1. Surface Power – CDR John Dankanich – March 6, 2001

2. Power Requirement Propellant Production
Cryogenic storage – 265 W / Tonne (Approximately 30 kWe)*
Life Support etc. – Operating Simultaneously
* US Department of Energy

3. Size of Reactor Why sized the way it is?
• Minimum Core dimension 0.6m Diameter
• Need room for reflector and shield
• Deployable Radiators need Surface Area
• Smallest Possible dimension approximately 1 m3 excluding Power converter with mass of approximately 25 tonnes!

4. Power from NTR Power Conversion (Brayton Cycle) 30 kg / kW
2 engines producing 25 kWe each = 1.5 Tonnes

5. Construction of Power Cable
• Helical to allow for stretch
• Redundant wiring

6. Cable Specifications
2 Strands 2 Gauge Wire (D = 6.54 mm) kg/km*
Length of 330 Meters (Wound to 324 m)
Mass of Approximately 200 kg
Insulation foam Mass of Approximately 50 kg
Covering Mass of Approximately 100 kg
Total Mass of 350 kg *

7. Modes of Failure • Excessive Tension • Micrometeorites • Power Surge
• NTR Failure
• Deployment

8. Summary How important is the additional redundancy? • Mass of 1850 kg
• Reliability 0.99*
• No Development
• Minimal Construction Costs
Therefore primarily cost is launch  $200 million dollars
Based in increased risk of mission*