Flexibility for in‐Space Propulsion Technology Investment Jonathan Battat ESD.71 Engineering Systems Analysis for Design Application Portfolio 2 Jonathan Battat Executive Summary This project looks at options for investment for in‐space propulsion technology development for human space exploration. Only two propulsion types are considered: Solar Electric Propulsion (SEP) and a Chemical Propulsion Stage (CPS). A simulation is built around cost data and mission profiles included in a presentation from NASA. These include precursor flights that sufficiently raise the Technology Readiness Level (TRL) of each technology for use in human spaceflight. The current mission campaign is designed for a Near‐Earth Asteroid (NEA) with the intention of creating technological readiness for Mars missions. While SEP and CPS will be required for Mars missions, the intermediate goal may be executed with CPS alone. The simulation includes uncertainty in the success of precursor flight demonstrations. This uncertainty demonstrates the real possibility that SEP is not actually available for the NEA mission. A scheme is proposed to maximize technology deve lopment cost effectiveness, while ensuring technology is available for the human exploration missions. Given the un certainty of successful flights, flexibility of a put option is included to delay development of SEP given insufficient TRL at set decision points. By creating a measure of effectiveness that rewards successful technology investment and including flexibility to revert to only CPS, total expected cost can be reduced. More importantly, the mean expected cost effectiveness is increased by over 35%. Suggested next steps include defining uncertainty of the costs and including more alternative propulsion technologies.3 Jonathan Battat Contents Executive Summary....................................................................................................................................... 2 Background ................................................................................................................................................... 4 In‐Space Propulsion .................................................................................................................................. 4 Exploration Destination ............................................................................................................................ 5 Setup for Analysis...................................................................................................................................... 5 The Model .....................................................................................................................................................7 Introducing Uncertainty............................................................................................................................7 Measure of Effectiveness.......................................................................................................................... 9 Setting up the Baseline Case..................................................................................................................... 9 Deterministic vs Uncertain Baseline Case............................................................................................... 10 Decision Rules .............................................................................................................................................12 Results......................................................................................................................................................... 12 Cost .........................................................................................................................................................12 Cost Effectiveness ................................................................................................................................... 14 When is SEP used? .................................................................................................................................. 16 Sensitivity .................................................................................................................................................... 17 Conclusion................................................................................................................................................... 18 Lessons Learned.......................................................................................................................................... 19 Appendix A: Sample Data............................................................................................................................20 Sources........................................................................................................................................................ 22 4 Jonathan Battat Background This project is focused on investment for in‐space propulsion technology development for human space exploration. That refers to the engines that will take people from Earth orbit to space exploration destinations (the engines do not operate in Earth’s atmosphere). For the purposes of this assignment only two propulsion types will be considered: Solar Electric Propulsion (SEP) and a Chemical Propulsion Stage (CPS). InSpace Propulsion SEP‐ shown below involves very large solar arrays to collect energy. Propulsion is achieved by an electric engine which is an order of magnitude more fuel efficient1 than chemical propulsion. While electric thrusters and solar arrays are not new technologies, developing them at sufficiently large sizes has not yet been demonstrated. Since the solar energy available at any given time (and location) limits the thrust of the engine, SEP systems have very low thrust despite their high efficiency. The thrust level influences time‐of‐flight to a destination. For most cargo, this does not matter much, however for transferring crew (people) it leads to transit times that are logistically infeasible due to extra mass of consumables and radiation shielding required. The result is that SEP cannot be the only in‐space propulsion technology for space exploration with humans. Figure 1 Solar Electric Propulsion In general CPS (shown below) is chemical rockets. Liquid fuel and oxidizer combine to create expanding gasses that are channeled through a