ENAE 484
Space Systems Design
Spring, 2003

Work Breakdown Structure

This is a sample work breakdown structure (WBS) for the (fill in the name of choice) program. If we've left anything out, we'll add it with a "new" tag as we go. This WBS is broken down by topics corresponding to your six groups. This isn't a hard-and-fast rule that each group has to actually do every task; rather, it means that this is the list of tasks your group is responsible for making sure is done correctly. Trading off tasks between groups and people is perfectly okay, but responsibility ultimately resides with the group it's assigned to in the WBS.

If you take from this list that there's a hell of a lot of stuff to do, you're right. If you take a look at this and throw your hands up and say, "There's no way we can do all that!", you're wrong - many of these tasks are simple, straightforward, and can be done (relatively) quickly. You will find that once you get a few things done, the same approach will work on a lot of the tasks. We do hope/plan/expect to see, at the end of the term, that there's something in the final report on each and every one of these tasks.

Another comment - one might look at this and deduce that the Systems Integration and Mission Planning and Analysis groups have a lot less to do than the others. The other four groups are really more "hardware" oriented, and it's a lot easier to break it down into fine detail for those four than it is for the first two. SI and MPA tend to be more "big picture" than the four technical groups, and the task requirements are therefore more dependent on the details of the program as they evolve. This breakdown is intended to distribute the work load in a fair manner over all six of the groups. If there is a problem due to the nature of your particular project, part of your responsibility is to dynamically reallocate responsibilities among the groups. There is no such thing as a "spare" person in a design team!


  1. Systems Integration
    1. Configuration Control
      1. Configuration Trade Studies
      2. Vehicle Layout
      3. Mass Budget
      4. Power Budget
      5. Cost Budget
      6. Center of Gravity Calculations
    2. Program Planning
      1. Establishment of Program Timeline
      2. Year-by-Year Cost Allocations
      3. Discounted Cost Analysis
    3. Program Management
      1. System Block Diagrams
      2. Interface Specification and Control
  2. Mission Planning and Analysis
    1. Mission Planning
      1. Program Baseline Operations Scenario(s)
      2. Operations Timelines
    2. Mission Analysis
      1. Trajectory and Delta-V Calculations
      2. Payload Specifications (e.g., what type of robot arms, how many, interfaces for cargo)
      3. Payload Requirements (e.g., mass, power, thermal, volume)
  3. Power, Propulsion, and Thermal
    1. Power Systems
      1. Power Generation/Energy Storage Systems
        1. System Requirements Analysis
        2. Trade Studies
        3. Primary System Specification
        4. Contingency Planning
        5. Emergency System Specification
    2. Propulsion Systems
      1. Primary Propulsion System
      2. Low-Contamination Propulsion System
      3. Attitude Control System
      4. Reaction Control System
    3. Thermal Analysis
      1. Equilibrium thermal analysis
      2. Passive thermal control/insulation
      3. Design of thermal control system
  4. Structures, Loads, and Mechanisms
    1. Loads Analysis
      1. Identification of Loads Sources
      2. Quantification of Loading Conditions
      3. Establishment of Required Factors of Safety
    2. Structures
      1. Primary Structure Design
        1. Configuration Trade Studies
        2. Analysis of Loading Conditions
        3. Component Sizing for Worst Case Loads
        4. Mass Estimation
        5. Compilation of Margins of Safety (all loading conditions)
      2. Secondary Structure Design
        1. Configuration Trade Studies
        2. Component Sizing
        3. Mass Estimation
    3. Special Structures
      1. Windows
      2. Micrometeoriod protection
      3. Radiation protection
      4. Pressure tanks
    4. Mechanisms
      1. Docking Mechanisms
      2. Hatches
      3. Deployable mechanisms
      4. Pyrotechnics
  5. Life Support and Human Factors
    1. Life Support
      1. Cabin Atmosphere Selection
      2. Air Maintenance
        1. O2 Replenishment
        2. CO2 Scrubbing
        3. Pressure Control
        4. Humidity Control
        5. Thermal Control
        6. Particulate Control
        7. Contaminant Control
        8. Consumables Resupply
        9. System Maintenance
      3. Water Maintenance
        1. Drinking Water Provision
        2. Waste Water Collection
        3. Water Replenishment
        4. System Maintenance
      4. Food Provision
        1. Food Storage
        2. Sanitary Maintenance
        3. Replenishment
      5. Radiation Remediation
        1. Galactic Background
        2. Solar Background
        3. Solar Flares
        4. Passive Mitigation Approaches (Shielding)
      6. Sanitary Provisions
        1. Urination
        2. Defecation
        3. Hygiene
        4. Trash Collection
        5. Systems Sanitization and Refurbishment
      7. Safety Systems
        1. Caution and Warning Systems
        2. Fire Prevention, Sensing, and Fighting
        3. Depressurization Remediation
        4. Health Monitoring
        5. Contingency Operations
        6. Emergency Operations
    2. Human Factors
      1. Cabin Sizing
      2. Interior Layout
        1. Flight Control Station
        2. Robot Control Station
        3. Access to Suit Arms
        4. Interior Stowage
        5. Window Requirements
        6. Acoustic Environment
        7. Body Positioning and Restraint System
      3. Docking System Design
        1. Sizing
        2. Placement
        3. Internal and External Access
        4. Internal Accommodations
        5. Docking System Accommodation for Consumables Transfer
        6. Contingency Egress
      4. EVA Support
        1. Suit Arm Specification
        2. Suit Station Layout
        3. Variable Pressurization Requirements
        4. Equipment for Denitrogenation
        5. Support Equipment Storage
          1. Interior
          2. Exterior
        6. Accommodation of Differing Users
        7. Contingency Operations
        8. Emergency Operations
      5. Controls and Displays
        1. Vehicle Flight Controls
        2. Vehicle Systems Operations
        3. Robotic Operating Controls and Displays
        4. Robotic Status Controls and Displays
        5. Suit Arms Controls and Displays
        6. Checklists and Operating Manuals
        7. Required Sight Lines
  6. Avionics
    1. Navigation
      1. Position Measurement
      2. Docking/Berthing Requirements
      3. Rendezvous and Proximity Operations Requirements
      4. Relative Vehicle-Station Measurements
    2. Guidance
      1. Attitude Determination
      2. Rendezvous
      3. Proximity Operations
      4. Docking/Grapple Flight Dynamics
      5. Cooperative Targeting Systems
    3. Control
      1. Attitude Control System
      2. Reaction Control System
      3. Propulsive Flight Controls
    4. Communications
      1. Vehicle-Station
        1. Bandwidth and Duty Cycles Requirements
        2. Frequency Selection
        3. Link Budgets
        4. Antenna Design
      2. Vehicle-Vehicle
        1. Bandwidth and Duty Cycles Requirements
        2. Frequency Selection
        3. Link Budgets
        4. Antenna Design
      3. Contingency/Emergency
        1. Bandwidth and Duty Cycles Requirements
        2. Frequency Selection
        3. Link Budgets
        4. Antenna Design
    5. Sensing
      1. Compilation of Monitoring Requirements
      2. System Specification
        1. Sensor Types
        2. Location
        3. Data Content
        4. Update Rate
        5. Wiring Harnesses
    6. Data Management
      1. Primary Flight Control Systems
      2. Backup Flight Control Systems
      3. Robotic Control Computers
      4. Distributed Systems
      5. Embedded Systems
      6. Networking
    7. Power Management and Distribution
      1. Distribution Voltage Selection
      2. Power Management Systems
      3. Power Distribution Systems
        1. Wiring Harnesses
        2. End Item Interfaces

Under every lowest-level item, you should realize that there is one lower level of tasks common to everything. (This isn't included, because it would make the WBS five times as long as it already is.) For each and every specific task identified above, you should further break the design process down into the following sub-steps: