1. Technical Resource Allocations
Michael Pryzby

2. Technical Resource Allocations Flight Dynamics
Delta V
Propellant

3. dV/Fuel Mass Allocation
Assumes 1480 kg wet launch mass
MRD-24: The launch vehicle must be capable of delivering a 1480 kg payload to a trajectory with a C3 > -1.85
Given dV budget, determine fuel mass assuming maximum wet mass at liftoff
Derives allocation for spacecraft dry mass
dV budget determined by analysis & lunar mission experience
MCC1 allocation is 3-sigma, could be improved by performing maneuver earlier than 24 hours but holding worst case
MRD-25: TLI accuracy at orbiter sparation from the LV third stage shall be within +/- 3 m/sec (TBR) (3-sigma) of target inertial velocity.
FDS 2.3.1: LRO shall perform an MCC1 maneuver at L+24 (TBD) hours to correct for LV dispersions.
LOI allocation is deterministic, detailed analysis exists to support, all physics not a function of perturbations
Stationkeeping is deterministic, detailed analysis exists to support, actual dV cost is only 150 m/sec, may move extra 30 m/s to margin
MRD-12: The primary mission shall be conducted in a circular mapping orbit with a nominal mean altitude of 50 +/- 20 km (altitude is measured to mean lunar surface).
Extended mission is place holder only, allows many options for unknown extended mission, could be used for contingency in mission orbit if needed
MRD-22: LRO shall carry sufficient consumables to allow for a four year extended mission in a low maintenance orbit.
Margin is 20 m/s
LOI and extended mission dV should not be used to calculate dV percent margin
8% dV margin on MCC1 and SK dV budgets (22% if 30 m/s moved from SK to margin)

4. dV/Fuel Mass Allocation
Mission Phase
LRO Baseline dV
(m/sec)
Fuel Mass
(kg)
 Comments 
MCC 75 52
3s, L+24 hours
Lunar Insertion – 1st burn
391
210
1st insertion burn, finite dV, any launch date, 20% off-pulsing
Lunar Insertion – All other burns
535
288
All other insertion burns, finite dV
Station-keeping
180 77
+/- 20 km altitude, 3s including errors
Extended Mission
125 48
Placeholder only
Margin 20 8
Momentum Unloading 16
Other 14
De-spin, Residuals, Pressurant
Total
1326
713
* Assumes 1480 kg launch wet mass

5. Technical Resource Allocations Mass
Consumables
Spacecraft Wet Mass
Spacecraft Dry Mass

6. Mass Technical Resource Allocations Document, 431-SPEC-000112
Mass allocations budges include:
Spacecraft Allocation – Wet
Spacecraft Allocation - Dry
Wet Mass Allocation (Consumables)
Allocation Derivations:
Spacecraft Wet Mass Allocation
MRD-1: The max allowable spacecraft mass – 1480 kg
MRD-24: The launch vehicle must be capable of delivering a 1480 kg payload to a trajectory with a C3 > -1.85
Wet Mass Allocation
Derived from dV / Fuel Mass Allocation
Spacecraft Dry Mass Allocations
Derived from Current Best Estimates
Contingency based upon Design Maturity Factor

7. Wet Mass Allocation - Consumables
Subsystem
Components
Allocation
 Comments 
SubSystem
Mass (kg)
Consumables
715.30
Propellant
713.0
Derived from Delta V budget - includes 3s
Pressurant
2.3
Table 3‑2 - Spacecraft Wet Mass Allocation - Consumables

8. Spacecraft Mass Allocation - Wet
Subsystem
Components
Allocation
 Comments
SubSystem
Mass (kg)
L/V Wet Mass Capability
MRD Req’t:
Derived Wet Mass Allocation
715.30
Propellant Budget derived from Delta V budget
Max Dry Mass Allocation
764.70
Remaining mass
 Table 3‑1 - Spacecraft Mass Allocation - Wet
Table 3‑2 - Spacecraft Wet Mass Allocation

9. Spacecraft Mass Allocation - Dry
Subsystem
Components
Allocation
 Comments
SubSystem
Mass (kg)
Total Dry Mass
710.3
Concept J
Spin balance Weight
25.0
Place holder
S/C Bus Subtotal
595.5
Mechanical
155.1
Mechanisms
52.8
Thermal
32.4
Power
76.2
ACS
63.4
PDE
16.8
Propulsion (Dry Mass)
105.8
C&DH
19.5
S Comm
12.6
Ka Comm
18.5
Electrical
40.0
Instruments Subtotal
89.9
CRaTER
6.4
Diviner
11.9
LAMP
5.3
LEND
23.2
LOLA
15.3
LROC
19.0
Mini RF
Table 3‑3- Spacecraft Mass Allocation - Dry

10. Mass Allocation Summary
Margins meet GOLD requirement (20%) – 20.8% on CBE
Allocation – kg
Current Best Estimate – kg
Max Dry mass – kg
System Margin – 54.4 kg (7.7%)
Or 79.4 kg (11.2%) including spin balance mass
Assume 1480 max LV capability

11. Technical Resource Allocations Power
Un-Switched Power
Instrument Heater Power
Switched Power

12. Power Allocations
Technical Resource Allocations Document, 431-SPEC
Power allocations include:
Un-Switched Power
Instrument Heater Power – Operational & Survival
Switched Power
Spacecraft Power Allocations
Switched and Un-Switched
Derived from Current Best Estimates
Contingency based upon Design Maturity Factor for each switch
Heater
Operational heater power allocations for each instrument/component are based on Beta=90° cold case orbit average predictions plus margin.
Survival heater power allocations for each instrument/component are based on Safe-hold orbit average predictions plus margin

13. Power Allocation Driving Requirements
Worst Case is based on “S+Ka Orbit” mission phase from LRO Mission Concept of Operations Document, 431-OPS as documented in the Master Equipment List
Driving Requirements
Power System
MRD-103: System sized for 823W On-Orbit Average
Solar Array Properties
35V
EOL properties for 14 month design life
Battery Spec
Max Depth of Discharge (DOD) is 30%
EOL properties for 18 month design life
Nominal 28V output
Energy Balance for Beta 0 case
48 minute eclipse
full battery recharge in single orbit

14. Power Allocation - Un-Switched
Power Allocation - Un-Switched
Table 4‑1- Un-Switched Power Allocations

15. Power Allocation – Instrument Heaters
* - Current analysis shows no heater power is necessary
 Table 4‑2 – Instrument Heater Power Allocations

16. Power Allocation - Switched
Table 4‑3 - Switched Power Allocations

17. Power Allocation Summary
Margins meet GOLD requirement at SRR (15%) – 21% on CBE
On-Orbit Average designed for 823W power system (MRD-103)
Power Allocations set at 745W max for S+Ka Orbit, Beta 0 case
10%+ margin on power system
Current Best Estimate for worst case power average is 680.4W
S+Ka Orbit from Mission Concept of Operations Plan
Margin = 21%

18. Technical Resource Allocations Flight Software
Processor Memory
1553 Bus

19. Data Allocations – Key Assumptions
750 Processor or equivalent
GNC Software resident on Main Processor
Using cFE for core FSW
Interfaces include only:
1553 bus interface
1355 (Spacewire)
Baseline no science data processing/compression onboard

20. Flight Software Allocation Summary
* From GSFC-STD-1000 (GOLD Rules - FSW)

21. LRO Processor Memory Utilization

22. 1553 Allocation