National Aeronautics and Space Administration
Spacecraft Fire Safety: Protecting Vehicles and Crews on Long-Duration Missions
Gary A. Ruff NASA John H. Glenn Research Center Cleveland, Ohio
Future In-Space Operations (FISO) Seminar
November 15, 2017 NASA’s Risk Management for Spacecraft Fire Safety
Fire Safety Philosophies
Fire-proof design Prevention
Maximize Use of Minimize Ignition Fire Triangle Good Materials Mechanisms
Utilize Good Practices
2 NASA’s Risk Management for Spacecraft Fire Safety
Fire Safety Philosophies
Fire-proof design Prevention
Practically Maximize Use of Minimize Ignition Can’tFire Be Triangle Done Good Materials Mechanisms
Utilize Good Practices
These are the focus of our fire safety activities! • Tasks “buy-down” the risk of fire for all manned exploration systems 3 What’s Different in Low-g and Exploration?
¨ Material Flammability Screening ● NASA STD-6001 Test 1: Upward Flame Spread Test ● Test is conducted at the worst-case atmospheric conditions in which the material will be used
• This has historically been 30% O2, 10.2 psia (shuttle pre-EVA atm)
• Future exploration atmospheres extend to 34% O2, 8.2 psia • A material fails the test if it burns more than 15 cm (6 inches).
Sample failing NASA Test 1
6” Gravity
4 Air Flow is very Important to a Flame
Buoyant or Forced Flow Direction
¨ What does increasing flow do? ● Brings in oxygen ● Removes heat faster ● Reduces time for chemical reactions and heating ● Makes flame closer to the surface (fuel)
Opposed Concurrent Opposed Concurrent Normal Gravity (Buoyancy) Microgravity
5 Material Flammability Maps
Typical Flammability Boundary for a Solid Fuel ¨ Material flammability depends on the ambient flow 0.23 ¨ In 1-g, the flame determines the flow by buoyancy (natural convection) … 0.22 1-g … but the material can burn just fine with a 0.21 ------lower flow and at a lower oxygen buoyant 0.20 flow limit concentration Flammable
¨ The 1-g flammability limit can be determined 0.19 by NASA-STD-6001 Test 1 0.18 ¨ No flow (quiescence) is least flammable but 0.17 the crew needs fresh air to breathe Oxygen Fraction ------
Ø Environmental control and life support flows 0.16 are around 15-20 cm/s Not Flammable ● Right around the conditions where 0.15 materials can still burn
1 100
Flow speed (cm/s) 6 A Lot of Other Low-Gravity Implications!
¨ Where there’s fire, there’s not necessarily smoke.
Candle flame in normal (left) and low-gravity (middle). The low- Cloud of condensed wax g flame emits vapor after extinction of little, if any smoke. low-g flame
¨ When it’s out, the hazard isn’t necessarily gone.
7 A Lot of Other Low-Gravity Implications!
¨ Flames can spread preferentially upstream – Into the incoming fresh air ¨ Ejecta from a melting solid (or firebrands) don’t settle and can travel farther in low-g ¨ Detection of aerosol or gaseous fire signatures depends on ventilation … which also aids flame spread Flame spreads preferentially upstream, opposite that Low-gravity in 1g. Paper is centrally ignited in low-speed opposed- air flows (1 and 2 cm/s).
PMMA Ejection of burning material
Normal-gravity 8 Ambient conditions depend on mission objectives
¨ The Exploration Atmospheres Working Group convened in 2004 and 2012 to provide recommendations for the cabin atmosphere for exploration vehicles
100 Shuttle/Mir/ISS ¨ Selection attempts to balance 14 Normoxic Equivalent competing effects of 90 Hypoxic Boundary flammability, decompression 12 sickness, and hypoxia 80 Historical Designs ¨ Long-distance transport 70 Shuttle-EVA 10
would favor standard 60 atmosphere conditions 8 50 • Known impact on crew and Early Apollo Design 6 equipment 40 Decompression sickness on EVA Skylab Mercury/Gemini/Apollo Total Pressure, kPa Pressure, Total ¨ Surface operations with 30 psia Pressure, Total 4 frequent EVA would favor 20 higher %O2 and hypoxic Flammability PMMA 2 10 operation Hypoxia
• Trade crew performance 0 0 against time for pre-breathe 0 10 20 30 40 50 60 70 80 90 100
Volume Percent Oxygen 9 What does NASA do to prevent/respond to fires?
¨ Material Flammability – NASA-STD-6001: Flammability, Odor, Offgassing, and Sample failing Compatibility Requirements and Test Procedures for NASA Test 1 Materials in Environments that Support Combustion • Test 1: Upward Flame Spread Test – Materials that fail Test 1 must undergo additional testing and/or configuration control as defined by NASA Materials and Processes personnel FGB SD ¨ Minimize ignition sources US CO2 fire – To the extent possible, designs attempt to minimize sources of extinguisher ignition ¨ Fire Detection
– On ISS, smoke detectors are positioned near air return vents US SD – FGB and SM smoke detectors use different technology (ionization) than US smoke detector (photoelectric) ¨ ISS Fire Extinguishers
– US: gaseous CO2, Fine water mist Engineering SM SD Engineering Development – RS: Water-based foam Development Unit of Unit of an ISS FWM PFE an Orion FWM PFE 10 Large-Scale Fire Demonstration
Examples of Terrestrial Large-Scale Fire Experiments ¨ We can conduct ground tests to assess many of these technologies but the data needs to be anchored using low-g data obtained at relevant length and time scales ¨ Testing requires:
– Low-g FAA full-scale aircraft test NIST full-scale fire test – Large scale – Relevant range of conditions including reduced pressure and elevated oxygen – Large volume Ex-USS Shadwell Submarine Fire Facility Naval Research Laboratory Ø We proposed and developed the concept of conducting a large-scale fire on an ISS resupply vehicle after it left the ISS.
Coal dust test explosion 11 Saffire-I, II, & III Overview
Fans Needs: ¨ Low-g flammability limits for spacecraft materials
¨ Definition of realistic fires for exploration vehicles Power ‒ Fate of a large-scale spacecraft fire Management Sample card (flame spread Objectives: sample shown)
¨ Saffire-I: Assess flame spread of large-scale Cameras microgravity fire (spread rate, mass consumption, heat release) Flow Duct ¨ Saffire-II: Verify oxygen flammability limits in low Avionics Bay gravity Signal ¨ Saffire-III: Same as Saffire-I but at different flow conditioning card conditions. Flow straightener • Data obtained from the experiment will be used to validate modeling of spacecraft fire response scenarios Saffire module consists of a flow duct containing the • Evaluate NASA’s normal-gravity material flammability sample card and an avionics bay. All power, computer, screening test for low-gravity conditions. and data acquisition modules are contained in the bay. Dimensions are approximately 53- by 90- by 133-cm 12 Sample Card Holder Configurations
Ø Sample card and samples are the only differences between the three flight units
Saffire-II Sample Card Saffire-I, -III Sample Card Saffire-II Samples (5 cm x 29 cm) Composite fabric (SIBAL cloth) • PMMA (flat and structured) (75% cotton – 25% fiberglass by mass) • Silicone (3 thicknesses, different (0.4 m x 0.95 m) ignition direction) • SIBAL • Nomex (with PMMA ignition) 13 Operations Concept
Pre-Launch
Unpowered Inhibits Open
Powered Inhibits Closed
Hawaii WGS 14 Saffire Operations
Launch Launch Mission Integration Launch Mission Ops Site Vehicle Saffire-I OA-6 KSC Atlas Jan 25, 2016 Mar 22, 2016 June 14, 2016 Saffire-II OA-5 WFF Antares May 12, 2016 Oct 17, 2016 Nov 21, 2016 Saffire-III OA-7 KSC Atlas Feb 3, 2017 Mar 27, 2017 June 4, 2017
¨ Operations received considerable coverage on Above: Saffire-II Mission Support Teams at NASA- social media GRC; Left: Saffire-II Flight Operations Team at Mission Control Dulles (backroom data assessment); Far Left: • NASA GRC and AES Saffire and Orbital ATK Flight Operations Teams at Mission Control-Dulles 15 Saffire-III Operations Concurrent Flow Igniter
Ø Images were taken 20 sec after ignition Ø Both samples are 40 cm wide ¨ Two of the most important factors for crew safety during on-board fires are: 1. How bad can the cabin conditions get during a fire? 2. How quickly can they get bad? ¨ Fire is only the beginning – combustion products Flow (smoke, CO, acid gases, …) (25 cm/s) also contribute to the hazard
Gravity
Still image of the Saffire-I material burning in Image of the Saffire-III concurrent (upstream) burn. normal gravity. 16 Saffire-I and III Results
Saffire-I (20 cm/s) Saffire-III (25 cm/s) ¨ Left: Sequence of concurrent flame images from Saffire-I and III. • Each image is 40-sec apart. • Saffire-I burned for 400 sec • Saffire-III burned for 320 sec Ø The flame speed is proportional to the air flow velocity ¨ Below: Comparison of the opposed (upper) and concurrent (lower) flames from Saffire-III. • The flame images were taken at different times (near the end of each burn) and superimposed.
25 cm/s 17 Saffire-II Summary
¨ Samples 1-4: Silicone sheets of varying thickness (0.25 mm, 0.61 mm, 1.03 mm, 0.36 mm respectively) – Samples ignited but flame did not propagate ¨ Samples 5-6: SIBAL cloth (20 cm/s and 25 cm/s - same as Saffire-I and III) – Burned to completion ¨ Sample 7: Nomex with PMMA igniter (1 mm thick PMMA) – PMMA burned ; flame did not propagate into Nomex ¨ Sample 8-9: Structured and Flat PMMA (10 mm thick) – Burned for the entire duration (6; 12 min); extinguished Flow when flow ceased 3 6 9
2 5 8
Composite picture of samples 1-9 at end of experiment. 1 4 7 Streaks are soot from Samples 7-9 deposited on card. 18 Saffire-I-III Results
Measurements of flame base, pyrolysis tip, and pyrolysis Spread rate summary for Cotton/Fiberglass fabric length from concurrent and opposed burns from Saffire-I. burning in microgravity The flame base is the most upstream portion of the flame and is bright and well-defined. The pyrolysis tip is the most downstream portion of the blackened (charred) fuel. The fuel was a 40.6-cm- wide cotton-fiberglass fabric. Air flow speed was 20 cm/s. 19 Summary of Saffire Results…So Far!
Saffire-I & III • Flame reaches a limiting length in forced convective concurrent flow even for very wide sample – Implies a steady spread rate and a limiting heat release rate – A fire on a spacecraft vehicle may reach a steady size (?) • Concurrent flame spread is proportional to the flow velocity • Concurrent flame spread rate was much slower than expected from previous space experiments – 65% less than observed in Burning and Suppression of Solids experiment on ISS – What is the impact of slower growth on release of combustion products? On fire detection? How does this depend on flow velocity? • Proximity to and interaction with side walls appears to impact the flame more than expected – Needs to be better understood through computational models; Review results of previous microgravity experiments • Opposed flames spread at about the same rate as concurrent flames – How does this depend on flow velocity? – Are concurrent flames always the worst case for microgravity fires? • We need to make a bigger fire to impact the vehicle
20 Summary of Saffire Results…So Far!
Saffire-II • Materials that burned all had slower spread rates than expected – Composite fabric, PMMA • Flame spread rates on composite fabric were similar to those seen in Saffire-I – Rapidly reached a steady spread rate and a limiting heat release rate • Examining material flammability limits in microgravity using a limited number of experiments is difficult – Repeat cases are required to understand the competing phenomena
21 Saffire-IV, V, and VI Summary
Needs: Saffire Flow Unit ¨ Demonstrate spacecraft fire monitoring and Approx. 53x90x133cm. New features include 2 side view cleanup technologies in a realistic spacecraft fire cameras, acid gas, O2, heat and scenario byproduct release to cabin
¨ Characterize fire growth in high O2, low pressure atmospheres ¨ Provide data to validate models of realistic spacecraft fire scenarios Objectives: ¨ Saffire-IV: Assess flame spread of large-scale microgravity fire (spread rate, mass consumption, heat release) in exploration atmosphere
¨ Saffire-V: Evaluate fire behavior on realistic Remote Sensors (6)
geometries Measure temp & CO2 in standoffs, ¨ Saffire-VI: Assess existing material hatch and end cone configuration control guidelines ¨ All flights will demonstrate fire monitoring Far Field Diagnostics (in Mid Deck Locker) and response technology Avionics, CO2 scrubber, Smoke Eater, Combustion Products Monitor, particulate monitors (DustTrack & Ion Chamber) 22 Saffire-IV, V, and VI Experiment Concept
¨ Concept consists of three distinct Far Field Saffire hardware locations Diagnostics (FFD) Flow Unit (SFU) • Saffire flow unit • Far-field diagnostic • Distributed sensors
¨ Far-field diagnostic module • Combustion product monitor
• CO and CO2 sensors • Post-fire cleanup module
¨ Distributed sensor network • Temperature
• CO2 Remote Sensors (RS) [6 total, 2 end cones, 4 central]
23 Expected Results of the Saffire-IV, V, and VI Experiments
¨ Flammability in normal and exploration atmospheres • Traceability to Saffire-I, II, and III ¨ Oxygen calorimetry for a large-scale microgravity fire • Rate of heat release for fire scenario modeling ¨ Rate of change of cabin pressure and temperature during a large-scale fire
¨ Transport and mixing of an inert gas (CO2) • Fire detection • Fire scenario modeling
¨ Demonstration of advanced combustion product monitor to quantify CO, CO2, and acid gases (HF, HCl) ¨ Transport/decay of acid gases in a post-fire environment
¨ Demonstration of advanced sorbents for cleanup of CO and CO2 • Sizing of smoke-eater for exploration applications
24 Other Considerations for Exploration
¨ Dormancy • Many of the mission scenarios include vehicles that are uncrewed and in a dormant state for extended periods of time. • Dormancy impacts protocols for detection, suppression and cleanup – Dormancy before crew arrives – Dormancy between crew visits
¨ Partial Gravity • Habitats on a anticipated planets, moons, or asteroids will have buoyant convection but at a smaller flow velocity than Earth • There are limited facilities on Earth in which we can conduct partial-gravity flame spread tests
Ferkul, P.V. and Olson, S.L., “Zero-gravity Centrifuge Used for the Evaluation of material Flammability in Lunar-Gravity,” AIAA 2010-6260, 40th International Conference on Environmental Systems, Barcelona, Spain, July 11-15, 2010. 25 Fire Safety Strategy Depends On Vehicle State During Dormancy
¨ Is there ECLSS ventilation? ‒ Pro: can use ventilation for fire detection ‒ Con: first response is to terminate ventilation after a fire alarm ‒ Impact: When can ventilation be re-initiated? ¨ What is the atmospheric composition?
• Lower O2 mole fraction (<15%), lower P, T reduces fire risk - periodic monitoring • Maintaining habitable environment requires continuous monitoring ‒ Pro: can make the atmosphere unable to support combustion
‒ Con: must increase O2 mole fraction before crew returns
‒ Impact: Does increasing O2 for a “short” time increase risk significantly? ¨ What systems are powered during dormancy? ‒ Pro: can monitor system state for abnormal current draw; terminate power if an electrical short is detected ‒ Con: powered systems are the most likely ignition source ‒ Impact: When can power be restored?
26 Fire Safety Strategy Depends On Vehicle State During Dormancy
¨ Is there gravity? ‒ Pro: In microgravity, termination of ventilation and power will most likely be effective for fire suppression ‒ Con: In a gravity field, propagation of fire is uncertain even if ventilation and power is removed ‒ Impact: When can power and ventilation be re-initiated? ¨ If a fire is detected, at what point do you initiate an active response? ‒ How do you confirm that any passive responses were not effective? • Monitoring is effective but takes time • Visual confirmation of the vehicle state would be effective ‒ Pro: An active response can assuredly extinguish a fire ‒ Con: (1) An active response changes the state of the vehicle (2) Active response during dormancy requires a fixed fire suppression system; mass, risk of failure (on or off) ‒ Impact: Clean-up of the suppression agent. When can power and ventilation be re-initiated?
27 Summary
¨ Low- and partial-gravity impacts many areas of the combustion process and, therefore, spacecraft fire safety ¨ Mission scenarios play a major role in determining the fire hazard… … and fire safety is never the driving factor! ¨ The Saffire missions were developed to investigate many of the knowledge gaps in spacecraft fire safety • Saffire-I-III primarily investigated flame spread and material flammability limits ¨ Future Saffire missions will investigate advanced material flammability questions as well as fire/vehicle interactions • Missions will also demonstrate technologies needed to protect the spacecraft and crew ¨ Periods of spacecraft or habitat dormancy pose unique hazards for fire safety • Primarily operational issues rather than new technology development • Need to have data in hand so that the operational environment and configuration can be appropriately analyzed
28 Future In-Space Operations Colloquium
SKYLAB II B Griffin Making a Deep Space Habitat from a Space Launch System Propellant Tank
March 27, 2013
Brand Griffin
“Skylab II, Making a Deep Space Habitat from a Space Launch System Propellant Tank,” B. Griffin, D. Smitherman, K. Kennedy, L. Toups, T. Gill, and S. Howe, AIAA Space 2012 Conference, Pasadena, CA, September 11-13, 2012, AIAA 2012-5207 1 Habitat for Humans Beyond LEO
B Griffin
Deep Space Habitat Crew of 4 Three 60 day missions L4 Grow to 180 day missions
EM L2 Moon
L1 L3 ES L2 (Telescopes) Earth
Different than ISS No rapid return Costly, infrequent reupply L5 More Hab than ISS Lab
Skylab II Deep Space Habitat from an SLS Propellant Tank 2 2 Skylab moved astronauts out of the couch
B Griffin
• Post Apollo (used Apollo assets) • Launch mass 77,088 kg (169,950 lb) • First US Space Station • “Dry” Workshop (3rd stage propellant tank) • 1973 Saturn V launch (fully provisioned) • Included telescope, airlock and docking • Occupied by 3 crews, 3 astronauts each adaptor • Crew duration: 28, 59 and 84 days • LEO ~ 440 km altitude, 50° inclination • Last crew 1974, re-entered 1979
Airlock Module Orbital Work Shop
Multiple Docking Adaptor
Apollo Telescope Mount
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 3 Heavy Lift, Large Diameter, Single Launch B Griffin
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 4 SLS Upper Stage H2 Tank B Griffin
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 5 ISS-Derived Deep Space Habitat
B Griffin
ISS Derived Deep Space Habitat ISS Multi Purpose ISS Node 1 Logistics Module
4.5 m (14.8 ft.)
ISS Derived DSH NASA, JSC
ISS Derived DSH Boeing 8.5 m SLS (27.6 ft.) LH2 Tank
ISS Derived DSH NASA, MSFC
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 6 DDT&E Complete, Existing Manufacturing B Griffin
Person shows scale of the H2 Tank SLS based on External Tank
Common End Domes Common Barrel Section
DSH would use the same SLS Facility and Personnel
External Tank SLS Family
Flight Experience-135 Launches
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 7 Common Sense Commonality B Griffin
ISS MPCV SLS Other First Element Launch 24 years ago Russian, European, Canadian, Japanese, AR&D Etc.
Technology over 30 yrs old by Cis-lunar launch
Example-Mgt. Decree Narrow Wide Assessment-by-subsystem Body Body •Structures What is the relevance of hardware and software to cis-lunar mission? •Mechanisms What does is take to make ground assets flight ready? •ECLSS Are the drawings and specs available? •Communication What re-verification/certification is required? •Guidance Nav. and Control Access to original suppliers, integrators, and fabrication techniques? •Software What is the lead time and process for procurement? •Data management What are the cost/benefits? How are the lessons learned incorporated into the cis-lunar Habitat •Crew Systems 757 767 •EVA Same Cockpits (Same type-rating for pilots) 03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 8 Volume Comparison B Griffin Crew Volume per Duration 900
837 1/3 Vol. Subsystems 800
1/2 Vol. Subsystems 700
600 Over Twice Minimum Volume Volume 500 495 (m3)
400 360 Skylab II 340 300
200 US Lab Flown Missions 106 106 Reference Study 100 46-62 3 6 6 4 4 DSH Options 4 84 180 180 500 500 180 crew days Skylab ISS Transhab SLS ISS Derived Previous H2 Tank 500 day Study 03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 9 More than Habitable Volume B Griffin
Skylab ISS USLab (Destiny) (Good Accessibility) (Cluttered, Difficult Access)
10
Volume to flight test AMU Additional DSH volume allows: • Subsystems designed for servicing • Improved access to utilities • Improved access to stowage • Offload Logistics Module to free up port • Margin for trash
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 10 Mass, Outfitting and Cabin Pressure B Griffin
LH2 Tank Weighs Outfitting Weighs Accommodates less than 2 SUVs less than LH2 Propellant All Cabin Pressures
Sport Utility Vehicle 2631 kg (5800 lb)
ISS-Derived SLS Cis-Lunar Hab LH2 w/consumables* LH2 Tank
Outfitting LH2 4200 kg 5262 kg 11,400 kg 33,100 kg (9,240 lb) (11,600 lb) (25,200 lb) (72,960 lb)
• Three 60 day missions using the Deep Space Habitat Based on ISS Systems, Advanced Exploration Systems, NASA, MSFC, February 14, 2013
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 11 External Equipment and Airlock
B Griffin
Saturn V
Instrument Ring External Hardware Deployable Systems
Skylab II
EVA Options
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 12 Habitat Configuration B Griffin
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 13 Incentive for Fewest Launches
B Griffin
$1.5 B to $435-500 M Assembly Cmplt Additional Skylab Single Launch Space Station
ISS 10 yrs 115 flights
* Delta 4 Heavy launches cost $435 million each (calculated from an Air Force contract of $1.74 billion for 4 launches)
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 14 Launch Cost Savings B Griffin 5 Fewer Launches or Approximately $2.175 Billion Savings
Previous Cis-lunar Study TOTAL Skylab II TOTAL
Year SLS Com/Log ELV/Log SLS Com/Log ELV/Log
2019 Node 1 Skylab II
2020 MPCV X MPCV
2021 MPCV X X MPCV
2022 MPCV X X MPCV Number 4 3 2 9 4 4 COST $M 20001 13052 8702 4175 2000 2000
2023 MPLM X MPCV X
2024 MPCV X MPCV X
1 Assume $500M per launch ($65M more than Delta IV Heavy) 2 Delta IV Heavy launches cost $435 million each (calculated from an Air Force contract of $1.74 billion for 4 launches)
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 15 Number of Elements B Griffin
10 Fewer Elements over first 4 years (Does not include MPLM)
Previous Cis-lunar Study TOTAL Skylab II TOTAL Year Node MPCV Bus Log MPLM Skylab MPCV Bus Log MPLM 1 Mod II Mod 2019 X X X X
2020 X XX X X X
2021 X XXX XX X X
2022 X XXX XX X X # 1 3 9 5 18 1 3 4 8
2023 X XXX X X 6 X XX X 4
Possible SLS-Derived Log Mod
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 16 Skylab Built During Budget Decline B Griffin NASA Administrator announces Dry Workshop (Skylab) Skylab Launched
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 17 Why Low Cost
B Griffin
SLS Class Missions
$
$
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 18 Funding Profile
(Representational) B Griffin
Previous Cis-lunar Study
Skylab II Lower Peak Cost •Fewer Elements Later Peak Cost •Fewer Buses Later Logistics Module •Fewer Launches Fewer Elements •Fewer Interfaces Lower Recurring Cost •Fewer Logistics Modules Fewer Elements
Lower Initial Cost •Fewer Elements •No DDT&E for tank •No Logistics Module
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 19 Fly Now, Upgrade Later Approach to Space Observatories B Griffin
Human Servicing at EML2
Low energy transit
• Similar to Hubble • ES L2 popular observatory site • Reduces initial cost • Very low delta v between EM L2 and ES L2 (~ 20 m/s) • Minimizes development schedule • No upper stage to transit between L2s (RCS) • Allows low TRL instruments later • Establish servicing capability at E-M L2
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 20 Lunar Science & Satellite Servicing B Griffin
Solar Arrays
MPCV
SLS Propellant Tank Deep Space Habitat
Radiators
Assembly, repair and servicing (Tool crib, propellant transfer)
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 21 Jumbo Logistics Vehicle
B Griffin
SLS-Derived Logistics Module Skylab II DSH
Logistics Module
Comparison-Resupply Options
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 22 Summary B Griffin
• Single Launch for 3 missions (no resupply for 4 years) • Large light weight pressure vessel • No design changes for SLS launch loads • Accommodates all cabin pressure options • Volume (exceeds habitable requirement, allows for stowage and maintenance) • Multiple vehicles over time (Mars transit Hab, LEO, Asteroid, etc.) • Early and Sustained Occupancy (no additional elements for 180 day stay) • Low Cost (and risk) • 5 Fewer Launches • 10 Fewer Elements • Fewer Interfaces • Avoid DDT&E for Tank • Manufacturing facility and labor in place (no unique procurement or tooling) • Commonality with SLS launch system • Jumbo Logistics Vehicle Option (DHS and ISS)
03/27/2013 Skylab II Deep Space Habitat from an SLS Propellant Tank 23 SLS Derived Vertical Habitat
Dr. Robert Howard NASA Johnson Space Center Habitability Design Center
FISO Telecon October 22, 2014
1 This presentation represents work conducted by the Habitability Design Center in support of the former AES Deep Space Habitat Project
2 Habitat Design Problem
• Cannot take a habitat designed for microgravity and use it in a planetary environment • Cannot take a habitat designed for planetary environments and use it in microgravity • Cannot afford to set up distinct habitat project offices for each destination: – Lunar Surface, Mars Surface, NEA Transit, Mars Transit, Cislunar, Captured Asteroid, Martian Moons • Is it possible to consider all environments upfront and design a habitat applicable to all destinations?
3 Proposed Skylab II
• Concept one of several based on use of an Space Launch System (SLS) propellant tank as a habitat – Similar to Skylab use of Saturn V S-IVB stage – Additional SLS upper stage hydrogen tank manufactured, but instead of filling with fuel is outfitted as habitat – 495 m3 – Launched as payload inside shroud 4 Original Skylab II Configuration
• MSFC proposed application designed exclusively for microgravity – Excellent use of volume in microgravity but problematic to use in planetary environment – Alternate configurations can make different use of same volume • Note: Additional MSFC Skylab II habitats have since been developed
for Mars surface 5 Proposed Skylab II Configuration
• JSC Habitability Design Center 38 ‘ explored alternative concept – Vertical orientation – Four decks – Four lateral docking ports – One dorsal docking port – Interior designed for multi-destination use 27 ‘ 6 Proposed Skylab II Configuration
• Cutaway View
Deck 3
Deck 2
Deck 1
Deck 0
7 Proposed Skylab II Configuration
• Deck 0
– Lower dome – Cannot use as normal Subsystems deck in gravity environment – VIS allow exercise to fit within height of deck 1 • With no VIS, exercise lowers into Deck 0 – Crawlspace allows access to all subsystems – Vertical translation enables removal of Subsystems failed hardware for servicing 8 Proposed Skylab II Configuration
DOCKING • Deck 1 PORT – Primary working deck – Note large maintenance and fabrication volume
DOCKING PORT
– Crew seats in gravity; hand and foot restraints in microgravity 9 DOCKING PORT Proposed Skylab II Configuration
– Primary private volumes • Deck 2
– Rapid access to medical from other decks
10 Proposed Skylab II Configuration
– Operations and group • Deck 3 social volumes
11 Proposed Skylab II Configuration
• Cutaway View
Deck 3
Deck 2
Deck 1
Deck 0
12 Teleoperations Workstation Detail
• Only notionally represented in CAD model • Important considerations – How many robots will be controlled at any given time? – What type of robots will be controlled from this station? (ATHLETE, RMS, Robonaut, etc.) – Will there be different types of robots controlled at the same time? (e.g. Robonaut on the end of 13 an RMS mounted on an ATHLETE) Teleoperations Workstation Detail
• Some lessons learned from NASA HDU DRATS incorporated to develop basic specifications – Six monitors available for crew display – Keyboard and mouse – Accommodate at least one RHC and THC – Accommodate experimental control interface devices (e.g. VR helmets, Kinnect sensors, Wii devices, sensor gloves, body-worn sensors, and video glasses)
14 Conclusions
• Providing additional effort in the design phase can enable accommodation of multiple gravity environments – Vertical and horizontal surfaces – Access volumes – Common solutions vs. interchangeable components (especially with respect to crew and equipment restraints) – Minimize effort to outfit for planetary vs. microgravity applications
15 Conclusions
• Accept inefficiencies – Not necessarily the “best” thing to have minimum mass, minimum function • Can be penny-wise but pound-foolish – Accommodating multiple gravity environments creates packaging or layout inefficiencies • Forced horizontal orientation for crew bunks • Subsystems and utility runs – Tradeoff is condensing multiple program offices, multiple prime contracts, multiple manufacturing centers into single organization 16 Conclusions
• Ideal volume unlikely to be achieved whether considering for multiple or single gravitational environment – Skylab, ISS, Shuttle, Orion, Apollo spacecraft volumes all impacted by factors unrelated to habitation – SLS upper stage hydrogen tank is a fixed volume (unless modify production line) – Design within volume given for solution that satisfies all mission environments
17