In 1865, the book ‘From the Earth to the Moon’ by Jules Verne was published. The book describes the adventures of three men: Barbicane, captain Nicholl, and the French poet Ardan, in launching themselves to the Moon in order to land there. Unfortunately they miss the Moon and four years later the struggles of getting back to Earth are described in the sequel ‘Around the Moon’. The books are an easy and fun read, and certainly a must-read for any space enthusiast. The crew are launched in a large bullet-like projectile (called ‘Columbiad’) using a giant canon (the creators are the Baltimore Gun Club, after all).
Jules Verne is very descriptive when it comes to the trajectory, quoting numbers with several digits at times. Having worked for years on Lunar transfers. I was always wondering….how accurate was he in describing the trajectory? Let’s find out..
Several parameters are known from the book.
Initial conditions: Launch from the city Tampa on 1 December 1872 at 22hrs 46m 40sec local time (which would be December 2 1872 3hrs 46m 40sec UTC). Launch is vertical with a velocity of 12000 yards per second (almost 11 km’s per second).
Moon conditions: Arrival at 5 December 1872 00:00. Closest passage was 25 miles. Fireworks were ignited at the Earth-Moon Lagrange point at 8 December 1:00 in order to return to Earth. At that point, fireworks are ignited to shoot the projectile back to Earth.
Earth arrival conditions: Splashdown on 12 December 1:17, at 27 deg 7′ North, 41 deg 37′ West.
There are several issues with trying to re-create the trajectory. First there is the ephemeris of the Moon; NASA/JPL’s HORIONS ephemeris models do not go back that far in time. Instead we have to rely on analytical ephemeris models, of which the accuracy at times far in the past is not too clear. In any case, it’s all we have so we’ll calculate the Moon’s position using analytical ephemeris models. Secondly there are a few impossible statements by Jules Verne. Firstly it is claimed that the Columbiad circles the Moon but later, without any propulsion, arrives at the Earth-Moon Lagrange point. This is not possible so for the sake of recreation we assume that Colubiad’s trajectory describes almost a full revolution around the Moon and then arrives at the Earth-Moon L1 point. This is in fact not contradicting to the text of the book, since the dates can be maintained. Secondly, Jules Verne describes two close points to the Moon: at North and South pole. This can only be possible with a (near) circular orbit. In my recreation I ignore the height of the closest point to the Moon (periselenium). But it does tell us that the orbit is (near) polar since both poles are observed. The book further describes that the aposelenium (furtherst point to the Moon) coincides with the Earth-Moon L1 Lagrange point. Therefore we assume the periselenium to be close to the Moon’s equator, since the Moon’s equator is tilted only slightly compared to the Moon’s orbit plane.
Using AGI’s Satellite Tool Kit, I recreated the trajectory in the following way:
1) Launch from Tampa. I target the vertical velocity and the shooting time (using Jules Verne’s data as initial guess), to reach the Moon’s azimuth and distance. This gave a launch time of 1 Dec 1872 03:56:37 UTCG, or 31 Nov 22:56:37 local time. The optimiser converged to the night before however certainly a solution the day after could be found.
2) I then target the vertical velocity and a small angular offset to reach the Earth-Moon L1 point (X & Y coordinates only). This gave a total velocity of 11.087 km/s, or 12,118 yards per sec (only 118 yards per sec more than Jules Verne!). So far the trajectory looked like this:
3) finally, a target a velocity change (X, Y and Z coordinates) to reach the indicated longitude and latitude and an altitude of 10 km on 12 December 1872 1:17.
The final result is shown below.
While the trajectory and dates may not match exactly Jules Verne’s description, they certainly come very close! It certainly shows that such a trajectory is feasible. The feasibility of surviving such a shot by a canon, stepping out of the capsule to let a dog out, etc. is another question… But the accuracy of some of the numbers given, amazes me. Well done Jules Verne!
Ciao!
Robin
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