Enhancing Space Communications: A Novel Approach to Solving the Multi-Satellite Scheduling Problem

Scheduling systems are the backbone of space communications, and the ability to solve scheduling problems quickly is of great importance to any space organization. Previously, the National Aeronautics and Space Administration's (NASA) Goddard Space Flight Center's (GSFC) Advanced Planning team utilized the Systems ToolKit (STK) application to solve scheduling problems. However, the process was time-consuming and computationally expensive. NASA GSFC has developed a novel web-based tool for generating representative schedules to aid in Near Space Network (NSN) mission design for the GSFC Advanced Planning team. The Loading Analysis Tool for Telecommunications Engineers (LATTE) efficiently addresses the Multi-Satellite Scheduling Problem (MSSP). The MSSP is a competitive resource allocation challenge caused by overlaps in possible communication windows that require intelligently distributing and scheduling ground station and relay satellite resources to maximize connection times. Visibility overlaps require the scheduling of connection time periods to meet mission objectives. LATTE utilizes Unity to analyze and visualize the scheduling of new missions in conjunction with WebGL to extend its capabilities to a web-based application. The tool allows users to visualize custom scenarios in an interactive three-dimensional space, providing a dynamic analysis of the MSSP while also servicing outreach and mission engagement applications. LATTE demonstrates the feasibility of future NSN missions in both the "Coverage" and "Loading" domains by combining high-resolution terrain and Unity's 3D Physics engine with a database of NASA Near Earth assets and missions. Due to its custom terrain system, LATTE can generate up to sub-arcsecond displays around various missions' interests and interpret Digital Elevation Models from a variety of sources, such as the Shuttle Radar Topography Mission. The tool uses Unity's built-in Raycasting System with custom algorithms and generated terrain to determine visibility and connection windows. Through a modified depth-first search style algorithm, the tool leverages constraints such as frequency bands and communications priorities to optimize scheduling windows for the longest service period usage for each mission interest. LATTE demonstrates the ability to drastically reduce the computational load and time needed to calculate MSSP solutions. In addition, the tool interactively visualizes the results for its users. This paper details the reasoning behind LATTE's development, a description of the algorithms used, and discusses example applications of the tool in supporting the future development of NASA's space missions and space communications infrastructure.