I wanted to take a moment to get the word out about an exciting new set of features for AGI Components related to high precision numerical propagation. If you are already an STK user, you are probably familiar with STK’s “HPOP” (High Precision Orbit Propagation) option for satellite objects. The AGI Components team has put together a design to provide similar functionality in the form of extensible .NET and Java class libraries. While we’re still in the process of reviewing the product offering, here is a brief look at what’s coming.
Numerical integrators such as “Runge-Kutta,” “Gauss-Jackson” and “Bulirsch-Stoer” will power the propagation in our initial release. In particular, the high-precision Runge-Kutta-Fehlberg 7/8th order adaptive step integrator is the mainstay of STK and is useful for a vast majority of orbital and non-orbital problems. At a low level, you’ll be able to integrate simple differential equations, or at a higher level you’ll be able to use the integrators with our numerical propagator to propagate a collection of customizable elements composing a state.
A state can be composed of vehicle positions based on high-precision force models and any other scalar parameters for which you can define custom differential equations such as mass, flight path angle, drag coefficient or anything related to your custom problem. With some customization, you’ll also be able to couple elements together to comprise complex dynamical systems, such as cooperative orbital rendezvous or other optimal control problems. We do this by abstracting the integration state through scalar and vector objects which you can use to define your models just like any other in our Dynamic Geometry Library.
Since the primary hurdle in modeling spacecraft trajectories is accurately modeling the space environment, our force models represent a large chunk of our initial feature set. Most of the forces and models represented in STK HPOP will be represented in the AGI Components version. Here is a short list of what we have planned: Spherical Harmonic Gravity (initially without tides), Third-Body Gravity, Solar Radiation Pressure, Jacchia-Roberts drag and various MSIS drag models.
While numerical integration is often necessarily single-threaded, we are exploring ways to take advantage of modern multi-core hardware. To start, many use-cases involve performing multiple propagations for a ”shooting method” or propagating multiple satellites at once, which can be easily threaded on a multi-core machine to reduce computation time. However, the major benefit of HPOP in AGI Components will be the flexibility of defining a state made up of custom elements along with the ability to extend the interfaces of the state and force models to plug in custom functionality seamlessly.
We’re currently planning a first release in the next few months. So, if you are interested in joining our discussions on what to support or to present a particular use-case you have, please post your thoughts in the AGI Components Analysis section of the AGI Developer Network discussion forums.