Arthur N. Guest, aguest@mit Wilfried K. Hofstetter, wk_hof@alum.mit

1. Interplanetary Transfer Vehicle Concepts for Near-Term Human Exploration Missions beyond Low Earth Orbit Arthur N. Guest, aguest@mit.edu Wilfried K. Hofstetter, wk_hof@alum.mit.edu Paul D. Wooster, paul@developspace.net DevelopSpace Initiative Inc. Presentation at AIAA Space 2010 Anaheim, August 30, 2010

2. Overview • This paper analyzes candidate minimalist system designs for potential “flexible-path” destinations, including the following mission types: • Lunar fly-by • Lunar orbit • Sun-Earth L2 libration point • Geo-synchronous orbit • Near-Earth objects • The analysis is based on the use of existing in-space propulsion stages (EELV upper stages), along with a heavy-lift launch vehicle, crew entry capsule (such as the Orion vehicle), and small habitation module (along the lines of the Altair crew compartment) • Overall goal is to identify options for conducting these types of missions with minimum additional development effort • This project is being undertaken as part of DevelopSpace’s open-source space development activities • All models, analyses, and supporting documentation is available through http://wiki.developspace.net/ITV and http://svn.developspace.net/svn/itv/ • Material is provided to serve as a basis for further development of these concepts

3. Agenda • Motivation for human deep space missions • Mission assumptions and requirements • Architecture-level analysis • Detailed discussion of mission designs • Conclusions and future work

4. Motivation for Human Deep Space Missions • Human deep space missions to destinations such as a Near Earth Object (NEO) could serve as near-term (this decade) stepping stones to human Mars exploration • Human deep space missions do not require development of capabilities for Mars entry, descent & landing (EDL) and planetary landing, and are therefore easier to achieve than lunar surface missions • NEO missions in particular offer deep space operational experience relevant to human Mars missions while also providing significant science return (e.g. samples)

5. Agenda • Motivation for human deep space missions • Mission assumptions and requirements • Architecture-level analysis • Detailed discussion of mission designs • Conclusions and future work

6. Mission Assumptions and Requirements • Basic requirements for the different mission types • The lunar missions are carried outusing only an entry capsule such asthe Orion Crew Module for habitation • For the SE-L2, GEO, and NEO missions,an additional habitation module similar tothe ESAS LSAM ascent crew module usused (no propulsion system) LSAMcrew module Orioncrew module

7. Agenda • Motivation for human deep space missions • Mission assumptions and requirements • Architecture-level analysis • Detailed discussion of mission designs • Conclusions and future work

8. Centaur V1 Architecture Analysis 2 x [3 SSME +2 x 4-Segment SRB,Side-Mount] 2 x [3 SSME +2 x 4-Segment SRB,Inline] 1 x [4 SSME +2 x 5-Segment SRB,In-line] 2 x [4 SSME +2 x 5-Segment SRB,Inline] NEO GEO Lunar Orbit CEV SM + 5 Centaur V1 SE-L2 CEV SM + 4 Centaur V1 CEV SM + 3 Centaur V1 Lunar Flyby CEV SM + 2 Centaur V1 CEV SM + 1 Centaur V1 1 x [3 SSME +2 x 4-Segment SRB,Side-Mount] 1 x [3 SSME +2 x 4-Segment SRB,Inline] 1 x [4 SSME +2 x 5-Segment SRB,In-line]

9. Delta IV Upper Stage Architecture Analysis 2 x [3 SSME +2 x 4-Segment SRB,Side-Mount] 2 x [3 SSME +2 x 4-Segment SRB,Inline] 2 x [4 SSME +2 x 5-Segment SRB,Inline] NEO GEO Lunar Orbit CEV SM + 5 Delta 4 Heavy Upper Stage SE-L2 CEV SM + 4 Delta 4 Heavy Upper Stage CEV SM + 3 Delta 4 Heavy Upper Stage CEV SM + 2 Delta 4 Heavy Upper Stage Lunar Flyby CEV SM + 1 Delta 4 Heavy Upper Stage 1 x [3 SSME +2 x 4-Segment SRB,Side-Mount] 1 x [3 SSME +2 x 4-Segment SRB,Inline] 1 x [4 SSME +2 x 5-Segment SRB,In-line]

10. Agenda • Motivation for human deep space missions • Mission assumptions and requirements • Architecture-level analysis • Detailed discussion of mission designs • Conclusions and future work

11. Numerical Earth Departure Analysis 4 Centaur V1 stages 3 Centaur V1 stages 1 Centaur V1 stage 2 Centaur V1 stages

12. Lunar Flyby Mission Storyboard Earth’smoon Lunar flyby Lunarorbit Centaur V1 stages discarded Trans-lunar coast Trans-Earth coast LEO Earth entry Launch 1 Earth landing Earth

13. Lunar Orbit Mission Storyboard Earth’smoon Science package remains in lunar orbit Lunar orbit operations Low lunar orbit capture Low lunar orbit departure Lunarorbit Centaur V1 stages discarded Trans-lunar coast Trans-Earth coast LEO Earth entry Launch 1 Earth landing Earth

14. SE-L2 Mission Storyboard Servicing payload left atthe observation asset SE-L2asset SE-L2operations SE-L2 capture SE-L2halo orbit SE-L2 departure Centaur V1 stages discarded Trans-SE-L2 coast Trans-Earth coast LEO Earth entry Launch 1 Earth landing Earth

15. GEO Mission Storyboard GEOasset Capture stage discarded Mission module and sciencepayload remains with asset or is discarded GEO operations GEO capture GEO GEO departure Centaur V1 stages discarded Trans-GEO coast Trans-Earth coast LEO Earth entry Launch 1 Launch 2 Earth landing Earth

16. NEO Mission Storyboard Capture stage discarded NEO Mission module and sciencepayload remains at destination NEO exploration NEO capture NEOvicinity NEO departure Consumables for trans-NEO coast discarded Trans-NEO coast Trans-Earth coast Centaur V1 stages discarded LEO Earth entry Launch 1 Launch 2 Earth landing Earth

17. Agenda • Motivation for human deep space missions • Mission assumptions and requirements • Architecture-level analysis • Detailed discussion of mission designs • Conclusions and future work

18. Conclusions • ITV designs based on NASA’s Orion and adapted EELV upper stages enable near-term human deep space missions • With a single launch of a heavy-lift launch vehicle (such as a side-mount or in-line shuttle-derived vehicle) lunar flyby, orbit, and SE-L2 missions can be carried out • With two launches, missions to GEO as well as missions to certain NEOs (similar to the NEO 1999 AO10 2025/26 opportunity) can be carried out • For lunar flyby and lunar orbit options, only an Orion-like vehicle (possibly also commercially developed), adapted Centaur V1 upper stages, and a heavy-lift launch vehicle are required • For SE-L2, GEO, and NEO missions, an additional habitation module similar in size to the ESAS LSAM crew module is required for additional pressurized volume and airlock functionality • With the Orion crew module, the human-rated heavy-lift launch vehicle, and possibly also the habitation module, the minimalist architecture would provide important elements extensible to future human Mars missions

19. Suggestions for Future Work • Further detailed analysis of the mission designs outlined • Including more detailed definition of science payloads, inflatable structures for the habitat module, and an in-depth analysis of hydrogen (and possibly also oxygen) boil-off • Detailed analysis of concepts based on a Delta IV Heavy upper stage design adapted for extended use • Extension of the NEO mission analysis to more NEOs • Analysis of alternative designs for the entry capsule (for example designs based on commercial crew systems) • Possible entry vehicle mass reductions which may lead to cost reductions and increased mass margin (or possibly fewer launches) • The DevelopSpace platform can support these types of follow-on activities – http://www.developspace.net

20. Background: DevelopSpace • DevelopSpace Initiative, Inc. is a not-for-profit, tax-exempt organization dedicated to advancing human space activities • We aim to apply open-source principles and development methodologies towards space endeavors • Our intent is to foster a community actively engaged in advancing knowledge, tools, and systems relevant to expanding humanity into space, and openly sharing the associated information resources to broaden adoption and speed development • The DevelopSpace platform at http://www.developspace.net/ provides a space-related knowledge base and project hosting infrastructure such as file repositories, wikis, mailing lists, etc., for open-source, space-related projects • We are open to contributions from all those interested in engaging in the open development space systems and exchange of knowledge related thereto

21. Backup Slides

22. Science Payloads

23. Launch vehicle data

24. Mission payloads

25. Consumables data

26. Launch vehicle shroud volume

27. SE-L2 Earth departure

28. GEO Mission GEO insertion

29. NEO Mission – NEO Insertion