SpaceNet

Simulation and modeling environment for space exploration logistics

Nodes

Nodes represent static locations either on the surface of planetary bodies or in space (stable orbits and Lagrange points). Nodes are often given three- or four-letter designations similar to airport codes. Some examples of nodes may include:

• KSC: Kennedy Space Center (Surface Node)
• LEO: Low Earth Orbit (Orbital Node)
• LLPO: Low Lunar Polar Orbit (Orbital Node)
• EML1: Earth-Moon Lagrange Point 1 (Lagrange Node)
• LSP: Lunar South Pole (Surface Node)

Time-Expanded Network

Elements and resources move between nodes during simulation through a time-expanded network. Edges correspond to transportation methods including impulsive rocket burns, surface-to-surface paths for surface elements, and abstracted flights for notional carriers. Edges connecting nodes may only be available at certain times corresponding to favorable orbital dynamics. Some examples of edges may include:

• Launch from KSC to LEO (Impulsive Burn)
• Travel from LSP to nearby surface location of interest (Surface)
• Cargo resupply from KSC to LSP (Abstracted Flight)

Elements

Elements are unique entities that move between various nodes and form the basis of a SpaceNet simulation. Elements may generate demands for resources during a simulation. There are many different specialized types of elements, ranging from surface vehicles, propulsive vehicles, carriers (able to carry crew and/or cargo), resource containers (able to carry resources), and crew members. Some examples of elements may include:

• Space Shuttle Discovery Orbiter (Propulsive Vehicle)
• Michael Collins (Crew Member)
• ISS Tranquility Module (Carrier)

Resources

Resources are non-unique commodity types that exist in set quantities during simulation. There are three main classes of resources: continuous, discrete, and generic (notional representation for abstracted resources treated as continuous). As elements produce or demand resources, the quantities of resources available inside containers and aggregated levels available at a node will change. Some examples of resources may include:

• Oxygen (Continuous)
• Electricity (Continuous)
• Toothbrush (Discrete Item)
• Generic Crew Provisional Items (Generic)

Events

Events drive the simulation by issuing commands to move elements throughout the time-expended network and directing consumption and production or resources. Seven core events are used at the lowest level (create, move, and remove elements; add, transfer, and use resources; reconfigure elements) and event compositions are used to handle more complex interactions such as transportation along edges and exploration at a node. Some examples of events may include:

• Create Space Shuttle Discovery Orbiter at KSC
• Move Neil Armstrong from Columbia command module to Eagle lunar module
• Launch Ares I stack from KSC to LEO using a specified burn/stage sequence
• Use 5 kilograms of Oxygen
• Explore at LSP for 7 days including 5 EVAs