I show. We’re looking down onto the ecliptic plane (the plane of the Earth’s orbit around the Sun), and the Sun is off-screen at about the 11 o’clock position. The blue arc shows the position of the Moon over about 4 days. And the red line is my own calculated position of the S-IVB, given its initial state vectors shortly after it had completed boosting Apollo 11 into a trajectory towards the Moon.
And according to my calculations (carried out every 16 seconds), the S-IVB rocket coasted towards the Moon, gradually getting slower and slower, and then turned towards the Moon as it approached, and swung round the back of it, passing about 200 km above its surface. Given that I have the S-IVB state vectors throughout the journey, I can (and should) check the accuracy of my calculations using its actual recorded positions.
Quite a few interesting things have come out of this little exercise. Back in 1969 I only had the vaguest idea of what its trajectory had looked like, as shown in newspapers. I now have a much better idea about it. And one thing that has become clear is that the Sun must have only just have been rising over Tranquillity Base when the landing took place. I suspect that this is because the surface of the Moon gets very hot in prolonged sunlight, and dawn was when you had to land on the Moon if you didn’t want your astronauts to be cooked. It also means that the only places you can live on the Moon right now are at the poles which never get much sunlight.
I also read somewhere that there was a lunar eclipse of the Sun during the journey. That certainly looks possible given the fact that Sun-Moon-Apollo 11 would seem to have been in a line towards the end of the journey.
Also I read somewhere of a message from the Russians:
Bruce McCandless, astronaut (CapCom), Green Team, Mission Control: Shortly after Apollo 11 dropped into orbit around the moon, Frank Borman got a message from the Soviet Union that said, “Congratulations on reaching lunar orbit. We have Luna 16 also in orbit around the moon and its orbital parameters are such and such. If it presents any problem, please advise and we will move it.” We didn’t need Luna 16 moved, but I thought it was a noble gesture in those days of the Cold War.
I think this must mean that the Russians were tracking Apollo 11. They knew the Americans were there. And given they had Luna 16 in orbit around the Moon, they’d have been able to take photos of Tranquillity Base, and blow the lid off the whole thing if there was nothing there.
But perhaps the oddest thing I discovered (in a table somewhere) was that Apollo 11 lift-off on 16 July 1969 took place at a rather interesting time – 16: 16: 16: 16 – that is to say the 16th second of the 16th minute of the 16th hour (UTC/GMT) of the 16th day of July. Shades of the end of WW1 on the 11th hour of the 11th day of the 11th month in 1918. Was that an accident, and that just happened to be the best time to launch? Or was it that a bit of number symbolism was being invoked?
Anyway, I now have almost enough information to be able to reconstruct the entire Apollo 11 mission. I could have my own Lunar Module, and I could drop in it into a 60-mile circular orbit above the Moon, and then do my own landing on Tranquillity Base. And I could do it all with a 3D view of the Moon as seen from the Lunar Module, perhaps with a map showing all the craters. And anyone else who’s interested could do it too.
Which reminds me that back in university in 1975, when we got a DEC PDP 11/40 mini-computer with a state-of-the-art VDU, it came with a Moon Landing game. And if you landed at just the right spot on the surface of the Moon, you found yourself next to a burger bar on the its surface, and could order “a cheeseburger and a Big Mac to go.” I think I’d like to have a burger bar like that in my Tranquillity Base. And of course they’d sell beer and cigarettes as well.
P.S. 16:16:16:16 looks like it wasn’t the lift-off time, but the time of one of the S-IVB burn ignitions, and so not a particularly important time and date at all. Lift-off was actually at 13:32:00 GMT.