Why would you create a coloring book about orbital mechanics?

Orbital mechanics are not an obvious subject for a coloring book, but the result can be beautiful. It can also be inspirational for children today who will become technologists tomorrow. We spoke to Hop David to learn why he chose to create such a unique product, which recently launched on Kickstarter. He explains how his coloring book fits into his previous experience and larger interests. He also shared with us his hopes about what the book’s impact will be.


Where did the idea come from to create an orbital mechanics coloring book?

I love math and art. Math-inspired artists like M. C. Escher, Albrecht Dürer, Leonardo Da Vinci, and others are an influence.

In 2008, Dover Publications commissioned me to do a coloring book of Escheresque tessellations. Since then, I have done three coloring books of geometrical designs for Dover.

Much of my coloring book is devoted to delta V, to the rocket equation, and to potential propellent sources outside of Earth’s gravity well. Click To Tweet

One of my favorite mathematicians is Johannes Kepler. By extending the edges of the Platonic solids, Kepler invented new types of solids. And Kepler’s study of ellipses and orbital mechanics is quite beautiful. Much of my orbital mechanics coloring book is built on Kepler’s geometry.

A lot of my coloring book comes from my blog, which was started in response to physicist Tom Murphy’s “Do the Math” essays. Tom Murphy correctly points out exponential growth isn’t sustainable, given a finite body of resources. So, he advises us to try to live within our means. This advice I wholeheartedly agree with. 

Where Tom Murphy and I part ways is his opinion that space resources are impractical. In spite of his advice to “Do the Math”, his arguments rest on wrong math. He is correct to emphasize delta V as a metric, but he doesn’t patch conics properly when making his calculations. 

The exponent in the rocket equation scales with delta V. And the delta V budget starts over with each opportunity to replenish propellant. The challenge becomes much less formidable if extraterrestrial propellent can bust up the exponent in the rocket equation. Much of my coloring book is devoted to delta V, to the rocket equation, and to potential propellent sources outside of Earth’s gravity well. 

I hope and believe our Solar System will be the next great frontier for humankind. I don’t know if this is possible. But, unlike Tom Murphy, I regard it as an open question. It is a goal we should try hard to achieve.

What effect do you hope the coloring book will have?

I hope to help get kids of all ages addicted to math and geometry. I hope to persuade more people that opening a new frontier is a doable goal. I would be very happy if my book helps to inspire future engineers and scientists who will open the new frontier.

What advice do you have for people who want to apply their artistic talents to their interest in space?

Work hard. Draw for fun. Draw what you’re passionate about.