Week 6 Presentation Thursday, Feb 19, 2009 Translunar Orbit Transfer Vehicle (OTV): Updates in Sizing and Optimization Mass Comparisons of Available Hall Thrusters Week 6 Presentation Thursday, Feb 19, 2009 Brad Appel Propulsion Group 1

OTV Sizing: Joint Effort with Mission Ops Group Trading between many parameters: Time of flight, thrust, specific impulse, mass flow rate, power, propellant mass, and cost Currently a TOF of 351 days provides the cheapest mission, but the story drastically changes if the solar panel price varies Brad Appel Propulsion Group 2

Comparison of Different Hall Thruster Systems Updated OTV Numbers Based on BHT-1500: TOF = 351 days Initial Mass [kg] 660 Power Required [W] 2574 Xenon Mass [kg] 170 Tank Diameter [m] 0.58 TOF = 186 days Initial Mass [kg] 598 Power Required [W] 6817 Xenon Mass [kg] 90 Tank Diameter [m] 0.47 Brad Appel Propulsion Group 3

Backup Slides: Optimum Isp for our Mission Note: Curve not steep: Can tolerate 1800-4250 s with only 6% loss Brad Appel Propulsion Group 4

Backup Slides: Various Empirical Curves Brad Appel Propulsion Group 5

Backup Slides: OTV Scaling Up Scaled up the GLXP design according to payload mass fraction and specific power, normalized to the maximum payload capacity of each launch vehicle. Worked with Power Group. Launch Vehicle IMLLO [kg] Dnepr 2,511 1,808 Falcon 9 5,363 5,137 Ares V 80,660 77,264 Method 1 Method 2 (Use this) Brad Appel Propulsion Group 6

Backup Slides: Other Information Density Supercritical Xe: 1673 kg/m3 (P = 150 bar) Cost Xe: $ 5.00 / liter* OR $1200 / kg** Assumptions for sizing code: Payload = 290 kg  Probably larger now (~315) OTV Structure/Thermal Mass = 120 kg Launch cost to LEO 400 km: $5000 / kg (roughly extrapolated from $3400 / kg to 200 km) *Source: Defense Energy Support Center – FY 2009 Data **Source: www.chemicool.com Brad Appel Propulsion Group 7