Put another way,the total system costs were highly REFERENCES sensitive to the efficiency of the observation and manipulation systems.Any user would be motivated to achieve the highest actual capability for the lowest mass 1.Galabonva.K..Bounova.G..de Weck.O.and (and,secondarily,power)when designing such Hastings,D.,"Architecting a Family of Space Tugs equipment. Based on Orbital transfer Mission Scenarios."AlAA The current tradespace analysis reveals three classes of paper2003-6368. potentially useful space tug vehicles.They are 2.Saleh,J.H.,Lamassoure,E.,and Hastings,D.E. highlighted on Fig.15.The Electric Cruiser occupies 'Space Systems Flexibility Provided by On-Orbit the "knee in the curve"for our nominal utilities, Servicing:Part 1,"Journal of Spacecraft and providing good value for cost.It could potentially provide even more value for a delta-V hungry user(see Rockets,Vol.39,No.4,July-Aug.2002,pp.551- Fig.8)although it is sensitive to user needs for 560. response time.Its features have been discussed in this 3.McManus,H.L.,and Warmkessel,J.M.,"Creating paper.The"Nuclear Monsters"were not discussed Advanced Architectures for Space Systems: here,but appear to be the only designs (out of the Emergent Lessons from New Processes,"Journal of design space considered)that can provide high delta-V, Spacecraft and Rockets,in press,modified from high capability,rapid response systems.A final range AIAA paper 2001-4738. of vehicles occupies the lower left region of the Pareto 4. front.These are cost effective vehicles built using Shaw,G.M.,Miller,D.W.,and Hastings,D.E., existing technology (e.g.storable bi-propellant systems) "Development of the Quantitative Generalized that can do a variety of jobs requiring less delta-V than Information Network Analysis(GINA) a LEO-GEO transfer.They could,for example,tend Methodology for Satellite Systems,"Journal of sets of vehicles in similar orbits,doing a variety of Spacecraft and Rockets,Vol.38,No.2,2001,pp. maintenance tasks.For this reason(and to extend the 257-269. naval support vessel metaphor)we have dubbed them 5.Smith,J.L.,"Concurrent Engineering in the JPL "Tenders."They are considered in depth in the Project Design Center,"Society of Automotive companion paper. Engineers,Inc.,Paper 98AMTC-83,1998. ACKNOWLEDGEMENTS 6.Aguilar,J.A.,and Dawdy,A.,"Scope vs.Detail: The Teams of the Concept Design Center,"2000 This work was performed by the authors,MIT students IEEE Aerospace Conference Proceedings,Big Sky, Laura Condon,Todd Wesley,Devjit Chakravarti, Montana,March 2000,Vol.1,pp.465-482 Gerganna Bounova,Lisa Messeri,and Matt Richards 7.Parkin,K.,Sercel,J.,Liu,M.,and Thunnissen,D.. and Cambridge University students Nishant Lalwani and Bill Cunliffe.The work was sponsored by DARPA "ICEMaker:An Excel-Based Environment for (TTO)with Dr.Gordon Roesler as Program Manager Collaborative Design,"2003 IEEE Aerospace Funding was administerd via AFRL and the"Grand Conference Proceedings,Big Sky,Montana,March Challenges"contract number F29601-97-K-0010.Ms. 2003 Charlotte Gerhart served as the AFRL project manager. 8.McManus,H.L.,Hastings,D.E.,and Warmkessel, J.M.."New Methods for Rapid Architecture 2000 Selection and Conceptual Design,"Journal of 1800 Spacecraft and Rockets,in press. 1600 9.Ross.A.M..Diller,N.P..Hastings,D.E..and Nuclear Monsters 1400 Warmkessel,J.M.,"Multi-Attribute Tradespace 1200 Exploration as a Front-End for Effective Space 1000 4 System Design,"Journal of Spacecraft and Rockets 800 in press 600 10."Project Freebird:An Orbital Transfer Vehicle", 400 Final report,16.83 Space Systems Engineering, 200 Tendersx Aeronautics and Astronautics Department,MIT, Electric Cruisers 0+ Spring 1994. 0.0 02 04 0.6 08 1.0 11.Weigel,A.L.,and Hastings,D.E.,"Evaluating the Utility (dimensionless) Cost and Risk Impacts of Launch Choices."Journal of Spacecraft and Rockets,in press. Fig.15.Promising designs 11 American Institute of Aeronautics and Astronautics11 American Institute of Aeronautics and Astronautics Put another way, the total system costs were highly sensitive to the efficiency of the observation and manipulation systems. Any user would be motivated to achieve the highest actual capability for the lowest mass (and, secondarily, power) when designing such equipment. The current tradespace analysis reveals three classes of potentially useful space tug vehicles. They are highlighted on Fig. 15. The Electric Cruiser occupies the “knee in the curve” for our nominal utilities, providing good value for cost. It could potentially provide even more value for a delta-V hungry user (see Fig. 8) although it is sensitive to user needs for response time. Its features have been discussed in this paper. The “Nuclear Monsters” were not discussed here, but appear to be the only designs (out of the design space considered) that can provide high delta-V, high capability, rapid response systems. A final range of vehicles occupies the lower left region of the Pareto front. These are cost effective vehicles built using existing technology (e.g. storable bi-propellant systems) that can do a variety of jobs requiring less delta-V than a LEO-GEO transfer. They could, for example, tend sets of vehicles in similar orbits, doing a variety of maintenance tasks. For this reason (and to extend the naval support vessel metaphor) we have dubbed them “Tenders.” They are considered in depth in the companion paper. ACKNOWLEDGEMENTS This work was performed by the authors, MIT students Laura Condon, Todd Wesley, Devjit Chakravarti, Gerganna Bounova, Lisa Messeri, and Matt Richards, and Cambridge University students Nishant Lalwani and Bill Cunliffe. The work was sponsored by DARPA (TTO) with Dr. Gordon Roesler as Program Manager. Funding was administerd via AFRL and the “Grand Challenges” contract number F29601-97-K-0010. Ms. Charlotte Gerhart served as the AFRL project manager. 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0.0 0.2 0.4 0.6 0.8 1.0 Utility (dimensionless) Cost ($M) Biprop Cryo Electric Nuclear Electric Cruisers Tenders Nuclear Monsters Fig. 15. Promising designs REFERENCES 1. Galabonva, K., Bounova, G., de Weck, O. and Hastings, D., “Architecting a Family of Space Tugs Based on Orbital transfer Mission Scenarios,” AIAA paper 2003-6368. 2. Saleh, J. H., Lamassoure, E., and Hastings, D. E. “Space Systems Flexibility Provided by On-Orbit Servicing: Part l,” Journal of Spacecraft and Rockets, Vol. 39, No. 4, July-Aug. 2002, pp. 551- 560. 3. McManus, H. L., and Warmkessel, J. M., “Creating Advanced Architectures for Space Systems: Emergent Lessons from New Processes,” Journal of Spacecraft and Rockets, in press, modified from AIAA paper 2001-4738. 4. Shaw, G. M., Miller, D. W., and Hastings, D. E., “Development of the Quantitative Generalized Information Network Analysis (GINA) Methodology for Satellite Systems,” Journal of Spacecraft and Rockets, Vol. 38, No. 2, 2001, pp. 257-269. 5. Smith, J. L., “Concurrent Engineering in the JPL Project Design Center,” Society of Automotive Engineers, Inc., Paper 98AMTC-83, 1998. 6. Aguilar, J. A., and Dawdy, A., “Scope vs. Detail: The Teams of the Concept Design Center,” 2000 IEEE Aerospace Conference Proceedings, Big Sky, Montana, March 2000, Vol. 1, pp. 465-482. 7. Parkin, K., Sercel, J., Liu, M., and Thunnissen, D., "ICEMaker: An Excel-Based Environment for Collaborative Design," 2003 IEEE Aerospace Conference Proceedings, Big Sky, Montana, March 2003. 8. McManus, H. L., Hastings, D. E., and Warmkessel, J. M., “New Methods for Rapid Architecture Selection and Conceptual Design,” Journal of Spacecraft and Rockets, in press. 9. Ross, A. M., Diller, N. P., Hastings, D. E., and Warmkessel, J. M., “Multi-Attribute Tradespace Exploration as a Front-End for Effective Space System Design,” Journal of Spacecraft and Rockets, in press. 10. “Project Freebird: An Orbital Transfer Vehicle”, Final report, 16.83 Space Systems Engineering, Aeronautics and Astronautics Department, MIT, Spring 1994. 11.Weigel, A. L., and Hastings, D. E., “Evaluating the Cost and Risk Impacts of Launch Choices,” Journal of Spacecraft and Rockets, in press