Modeling a Lunar Eclipse with Volumetric Analysis in STK

The spatial analysis tool in STK Analysis Workbench, enables you to define calculations and conditions that depend on locations in 3D space and visualize them across volumetric regions populated by a series of grid points. There is a wealth of potential uses for volumetrics including space surveillance, communications and jamming, and access calculations.

Lunar eclipse modeling is a unique challenge and opportunity for volumetrics. Systems Tool Kit (STK) has sunlight constraints for access and sunlight reports for objects. However, with volumetrics you can fully model the spatial effects of an eclipse in the volume directly around the Moon. This analysis is helpful for orbit or insertion trajectory design during lunar missions to predict eclipses that could cause power system issues.

To demonstrate lunar eclipse modeling, I created a spherical volumetric grid at a series of altitudes above the lunar surface. Then I created a new spatial calculation to compute solar intensity using Earth as an obstructing body. Finally, I applied that calculation across the entire grid using a Volumetric object. This kind of analysis gives you much more information than a simple sunlight report on the lunar surface. And, you can use STK Parallel Computing to complete an intense calculation in a fraction of the usual time.

Continuing with my demo, I created a spatial condition that is satisfied with sunlight conditions of Umbra or Penumbra, with Earth as the obstructing body. This enables you to create a satisfaction volume report to determine the peak eclipse time, eclipsed percentage, and the start and end times of the eclipse.

If you’re interested in learning more about volumetrics in STK, we have a variety of tutorials in the STK Help, including one that is particularly focused on the Volumetric object and the spatial analysis tool in Analysis Workbench.

You can download the STK 12.2 scenario used for this blog post from AGI’s STK Data Federate (SDF).