5.4.6.1 Introduction
This module calculates the cost of operations by using spacecraft quantity and reliability data to size the required workforce. Learning curves are used on each of the seven different types of personnel to account for increasing personnel capability as the operations team gains experience throughout the mission lifetime. The cost of the required facilities is calculated, while segregating the startup and recurring expenses. The output variables are sums of different components of these cost structures. The operations code is contained within the operations.m file.
5.4.6.2 Required Inputs
The operations module takes inputs from the following modules:
DESIGN CONSTANTS SWARM SWARMREL
The inputs are as follows:
DESIGN.swarms_per_plane DESIGN.number_of_planes SWARM.tdrss_links
SWARMREL.steady_state_reliability CONSTANTS.checkout_ratio
CONSTANTS.staffed_shifts CONSTANTS.satellites_controller CONSTANTS.pay_rates
CONSTANTS.turnover_rate CONSTANTS.train_hours_skill CONSTANTS.ojt_ratio
CONSTANTS.group_train_scale CONSTANTS.engineer_learning_curve CONSTANTS.minimum_engineering CONSTANTS.maximum_engineering CONSTANTS.orbitanalyst_learning_curve CONSTANTS.tasks_plan
CONSTANTS.plans_satellite_day CONSTANTS.time_task
CONSTANTS.unconflicted_tdrss_access CONSTANTS.planner_learning_curve CONSTANTS.manager_ratio
CONSTANTS.hardware_maint CONSTANTS.software_maint_ratio CONSTANTS.overhead_ratio CONSTANTS.computer_cost CONSTANTS.cubicle_cost CONSTANTS.connectivity_cost CONSTANTS.floorspace_person CONSTANTS.construction_cost CONSTANTS.leasing_cost
CONSTANTS.facility_maintenance_cost CONSTANTS.additional_nonrecurring_cost CONSTANTS.additional_recurring_cost CONSTANTS.ops_scale_factor
CONSTANTS.ops_plot_flag CONSTANTS.ops_output_flag CONSTANTS.mission_life CONSTANTS.tdrss_link_cost
CONSTANTS.no_tdrss_time CONSTANTS.shift_duration CONSTANTS.mission_type
CONSTANTS.connectivity_annual_cost 5.4.6.3 Output Descriptions
The outputs from the operations module are a series of cost structures that integrate into the costing module. In addition, the operations module produces a matrix of labor statistics useful for quantifying the size and ability of the operations workforce. The following table lists the components of this matrix.
Row (labor type) Column (labor data) Controllers Pay Rate ($/hr)
Engineers Turnover Rate (fte/yr) Support Training Time (hrs)
Orbit Analysts Post-launch Checkout Daily Work (hrs/day) Mission Planners Normal Operations Daily Work (hrs/day) Trainers Annualized Cost ($/yr)
Managers Total Labor Cost ($) Overhead
The output variables are as follows:
OPERATIONS.total_mission_ops_cost OPERATIONS.annual_ops_cost OPERATIONS.nonrecurring_costs OPERATIONS.recurring_costs OPERATIONS.labor
5.4.6.4 Key Assumptions Rationale for simplifications
The costing module is based upon the small spacecraft cost estimating relationship.
The fundamental premise for the simplifications in this module is that labor costs account for the majority of operations costs for a space system. Facility and computer costs are included but the modeling accuracy emphasis remains on the labor calculations. In addition, the operations center cost model assumes an entirely new center must be constructed with a devoted operations staff.
In reality, operations facilities would probably be acquired from previous space missions, and operations personnel might migrate between multiple space missions. Since this dynamic would be challenging to model accurately, and since the results would be very specific to the organization that actually operated the space mission, it was not incorporated into the B-TOS model.
Modern operations center design focuses heavily on reducing space mission costs through increased use of autonomous control in both the space and ground segments. The effects of satellite autonomy are modeled by reducing the number of spacecraft the operations center is responsible for observing and controlling. The number of spacecraft is dependent on the number of TDRSS links required to operate the space segment. This, in turn, relates to the number of swarm motherships, since each mothership has the space-to-ground TDRSS communication package on board.
Evolution of calculations
The operations module has a highly modified evolution chain that begins with the TechSat21 code developed in MIT’s Space Systems Laboratory. In the fall of 1999, another class used the TechSat21 operations module code as a baseline for its operations module in a similar space systems design process. David Ferris, a graduate student in that class was responsible for this major revision to the operations module. He later updated the code for A-TOS, the first design iteration of this space mission, in the winter of 2000-2001. This A-TOS code was slightly modified to account for different reliability and spacecraft inputs for B-TOS.
5.4.6.5 Fidelity Assessment
Adequate modeling of the impact of space segment and especially ground segment autonomy are the most significant calculations absent from this module. In addition, a number of the constants used to calculate costs were unavailable or questionable. Most notably, these included the cost of continuous access to TDRSS and the cost of ground software development and maintenance.
The model does, however, account for labor training, turnover, and varying workloads as the mission progresses through its operational life. The numbers used for these calculations were derived from direct operational experience in U.S. Air Force space operations facilities.
5.4.6.6 Verification
The operations module output was verified by comparing test cases against first hand operational experience. This served to verify the learning curve assumptions and labor data. The facility construction values for the different test cases also matched anticipated results.