1. Mission Architecture
   1. Operational Concept Description
   2. Multiple Missions –
      1. Primary
      2. Production
      3. Deployment
      4. Test
      5. etc
2. OpsCon: Scenarios and Use Cases
3. SysML UC – Use Case Diagram

System Requirements (from MISR)

1. Category: Operational Coverage

Reference Frame Definition: Orbital elements shall be defined in the Earth-Centered Inertial (ECI) frame at reference epoch t₀.

Sub Category: LEO

1. The IOR System shall be capable of servicing client spacecraft in Low Earth Orbit (LEO) with semi-major axis 6678 km ≤ a ≤ 7878 km.
2. The IOR System shall be capable of servicing client spacecraft with orbital eccentricity 0 ≤ e ≤ 0.02.
3. The IOR System shall be capable of servicing client spacecraft with orbital inclination 0° ≤ i ≤ 98°.
4. The IOR System shall be capable of servicing client spacecraft with Right Ascension of Ascending Node (RAAN) 0° ≤ Ω < 360°.
5. Each IOR system install shall be able to service LEO CVs with RAAN angles within ±5° of Service Orbit RAAN.
6. IOR system shall be able to service LEO spacecrafts with orbits with Argument of perigee (ω) 0° ≤ ω < 360°

Sub Category: GEO

5. The IOR System shall be capable of servicing client spacecraft in Geostationary Orbit with semi-major axis 42100 km ≤ a ≤ 42200 km.
6. The IOR System shall be capable of servicing client spacecraft with orbital eccentricity 0 ≤ e ≤ 0.001.
7. The IOR System shall be capable of servicing client spacecraft with inclination 0° ≤ i ≤ 0.1°.
8. The IOR System shall be capable of servicing client spacecraft located at geodetic longitude 0° ≤ λ < 360°.

2. Category: Functional Capability

Sub Category: Physical and Launch

1. IOR-SYSR-FUNC-101 The System shall enable transportation of the Depot and Service Vehicle (SV) to the designated launch site using standard terrestrial logistics methods.
2. IOR-SYSR-FUNC-102 The System shall enable propellant loading of the Depot at the launch site in accordance with applicable ground safety and handling requirements.
3. IOR-SYSR-FUNC-103 The System shall ensure compliance with launch vehicle spaceflight safety requirements when integrated as a fully fueled configuration (Depot and SV).
4. IOR-SYSR-FUNC-104 The System shall enable mechanical and electrical integration of the fully fueled Depot and SV with the selected Launch Vehicle.
5. IOR-SYSR-FUNC-105 The System shall enable insertion of the fully integrated Depot and SV into the specified target orbit following launch.

Sub Category: IOR Capability Levels

1. IOR-SYS-OPER-101 The system shall support servicing of client spacecraft equipped with a compliant and compatible refuelling interface (IOR-Enabled).
2. IOR-SYS-OPER-102
   The system shall support servicing of IOR-Aware client spacecraft providing operational telemetry to support RPOD and refuelling operations.
3. IOR-SYS-OPER-103
   The system shall support servicing of IOR-Cooperative client spacecraft participating in coordinated RPOD operations.

Sub Category: RPOD and Refueling

1. IOR-SYS-OPER-XXX
   The system shall perform autonomous Rendezvous, Proximity Operations, Docking (RPOD), and propellant transfer operations.
2. IOR-SYS-OPER-XXX
   The system shall perform RPOD and refuelling operations across IOR-Enabled, IOR-Aware, and IOR-Cooperative spacecraft categories.

Sub Category:Cooperative Capability Allocation

1. IOR-SYS-OPER-XXX
   The service vehicle shall support IOR-Cooperative operational capability.
2. IOR-SYS-OPER-XXX
   The propellant depot shall support IOR-Cooperative operational capability.
3. IOR-SYS-OPER-XXX
   The resupply vehicle shall support IOR-Cooperative operational capability.

Sub Category: Communications Capability

1. The Depot and SV both have independent communication and navigational capabilities

System Element: Depot

1. The Depot shall be able to perform two way communications with the GS
2. The Depot shall be able to send Ephemeris data (state vector: position + velocity) to the GS
3. The Depot receives Mission Plan (MP) on a regular cadence from GSs
4. The Depot uses the MP to determine it trajectory and communication times with GSs,

System Element: SV

1. SV when docked onto Depot is in deep sleep mode and does not communicate with GS.
2. The SV when undocked from Depot shall be able to perform two way communications with the GS
3. The SV when undocked shall be able to send Ephemeris data (state vector: position + velocity) to the GS
4. The SV receives Rendezvous Plan (RP) during the Rendezvous period from the GSs

System Element: GS

1. GS sends Mission Plan on a regular cadence to Depot
2. GS receives Ephemeris data (state vector: position + velocity) from the Depot and uses for Mission plan calculations.
3. GS receives Ephemeris data (state vector: position + velocity) from the SV and calculates the plan calculations.

3. Performance/Through put

1. Depot servicing LEO shall be able to carry a minimum of 2000 Kgs of propellant to enable fewer trips
2. Depot servicing GEO shall be able to carry a minimum of 5000 Kgs to account for larger GEO fuel requirements and further distance.
3. Each SV fuel delivery should support at least 10Kg of delivery for LEO and at least 100 Kgs for GEO
4. The total delivery time for Proximity Operations should be less than1 hour (now where does this come from, but we need a limit?)
5. Total Fuel Delivery time after docking should be max 1 min/kg (again, traceability is lacking)
6. The SV can make multiple trips between Depot to SV to complete delivery. The number of deliveries are not limited in system design.

4. Robustness/Availability/Sustainability

1. Once deployed the IOR system should be in operations for 15 years

5. Safety – system maintains safety

6. Economic/Business

7. Regulatory compliance