Interplanetary Supply Chain Management and Logistics Architecture
A vast number of scientific principles and techniques have been developed since World-War-II to improve the effectiveness and efficiency of terrestrial supply-chains in the private and military sectors. The potential benefits of this body-of-knowledge are currently only poorly understood in the context of space exploration.
Sustainable Space Exploration
Sustainable space exploration, however, is impossible without appropriate supply-chain management (SCM). Unlike Apollo, future exploration will have to rely on a complex supply-chain network on the ground and in space. The primary goal of this NASA-funded project is to develop a comprehensive SCM framework and planning tool for space-logistics, which is a critical gap in needed capabilities.
Four steps to an integrated space-logistics capability:
Terrestrial supply chain analogies
We investigate and contrast lessons learned from SCM in (i) major industries specialized in "low-quantity", capital-intensive products, (ii) long-range military operations such as aircraft and naval-submarine logistics, and (iii) supply-chains for operations in remote environments, specifically the NASA Haughton-Mars-Project (HMP), which is being developed into the functional equivalent of a Mars Exploration base in the high Arctic (75N 90W). This provides initial class-of-supply and logistics information for modeling purposes. This will categorize the tradeoffs between transportation modes in terms of unit cost, time and availability and the bulk-density and criticality of goods to be transported. We also identify where terrestrial logistics analogies break down, when applied to space exploration.
Space Logistics network analysis
We are building an integrated network model of space logistics, where the nodes are Earth-Moon-Mars-orbits, Lagrangian points and expected landing-exploration sites. The arcs represent cargo and element flows between the nodes. These cargo flows are manifested into individual flights. Cargo (and crew) reach a planetary surface using one of the following three modes: (i) pre-deployment, (ii) carry-along with the crew (iii) scheduled or on-demand resupply. One significant difference between terrestrial and space logistics is that the nodal-motion in space creates time and energy dependencies in the network that do not exist on Earth.
Exploration demand-supply modeling with uncertainty
Major uncertainties in supply and demand of the space-logistics-network are quantified such as cyclical demand variations, changes in the cargo-mix, transportation costs, and unplanned supply-line interruptions. These models also include storage and lifetime issues (degradation, obsolescence, cryo-boiloff) as well as consumption rates and are used to populate the supply-chain network model in order to run different logistics scenarios, starting with CEV development and deployment (2010-2014), all the way to lunar sortie missions (2018-2020) and the buildup of a lunar outpost (2021-2023). We base the exploration logistics model on a system of 10 functional classes-of-supply (COS), including propellants, crew consumables, spares, and exploration and mobility equipment. The COS are further broken down into sub-classes-of supply.
Interplanetary Supply Chain Architecture: Trade Studies
We are combining the network and supply/demand models with existing space logistics models from the Space Shuttle and the International Space Station. This allows us to execute trade studies to help answer the following questions:
- Vertical Integration: Assembly and staging at launch site versus LEO?
- Choice of transportation modes: Effect of bulk-density, value and time-criticality. Relationship to ORU-analysis for ISS?
- Location of facilities and transfer points: optimal placement of intermediate depots and buffers in the space-exploration-network (e.g. for propellant pre-positioning)?
- Push-pull boundary: cargo pre-positioning vs. carry-along vs. ISRU?
- Information architectures: benefits of automatic tagging, status reporting of deployed spares and stocks, space-logistics data-basing?
SpaceNet Software Environment
The space-logistics planning framework is implemented in a software environment referred to as SpaceNet, populated with a detailed human-cargo database. There are currently two versions of SpaceNet:
- SpaceNet 1.3 - Matlab/Excel based version (User Manual)
- SpaceNet 2.5 - Java standalone version (Project Website)
The Phase I model includes nodes and arcs in the Earth-Moon system and allows to run logistics scenarios up to and including buildup of a lunar outpost. The expanded model developed in Phase II will include additional nodes and edges in the Earth-Moon-Mars system and will allow simulating the interplanetary supply chain up to and including Mars missions.
This project brings to bear a unique combination of academic strengths in space systems and supply chain management at MIT with our partners at:
- Jet Propulsion Laboratory/California Institute of Technology
- United Space Alliance
- Payload Systems Inc. (now Aurura Flight Sciences)
to provide a theoretical and practical foundation for interplanetary supply-chain-management.
Any interplanetary supply-chain has to balance the requirements of reliability (redundant transportation modes) with cost-efficiency (few buffers, routes). We are helping NASA address this challenge directly.