V.E.G.E.T.A.B.L.E. Melissa Adams, Dylan DiBernardo, Caleb Fricke, Dale Martin, Christopher Moseman, Luke Renegar

Transcription

1 V.E.G.E.T.A.B.L.E. The Variable Environmental Gravity Exploration Transit Accommodation with Baseline Landing Extension Melissa Adams, Dylan DiBernardo, Caleb Fricke, Dale Martin, Christopher Moseman, Luke Renegar 1

2 Table of Contents Spacecraft Configuration Life Support Reference Mission Concept of Operations Lunar Distant Retrograde Orbit (LDRO) Mission Operations Lunar Surface Emplacement Mars Surface Emplacement Experimental Testing 2

3 VEGETABLE Dimensions: Length: 51.2 m Width: 51.2 m Height: 16.7 m Pressurized volume: 706 m3 (including surface habitat); Mass: Center module: 29,000 kg Outer modules: 42,200 kg Connector Arms: 33,500 kg Surface habitat: 30,700 kg 3

4 Spacecraft Configuration Radiators docking interface solar arrays 4

5 Spacecraft Configuration - Center Module arm connections Dimensions: Diameter: 5.4 m Height: 5 m Mass: 29,100 kg Pressurized volume: 104 m3 EVA airlock airlock 5

6 Spacecraft Configuration - Connecting Arms Dimensions: Diameter: 1.5 m Length: 22.1 m Pressurized volume: 27.1 m3 Ladder running the length of the arm COMIT system 6

7 Center-Outer Module Internal Transport (COMIT) Used to assist the transport of goods along the connecting arms Rated for 170 kg (approx. two triple size CTBs with maximum load of kg each) Motor-driven pulleys mounted to housings on the walls run a loop the length of the arm, controlled from either end. Cargo can be tethered to the loop to be drawn through the arm. The basic diagram below shows the arm cross-section, and includes a single triple size CTB for scale 7

8 Spacecraft Configuration - Outer Modules 3 outer modules 25 m away from center module Module 1: 3 sleeping quarters, hygiene, and galley Module 2: 3 sleeping quarters, hygiene, and exercise Module 3: Workstations, storage Dimensions: Diameter: 3.49 m Length: 11.5 m Pressurized volume: 88.2 m3 per module Rotates at 6 rpm to get an acceleration of 1 g at the outer surface 8

9 Spacecraft Configuration - Outer Module 1 3 sleeping quarters, hygiene, and galley 68.9 m3 storage volume CO2 scrubber propellant storage sleeping quarters ladder toilet 9 sink hygiene food storage water recycling window window galley with table medical supplies/closet

10 Spacecraft Configuration - Outer Module 1 10

11 Spacecraft Configuration - Outer Module 2 3 sleeping quarters, hygiene, and exercise 68.6 m3 storage volume CO2 scrubber sleeping quarters ladder closet window exercise equipment exercise area propellant storage toilet 11 sink hygiene water recycling window medical supplies/closet

12 Spacecraft Configuration - Outer Module 2 12

13 Spacecraft Configuration - Outer Module 3 Workstations, storage 70.6 m3 storage volume CO2 scrubber shelves ladder medical supplies window lab table desks propellant storage 13 window

14 Spacecraft Configuration - Outer Module 3 14

15 Mars Habitat Configuration 2.5-story baseline habitat Height: 7.2 m Max. Diameter: 7.5 m Pressurized volume: 187 m3 Mass: 30,700 kg Docked to front of spacecraft Common docking interface with Orion Provides additional low-gravity living/storage space during transit Mars entry via low-density supersonic decelerator Crew descends separately 15

16 Mars Habitat Configuration First/ground floor: Ceiling height: 2.37 m Volume: m3 Second floor: Ceiling height: 2.3 m Volume: m3 Storage level: Ceiling height: 1.54 m Volume: m3 Total pressurized: volume: m3 16

17 Mars Habitat Configuration - Split View 17

18 Mars Habitat Configuration - First/ground floor 18

19 Mars Habitat Configuration - First/ground floor 19

20 Mars Habitat Configuration - Second Floor 20

21 Mars Habitat Configuration - Second Floor 21

22 Mars Habitat Configuration - Second Floor 22

23 Mars Habitat - Storage 23

24 Mars Habitat Configuration - Storage 24

25 Pressure Loads Stress in a thin-walled pressure vessel: σhoop = hoop stress σlongitudinal = longitudinal stress p = pressure = 10.5 psi = Pa r = pressure vessel radius Material: Aluminum 7075-T6 Yield stress = 503 MPa 25 t = pressure vessel thickness

26 Launch Loads on Outer Module σ = stress (Pa) Buckling stress: E = Young s modulus (Pa) t = thickness of thin wall Material: Aluminum 7075-T6 Young s modulus = 71.7 GPa Poisson s ratio = 0.33 Ultimate stress = 572 MPa 26 r = radius of cylinder = m tmin = m

27 Launch Loads on Outer Module Pcr = critical buckling load Buckling force: I = Moment of Inertia (hollow rod) k = column effective length factor (assuming 1) Material: Aluminum 7075-T6 Young s modulus = 71.7 GPa Ultimate stress = 572 MPa L = length = 8 m t = m Pcr = 2.07 MN σ_exp = 1.10 MPa 27 r = m F_exp = 1.45 MN

28 Launch Loads on Connecting Arms L = 22.1 m Buckling force: r = 0.75 m t = m Material: Aluminum 7075-T6 Young s modulus = 71.7 GPa Ultimate stress = 572 MPa Pcr = MN F_exp = 1.15 MN σ_exp = 2.13 MPa 28

29 Launch Loads on Center Module r = 2.7 m Buckling Force: L=5m t =.125 m Material: Aluminum 7075-T6 Young s modulus = 71.7 GPa Ultimate stress = 572 MPa 29 Pcr = GN F_exp = 1000 kn σ_exp = 483 kpa

30 Launch Loads SLS payload acceleration estimates: 30

31 Operating Loads Axial force from connecting arms: Parm max = maximum axial force in the arm (occurs at connection to center module) marm = arm mass = 33,500 kg = rotational speed = 6 rpm Parm max = 13.3 MN (tension) ℓarm = arm length = 22.1 m σ = 24.7 MPa 31

32 Operating Loads Axial force from outer modules: Pmodule = axial force experienced by the arm, generated by outer module mmodule = outer module mass = 42,200 kg = rotational speed = 6 rpm Pmodule = 36.2 MN ℓarm = arm length = 22.1 m σ = 47.8 MPa dmodule = diameter of outer mod = 3.49 m 32

33 Loads Summary Launch loads: Operating loads: Connecting Arms Outer Modules Pcr = 186 MN Pmodule = 36.2 MN F_exp = 1.15 MN σ = 47.8 MPa σ_exp =2.13 MPa Connecting Arms Center module: Parm max = 13.3 MN Pcr = 204 MN σ = 24.7 MPa F_exp = kn σ_exp = 483 kpa Outer modules: Pcr = 2.07 MN F_exp = 1.45 MN σ_exp = 1.1 MPa 33

34 Life Support - Atmospheric Composition 10.5 psia; 30% oxygen by volume Normoxic limit without violating 30% O2 flammability limit ppo2: 3.15 psia Pressure maintained by N2 ppo2: 3.15 psia Consumables aboard to replenish leakage Assumed ISS leakage value of 0.02%/day by mass (Schaezler et al.) 34

35 Life Support - Atmosphere Recycling 3 Sabatier reactors (1 in each outer module) Each sized for 1/2 of environmental load (3.5 kg/day/reactor) Assumed 70% effective at recovering O2 CO2 + 4H2 CH4 + 2H2O Electrolyze waste water to recover oxygen Re-use some hydrogen; vent excess overboard 35

36 Life Support - Water 2 fully redundant VCD units 1 in each sleep module Each rated for 60 kg H2O/day Assumed 93% recycling (ISS level) 36

37 Life Support - Consumables Budget Consumable Raw usage (kg/person-day) Usage with recycling (kg/person-day) Mission budget (kg) Food solids Potable Water Hygiene Water Metabolic Oxygen

38 Life Support - Consumables Budget (cont.) Consumable Mission budget (kg) Leak Replenishment Oxygen 63.5 Leak Replenishment Nitrogen 130 Repressurization Oxygen 380 Repressurization Nitrogen

39 Life Support - Thermal and Ventilation Forced circulation between modules to encourage mixing 3 loops - 1 per outer module, loops connected at center module Ducts run inside radial arms and along floor/ceiling of outer modules Fans force circulation Sabatier reactor in each loop Radiators on radial arms for heat rejection Electric heating in each module as necessary 39

40 Contingency Operations Fire In the event of difficult or inaccessible fire, module venting capability down to 30 kpa or less within 10 minutes Upon detection of fire, isolate/shut down module ventilation. CO2 fire extinguishers for local fire suppression Depressurization In the event of rapid depressurization, each outer module can be sealed off from the rest of the configuration and isolated via double hatches. Repairs can be done externally via EVA from the center module or internally via IVA (using the hatches as a makeshift airlock) In the event of loss of pressure to the entire module configuration, the crew can shelter in the habitat module. The habitat docking port has airlock capability, allowing IVA access to the modules and to the EVA port in the center module 40

41 Contingency Operations (cont.) Radiation With module wall thickness of ⅛ m (12.5 cm), structural aluminum shielding is approx g/cm2, more than enough for solar radiation and most SEP events Use of water/polyethylene/structural shielding for galactic cosmic ray negation is impossible in deep space under realistic mass constraints Hydrogenated boron nitride nanotubes (BNNT), currently in final development stages, could be used for better GCR shielding and secondary radiation shielding than any previous shielding materials. Processable into composite or fabric lining that can be applied to entire surface (interior or exterior) of structure or pressure vessel 41

42 Concept of Operations Sleep: 8.5 hr Postsleep: 1.5 hr Morning and Evening Daily Planning Conference: 0.5 hr each Experiments, maintenance, repairs, and housekeeping: 6.5 hr Midday meal: 1 hr Exercise: 2 hr Free time: 2 hr Presleep: 1.5 hr 42

43 Concept of Operations Stagger sleeping schedules so at least 2 people are awake at all times Communication delay could reduce the effectiveness of flight controllers on earth alerting the crew in the event of an emergency 43

44 Reference Mission Mars Crew Conjunction-class mission days 180 days outbound transit 545 days at Mars 180 days return transit Depart from/return to Deep Space Gateway 44

45 Reference Mission - Logistics Initial provisioning and checkout in cislunar space Leverage Deep Space Gateway Habitat capable of full 905-day Mars orbit mission without resupply Mars surface would require pre-positioned supply cache Consumables for use on Mars surface Extra habitat components Crew EDL/ascent vehicle (CEAV) Crew changeout in cislunar orbit with Orion/SLS Cargo resupply concurrent with crew changeout or via Falcon Heavy 45

46 Reference Mission - Mars Landing Crew lands habitat module on Mars via remote control After habitat landing, crew docks with pre-positioned CEAV in Mars orbit Crew performs remote checkout of habitat Crew lands on Mars ~20 days after arrival ~500 days (~490 sols) on Mars Crew returns to transit vehicle via CEAV ~20 days before Mars departure Can abort surface mission at any time for contingency 46

47 Reference Mission - Goals Geologic research Pre-position caches could include sensitive instruments for analysis Potential to survey much more ground than MER/MSL Human factors research Health effects of long-term exposure to partial gravity Surface habitat design Technology development/validation Habitat module would be largest ever Mars EDL Crew survival not dependent on success - sufficient supplies to remain in orbit 47

48 Cislunar Orbit Mission Operations Launch to cislunar orbit 3 outer modules, 3 arm elements on 1 SLS Arms are launched as 22.1 m segments Center module, assembly crew on 1 SLS 3 arm segments, construction supplies on Falcon Heavy Assembly in cislunar space based at Deep Space Gateway (DSG) Potential for human factors studies/checkout at DSG Verify systems and procedures before committing to Mars campaign 48

49 Cislunar Orbit Mission Operations (cont.) Dock to DSG to facilitate crew/cargo transfer Crew movements with Orion Docking port at end of VEGETABLE center module Mars surface habitat module launched aboard SLS Checked out remotely from ground Mating with habitat module is last task before departure for Mars Undock from DSG, dock with Mars surface habitat module 49

50 Mars Surface Emplacement Surface habitat detached from VEGETABLE and lands under remote control from crew Low-Density Supersonic Decelerator (LDSD) provides initial aerobraking Large parachutes provide additional drag at lower altitudes Terminal guidance and deceleration with retro-rockets Crew follow on ~10 days later in CEAV Habitat expandable with pre-positioned inflatable modules 50

51 Mars Surface Emplacement (cont.) 51

52 Lunar Surface Emplacement Surface habitat detached from VEGETABLE and lands under remote control from crew Descent via retro-rockets Lunar-configured surface habitat replaces LDSD and related systems with extra propulsion Crew follow on ~10 days later in descent/ascent vehicle Habitat expandable with pre-positioned inflatable modules 52

53 Experimental Testing Issues to be addressed: Climbing a ladder in variable gravity Climbing ability Climbing up starting at 1g Climbing down starting at 0g 0 g to 1g transition over the length, potentially flipping orientation partway through Physiological effects Attaching/detaching cargo to COMIT system 53

54 Experimental Testing - Schedule Nov. 6th - 24th (3 weeks) Design mock-up replicating a section of the habitat connecting arm with ladder for testing in neutral buoyancy tank Design mock-up replicating entrance hatch area from outer module to connecting arm, and short length of arm (with corresponding section of COMIT system and ladder) for use on land in 1 g Nov. 27th - Dec. 15th (4 weeks) Fabricate mock-ups Winter Break: Dec. 19th - Jan. 24th 54

55 Experimental Testing - Schedule (Cont.) Jan. 29th - March 2nd (4 weeks) Test the maneuverability of a person on the ladder in the arm section mock-up, simulating varying gravity levels from 0-1g. Climbing upside-down, or headfirst towards the ground, under what conditions do they struggle to climb? To fall? Starting from an upside-down position, how easily can they right themselves under the different gravitational conditions? Test the ease of attaching and detaching loaded CTBs to the COMIT system with one or more crew members under 1 g conditions (the most difficult that would be experienced). 55

56 Experimental Testing - Anticipated Results Connecting arm variable gravity test This will provide useful data concerning how the crew will move through the arm at different points along its length. Knowing the gravitational conditions at which it becomes difficult or dangerous to maneuver down the ladder (towards the outer modules in the design) will allow us to gauge at what position in the arm at which maneuvering feet-first becomes important. This should help to determine an optimal technique for traversing the connecting arm. COMIT loading testing This will provide data as to the effectiveness of the COMIT system design, and should reveal difficulties to be addressed and improvements to be made in the design and implementation of the system. 56

57 Selected References Aluminum 7075-T6, 7075-T651, Aerospace Specification Metals Inc. Chris Calfee, David Alan Smith, SLS Mission Planners Guide (MPG) Overview, NASA M , February 2014 European Space Agency blogteam, Planning Down to the Minute, July 2014 Friedman, R. Fire Safety in the Low-Gravity Spacecraft Environment, NASA Technical Reports Server ID , July 1, 1999 Junaedi, C., et al. Compact and Lightweight Sabatier Reactor for Carbon Dioxide Reduction, Proceedings of the 41st International Conference on Environmental Systems, Low Density Supersonic Decelerators, NASA JPL , Space Launch System Program Exploration Mission 1 Safety Requirements for Secondary Payload Hardware, NASA SLS-RQMT-216, April 2015 Schaezler, R., Cook, A., and Leonard, D. Trending of Overboard Leakage of ISS Cabin Atmosphere, Proceedings of the 41st International Conference on Environmental Systems, Thibeault, Sheila A., et al. Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study - Phase I, NASA NIAC Final Report, Sept Background images from National Geographic and NASA 57