Contractor 7 “The Space Savers”

1. Matthew Craig Thomas Kennedy Mark Landreneau Austin Probe Travis Robison David Surovik Robert Timmermann Contractor 7“The Space Savers”

2. Mission Statement • Develop and execute a mission to send and safely return astronauts to a Near-Earth Asteroid. This mission will provide compositional data for future exploitation of NEAs. Secondly, the mission will provide an environment for the testing and validation of deep-space capabilities.

3. Objectives • Study asteroid composition • Sample return • En Route • Zero-g mitigation • Deep space experiments • Experiments from NASA, universities, private institutions • Testbed for deep space technology

4. Necessary Skills and Crew • Skills • Geologist/Scientist • Pilot/Engineer/Technician • Doctor • Communication • Crew • 4 people

5. Asteroid Selection • Search criteria • H < 25 (diameter > 40 m) • i < 3° (correlates with ΔV) • e < 0.10 (correlates with ΔV) • MOID < 0.1 (correlates with trip time) • Selection criteria • Close approach between 2020 and 2050 • Relative velocity • Max thrust required for year-long trip

6. Mission Outline 6. Parking orbit 8. Return to Earth 9. Capture into Earth parking orbit 7. Lander separation and transport to asteroid 2. Rendezvous with spacecraft 5. Arrival at asteroid 1. Launch 4. Flight to asteroid 3. Leave Earth

7. Mission Outline Cont. • Spacecraft will be assembled on orbit • Start of mission will necessitate a launch in a transfer vehicle to reach main spacecraft • Spacecraft will not enter atmosphere, will remain in parking orbit above Earth • Transfer vehicle will return crew to Earth • Spacecraft will remain in orbit for reuse for future missions

8. Trajectory

9. Crew Schedule • Shift One • Shift Two

10. Spacecraft Description • Segmented rotating spacecraft • Center propulsion section • Arms connect to radiators, habitation, storage, and reactor • Assembled on orbit • Separate landing craft for asteroid transfer • Upper-stage capable of ferrying between asteroid and spacecraft

11. Configuration Habitation Module Lander Communications Array Zero-G Section Fuel Tanks Radiators VASIMIRs Storage Section Reactor

12. Mass Budget

13. Spacecraft Arrangement

14. Propulsion System • VASIMR propulsion • 4 VF-200 engines • 20 N total thrust at Isp of 5000s • Allows for continuous thrust • Effect of throttling of VASIMR on thrust and Isp unknown

15. Power System • Nuclear fission reactor • Brayton cycle thermal conversion • ~30% thermal efficiency • 1 MWe • Mass including thermal conversion system, reactor: • 17,600 kg • Radiators • 387 m2 • 1065 kg • Tradiator = 650 K • Carbon-carbon radiator panels (Tradiator : 600-1000K) Source: http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212596.pdf

16. Telecom System • System assumptions: • 34 m diameter ground antenna (NASA DSN) • 3 m diameter spacecraft antenna • Max distance of 0.15 AU • System performance: • Data Rate: 100 Gbps • Band Type: K Band – for color video transmission/receive • Estimated spacecraft power requirements: • Transponder Power Requirement: 21 kW • 63 kW for a triple redundant system

17. Lander • Two man crew • Weight – 8 MT • Sample Return Payload – up to 1 MT • Grappling system to attach to surface • Detachable grapples for relocation • Equipment: • Ground penetrating radar • Spectrometer • Core drill for sample collection • Chemistry lab cell • Self contained mineral analyzer

18. Advantages • Uses near future or available technologies • Redundancy included in propulsion system for increased probability of mission success • Spacecraft can be reused for future missions • Artificial gravity reduces health concerns and provides scientific data on zero-g mitigation

19. Fin

20. Sources • Mason, Lee S. "A Power Conversion Concept for the Jupiter Icy Moons Orbiter." NASA Technical Report n. pag. Web. 1 Nov 2010. <http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212596.pdf>. • Presby, Andrew. "THERMOPHOTOVOLTAIC ENERGY CONVERSION IN SPACE NUCLEAR REACTOR POWER SYSTEMS." Naval Postgraduate School, 01 Dec 2004. Web. 2 Dec 2010. <http://www.projectrho.com/rocket/Presby_Engineer_Degree_Thesis.pdf>

21. Backup

22. Propulsion Systems • Hybrid system selected • VASIMR main thrusters with chemical maneuvering thrusters • VASIMR main propulsion offers the lowest fuel weight. • Individual 200 kW engines weight approximately 300 kg. • Chemical maneuvering thrusters allow for easier maneuvering • Chemical main thrust needs too much fuel

23. Psychological Effects Multiple crews will be selected Selected crews will undergo survival training in a remote area in order to evaluate their performance as a team under stress. Crews that meet expectations will be scheduled for missions

24. Radiation Exposure Mitigation • Physical shielding selected (plastics and water layer) • Plastics offer best protection for weight • Water layer possible for inflatable sections • Magnetic shielding not used for primary shielding, due to its untested nature and large power requirements (not applicable for permanent magnets)

25. Zero-G Effects Mitigation • Segmented spacecraft provides artificial gravity will less mass than a torus • Exercise equipment will still be carried to maintain muscle strength

26. Power Systems • Nuclear power chosen to provide enough power with a reasonable weight for VASIMR • RTG do not produce enough power efficiently • Solar panels require too much area, and therefore weight • Microwave beamed power has not been built/tested

27. En-Route Experiments • Astronauts need things to do, but en-route experiments should not take up all of their time

28. Possible Spacecraft Configurations Toroidal Asymmetric Rotator

29. Artificial Gravity Range of Operability

30. Mass Budget Cont. • Habitation, storage, and central section masses estimated based on similar sized ISS modules • Food estimates based on 0.5 kg per person per day • Water estimates based on 20 L per person per day for 3.6 months. • Use water recycling to reuse water

31. Water Recycling • Use an ISS derived water recycling system • 3 step process • Filter removes particles and debris • “Multifiltration beds” removes impurities • “Catalytic oxydation reactor” removes bacteria and viruses • Will recycle humidity in the air, wastewater and drinking water Source: http://science.nasa.gov/science-news/science-at-nasa/2000/ast02nov_1/

32. Power System • Nuclear fission reactor • Brayton cycle thermal conversion • ~30% thermal efficiency • 1 MWe • Mass including thermal conversion system, reactor: • 17,600 kg • Radiators • 387 m2 • 1065 kg • Tradiator = 650 K • Carbon-carbon radiator panels (Tradiator : 600-1000K) Source: http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212596.pdf

33. Reactor Selection Source: http://www.projectrho.com/rocket/Presby_Engineer_Degree_Thesis.pdf

34. Reactor Selection Cont. Source: http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212596.pdf

35. Radiator Sizing Primary Inputs: Propulsion, life support, communications  Power Required = 1 MWe Thermal conversion cycle (Brayton)  Thermal Efficiency = ~30% Radiator material (Carbon-carbon)  Radiator Temperature = 650 K

36. Radiator Sizing Cont. Radiator sizing governed by: Where: Arad = Radiator Area [m2] Qrad= Heat Emitted [W m-2] F = View Factor ε = Emissivity σ = Stefan-Boltzmann constant [W m^-2 K^-4] Trad = Radiator Operating Temperature [K] Tsink = Environmental Sink Temperature [K]