1. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Point Design for 2.5 Megawatt VASIMR Engine For Mission to Callisto in 2045 Developed with input from ASPL Team and collaborators at Oak Ridge National Laboratory, Los Alamos National Laboratory, NASA Goddard Space Flight Center, University of Texas, University of Houston, Rice University, and MIT Provided to RASC Team, NASA Langley Research Center October 2002

2. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Point Design for 2.5 Megawatt Engine 45 cm 180 cm 63 cm Helicon 50 MHz RF Source (750-1250 kW) RF Power Distribution Magnet power supply 3 High-temperature superconducting magnets (60-70 K) 2.5 MW DC Power 15 kV Magnet cryocoolers (3 plus 1 spare) (Power Required: 375 W) Propellant control 177 – 296 mg/sec Deuterium 30 cm System Controller ICRF 1.5 MHz RF Booster (1250-1750 kW) Power Processing Unit Engine Exhaust Oct 21 2002 Radiators 1351 kW @ 500 C 75 m 2

3. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Field Strength (T) Axial length (m) Magnet Coils and Resulting Field Lines Magnetic Field Profile Magnetic Field for 2.5 Megawatt Engine Magnet inner diameter: 76 cm ICRFHelicon

4. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Magnet coil (actively cooled) Thermal shield (actively cooled) Outer shield and insulation 6 x 6 cm3.2 x 3.2 cm4.4 x 4.4 cm 76 cm 80 cm 130 cm 165 cm Magnet Mass : 117 kg for three coils Basis: BSCCO- 2223 (Bismuth-Strontium-Calcium-Copper Oxide) superconducting material Critical temperature for BSCCO-2223 is 106 K with usable current density below 80 K. Ideal operating temperature with existing magnet is 40 K. In this design an operating temperature of 60-70 K is assumed based on modest technology advancement. Magnetic Coils for 2.5 Megawatt Engine

5. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Dimensions: Cold head: 15 cm diameter, 35 cm length (4) Electronics: 20 x 20 x 10 cm (4) Radiator: 140 cm x 45 cm (top of enclosure) Cryocooler enclosure: 150 x 45 x 30 cm Assuming 60-70 K superconductor Conduction & radiation load for three magnets: 3-7 W, Heat load for leads: 5-7 W Total Heat Load: 14 W Three coolers plus spare: 5 W capacity each at 60-70 K Similar to TRW cooler used for Terra and Aqua EOS spacecraft (TRL = 9) Total input power: 375 W Radiating 375 W at 55C yields 0.63 sq. meter radiator area Mass: Total: 80 kg4 cold heads: 4 x 10 kg = 40 kg 4 electronics units: 4 x 6 kg = 24 kg Structural support: 64 kg x.15 = 10 kg Radiator (0.51 m 2 ): 2.7 kg Heat Pipe: 3 kg Based on information provided by: Rob Boyle and Shuvo Mustafi NASA Goddard Space Flight Center Magnet Cooling Cold head

6. NASA Johnson Space Center, Advanced Space Propulsion Laboratory 200 cm 180 cm Diameter: 125 cm Diameter: 63 cm RF Electronics (PPU) Magnet Cryocoolers Magnet Power Supply Point Design for One Megawatt Engine Engine, PPU and Cryocoolers Outer diameter: 80 cm

7. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Overall radiator diameter for cluster ~ 15 meters Looking forward Looking aft Cluster of Four 2.5 MW VASIMR Engines Heat rejection requirement for each engine and PPU: 1350 kW Radiator area required: 75 m 2 @ 500 C One quarter-disk-shaped panel around engine exhaust: 640 cm radius One double-sided panel along engine and PPU: 380 cm x 580 cm

8. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Radiator Panel Mass: One-sided: 4.9 kg/m 2 Two-sided: 8.9 kg/m 2 Antenna sizing based on 10 MW/m 2 Mass Estimate for 2.5 MW Point Design Engine: 600 kg  = 0.24 kg/kWe PPU: 1300 kg  = 0.52 kg/kWe Total System: 1900 kg  = 0.76 kg/kWe Mass Estimate

9. NASA Johnson Space Center, Advanced Space Propulsion Laboratory Performance