and other interesting stuff...
Gravity Engine 2 is now available. Gravity Engine 2 is a completely new, reconceived Unity package for modelling gravitational interactions and orbital mechanics. While it stands on the shoulders of the long standing and well regarded Gravity Engine Unity asset I created, it is a completely new formulation and a new architecture that retains the [ ]
Even though I already have a sizable collection of books on orbital mechanics I cannotresist adding more. Recently two new books came to my attention and inevitably the references in one of them led me to a third book. Here is a brief overview based on a reading (i.e. not studying in depth) of the [ ]
My Unity asset Gravity Engine models orbits around planets. These are typically ellipses so gravity engine generates a lot of ellipses. The simplest way to do this is to use an equation for the ellipse in polar coordinates and take equal angle steps in the angle and link the points together. These points are then [ ]
A Hohmann transfer calculation changes the circular orbit of a spacecraft using an impulse burn along the prograde direction of the initial orbit. Real spacecraft burns take time, e.g. the Apollo transfer to the moon requires a burn of about 350 seconds. I was recently asked by a developer using Gravity Engine about how the [ ]
The thing I love about having diverse customers for Gravity Engine is that the questions they raise force me to extend my knowledge of orbital mechanics beyond the simple treatments presented in the textbooks. Recently, the developer of the very impressive ReEntry game highlighted the fact that the Hohmann and Lambert rendezvous code in Gravity [ ]
Sometimes a web comic speaks to your soul. The title comes from the hover text of this SMBC comic. At the time I was working on my third attempt to create code for a Lunar free-return trajectory and add it to gravity engine. With the release yesterday of Gravity Engine 3.2 there is now a [ ]
As the creator of the Unity asset Gravity Engine I was curious about how well Unity modeled orbits without all my extra work. In investigating the way that Unity is doing physics I came across a very dramatic difference in performance based on the order of two lines of code and a numerical method I should [ ]
I recently spent a week as the dumbest guy in the room at the 2017 Atlantic General Relativity conference in St. John’s, Newfoundland. The last relativity meeting I attended was in 1996 when I was a graduate student finishing my PhD in general relativity at Queen’s University. Since then I have collected and browsed GR [ ]
My list of engrossing side projects get longer year after year. This year as I ticked over another birthday, I decided it was time to take some me time and choose a project from the list and make some serious progress. What was needed was a sabbatical week a week off from work dedicated to goal [ ]
I have developed an enthusiasm (aka weird obsession) for celestial mechanics and developed several games and the Unity Asset Gravity Engine . In developing Gravity Engine I learned a great deal about high pedigree N-body simulations, but in some cases (e.g. a model of the solar system) it is not really necessary to simulate the system but [ ]