1.1 Mission Business Analysis

Problem Statement

Spacecraft operational life is frequently limited by depletion of onboard propellant rather than payload capability or platform health. Replacing a spacecraft at end-of-fuel life incurs significant cost including:

• Cost of spacecraft manufacturing
• Launch and deployment cost
• Mission planning and transition cost
• Loss of service and revenue during replacement

A cost-effective alternative is required to extend operational life through in-orbit refueling.

Mission Value & Strategic Benefits

In addition to life extension, in-orbit refueling enables broader operational and strategic advantages:

• Enhanced mobility and maneuverability of spacecraft
• Support for new missions and business models
• Enablement of Active Debris Removal (ADR) operations
• Expansion of mission capabilities beyond initial design constraints
• Enablement of Dynamic Space Operations (DSO)
• Reduced dependence on specific launch windows and ground-based resupply
• Improved collision avoidance through extended maneuver capability

Refueling costs elements consists of:

1. IOR System Lifecycle Costs

• Initial launch, deployment, and in-space commissioning of IOR system components (one-time program cost)
• Continuous station-keeping and maneuver management of IOR assets

2. Fuel Delivery Operational Costs

• Launch and transport of propellant to orbit
• On-orbit storage and positioning of propellant
• Rendezvous, docking, and transfer operations
• Mission planning and execution of refueling activities

If cost of propellant delivery can be reduced it enables DSO in addition extending the life.

Mission Statement

The purpose of this project is to develop an In-Orbit Refueling (IOR) capability that:

1. Services both LEO and GEO spacecraft
2. Significantly reduces lifecycle cost compared to spacecraft replacement (target cost reduction ~60% relative to replacement)
3. Supports servicing of cooperative spacecraft across varying mass, geometry, and configuration with defined capability levels (Interface Enabled, IOR Aware, IOR Cooperative)
4. Provides scalable propellant delivery to extend mission life
5. Defines standardized operational and technical interfaces across the IOR ecosystem, including:
   1. Client spacecraft ↔ Service vehicle
   2. Service vehicle ↔ Depot
   3. Depot ↔ Resupply vehicle
   4. IOR Ground segment ↔ Client mission operations
   5. IOR Ground segment ↔ Spacecraft (Service Vehicle, Depot, Resupply Vehicle)
   6. IOR Ground segment ↔︎ Resupply provider ground segment
6. Establishes interoperable interaction frameworks, including proximity operations and servicing behaviors, enabling independent vendors to develop compatible components aligned to common interface and operational specifications

Mission Objectives

1. MO-1 Enable a multi-stakeholder ecosystem where the following entities independently develop and operate interoperable capabilities under a unified IOR mission framework:
   1. IOR service providers
   2. RPOD technology vendors
   3. Satellite manufacturers
   4. Constellation operators (clients)
   5. Resupply providers
2. MO-2 Support standardized operational communication interfaces between client mission operations / ground systems and IOR mission operations system to enable coordinated planning, authorization, execution, and monitoring of refueling services
3. MO-3 Support development or identification of standardized refueling interfaces enabling servicing across multiple satellite platforms.
4. MO-4 Enable servicing across multiple satellite capability levelsDefine progressive levels of client satellite cooperation capability:
   1. MO-4a Interface Enabled Satellite provides a compatible physical refueling interface allowing propellant transfer but does not actively participate in refueling operations.
   2. MO-4b IOR Aware In addition to the physical interface, the satellite provides telemetry feedback to its ground system indicating refueling status and progress.
   3. MO-4c IOR Cooperative In addition to IOR awareness, the satellite actively cooperates with the Service Vehicle (SV), assisting proximity operations through coordination signals or local navigation support.
5. MO-5 Enable cooperative proximity operations capabilities required for safe and efficient rendezvous, proximity operations, and docking between servicing vehicles and client spacecraft.
6. MO-6 Enable efficient and standardized propellant supply logistics from Earth to the IOR depot, allowing independent resupply providers to deliver and replenish propellant without tight integration with the servicing vehicle operator.
   1. MO-6a (Operational Interfaces) – Support standardized operational communication interfaces between IOR mission operations and resupply provider ground systems to enable coordinated planning, authorization, execution, and monitoring of resupply services.
   2. MO-6b (RPOD Interfaces) – Support standardized RPOD and physical/operational interfaces between depot and resupply vehicle to enable safe, coordinated propellant transfer.
7. MO-7 Support guided proximity, docking, and fuel transfer operations following guided rendezvous operations.
8. MO-8 Support autonomous proximity, docking, and fuel transfer operations following guided rendezvous operations, where operations from proximity initiation through docking and propellant transfer are executed autonomously

Assumptions

• Customer spacecrafts have compatible fuel interface.
• Market demand exists for LEO and GEO refueling

Constraints

The system is currently constraint by 2 choices of fuel.

• Electric propulsion propellants
• Storable chemical propellants

System Of Interest

The System of Interest is the In-Orbit Refueling (IOR) System, defined as an integrated capability that provides end-to-end management, transport, storage, and transfer of propellant to customer spacecraft, where individual components and services may be delivered by independent vendors within a standardized framework.

The integrated IOR System includes:

• Service Vehicle (SV) for rendezvous, proximity operations, and propellant transfer
• On-orbit propellant depot (optional, depending on architecture)
• Resupply vehicle for replenishing propellant to the depot
• Ground segment for mission planning, coordination, and control

These components together form the integrated IOR capability.

External Systems

1. Customer spacecraft requiring refueling
2. Customer systems providing real-time information of their spacecraft
3. Launch vehicles for delivery of IOR components and propellant
4. Space surveillance and tracking systems