# CBS (Cost Breakdown Structure)

```Cost Modeling
1.
Detailed bottom-up estimations
 Best for detailed design phase
 Sum up costs starting at component level
2.
Analogous estimations
 Best for similar missions
 Compare design with similar item (system, subsystem, component)
3.
Parametric estimations
 Best for conceptual/preliminary design phase
 Use CER's (cost estimating relationships)
 Express cost as function of one or more design sizing parameters (usually weight and/or power)
 Generated by regression analysis of cost data from known systems
 Beware of exceeding valid parameter range! (but  10% OK)
CBS (Cost Breakdown Structure)
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Read Ch. 20 in Wertz &amp; Larson
 (also talks about Work Breakdown Structure --WBS)
RDT&amp;E (Research, Development, Testing &amp; Evaluation)
 Space Segment
 Launch Segment
 Ground Segment
 Program Level Costs (wrap-arounds or “wraps”) -- Table 20-7
 Mgmt,
 Engr.,
 Prod. Assurance
 Sys. Test &amp; Eval.
TFU (Theoretical First Unit)
Table 20-4 RDT&amp;E only
Table 20-5 TFU only
Table 20-6 RDT&amp;E and TFU for Earth-orbiting s/c
Protoflight – refurbish test model and fly it – use only 30% of TFU cost
On-line cost models (JSC web site) http://www.jsc.nasa.gov/bu2/models.htm
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Models
 Space/vehicle level
 Expendable LV’s
 DSN cost estimating (this one estimates the cost of estimating the cost – really)
 Mission operations (includes DSN for planetary missions)
 Inflation factors
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Example CER:
Thermal subsystem TFU cost (FY00\$K) = 50.6 X 0.707
X = thermal ctrl. wt. in kg.
Std. Error (1) = 61%
Notes:
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Use of FY00\$K (constant-year dollars)
Can use Table 20-1 to correct for inflation
Start with high-level estimates (total s/c mass)
 Use only item 2 (Tables 20-4, 20-5, 20-6)
Then go to more detail (indiv. subsystem masses)
 Replace item 2 with sub-items (2.1 – 2.6)
Use cost adjustments in Table 20-8 (e.g., for composites, new designs)
TABLE 20-4 (abbrev.)
Cost Component
1.1 IR
1.2 Visible
1.3 Comm.
Antenna
Comm. electr.
2. s/c bus
2.1 Struct./therm.
2.2 TT&amp;C
2.3 Att. Ctrl.
Determ.
Control
2.4 Power
3. AKM
4. Ground Equip.
5. Program Level
Parameter, X
Applicable Range
aper. diam. (m)
0.2-1.2 m.
wt. (kg)
wt. (kg)
dry wt. (kg)
wt. (kg)
wt. (kg)
dry wt. (kg)
dry wt. (kg)
EPS wt  BOL pwr
(kg W)
Total imp. (N s)
RDT&amp;E + TFU
H/W cost (\$K)
CER
0 + 110791 X0.562
Std. Error
16629[0.65]
```