Lunar Hammer, Part 4 - Origins, and 'Bit by Bit'.

I first came across the Galilean Cannon in 1993, at a science fair while at uni. It was a simple arrangement of three rubber balls. The idea stuck, but thinking back, it was the accidental find of a student assignment question, which I probably still have somewhere, that first triggered some desire to solve the problem. Not the mathematical solution of how many balls are necessary to achieve escape velocity on Earth, but to design a practical solution to do just that.

My notes and journals show that I was engaging with the problem, first in 1994, then coming back to it from late '95 into 1996. Quite a few sketches are undated, annoyingly, and by not having them I can't place them into context.

It looks like I left the problem alone until 2001. That's when the game changed. I was coming back to the problem frequently through the year, then in November that year I drew this:

I was certain I had arrived at the beginnings of a workable solution that could be applied to a stack of any size. Anyone seeing this will think, 'oh, that's obvious', but such thoughts only exist when the answer is right in front of you. When something doesn't exist, it is not 'obvious'. I took my work to UKC and the physicist who presented the demo I saw in '93. I was more than a bit nervous on the day, but he said, "yes, that would work", without hesitation.

I have felt a slightly surreal tone in my endeavours, realising only much later that I was tackling a problem, in isolation, that no one in history (as far as I could discover) has ever attacked in earnest. The first explorer into a new space of ideas. In retrospect, there is a good reason why my output that year, 2001, was different to what preceded it. In 1999 I started to develop my passion for art and design. As a teen I had the opportunity to study graphic design at college, but passed on it.


Bit by Bit
Cutting down each sphere is the first stage in a vitally important design methodology. The Hammer and the next few Transmitters are going to be massive lumps of elastic material. Creating these, and then shipping them to the Moon, is a fools errand. So, what can we do? We employ modular design concepts. The bulk of each object can be made up from layers (ideally manufactured on the Moon). The top and bottom presents a more difficult problem with much R&D needed, and I am leaving this to be addressed later in the event my project gets taken seriously.

Why does cutting down the balls make a difference? Think about the elastic deformation of a solid rubber ball when it bounces. The ball compresses along an axis passing through its centre of gravity and point of contact. This compression reduces as the deformation spreads through the whole ball, falling to zero at its circumference. Having practical experience with cutting up toy balls, I have seen the result of this phenomenon. For a test example I cut right through a ball clamped into a lathe, perpendicularly at about a third of its diameter. Since it needed to be secure, the ball was compressed, so I was cutting a straight line through a deformed object. When the pressure of clamping was released, the ball reformed, leaving a well defined 'hump'. I wasn't looking to achieve this as proof, it was actually incidental, but nonetheless I noted the outcome of the test, and got practical proof for my original assertion. In general, beyond the middle third, we can say "don't need that" and not lose much elastic potential.

This is my last post on the Hammer for now, next time I will be looking at its application. I'm sure some will consider this to be a load of tosh (or, to semi-quote Adam Rutherford, a steaming glob of weapons-grade fartgargle).

Thankfully for me, I will have any last laugh when I build the model that will project a ball-bearing at a kilometre a second.