Human Spaceflight Graduate Project
Midterm Report For the Crewed and Uncrewed Semi-autonomous Habitat for the Exploration of Deep Space (CU SHEDS)
In Support of
HOME and the NASA Exploration Program
Document Number: CU BIOASTRO 2021-Spring-007
March 18, 2021
This Document is for Educational Purposes Only
Prepared for: University of Colorado 3100 Marine St, 572 UCB Boulder CO 80309
Bioastronautics Group Department of Aerospace Engineering Sciences College of Engineering and Applied Science University of Colorado 3775 Discovery Drive Boulder Colorado 80303
1 REVISIONS ISSUE DESCRIPTION DATE BY Notes / Major Changes 1.0 Initial Issue March 18, 2021 Rydell Stottlemyer, Colin Claytor, Kaitlyn Olson, Conner McLeod, Sam Schrup,
Alex Liem, Marta Stepanyuk, Aaron Stirk, Neil Banerjee
2 Table of Contents 1. INTRODUCTION...... 5 2. PROJECT OVERVIEW ...... 5 2.0 SCOPE ...... 5 2.1 INDUSTRY PARTNER INFORMATION ...... 5 3. STATEMENT OF WORK AND REQUIREMENTS INFO ...... 6 3.0 GROUND RULES ...... 6 3.1 ASSUMPTIONS ...... 6 3.2 TASKS AND DELIVERABLES ...... 6 3.3 REQUIREMENTS ...... 8 4. WORK BREAKDOWN STRUCTURE ...... 8 4.0 ORGANIZATIONAL CHART ...... 10 4.1 DETAILED SCHEDULE ...... 13 5. BUDGET ...... 14 6. SAFETY PLAN AND RISK MANAGEMENT ...... 14 6.0 TEAM SAFETY ...... 14 6.1 HUMAN FACTORS AND MOCKUP SAFETY ...... 14 6.1.0 Emergency Procedures...... 15 6.2 RISK MANAGEMENT ...... 15 7. CONCEPTUAL DEEP SPACE HABITAT DESIGN ...... 17 7.0 OVERALL LAYOUT AND DESIGN ...... 17 7.1 SUBSYSTEM BREAKDOWN ...... 20 7.1.0 Structures / Mechanisms ...... 20 7.1.1 ECLSS...... 22 7.1.2 Avionics and ADCS ...... 38 7.1.3 Power ...... 40 7.1.4 Thermal ...... 41 7.1.5 Communications ...... 42 7.1.6 Crew Accommodations ...... 43 7.1.7 Robotics ...... 46 7.1.8 EVA ...... 47 7.1.9 Propulsion ...... 48 7.2 CONCEPTUAL DESIGN STATUS UPDATE ...... 49 7.2.0 Work Completed ...... 49 7.2.1 Work Remaining ...... 50 7.2.2 Integration Plan ...... 50 8. MOCKUP MODIFICATION ...... 50 8.0 PREPARATION AND RELOCATION ...... 50 8.1 DOCKING PORT AND EVA HATCH ...... 51 8.2 OBSERVATION WINDOW ...... 52 3 8.3 CREW AND EVA ACCOMMODATIONS ...... 53 8.4 ROBOTICS WORKSTATION ...... 54 8.5 GENERAL REFURBISHMENT ...... 54 8.6 FINAL INTEGRATION, PRE-TEST PREPARATION, AND “BETTER/NICER” TASKS ...... 55 9. HUMAN FACTORS TESTING ...... 55 9.0 PROGRESS TO DATE ...... 55 9.1 TEST GOALS AND EVALUATIONS ...... 56 9.2 TEST PROCEDURE SUMMARY ...... 56 9.3 TEST SUBJECT RECRUITMENT PLAN ...... 57 9.4 TEST DATA ANALYSIS PLAN ...... 58 9.5 FUTURE WORK ...... 60 10. OVERALL STATUS UPDATE ...... 60 10.0 TASK AND DELIVERABLE STATUS ...... 60 10.1 HOURS WORKED ...... 60 10.2 SPENDING SUMMARY ...... 60 10.3 ISSUES AND CONCERNS ...... 61 11. REFERENCES ...... 62 12. ACRONYMS AND ABBREVIATIONS ...... 66 13. APPENDIX A – MASS, POWER, AND VOLUME ESTIMATES ...... 68 14. APPENDIX B – TRADE STUDIES ...... 71 14.0 RADIATION PROTECTION ...... 71 14.1 BRINE PROCESSING ...... 71 14.2 POWER ...... 72 14.3 PROPULSION ...... 73 14.4 ADCS ...... 74 14.5 THERMAL ...... 74 15. APPENDIX C – MASTER EQUIPMENT LIST ...... 76
4 1. Introduction The Spring 2021 Human Spaceflight Graduate Projects Team (CU SHEDS) has been tasked with designing a Deep Space Habitat (DSH). This project will be supporting Habitats Optimized for Missions of Exploration (HOME) Space Technology Research Institute (STRI) which is funded through NASA. The scope of the HOME Team’s research is focused on two overarching operational requirements of a deep space habitat: (1) Keep humans alive while they are resident, and (2) Keep the vehicle alive while they are not. The CU SHEDS team will design a deep space habitat that can be utilized for a variety of long-duration missions and meets these criteria. This will be achieved in part by designing the vehicle to be ‘self-aware’ and ‘self-sufficient’. In addition to designing this habitat, the CU sheds team will modify the mockup created by the Fall 2020 Graduate Projects team to serve as an airlock / robotics / logistics module of the DSH. Human factors testing will be performed on this module to evaluate the adequacy and functionality of this portion of the design. This Midterm Report document is designed to summarize the work that has been performed so far, and to describe the plan for the remainder of the work to be performed this semester.
2. Project Overview
2.0 Scope The scope of work for the project this semester consists of three parts: designing a multi- module deep space habitat for long duration missions, modifying the existing mockup to serve as one of the modules of the deep space habitat, and performing human factors testing to evaluate the adequacy of the mockup design. The primary tasks are derived from the Statement of Work and are listed below. 1. Conduct a Kickoff Meeting with BIOASTRO management and the BIOASTRO HOME Team researchers to refine work to be completed in support of the Deep Space Habitat and mock up design. Agree on scope of work to be performed. 2. Conduct Technical Interchange Meetings (TIM) with BIOASTRO HOME Team researchers to verify the concept for the HOME mock up to support future research needs and human factors evaluations. 3. Complete systems engineering documents in support of the Deep Space Habitat design. 4. Complete design of a Deep Space Habitat. 5. Complete work to repurpose the existing TALOS mock up. 6. Complete limited human factors evaluations of the HOME mock up. 7. Prepare and conduct additional meetings and reviews of program progress, readiness, and status.
2.1 Industry Partner Information This project will be supporting Habitats Optimized for Missions of Exploration (HOME) Space Technology Research Institute (STRI). The HOME project is a multi- university endeavor which is funded through NASA. The HOME team at CU Boulder consists of four professors: James Nabity, Torin Clark, Allison Anderson, and David Klaus. Dr. Allison Anderson will serve as the primary point of contact for the HOME that the CU SHEDS team will interface with. Funding for this project is provided through the HOME team via Dr. David Klaus’s Marlar fund.
5 3. Statement of Work and Requirements Info
3.0 Ground Rules The Graduate Project Team HOME habitat design shall conform to these specific ground rules: 1. The habitat will reside and operate in deep space. 2. The habitat will provide a minimum of 100m3 of habitable volume for the crew. 3. The habitat design will provide all support required for the HOME mission using a crew of 4 astronauts. 4. The habitat will have a 15 year lifetime. 5. The habitat will be launched on the SLS. 6. The dry mass of the habitat will not exceed 21t. 7. The habitat will accommodate autonomous operations and robotic interfaces. 8. The habitat design will use the standards outlined in the NASA Space Flight Human- System Standard Volume 2: Human Factors, Habitability, and Environmental Health document as general guidance. 9. The habitat will be occupied no more than 15% of its lifetime.
The Graduate Project Team HOME mockup shall conform to these specific ground rules: 1. The CU SHEDS mockup design will have a structural support system to accommodate 4 crew and 4 trainers. 2. The Graduate Project Team will design for all mock-up structural analyses to have a minimum factor of safety of 2. 3. The CU SHEDS mockup will provide systems interfaces and representations to support human factors testing.
3.1 Assumptions The Graduate Project Team design will be based on the following assumptions: 1. The Orion capsule will be used to transport crew to and from the habitat. 2. The Orion capsule will remain docked with the habitat at all times during human occupation of the habitat. 3. NASA will provide advanced spacesuits that will be adequate to perform contingency EVAs.
3.2 Tasks and Deliverables Per the Statement of Work, the table below depicts the team’s overall schedule for the semester, including presentation and documentation milestones.
6 Table 1. Spring 2021 Schedule Format SDRL Delivery Title (Microsoft Date Due # Method Products) Review - Kickoff briefing with SOW review PowerPoint. Plan, Jan 26, S001 and delivery of Project Plan, Electronic Schedule, Budget 2021 Schedule, and Budget - Word Weekly status updates: prepare and conduct additional meetings and Briefing S002 PowerPoint Weekly reviews of program progress, Only readiness, and status Briefing Jan 28, S003 Technical Interchange Meeting OneNote Only 2021 Deep Space Habitat Systems Review – Feb 11, S004 Requirements Review and delivery PowerPoint Electronic 2021 of System Requirements Document Document - Word Deep Space Habitat Concept Review – Feb 25, S005 Definition Review and delivery of PowerPoint Electronic 2021 Concept Definition Document Document - Word Complete systems engineering Feb 25, S006 documents in support of the Deep Word Electronic 2021 Space Habitat design Human Factors Test Plan Review Review – March 4, S007 and Delivery of Human factors Test PowerPoint Electronic 2021 Plan Document - Word Deep Space Habitat Preliminary Review – March 11, S008 Design Review and delivery of PowerPoint Electronic 2021 Design Definition Document Document - Word Complete design of a Deep Space March 11, S009 PowerPoint, Word Electronic Habitat 2021 Review – Midterm Detailed Status Review March 18, S010 PowerPoint Electronic and delivery of Midterm Report 2021 Report - Word April 1, S011 Mock Up Safety Review PowerPoint Electronic 2021 Complete work to repurpose the April 1, S012 N/A N/A existing TALOS mock up 2021 Human Factors Test Readiness April 1, S013 PowerPoint Electronic Review 2021 Complete limited human factors April 23, S014 N/A N/A evaluations of the HOME mock up 2021 End of Semester Detailed Status Review – April 29, S015 Review and delivery of Final PowerPoint Electronic 2021 Report Report - Word
7 3.3 Requirements The methodology for deriving this semester’s requirements along with the requirements themselves for the CU SHEDS DSH, mockup, and human factors testing can be found in CU BIOASTRO-2021 Spring-007-Systems Requirements Document.
4. Work Breakdown Structure WBS Task Title Task Owner Number 1.0 Overall 1.1 Kickoff Briefing Rydell 1.2 Technical Interchange Meeting Rydell 1.3 Formulate Functional Requirements Kaitlyn 1.4 Derive Design Requirements Kaitlyn/Conner 1.5 Subteams Derive Design Requirements Subteam Leads 1.6 Review Requirements Kaitlyn/Subteam Leads 1.7 Deep Space Habitat System Requirements Review Rydell 1.8 Revise Requirements Kaitlyn 1.9 Formulate Subteam Schedules Colin 1.10 Assign Subteams Requirement Ownership Kaitlyn/Conner 1.11 Integrate Subteam Schedules Colin 1.12 Revise Subteam Schedules Colin/Subteam Leads 1.13 Subteams Formulate Design Concept Subteam Leads 1.14 Integrate Preliminary Design Concept Conner 1.15 Deep Space Habitat Concept Definition Review Rydell 1.16 Human Factors Test Plan Preparation Neil 1.17 Human Factors Test Plan Review Neil 1.18 Human Factors Test Plan Revisions Neil 1.19 Prepare Mock Up for Modification Alex 1.20 Design and Build Mock Up Alex 1.21 Final Integration and Human Factors Prep Alex 1.22 Deep Space Habitat Preliminary Design Review Conner 1.23 Midterm Detailed Status Review Rydell 1.24 Mock Up Safety Review Alex 1.25 Human Factors Test Procedure Preparation Neil 1.26 Human Factors Test Procedure Revisions Neil 1.27 Human Factors Beta Testing Neil 1.28 Human Factors Test Readiness Review Neil 1.29 Human Factors Testing Neil 1.30 Human Factors Data Analysis Neil 1.31 Final Presentation Prep Rydell 1.32 Complete Documentation Rydell/Colin 1.33 End of Semester Detailed Status Review Rydell 2.0 ECLSS 2.1 Formulate Subteam Schedule Sam 2.2 Develop System Design Requirements Sam 2.3 Review Subsystem Requirements Team 2.4 Formulate Design Concept Team 2.5 Integrate Preliminary Design Concept Team 2.6 CDR Team 2.7 Develop Crew and Robot Access Doctrine Sam 2.8 Smart Optimization HOME 2.9 Information to CNS Kaitlyn 2.10 Develop Modes of Operation HOME 2.11 Automated Resupply of solids Rydell 2.12 Automated Resupply of fluids Rydell
8 2.13 CO2 removal Sam 2.14 CO2 reduction Sam 2.15 O2 Storage Sam 2.16 N2 Storage Sam 2.17 OGA Sam 2.18 Pressure Regulation Sam 2.19 Gas Distribution Sam 2.20 Air Circulation Sam 2.21 Humidity Control Sam 2.22 Temperature Control Sam 2.23 Food Storage Marta 2.24 Food Preparation Marta 2.25 WMS (WC) Sam 2.26 Waste Collection Marta 2.27 Waste Storage Sam 2.28 Waste Recycling system Kaitlyn 2.29 Human Waste Recycling system Marta 2.30 Waste Disposal Rydell 2.31 Water Storage Sam 2.32 Water Distribution Sam 2.33 Wastewater Bus Sam 2.34 Water Purification Sam 2.35 TCC Kaitlyn 2.36 Particulate Filtration Kaitlyn 3.0 EVA/ Comm/ CA/ Robotics 3.1 Exercise Machine Conner 3.2 Personal Hygiene Conner 3.3 Sleep Accommodations Aaron 3.4 Leisure/Entertainment Aaron 3.5 Medical Supplies Marta 3.6 Food Preparation/Storage Marta 3.7 Trash Disposal Aaron 3.8 Other accommodations Conner 3.9 Earth to habitat comm Conner 3.10 Inter habitat comm Aaron 3.11 Between spacecraft comm Marta 3.12 xEMU storage Conner 3.13 Handrails and restraints Aaron 3.14 Tool storage Marta 3.15 Airlock and hatch placement Marta 3.16 Robotic workstation Team 3.17 Robotic Rails Team 3.18 Robotic Storage Team 3.19 Robotic integration Team 4.0 Human Factors 4.1 Schedule HF Briefing Neil 4.2 Write HF Test Plan Neil 4.3 Get HF Test Plan Feedback Neil 4.4 Iterate HF Test Plan Neil 4.5 Write HF Test Procedure Neil 4.6 Get HF Test Procedure Feedback Neil 4.7 Human Factors Test Plan Review Neil 4.8 Perform HF Testing Internal Dry Runs Neil 4.9 Perform HF Testing Beta Testing Neil 4.10 Human Factors Test Readiness Review Neil 4.11 Perform HF Testing of AERO/external Participants Neil 4.12 Analyze HF Test Data Neil 9 5.0 Mock Up 5.1 Clear items from under the mockup Alex (group effort) 5.2 Remove all items from inside the mockup Alex (group effort) 5.3 Temporarily remove interior electronics Alex (group effort) 5.4 Remove windows and walls around windows Alex (group effort) 5.5 Remove damaged wall sections needing replacement Alex (group effort) 5.6 Move mockup/platform assembly Alex (group effort) 5.7 Construct new staircase assembly Sam/Rydell 5.8 Design and build observation window Aaron/Sam 5.9 Create docking port/EVA hatch Aaron/Sam 5.10 Build crew accommodations Marta/Kaitlyn/Conner 5.11 Build EVA accommodations Marta/Kaitlyn/Conner 5.12 Add in wall sections that needed replacement Alex/Neil/Rydell 5.13 Reattach modified robotics station/interior electronics Colin/Conner 5.14 Final integration and pre-test preparation Alex/Neil 6.0 Power/ Thermal/ Propulsion/ Avionics 6.1 Establish Subteam Meetings Colin 6.2 Develop Design Requirements Colin 6.3 Conduct Literature Study Colin/Alex 6.4 Conduct Trade Studies Colin/Alex 6.5 Design Power System Colin 6.6 Design Thermal System Colin/Sam 6.7 Design Propulsion System Colin 6.8 Integrate Systems into Module Design Colin 6.9 Integrate Module into Habitat Design Colin 7.0 Structures/ Mechanisms 7.1 Review/Clarify Design Requirements Aaron 7.2 Develop First "Big Picture" Design Team 7.3 Create Updating Document of Subteam Space requirements Team 7.4 Design Space Allocation for EVA Hatch Aaron 7.5 Decide on Docking Methods for Module 1 & 2 (IDS) Sam/Alex 7.6 Working CAD Model for Design Aaron/Team 7.7 MLI Team 7.8 MMOD Team 7.9 Pressure Hull Team 7.10 Subteam Specialty Team 7.11 Internal Structure Team 7.12 PPE Docking Team 7.13 Radiation Team
4.0 Organizational Chart The work to be done this semester has been divided into two phases; Phase 1 encompasses the paper design of the habitat while Phase 2 includes the mockup modifications and human factors testing. As such, the organization of the CU SHEDS team differs based on the phase the project is in. In both phases, the Project Advisor and Senior Engineer is Colonel James Voss who represents the CU AES BIOASTRO Group. The senior manager position is filled by Rick Hieb, a scholar in residence at CU and former astronaut. The HOME team is included as a vital component of the team and is represented by the point of contact Dr. Allie Anderson. The manager of the CU SHEDS team is Rydell Stottlemyer. She is assisted by the deputy project manager, Colin Claytor. Reporting directly to the project manager are the financial manager, Marta Stepanyuk, who oversees the budget and purchasing for the team, and the safety lead, Neil Banerjee, who ensures all practices of the team are safe and spearheads
10 the COVID-19 response of the team. This management structure remains consistent in both Phase 1 and Phase 2. In Phase 1, the team is focused on the paper design of the habitat and is organized as shown in Figure 1 such that design subteams exist. In this structure, the systems engineer, Kaitlyn Olson, and the technical director, Conner McLeod, report directly to the project manager. The systems engineer oversees the documentation and requirements of the project. Assisting with these duties is Neil Banerjee. The technical director oversees the work of the individual subteams and assists with technical integration efforts. Reporting to the technical director are four subteams each in charge of different aspects of the paper design of the habitat. These four subteams include: structures and mechanisms, led by Aaron Stirk, ECLSS, led by Samuel Schrup, thermal, power, avionics, ADCS and propulsion, led by Colin Claytor, and EVA, CA, communication, and robotics led by Marta Stepanyuk.
Figure 1. Phase 1 Organization Chart
In Phase 2, the team is focused on the modification of the mockup and human factors testing. The team organization in Phase 2 is shown in Figure 2. In this structure, the systems engineer, Kaitlyn Olson, oversees these two aspects. The role of technical director is removed for this phase as the technical design work of the mockup has been completed. As such, the technical director from Phase 1 shifts into a systems engineering support role. The four subteams from Phase 1 are reorganized into two subteams in Phase 2: mockup and human factors. The mockup team, led by Alex Liem, is responsible for the building the physical mockup of the HOME habitat module. The human factors team, led by Neil Banerjee, develops the human factors testing goals and plan, as well as organizing test participants and conducting the planned tests.
11 Figure 2. Phase 2 Organization Chart
12 4.1 Detailed Schedule
5. Budget CU SHEDS have an approved budget of $4,000 and we have currently spent $647.28 of the budget, with most of the spending going towards mock up construction.
Table 2. CU SHEDS Budget ALLOCATED SPENT REMAINING MOCK-UP $3,033.18 $368.75 $2,664.43 SAFETY $275.50 $6.87 $268.63 HUMAN FACTORS $100.00 $0.00 $100.00 ADMINISTRATION $385.00 $271.66 $113.34 SUB TOTAL $3,793.68 MARGIN $206.32 TOTAL $4,000.00 $647.28 $3,146.40
6. Safety Plan and Risk Management
6.0 Team Safety The team has been tracking issue relating to its own health and safety, namely in relation to COVID-19. The safety lead has published explicit protocols for the team to follow regarding COVID-19 safety, including avoiding crowding in classrooms and the high bay, refraining from social gatherings, and scheduled weekly monitoring tests. These protocols were distributed
6.1 Human Factors and Mockup Safety Table 3 documents the risks associated with human factors testing and mockup construction. Table 3 Human Factors and Mockup Safety Risks Risks to Human Test Subject: Inherent Design Risks: • Exposure to COVID 19 • Structural failure of frame • Tripping inside CU SHEDS mockup • Structural failure of displays • Falling in or out of the hatch during • Structural failure of base ingress/egress • Electrical and fire hazards of • Collision with CU SHEDS mockup running power cords across the lab • Utilizing displays as a handhold • Sharp edges in and around the causing structural failure and mockup collapse of the displays • Falling while donning or doffing EVA suits • Fainting while wearing the EVA suit due to over-exertion and/or over- heating
14 To ensure the test participants and test conductors will be safe from COVID 19, the mockup will be cleaned prior to every testing session, masks will be worn, and social distancing guidelines will be followed. To mitigate the risks due to human error, the lab space will be carefully cleaned and inspected for hazards prior to the commencement of testing. The test participants will be provided a walkthrough and orientation of the mockup prior to testing. Once testing commences, test monitors will be positioned near the mockup to assist the participants in interacting with the mockup. Handholds will be secured to structural members capable of undergoing lateral loading, and these same members will allow the participants some places to lean if necessary. Even the structural members that cannot support a leaning participant will deform before collapsing, giving ample time for a participant to understand that the structure is giving way and to remove their weight. Test subjects will also be constantly observed for any visible signs of fatigue or a lack of situational awareness. If the test subject is observed to exhibit or report any signs of a declining ability to perform the activities, the test will be terminated. To mitigate the inherent design risks, the design of the mockup will be evaluated by the human factors and safety team through concept definition, baseline design, final design, and construction. In order to mitigate the design risks associated with the build of the mockup, a safety review will take place prior to the initiation of human factors testing and the resulting recommendations will be implemented to mitigate any remaining risks prior to testing. Section 4.5 explains how the mockup will be certified as safe for testing, while Appendix E provides more information regarding the safety plan for during testing.
6.1.0 Emergency Procedures A full description of emergency procedures is included the Safety Plan located in Appendix E of this test plan. These emergency procedures include call lists for emergencies and test personnel procedures for emergency situations that may occur during testing. In response to COVID-19, the team has followed safety guidelines in the high bay that meet the university standards. All test participants will have their temperature taken with an infrared thermometer before testing proceeds and will be provided with a new mask and gloves. The interior surfaces of the habitat will be thoroughly sanitized prior to every new trial to ensure they do not pose an infection risk to the participants. Participants will be asked to inform the team of any positive result or potential exposure for the next two weeks to ensure the safety of all participants and test conductors. Social distancing will be observed, and we will accrue no more than 15 cumulative minutes of close contact over the course of a testing day, which is the mandated limit for such contact. The number of test conductors will be kept to a minimum. In the event of a potential COVID 19 exposure, the university administration will be notified, and all test conductors and test participants will take a Polymerase Chain Reaction (PCR) test (the PCR test will indicate whether the recipient has an active COVID 19 infection).
6.2 Risk Management The CU SHEDS safety and risk management lead is tracking several risks pertaining to the risks and delays for this semester. We have identified nine significant risks for the semester, outlined below:
1. Project Halted due to COVID-19 2. Individual team member illness 3. Restricted Access to High Bay 4. Human Factors Testing Delay 5. Inefficiency in team communication
15 6. Budget Overshoot 7. Construction Schedule Slip 8. Manufacturing Delays 9. Expanding Scope
Given these risks, we have also devised several mitigation strategies to implement througout the semester. Risks 1 through 4 are mitigated by beginning the semester working from home, practicing good hygiene, abiding by the internally published protocols, seeking special access to the high bay, using the shared high bay schedule, and the restriction of the human factors testing pool. For risk 6, we plan to take advantage of significant carryover from the previous semester and the use of Microsoft Teams to keep files and conversations organized. Our schedule slip risks are midigated by the early start to construction and the purchase of surplus materials early on. Additionally, our team has kept open communication with the machine shop in order to access their help if we need it. Furthermore, multiple all- hands work sessions in the AERO building are executed/planned over the course of the semester. Finally, Risk 9 of expanding scope is mitigated by the initial negotiation of expectations and constant contact with project leadership. The pre-mitigation (Figure 3) and post-mitigation (Figure 4) risk matricies are shown.
Figure 3. Pre mitigation risk matrix
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Figure 4. Post mitigation risk matrix
7. Conceptual Deep Space Habitat Design
7.0 Overall Layout and Design Figure 5 displays a 3D CAD model of the conceptual design of the DSH. The DSH is comprised of three major elements including a Power Propulsion Element (PPE), the main habitat module called the Laboratory Module, and the Airlock, Robotics, and Logistics (ARL) Module.
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Figure 5. DSH Conceptual Design Layout
Figure 6 displays a 3D CAD model of the DSH with a transparent external shell to show off the DSH subsystems located within the habitable volume. Each subsystem is represented by colored boxes indicating accurate volumes and locations of each technology and component within the DSH. Subsystems are colored according to the key in Figure 6.
Figure 6. 3D CAD Layout of DSH
Figure 7 displays a more detailed and isolated view of Laboratory Module of the DSH. The Laboratory Module is the laboratory and living area of the DSH. Located within the Laboratory Module is the ECLSS, Avionics, Power, Communications, Crew Accommodations, and Robotics subsystems.
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Figure 7. Laboratory Module
Figure 8 displays a more detailed and isolated view of the ARL Module of the DSH. The ARL Module is equipped with two airlocks, an inter-module hatch, and an EVA hatch. Located in the ARL Module is the ECLSS, Crew Accommodations, Robotics, and EVA subsystems.
Figure 8. Airlock/Robotics/Logistics (ARL) Module
19 Figure 9 displays a more detailed and isolated view of the Power and Propulsion Element (PPE) of the DSH. The PPE supports orbital maneuvers and provides power and a communications relay to the DSH. Located within the PPE is the Avionics and ADCS, Power, Thermal, Communications, and Propulsion subsystems. While the CU SHEDS team understands the importance of the PPE, emphasis has been placed on the habitable module elements and systems that focus primarily on robot and human interaction, which are the main research focus areas of the HOME team.
Figure 9. Power Propulsion Element (PPE)
7.1 Subsystem Breakdown
7.1.0 Structures / Mechanisms
7.1.0.0 Chosen Technologies and Components
7.1.0.0.0 MMOD Protection The Micrometeoroids and Orbital Debris (MMOD) protection structure will consist of a five-layer Whipple shield. The layers shown in Figure 10 consist of an aluminum bumper to break up the MMOD particle followed by a layer of multi-layer insulation (MLI), an intermediate bumper comprised of Nextel and Kevlar to collect and slow the debris cloud, and an aluminum rear wall to stop remaining particles. This configuration was selected because it, and many very similar ones, are used heavily on the ISS for MMOD protection and strike a good balance between weight and volume taken. (Arnold J. et al., 2009)
Figure 10. Five-layer Whipple shield in outer shell of the habitat
20 7.1.0.0.1 Insulation MLI will be present in the primary shell of the spacecraft to maintain appropriate temperature conditions within the habitat. MLI is the most common insulation material for spacecrafts and is heavily used across the industry because of its light weight and effectiveness in reducing radiative heat transfer.
7.1.0.0.2 Primary Structure The primary structure of the pressure vessel will consist of Aluminum 2219-T87 due to its extensive flight heritage and strong physical properties. The shell will have a thickness of 0.2 in with isogrid ribs on the exterior to provide appropriate rigidity and stiffness profiles. This shell thickness passes leak before break design test and provides a ~10x factor of safety for hoop and band stresses. The primary structure will support an observation window in the ARL.
7.1.0.0.3 Secondary Structure The secondary structure of the spacecraft will consist primarily of extruded aluminum alloy for mounting of racks and subsystem components as required. Aluminum was selected because of its high strength to weight ratio. Titanium and Steel are also in consideration for material choice determined based on needs for extra strength.
7.1.0.0.4 Radiation Protection Water and High-Density Polyethylene will be the primary materials to provide radiation protection. The crews sleeping quarters will be constructed from HDPE and water stored for ECLSS purposes will be located in bladders around the exterior of the quarters. Radiation protection was traded on with factors, scores, and results shown in Appendix B (radiation protection).
7.1.0.0.5 Docking All exterior docking will be via International Docking Standard System (IDSS) docking ports (two on the ARL and one between the Laboratory Module and the PPE). Docking between the ARL and the Laboratory Module will also serve as an airlock modeled after the quest airlock which is further discussed in EVA 7.1.7.1. A full subsystem layout with locations of technologies is shown below in Figure 11.
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7.1.0.1 Layout and Location within Habitat
Figure 11. Full structures subsystem layout
7.1.1 ECLSS
7.1.1.0 Chosen Technologies and Components
7.1.1.0.0 Atmospheric Revitalization 7.1.1.0.0.0 Atmospheric Composition The CU SHEDS DSH cabin atmosphere will have a pressure between 92.9 kPa (14.2 psia) and 102.7 kPa (14.9 psia), partial pressure of nitrogen (ppN2) below 80 kPa (11.6 psia), and a partial pressure of oxygen (ppO2) between 19.5 kPa (2.83 psia) and 23.1 kPa (3.35 psia), identical to that found on ISS (Perry et al., 2015). Based on assumptions from the NASA Baseline Values and Assumptions Document (BVAD), astronauts consume approximately 0.82 kg of O2 per day. They will produce 1.04 kg of CO2 and 1.6 kg of atmospheric H2O from respiration and perspiration (Anderson et al., 2018). These gases, along with trace chemical, biological, and particulate contaminants will be managed by the atmospheric revitalization subsystem. This atmosphere was selected to minimize variables between space and ground experiments, providing an ideal test platform for the HOME team.
7.1.1.0.0.1 Carbon Dioxide Removal The CU SHEDS DSH will make use of a four-bed molecular sieve (4BMS) carbon dioxide removal assembly (CDRA) similar to that used on ISS. The four beds will be populated with zeolite 13x. This design choice was driven by the needs of the HOME team rather than trade studies with other candidate technologies. The goal of HOME is to increase reliability with automation. The zeolite-based 4BMS technology is already used and well understood in the carbon dioxide removal assembly (CDRA) used onboard ISS (Weiland, 1998). Such a system therefore serves as an ideal baseline for investigation into how to monitor, manage, and maintain CO2 removal in an exploration habitat. The zeolite beds of the 4BMS are arranged into two banks. One bank is in the adsorb configuration while the other is desorbing. Air passes through a desiccant bed comprised of 22 both zeolite 13x and silica gel to dehumidify the air. This allows the second bed to adsorb
CO2 rather than become saturated with atmospheric water. A blower is used to pump air through the second bed. After the CO2 has been removed, the “clean” air passes through the desiccant bed on the opposite (desorbing) bank. This re-humidifies the clean air and desorbs the water from this bed. The banks then swap roles to become desaturated of CO2 and H2O (Weiland,
1998). The saturated CO2 adsorbing beds are cleaned by heating and exposure to low pressure.
CO2 can then be sent to the Sabatier reactor for reduction or disposed via a vent in the hull of the habitat (Nabity, 2021). A diagram of a 4BMS can be seen in Figure 12.
Figure 12. Diagram of 4BMS taken from one of Dr. Nabity's presentation (Nabity, 2021). In the event the CDRA fails, the DSH will use contingency LiOH canisters to provide a week of CO2 removal to the crew of four. This will give the crew or robotics time to repair the system or enter the Orion spacecraft and return to earth.
7.1.1.0.0.2 Carbon Dioxide Reduction
CO2 will be done via a Sabatier reactor. CO2 removed from the habitat atmosphere is premixed with two molar equivalents of hydrogen from the oxygen generator assembly (OGA). The gas mixture is compressed and heated by way of a heat exchanger with the products of the reactor. The reactant H2 and CO2 then pass into the reactor where with the help of a ruthenium catalyst the CO2 is reduced with the hydrogen forming CH4 and H2O. The reaction is summarized by the stoichiometric in Eq 1.
Eq 1. 퐶푂2 + 4퐻2 → 퐶퐻4 + 퐻2푂 The Sabatier reaction is exothermic and will produce approximately 165 kJ of heat per mol of CO2 reduced in the reaction (Hintze & Guardado, 2018). To reduce half of the
CO2 produced by a four-person crew the Sabatier reactor will produce a time average of approximately 90.3 W of waste heat. Other technologies such as electro-chemical reduction and the Bosch reactions were considered, but they were rejected due to low technology readiness (TRL) or volumetric constraints (Jones, 2011) (Nabity, 2021). Pyrolysis of CH4, resulting in pyrolyzed graphite and H2, was also considered but it requires a temperature of approximately 1,200°C 23 and is not suitable for our purposes. The primary disadvantage of the Sabatier reactor, compared to the other systems considered, is the capability to reduce only 50% of the CO2 with the hydrogen available as a biproduct from the oxygen generation system. While this meets the requirements set by the HOME team, oxygen will need to be brought as a consumable, as the loop is not fully closed.
7.1.1.0.0.3 Oxygen Generation To convert stored, and Sabatier produced, water into oxygen for the crew, CU SHEDS will make use of an oxygen generator assembly (OGA). The OGA works through electrolysis across a membrane. Hydrogen and oxygen gas are pumped into liquid separators where undesired water is removed and returned to the wastewater bus as seen in Figure 13 (Weiland, 1998). Observation of the OGA onboard ISS have resulted in improvements such as removal of the nitrogen purge system and modifications to the hydrogen sensor system have improved reliability, volume, and mass resulting in a new system called the advanced oxygen generator assembly (AOGA) (Takada et al., 2019). O2 generated at the OGA is pumped into oxygen distribution lines for distribution by the pressure control assembly. The AOGA on CU SHEDS will be capable of generating 3.5 kg of O2 per day, enough for a crew of four as well as habitat leakage. An electrolysis-based system has strong flight heritage and is necessary for the selected oxygen storage system.
Figure 13. Notional diagram of OGA. Taken from Weiland, 1998. 7.1.1.0.0.4 Oxygen Storage Oxygen for the crew and on-board experiments is stored in two ways. Primary oxygen storage is in the form of water located in bladders around the crew sleeping quarters. This is an ideal location as it provides additional radiation protection to the crew. CU SHEDS will require approximately 250 kg of water to provide oxygen for 15% crew habitation over the course of two years while making use of the onboard Sabatier reactor. This water will be stored with supplies of potable water for other applications. Information about this storage system is included in Section 7.1.1.0.1.0. Water oxygen storage was selected for its high density, stability, and low risk.
24 Two additional composite overwrapped pressure vessels (COPV) similar to the nitrogen oxygen resupply system (NORS) will provide high pressure oxygen. These tanks will provide oxygen in contingency scenarios such as OGA failure, hull leaks, or hazardous atmospheric conditions, as well as provide oxygen for EVA. Based on estimates drawn from the BVAD, a COPV will provide an additional 76 kg of oxygen.
7.1.1.0.0.5 Nitrogen Storage Nitrogen for the habitat atmosphere will be stored in a similar manner to the contingency oxygen storage tanks. Five tanks will provide 145 kg of nitrogen. Nitrogen, while not consumed directly by the crew will be lost through hull leakage, airlock depressurization, and possible contingency scenarios. 145 kg accounts for the leakage losses over the course of two years, two EVAs and recycling of a hazardous atmosphere before the need to resupply. High pressure nitrogen will be regulated before entering the nitrogen supply lines to the pressure control assembly. Other technologies such as cryogenic and chemical storage were considered but were rejected on the grounds of excessive power consumption and crew safety.
7.1.1.0.0.6 Air Circulation
To minimize CO2 buildup around the habitat forced airflow will be used to compensate for the lack of buoyant convection. Ducting output air away from the temperature and humidity control assembly (THCA) towards the ends of the habitat module, help to ensure CO2 mixes with other gasses as it returns to the CDRA and THCA. As much of the habitat air passes through the primary air duct the fire detector and trace contaminant control systems (TCCS) will be located along the length of the duct. Forced air will also be used to remove moisture from the ionomer water processor (IWP). The primary airduct runs along the length of the habitat and has a cross section of 15 cm. This allows the ventilation fans to circulate approximately 200 L of air per second considered adequate aboard ISS (Wieland, 1998). No ventilation alternatives were considered due to the strong flight heritage of forced air circulation.
7.1.1.0.0.7 Trace Contaminant Control The trace contaminant control subassembly (TCCS) will remove and dispose of gaseous contaminants in the atmosphere of the habitat. The total mass of this subassembly is 77.2 kg and the volume of the subassembly is 0.25 m3. The sub assembly consumes 180 W of power on average it has a peak power requirement of 250 W, which is also its emergency power requirement. The TCCS also dissipates 130 W of heat (Wieland, 1998). A schematic of this hardware can be seen in Figure 14.
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Figure 14 Schematic of Trace Contaminant Control Subassembly (Wieland, 1998) The operation of the trace contaminant control subsystem is as follows; first, a blower and flowmeter downstream of the charcoal bed will pull air through the charcoal bed at a flow rate of 4.2 L/s. The charcoal bed is impregnated with phosphoric acid for ammonia removal and will remove high molecular weight contaminants. Once high molecular weight contaminants are removed, the air will flow through the high temperature catalytic oxidizer which will remove low molecular weight contaminants such as CH4, H2, and CO. Finally, the air will enter a LiOH bed to remove any acidic byproducts generated in the oxidation process before being returned to the atmosphere (Wieland, 1998). This process is illustrated in Figure 15.
Figure 15. TCCS process diagram (Wieland, 1998) 26 The concentrations of contaminants allowed by this system are listed in Table 4. Table 4. Maximum allowable concentrations of atmospheric contaminants (Wieland, 1998)
Three components of this subassembly must be periodically replaced as part of the scheduled maintenance of the TCCS. The charcoal bed assembly (dimensions: 0.84 x 0.43 dia m, volume: 0.12198 m3, mass: 32.2 kg) must be replaced every 90 days. The catalytic oxidizer assembly (dimensions: 0.46 x 0.28 dia m, volume: 0.028325 m3, mass: 13.7 kg) must be replaced once per year. The LiOH sorbent bed assembly (dimensions: 0.38 x 0.20 dia m, volume: 0.011938 m3, mass: 4.2 kg) must be replaced every 90 days (Wieland, 1998). These replacements are done by ORUs and equate to a yearly amount of 159.3 kg and 0.6 m3 of orbital replacements, and 2389.5 kg and 8.5 m3 of ORUs over the 15-year lifetime of the habitat.
7.1.1.0.0.8 Airborne Particulate and Airborne Microorganism Removal Airborne particulate contaminants and airborne microorganisms will be removed via filters before the air enters the ventilation system ducting. HEPA filters, made of a “paper” of borosilicate glass fibers, will be installed at the front of the ventilation system and remove 99.97% of particulates that are 0.3 microns or larger in diameter. These filters have been shown to be capable of maintaining a maximum daily average concentration of 1,000 CFU/m3 of microorganisms. An ethyl-tetrafloroethylene pre-filter screen will also be. installed directly in front of the HEPA filter to prevent free liquids from passing through the HEPA filters. These filters will be checked every 90 days, cleaned as necessary via vacuuming, and replaced once per year. HEPA filters have been shown to be effective in both space and terrestrial applications. As such no alternative technologies were considered.
7.1.1.0.0.9 Temperature and Humidity Control Humidity and temperature control are integrated into a single unit: the temperature and humidity control assembly (THCA). Cabin air is pumped in by way of a blower. The temperature is measure and used to inform a temperature control and check valve (TCCV). The 27 valve uses a proportional integral (PI) controller to regulate the temperature to a set value, rather than oscillate around the selected value. Input air is diverted by the TCCV either to, or around, a condensing heat exchanger (CHX). The condensing heat exchanger uses the internal thermal control loop (ITCL) to cool and dehumidify the air. The CHX will be designed to maximize surface area. Based on estimates used during the construction of ISS the CHX will circulate 200 L/s at maximum depending on temperature. This air is then directed back to the air duct for circulation around the cabin. Humidity is removed via condensation on the CHX and is not independently controlled. A hydrophilic surface will minimize the chance of water droplet formation within the heat exchanger (Weiland, 1998). A liquid water and air mixture will be pumped into a centrifugal water separator where the water can be returned to the wastewater bus. A condensing heat exchanger was selected over other humidity control techniques because of the simplicity of returning condensate to the wastewater loop for reuse. The internal thermal control system (ITCS) will pump waste heat from the THCA and other heat generating components to an external heat exchanger. The thermal control loop will pass through cold plates attached to heat generating components for maximum heat conduction. The ITCS will also provide cooling to experiments racks by way of quick disconnects. The ITCS will consist of two loops. The primary loop will remove heat from life critical systems such as the CDRA, OGA and THCA. The secondary loop will remove heat from less critical subsystems such as the experiments racks and the Sabatier reactor. A water propylene glycol mix will be used to transport heat to an external heat exchanger to be removed and radiated by the ammonia-based loop in the PPE. Water was selected for its low toxicity and excellent thermal properties. The condensing exchanger will remove approximately 700 W of form the atmosphere for cooling the crew as well as small components. An additional 2,250 W will be removed from the ECLSS systems in the habitat at full power. A water flow rate of 1 kg/s or less will accomplish heat removal for the entire ECLSS system.
7.1.1.0.0.10 Pressure Monitoring and Regulation Pressure regulation and gas distribution are managed by a single assembly, the pressure control assembly (PCA). The pressure control assembly monitors the atmospheric pressure inside the habitat and adjusts gas inflow streams accordingly, or if necessary, vents internal atmosphere to space (Weiland, 1998). The PCA attaches to N2 and O2 inlet lines. Each line is equipped with a cutoff valve to control pressure, and a pressure monitor (Schaezler & Cook, 2015). Information from the line pressure monitors is used to modify output of the OGA and pass data to the habitat’s computer for diagnostic purposes. The system will also mix introduced gases by way of diffuser to prevent the formation of oxygen deprived areas within the cabin. In the event of decompression, rapid or otherwise, pressure sensors and the PCAs will detect the pressure change. Automatic procedures will seal possible leak sites such as O2 and
N2 inlet ports and set the CDRA to standby. The crew will be alerted to either significant pressure changes or low pressure, depending on the situation. Crew intervention may be needed depending on the leak location. The PCAs are capable of imputing approximately 1 kg of atmosphere per minute. In the event that the leak cannot be repaired, or that the leak rate exceeds the capability of the habitat to replace lost atmosphere, a feed the leak scenario will give the crew time to enter the Orion spacecraft for shelter or repair the leak. For information on the PCAs response to a fire or contaminated atmosphere please see Section 7.1.1.0.4. The pressure control assembly was selected for its strong flight heritage onboard ISS.
28 7.1.1.0.0.11 Gas Analysis
To adjust the partial pressure of N2 and O2 the PCA receives information from the major constituent analyzer (MCA). The MCA makes use of mass spectrometry to identify six major component gases in the atmosphere. Incoming atmospheric samples are ionized and accelerated by an electric current. The ions pass through magnetic field thereby warping their trajectory. This sorts the ions bases on mass, as all ions possess the same charge (Reysa et al., 2004). Additional atmospheric monitoring is provided by the volatile organic analyzer (VOA). The VOA combines data from gas chromatography and ion-mobility spectrograph to build unique profiles for volatile organic compounds of interest to crew and mission safety (Limero et al., 1992). If contaminant levels exceed predefined boundaries the VOA would alert the crew and begin emergency procedures similar to those used during a fire. In the event of a significant leak, the habitat can vent and replace a portion of the atmosphere provided sufficient N2 and
O2 provisions remain. The MCA and VOA pass information to the crew and habitat computer for monitoring. Mass spectrometry has flight heritage and was selected for simplicity of design.
7.1.1.0.1 Water Supply 7.1.1.0.1.0 Water Storage All potable water aboard the DSH will be stored in bladders around the crew sleeping compartments. Based on estimates given in Table 5 the crew will only use approximately 750 kg of water over the course of a sixteen-week mission. Wastewater will be stored by the water processor in the 60-liter wastewater storage tank between purification cycles. Table 5. Water use for 8-and 16-week missions. Negative values denote water recovered from waste streams. Individual Usage Water Crew usage (kg/d) 8 weeks (kg) 16 weeks (kg) (kg/CMD) Drinking 2 8 448 896 Food 0.62 2.48 138.88 277.76
Oxygen Production 1 4 224 448
CO2 reduction -0.377 -1.508 -84.448 -168.896 Respired -0.89 -3.56 -199.36 -398.72 Perspired -0.7 -2.8 -156.8 -313.6 Total 1.653 6.612 370.272 740.544
7.1.1.0.1.1 Water Distribution and Wastewater Recovery To minimize complexity, the DSH will make use of two water buses. The potable water bus (PWB) will supply fresh water from the water bladders to the crew as well as components and experiments that require water such as the OGA. The wastewater bus (WB) will return all water to the WP. The WP will cycle as needed over the course of the mission refilling the water bladders with potable quality water. The potable water supply will be continuously monitored for chemical or biological contamination via the WP and similar sensor arrays. Ridged water pipes will transport most of the water to and from needed locations with flexible hoses and quick disconnects providing final connections with and between components.
29 7.1.1.0.1.2 Water Purification Wastewater will be delivered by the wastewater collection bus to the water processor (WP). The WP is responsible for the purification of up to 55 kg of wastewater to potable water each day. The system works in several stages. Water is received and gas bubbles are centrifugally separated from the stream before it is stored in a preprocessing tank. The wastewater then passes through a 0.5 µm filter removing large particles before moving on to a pair of sorbent and ion exchange resin beds, which remove large organic molecules and inorganic contaminants, respectively. Wastewater now passes via a heat exchanger to a preheater and then into to the volatile removal assembly (VRA) (Weiland, 1998). The VRA is a reactor making use of elevated temperature and pressure to react volatile organics in a packed bed of cobalt, iron, or nickel carboxylate catalysts (Guo et al., 2005). O2, supplied by the
O2 delivery bus is used to oxidize most of the remaining contaminants into CO2. The water now passes through an additional liquid/gas membrane separator to remove excess O2 and CO2. A final ion exchange bed is used to remove remaining organic acids. Water from the WP is tested via conductivity, for ions, pH, for organic and inorganic acids and IR for organic carbon content and CO2. Water acceptable in all metrics is pumped to the potable water holding tank. Water deemed unacceptable is routed back to the preprocessing tank for reprocessing (Weiland, 1998). A block diagram of the water processor aboard ISS is shown in Figure 16.
Figure 16. Block diagram of WP used aboard ISS (Weiland 1998). CU SHEDS will make use of a similar system to process most wastewater streams. Two candidate technologies were considered. A water processing assembly similar to that found aboard ISS and a new cascade distillation system. While the cascade distillation system appears promising and may reduce mass and volume significantly it is at a low TRL (Loeffelholz et al., 2014). Furthermore, research into the system appears to have halted in recent years. Therefore, it was not seriously considered for application on the CU SHEDS DSH
30 7.1.1.0.1.3 Urine Processing Most wastewater sources including hygiene water and condensate from the THCA will be sent directly to the water processing assembly. However, urine from the UWMS must first be distilled before it can enter to the wastewater bus. The vapor compression distillation system (VCDS) is a simple low pressure distillation loop as seen in Figure 17. Urine is stored into a pretreated tank. It is pumped into a drum and held to the walls via centrifugal forces. A compressor is used to lower the pressure within the drum. Water and volatiles evaporate and are removed by the compressor. The remaining brine is periodically purged. Brine is sent to a filtration bag before being recycled back into the pretreated urine line. Concentrated brine remains in the filtration bag which must be removed and transferred to the brine processor approximately once a month (Holder & Hutchens, 2003). When in use the VCDS will be capable of refining approximately 6 kg of urine per day.
Figure 17. Block diagram of ISS UP taken from Holder & Hutchens, 2003. Note: instead of using a disposable recycle and filtration tank, the CU SHEDS DSH will use brine processor bag with similar filtration characteristics. Reliable function of distillation systems such as VCDS has been a significant challenge for spaceflight applications. The inclusion of a urine processor aboard the DSH is to aid in closing the water loop for future missions by providing additional experience with such a system. When functioning properly the UP will minimize consumable water up mass as seen in Table 6. Water recovered can be saved for future habitation periods in the potable water system. Table 6. Water usage with functioning urine processor and ionic water processor.
Water kg/CMD 4 crew 8 weeks 16 weeks Drinking 2 8 448 896 Food 0.62 2.48 138.88 277.76 Oxygen Production 1 4 224 448 CO2 reduction -0.204 -0.816 -45.696 -91.392 Respired -0.89 -3.56 -199.36 -398.72 Perspired -0.7 -2.8 -156.8 -313.6 Urine -1.5 -6 -336 -672 Totals 0.326 1.304 73.024 146.048 31
7.1.1.0.1.4 Brine Processing To minimize consumable mass, a brine processing system will be used in the CU SHEDS DSH. The selected unit will require a maximum mass of 53 kg for both components and consumables over the course of the 1,100 days of occupation and will save approximately 1,600 kg of water. This results in a water reclamation rate from urine of 97%. While this exceeds the requirements of the home team the mass savings are significant to justify the inclusion of such a system. Four novel brine processing technologies were considered. These are the forward osmosis brine dryer (FOBD), brine evaporation bag (BEB), capillary residual brine in containment (CapiBRIC), and ionomer water processing (IWP). These technologies are being developed separately by several research centers and private companies (Carter & Gleich, 2016). A trade study was conducted between the technologies and the results are summarized in the following tables. Parameters were chosen to minimize mass and volume of components. Other parameters such as percent water recovered, and production rate were considered however their weight was minimized as all exceed the set requirements. Tables for this trade study can be seen in Appendix B. Reliability numbers are based on 1g testing and assessment of design aspects that may affect functionality in micro gravity. The parameters were weighted and justified as is shown in Table 13 of Appendix B. The trade study results, shown in Table 14 of Appendix BTable 14, indicated that the ionomer water processing technology is the best option. For the mission. This is supported by a conference paper from Carter and Gleich at ICES 2016 in which they came to the same conclusion. Furthermore, various sanity checks such as zeroing certain parameters, and eliminating weighting showed that IWP remained the optimal system for our purposes. The ionomer water processor (IWP) uses a fan to force convection of heated cabin air over an ionomer membrane bag containing the urine brine. A block diagram of the system can be seen in Figure 18. The membrane is designed to only allow O2, N2, H2O, and small trace contaminates to pass through. The air is preheated by a small inline heater allowing the air to efficiently humidify as it passes over the bag. The humidified air is returned to the cabin where the humidity is extracted and returned to the wastewater bus by the condensing heat exchanger (CHX). After the bag evaporated approximately 89 percent of the water it is removed of and disposed of in the resupply vehicle. The IWP can process approximately 20-25 kg of brine per month, adequate for a crew of four. The expected bag resupply mass is 53 kg over the course of the expected life of the DSH.
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Figure 18. Block diagram of IWP taken from Carter & Gleich 2016.
7.1.1.0.2 Food Supply The DSH will include a galley for the safe preparation of food. A food warmer will heat packaged hydrated items. Dehydrated meals and beverages are rehydrated via a temperature adjustable water dispenser. Food provisions will be transported to the DSH via autonomous resupply. Most food provisions will remain stored aboard the autonomous resupply vehicle inside single sized cargo transfer bags. Approximately one week’s worth, or one to two CTBs, of food provisions will be brought into the habitat at a time. Food resupply mass estimates can be found in the master equipment list and are based on estimates in the BVAD (Anderson et al., 2018). Waste Management
7.1.1.0.3 Waste Management 7.1.1.0.3.0 Human Solid Waste Collection and Storage The universal waste management system UWMS, shown in Figure 19, will handle crew feces and urine collection. The UWMS was developed recently for the International Space Station (ISS) and Orion spacecraft with lessons learned from previous waste management systems such as those found in both the US and Russian segments of ISS as well as the space shuttle. The new design has reduced both mass and volume by 75%. Furthermore, the UWMS features improved ergonomics for use and cleanliness (Stapleton et al., 2013). For the above reasons it was the clear choice for the DSH.
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Figure 19. Universal waste management system undergoing testing. For fecal collection, the UWMS makes use of a collection bag. After the bag has been filled it is compacted into a canister with a hand lever. The usage of bags has been praised by the crews as highly sanitary, and the new hand lever compactor is significantly lighter than the previously used mechanized system and minimizes crew time for compaction (Stapleton et al., 2013). Urine collection is done by way of a hose and vacuum fan. Urine can either be directed towards the urine processor assembly for water recovery or directed towards a collection bag in a canister for disposal.
7.1.1.0.3.1 Trash Collections and Storage For waste collection the DSH will make use of disposable trash bags. Waste that cannot be recycled such as packaging, food scraps, and spent filters and beds will be bagged, hand compressed, taped, and replaced into the empty volume on the resupply vehicle. The CU SHEDS team had decided against ejecting solid waste into space unless some contingency or emergency calls for it. This is because the team does not want to contribute to the potential future problem of orbital debris throughout deep space. Any gaseous or liquid waste, however, may be vented into space.
7.1.1.0.3.2 Wet Dry Vacuum A wet dry vacuum will be provided near the galley. The vacuum will be useful for cleanup of spills, personal hygiene, and any additional crew needs. The system will centrifugally separate collected water and return it to the wastewater bus. Particulate filtration will be accomplished via filters.
7.1.1.0.4 Fire Detection and Suppression An array of 5 smoke detectors will be used in the ECLSS and experiment racks, as well as in the air duct system in both modules. The fire detection system must be redundant to prevent a single fault from causing greater fire hazard. The crew also will have the capacity to manually trigger a fire alarm. If the alarm is triggered series of automatic procedures will activate to minimize the possible spread of the fire. Ventilation, including the CDRA, THCS, and IMV, will be suspended or placed on standby. PCA inlet valves will be closed. The possibility of venting the atmosphere to space, via the PCAs, to lower the total atmospheric pressure to approximately 10 psia, and the partial pressure of oxygen to around 2 psia will also be provided. Portable CO2 fire extinguishers are made available to the crew. Quick don masks 34 are provided by the crew to minimize the risk of exposure to combustion products, toxic chemicals, or low partial pressure of oxygen.
7.1.1.0.5 EVA Support The ECLSS subsystem will support EVA operations by providing the necessary consumables via the established ECLSS systems. Potable water for suit thermal control and crew consumption will be provided by the potable water bus. High pressure O2 for suit provisions as well as the rebreathe will be provided via NORS tanks. LiOH cartridges for the suits will also be stowed within the ECLSS stowage volumes. A PCA will support depressurization for egress and depressurization for ingress, using atmospheric gasses from the primary nitrogen and oxygen supply systems. 7.1.1.2 Layout and Location within Habitat Most of the main components of the ECLSS are organized into 2m tall racks. These racks have a footprint of 0.5 x 0.5 m allowing them to fit through the IDSS docking ports. Because of their significantly reduced size larger systems such as the water processor and four bed molecular sieve will are distributed across multiple racks. A summary of the primary rack system is given in Figure 20. Racks are arranged to minimize the need for long tubing between racks. Flexible tubing and quick disconnects. Racks will make use a pallet style system for component maintenance, repair, or replacement. Components will fit onto pallets using small guide rails. Figure 21 is an example of the system with multiple components on a pallet. To transmit data between elements of the ECLSS system and to pass information onto the habitat’s main avionics array a redundant local area network is used. They system utilizes ethernet connection between main components, such as the water processor and urine processor. Within each component wi-fi connections are used. The system will make use of a publish subscribe software architecture. Each component will publish all information gathered but subscribe to only relevant other components. This system will provide flexibility for future developments of the CU SHEDS artificial intelligence monitoring and control system.
Figure 20. Block diagram of ECLSS system showing the individual rack system.
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Figure 21. Mock-up of pallet rack system taken from Banerjee & Dekarske 2020.
Figure 22. Isometric view of ECLSS components in laboratory module.
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Figure 23. Side view of primary ECLSS racks. From right to left; 1 rack for urine processing, 3 racks for water processing, 3 racks for CO2 removal, 1 rack for TCCS and MCA, 1 rack for IWP and CHX.
Figure 24. Cross section showing ECLSS components on port side.
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Figure 25. Cross section of ECLSS components starboard side.
7.1.2 Avionics and ADCS
7.1.2.0 Chosen Technologies and Components The ADCS software will be run on a processor that is robust to the deep space environment and capable of withstanding increased radiation exposure from passing through the Van Allen Belts. Radiation-induced problems include single event upsets, single event gate rupture, and more. The processor will be able to recover without any downtime and will also be able to correct for upset events as quickly as possible. The RAD5545 was selected for this spacecraft as the primary processing unit. A large benefit of the RAD5545 processor is the quad-core architecture, which allows for a triple-redundant execution of flight code, enabling a best-of-three voting protocol, while the fourth core carries out commands (Ottavi, 2018). This entire quad-core system is duplicated in the CU SHEDS design to allow for a further level of redundancy. The RAD5545 is comes radiation-hardened and ready to use, making it a good choice for the habitat’s computing needs. Moreover, the hardware is compatible with SpaceWire I/O protocols and provides up to 5200 MIPS and 3700 MFLOPS of performance. To prevent common-cause failures of the flight computer, a Vision Processing Unit like the one used on the Orion capsule will also be included. This system acts as a hot backup to the primary RAD5545-based flight computer modules (Timmons, 2018). For data storage, the team has elected to select an existing space-grade COTS solution in the Mercury Systems TRRUST-Stor VPX RT 2nd Generation Radiation-Tolerant Large Geometry SLC NAND SpaceDrive. Each storage device has a capacity of 960GB, and we will fly ten of these units for a total of 9.6TB of data storage. This overall storage capacity was selected considering the limitations on communication bandwidth to Earth and the large file size of image and data files produced by the DSH. As for GNC instrumentation, the CU SHEDS habitat will employ a number of sensors. The suite of GNC sensors includes star trackers, sun sensors, IMUs, and a rendezvous and docking sensor. Specific hardware choices selected are the Ball Aerospace CT-2020 (x3), New 38 Space NFSS-411 (x3), Honeywell MIMU (x6), and Optronik RVS 3000 (x2). These sensors will also incorporate navigation data derived from the Deep Space Network. The location of the avionics hardware is noted in Figure 26. The habitat will use control moment gyroscopes for attitude control and reaction control thrusters for backup attitude control and control moment gyroscope desaturation. The habitat will feature 4 control moment gyroscopes: three of these gyroscopes are required to completely reorient the habitat, making the fourth a backup unit. Control moment gyroscopes can be rendered incapable of reorienting the spacecraft due to gimbal lock, and it is possible for the gyroscopes to experience saturation as well: both conditions can be corrected using the onboard reaction control system. These small hydrazine/nitrogen tetroxide thruster blocks will only be used to supplement the control moment gyroscopes owing to their limited fuel supply. The reaction control system tanks will be stabilized with helium as the fuel and oxidizer are used up. The control moment gyroscopes will be reparable by both human and robotic agents. The ADCS hardware located within the PPE is shown in Figure 27.
7.1.2.1 Layout and Location within Habitat
Figure 26. Avionics in the Laboratory Module
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Figure 27. ADCS Components in the PPE
7.1.3 Power
7.1.3.0 Chosen Technologies and Components The power system is based on a solar panel/battery combination based upon the ISS’s architecture and work done by MAXAR for their Power and Propulsion Element concept. The Solar Arrays will take the form of two solar wings on opposing sides of the Power and Propulsion Element which will rotate for maximum solar exposure, and two static solar panels affixed to the sides of the Power and Propulsion Element. The batteries will take the form of two lithium-ion orbital replacement units mated to two Battery Charge/Discharge Units identical to those in use on the ISS. The battery system is designed to be modular and replaceable as components wear out. The units are capable of being handled by both humans and robotic agents. The power system located on the PPE is shown in Figure 28, and the battery backup for the internal robotic system is shown in Figure 29.
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7.1.3.1 Layout and Location within Habitat
Figure 28. Power Hardware on the PPE
Figure 29. Backup Battery for the Internal Robotics
7.1.4 Thermal
7.1.4.0 Chosen Technologies and Components The habitat will utilize a radiator-based thermal regulation concept, which will be a dual- loop ammonia-water system like the one used on ISS. The radiators will take the form of two dual-sided rotatable vanes affixed to opposing sides of the Power and Propulsion Element. Each radiator will feature an associated ammonia pump and tank, allowing for an outer loop that can function as two thermal loops if necessary. Two separate heat exchangers will interface the ammonia loops with the water loop. This system is therefore redundant, with the ability for single radiator and outer loop operation if necessary. Due to the varying thermal load expected 41 from only having partial habitat occupancy over a given time, the radiators will have the ability to operate while partially retracted, which will lessen their thermal rejection capability. This will allow for the habitat to retain as much heat as is required to keep its systems functional, as well as protect the thermal loops from freezing. The location of the components of the thermal management system is called out in Figure 30.
7.1.4.1 Layout and Location within Habitat
Figure 30. Thermal Hardware on and in the PPE
7.1.5 Communications
7.1.5.0 Chosen Technologies and Components Communication between Earth and the DSH will be achieved using the same communication system that will be used on NASA’s Lunar Gateway project. The MAXAR Power Propulsion Element (PPE) used for NASA’s Gateway will serve as a communications relay between CU SHEDS, Earth, visiting vehicles, and lunar surface systems. The communication system can be seen in Figure 31 the Communication Layout. The communications system fit to NASA’s PPE was chosen for use in the DSH as it uses well established radio wave communication technology using KA, X, and S bands depending on the communication scenario. Radio wave communication was chosen over optical/laser communication technology, such as the Laser-Enhanced Mission Communication Navigation and Operational Services (LEMNOS) system, as there is an established flight heritage, a well- established Earth ground station ecosystem, and is the current primary method of deep space communication. A high gain antenna pointing towards the Earth will provide the DSH the ability to communicate with the three DSH Earth ground station using the X band. The antenna fitted to the DSH will be sized to fit the communication needs of the mission. If needed, data may also be relayed to ground using relay signals, in particular the Tracking and Data Relay 42 Satellite System (TDRSS). Communication between the DSH and the Orion spacecraft will also be achieved using the same communication system fit to the MAXAR PPE. The high gain antenna will be used to facilitate communication between the DSH and the Orion capsule using KA and/or S bands. Inter-Habitat communication will be carried out through an intercom system on board the habitat. There will be speakers and microphones located in various places of the habitat so that crewmembers can easily communicate to one another while in different areas of the habitat. Communication with EVA missions will be carried out through the Space-to-Space Station Radio (SSER) which directly sends signals to the spacecraft as well as being able to communicate with the other crewmember on an EVA mission.
7.1.5.1 Layout and Location within Habitat
Figure 31. Communication Layout
7.1.6 Crew Accommodations
7.1.6.0 Chosen Technologies and Components The DSH will be equipped with resistive and aerobic exercise equipment that will help astronauts maintain their muscle mass, bone mass, and cardiovascular strength. A cycle ergometer located in the ARL will be provided as requested by the HOME team and will assist with ensuring astronauts maintain their lower body muscle and bone mass. A Resistive Overload Combined with Kinetic Yo-Yo (ROCKY) device will also be placed in the habitat and can be reconfigured and customized for astronauts to exercise both their upper and lower body. Together the stationary bicycle and the ROCKY device can provide astronauts with a flexible workout solution that allows them to maintain their health while on board the DSH. The DSH will also support personal and habitat hygiene activities using the following technologies. Personal hygiene areas in the Airlock, Robotics and Logistics Module will be provided by the DSH so that crewmembers can have a private space to conduct their personal
43 hygiene activities but also isolate potential contaminations from other areas of the DSH. Clean potable water will be provided by the ECLSS to maintain crewmembers skin, hair, and dental health. Given that crewmembers will inhabit the DSH for long periods of time reusable towels that can be soaked with water in order to achieve whole-body cleansing will be provided. Each crewmember will also be provided with a personal hygiene kit: which includes a toothbrush, toothpaste, hairbrush, deodorant, shaving supplies, nail clippers, menstrual hygiene products, contact lens kits, and any other personal hygiene supplies that the crewmember desires if possible. The DSH will also support the collection of hygiene byproducts such as hair, fingernails, and saliva using the suction hose provided by ECLSS. Crewmembers will be provided with enough clean clothing to maintain adequate personal hygiene. Depending on mission length additional clean clothing and other consumable hygiene supplies can be provided via resupply missions. Providing clean clothes via resupply was selected over including a clothes washer and dryer, because the washer and dryer have a large mass and volume and would use the habitats supply of potable water. The cleanliness of the DSH and group areas such as galley and exercise area will be supported by a vacuum cleaner and other housekeeping items such as antibacterial wipes to collect loose debris and wipe down dirty surfaces. The DSH will be equipped with 22 handholds and footholds located roughly 5 feet apart within the DSH in order to provide crewmembers with a means to both stabilize themselves and navigate the habitat in the microgravity environment. Torso and waist restraints will be included with the stationary bicycle and ROCKY exercise device for more body control and stability while exercising. The DSH will be equipped with orientation indicators and labeling located strategically throughout the habitat in order to facilitate crew comfort and safety. Additionally, where possible the layout and design of the habitat have been designed with adequate orientation indication in mind. The DSH will be equipped with Medical supplies following the NASA-STD-3001 requirements. A Level IV Medical care kit will be provided which shall include, space motion sickness prevention, basic life support, first aid kit, private telehealth audio and video, ultrasound equipment, anaphylaxis response, clinical diagnosis measures, sustainable life support, trauma care, and limited surgical and dental care. A crew medical restraint system (CMRS) will also be provided to immobilize the injured crew member allowing the rest of the crew to provide direct medical care. Biological and medical equipment disposal will be on the habitat in the form of a KBO-M bag for BB waste (Biological/Biomedical). In case of a deceased crew member, four body bags will be on board. A food preparation area in the galley will also be provided. A pullout table will be installed in order for the astronauts to maintain normal social activities. In order to avoid spillage and for easier clean up, a food tray with Velcro straps will be provided. Food will be able to be heated up through the heater and an adjustable temperature potable water dispenser. Utensils consisting of a fork, knife, and scissors will be provided. Sleep and leisure accommodations will be provided to the crew. Each crew member will have designated sleep cabins with a door for privacy. Cabins will include sleeping bags, restraints, and eye coverings, as necessary. Each cabin will also allow for laptop/tablet mounting for leisure and entertainment purposes. A storage area will be included for each crew member in their cabin allowing for stowage of personal belongings, clothing, hygiene products, or any entertainment items they may bring. The sleep stations are constructed with HDPE paneling and flanked with water bladders for radiation protection. Trash will be collected and stored in trash bags stored onboard the habitat. Trash will then be removed from the habitat periodically during regular resupply missions. The above accommodations can be seen in Figure 32, Figure 33, and Figure 34.
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7.1.6.1 Layout and Location within Habitat
Figure 32. ARL Module Crew Accommodations
Figure 33. Crew Accommodation within the Habitable Module
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Figure 34. Crew Accommodation within the Habitable Module view 2
7.1.7 Robotics
7.1.7.0 Chosen Technologies and Components The chosen robotics technologies break down into two categories: external and intra- vehicular robotics. External robotics will contribute to station maintenance and up-keep of the habitat. The external robotics closely align with the robotics of the International Space Station and proposed Lunar Gateway. The external robotic arm will be modeled after the Canadarm 2, currently on the ISS, and proposed Canadarm 3 on the Lunar Gateway. The external robotic arm will provide 6 degrees of freedom and will be 7.62 meters in length, fully extended. The external arm design will be able to move supplies and ORUs from the PPE in order to maintain the external habitat. Furthermore, the external robotic arm will be made up of parts that can be replaced in space, swapped out individually, and can be operated from both the habitat and from the ground. The external robotic design will be equipped with grapple fixtures, strategically located on the external shell of the habitat, enabling it to move end-to-end and latch onto different parts of the habitat to have a greater reach. Within the laboratory module, a robotic rail system will be installed, and a UR5e robotic arm will serve as the internal robotics of the habitat moving along the rail. The decision to install a robotic rail system came in part from the HOME team, but overall, it will provide the robotic arm with the greatest reach to all parts of the habitat internal volume, especially the ECLSS modules. The design of the rail system was also to maximize the reach of the UR5e arm. The UR5e robotic arm allows for 6 degrees of freedom and is .85 m in length, fully extended. The internal robotic system will be able to provide habitat maintenance, along with assisting on-board research experiments. A robotics workstation will be housed within the DSH Airlock, Robotics and Logistics Module. This can be seen in Figure 35.
46 7.1.7.1 Layout and Location within Habitat
Figure 35. Robotic Arm, Robotic Rail, and Robotics Workstation
7.1.8 EVA
7.1.8.0 Chosen Technologies and Components The airlock on the DSH will model after the crew lock of the Quest Airlock on the ISS. The crew lock will provide the astronauts ingress and egress capabilities and house the EVA suits. It will also provide an environment for pre-breathing activities prior to EVA. It will be equipped with lighting, rails, and an Umbilical Interface Assembly (UIA). The UIA will be housed inside of the crew airlock and will provide communication gear, spacesuit power interfaces, water supply/return line, and an oxygen supply line. It will also be able to support two EVA suits simultaneously. Furthermore, the Airlock, Robotics and Logistics Module will house the robotic workstation. The DSH will accommodate storage of two EVA spacesuits by securing the spacesuits to the wall of the Airlock, Robotics, and Logistics Module. To save additional space the soft portions of the spacesuits can be rolled up and secured to the wall of the module using straps. Additional storage shelves will be provided to store spare parts, EVA tools, and crew food. The internal and external surfaces of the spacecraft will be outfitted with approximately 22 handrails and foot rails taking into account appropriate ergonomic measurements for crew safety and use for traversing. All of the EVA hardware is shown in Figure 36.
47 7.1.8.1 Layout and Location within Habitat
Figure 36. EVA Hardware Layout
7.1.9 Propulsion
7.1.9.0 Chosen Technologies and Components The habitat will utilize Hall Effect Thrusters to perform orbital change maneuvers. These Hall-Effect Thrusters will be powered using the onboard electricity generated by the power subsystem, with Xenon acting as the fuel. The Hall Effect Thrusters will consist of two 13.5 kW thrusters (Isp 2600 s, Thrust 589 mN) and four 6.7 kW thrusters (Isp 1800 s, Thrust 386 mN), all sharing one common Xenon tank for fuel. The propulsion hardware is shown in Figure 37.
48 7.1.9.1 Layout and Location within Habitat
Figure 37. Propulsion Hardware on and in the PPE
7.2 Conceptual Design Status Update
7.2.0 Work Completed The following work has been done regarding the conceptual design of the CU SHEDS Deep Space Habitat. • Completed systems engineering deliverables in support of the conceptual Deep Space Habitat design. o Completed a HOME Deep Space Habitat System Requirements Review based on the Human Spaceflight Graduate Project Requirements Guidelines Document (CU BIOASTRO 2021-Spring -003) and the Human Spaceflight Graduate Project Design Reference Mission – HOME (CU BIOASTRO 2021-Spring -002) and Technical Interchange Meeting. o Complete a Concept Definition Review for the HOME Deep Space Habitat design based on the Kickoff Meeting and TIMs with BIOASTRO HOME. ▪ Performed trade studies to identify appropriate technology and component selection. ▪ Completed first pass of the Master Equipment List / Functional Decomposition document. ▪ Completed preliminary DSH CAD model detailing: approximate locations and volumes of subsystems within the DSH conceptual spacecraft. o Completed a Preliminary Design Review for the HOME Deep Space Habitat design that documents the final conceptual design. ▪ Completed a Master Equipment List with mass, volume, and power estimates for the systems in the DSH spacecraft and determined total habitable volume. ▪ Completed conceptual DSH CAD model detailing: locations and volumes of subsystem technologies and components within the DSH conceptual spacecraft.
49 ▪ Showed compliance with HOME Deep Space Habitat System Requirements Document.
7.2.1 Work Remaining The following is remaining work regarding the conceptual design of the CU SHEDS Deep Space Habitat. • Complete Delta Concept Definition Review Document implementing feedback and design updates to the ECLSS, Crew Accommodations, and Robotics subsystems.
7.2.2 Integration Plan The following outlines the integration plan for the design of the CU SHEDS Deep Space Habitat. • Integration of the ARL Module performed by Spring 2021 CU BIOASTRO Graduate Project Team: o Work with Mockup and Human Factors subteams to ensure critical aspects of the conceptual design of the ARL Module are translated to the physical mockup design for the ARL Module to facilitate collection of valuable human factors data. ▪ Transition from concept ARL Module to mockup ARL Module • Future Integration of the Laboratory Module performed by Fall 2021 CU BIOASTRO Graduate Project Team: o The Spring 2021 CU BIOASTRO Graduate Project Team will provide integration recommendation and lessons learned documentation to the Fall 2021 CU BIOASTRO Graduate Project Team by the Final Review.
8. Mockup Modification For Spring 2021, the project team is going through a slightly different process than in previous semesters, in that the existing mockup used by the Fall 2020 TALOS team will be modified and repurposed into the combined airlock, robotics, and logistics (ARL) module that was part of the CU SHEDS paper design. This semester’s mockup sub-team work has been broken up into the areas as follows.
8.0 Preparation and Relocation The first task the sub-team began with this semester was to strip down and relocate the TALOS lander mockup. This involved cleaning out and removing all retired and unnecessary hardware, including the pilot platform, xEMU suits, xPLSS storage shelf, and multipurpose workstation. Some additional hardware that will continue to be used was removed to avoid damage as well, including the translational and rotation hand controllers and dual monitors previously used for control of the lunar landing simulation. The platform on which the mockup sits was also modified, as a projector and dome system is not needed for the human factors testing being conducted during the Spring 2021 semester. Once this work was completed, the mockup was moved to a new location in the Bioastronautics High Bay to accommodate the space needed for the main habitat module of the CU SHEDS paper design, which will be constructed by future grad project teams. At present, all preparatory work on the ARL module mockup has been completed, and the mockup is ready for the construction phase. The following construction tasks have been scheduled to be completed concurrently with a build completion date of March 21st, 2021. Following that, the final integration, pre-test preparation, and any potential work that is beyond the scope provided 50 in the Statement of Work will be completed by March 26th. Figure 38 shows the progression of the mockup this semester.
Figure 38. The mockup during the TALOS human factors testing (left) and the mockup in its current state (right)
8.1 Docking Port and EVA Hatch As part of the ARL module’s functions as an airlock and logistics module, the mockup requires an EVA hatch and docking port (per the Statement of Work, the mockup only needs to include one of the two docking ports included in the CU SHEDS paper design). Based on conversation with senior management, it was decided that these features did not need to be fully-functional, but rather visual facsimiles. It was also decided that the original EVA hatch that was built for the mockup in the previous semester, would remain in place and serve as an entry and exit door to allow individuals to enter and exit the mockup during human factors testing. The docking port is being placed in the ceiling of the mockup, while the EVA hatch is on the wall roughly opposite of the door. As they are non-functional facsimiles, both the docking port and the EVA hatch will be created in the form of posters of the proper size and shape that will be mounted on the ceiling and wall, respectively. This is shown in Figure 39. These posters will be printed by the CU Boulder ITLL program or by a commercial printing company, depending on price and lead time. The design for these is currently in work, and the anticipated completion date for the docking port & EVA hatch is March 21st, although this may either be completed early or slightly later depending on printing lead time.
51
Figure 39. A design for the EVA hatch (left) and design options for the docking hatch (right)
8.2 Observation Window The most significant structure change to the mockup this semester is likely the removal of the old lunar lander windows and the addition of a 20 inch-diameter circular observation window. This will require slight modification to one of the vertical bars that, along with the others, comprise the “bird cage” as seen in Figure 40. The window itself will be made of a single piece of stock transparent plastic sheet (likely Lexan/polycarbonate) and will laser-cut into a circle with four tabs with holes that will allow the window to be secured to the 80/20 frame. The modification to the 80/20 “bird cage” will include removing a middle section of one of the vertical beams and placing horizontal support bars at the top and bottom of the removed section. This is required as the specified diameter of the window exceeds the maximum distance between the vertical beams where the window is to be located per the CU SHEDS paper design. Finally, fused deposition modeled (FDM) 3D-printed rim/skirt parts will be made, likely with PLA, and placed on the exterior and interior of the window to prevent light bleed from the edges and make the window more realistic-looking. Design work on the window is currently underway, with a CAD rendering being done so that basic simulations can be performed to ensure safety of the new structure. The entire process, including design and build, is anticipated to be completed by March 19th, although it is possible work on the 3D-printed rim and skirt may push into the following week. However, this is not a significant issue, as these parts are more cosmetic and are not required for human factors internal and beta testing.
52
Figure 40. The simple CAD model for the new observation window (left) and the general placement on the main structure (right)
8.3 Crew and EVA Accommodations The work being done for crew and EVA accommodations covers specific items included in the CU SHEDS paper design as well as the Spring 2021 Statement of Work. For crew accommodations, the specified tasks comprise construction of a cabinet to store five CTBs, develop a stowage method for the ROCKY exercise equipment, insert hand holds throughout the module cabin, and finally build footholds in front of the robotics workstation. For EVA accommodations, the list includes a quick inspection and tidying-up of the Fall 2020 TALOS xEMU suits (which will serve as analogs for EMU suits), attach a depressurization panel to the wall of the module next to the EVA hatch, and build a suit stowage method. The CTB cabinet and suit stowage system comprise the bulk of the design and build work in terms of work time and material usage. The CTB cabinet will be stacked vertically, with each CTB being contained by a cubby with its own functional door. The structure of the CTB cabinet will also contain two slots for the xPLSS backpacks. Figure 41 shows the overall layout of the CTB and xPLSS cabinet system. This setup has been volumetrically tested out inside the mockup and it has been found that it does indeed properly fit inside the cabin against the wall as desired. Next to the CTB and xPLSS shelf, the two xEMU suits will be “packed” and stored. This means that the legs of each suit will be folded up into the hard upper torse of the xEMU to reduce each suit’s overall volume. One suit will be simultaneously strapped to the wall and sit on the floor, while the other suit also be strapped to the wall, but sit on a shelf above the first suit as well. These design changes represent a slight departure from the layout presented in the CU SHEDS paper design, but it was ultimately decided this was necessary to accommodate the human factors testing. The remaining CA and EVA hardware will be added using the CU SHEDS paper design layout. The anticipated completion date for all CA and EVA work is March 19th.
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Figure 41. The CTBs being used (left) and the CTB and xPLSS cabinet layout (right)
8.4 Robotics Workstation The robotics workstation tasks this semester is quite minor. The team will be reusing the translational and rotation hand controllers as well as dual monitors and non-functional switch panels that were collected and used during the previous semester. The only changes will include configuring the dual monitors in their standard landscape/horizontal configuration (with one monitor on top of the other) and making better use of anthropometric data to better place hardware. Data collected from previous semesters as well as the expertise of the project team’s senior management will be used to determine placement. The anticipated completion date for the robotics workstation is March 19th.
8.5 General Refurbishment The last task that falls under the “construction” category of the mockup work is general refurbishment of the old mockup. While the Fall 2020 TALOS team left the mockup in relatively good condition, general wear and tear from continuous use last semester as well as changes in the interior hardware has resulted in the need to perform some light maintenance and renovation of the existing mockup. This includes replacing damaged wall sections or sections of wall that were custom sized to fit around now-unnecessary hardware, inspecting and tightening all screws that are part of the main support structure, patching holes in the interior floor, and covering any edges or sections of wall that produce excessive light bleed. This work was started on March 8th and will continue until March 21st. Additional refurbishment and maintenance work may be required as mockup construction continues and as human factors testing runs its course, but this will be handled on an as-needed basis.
54 8.6 Final Integration, Pre-Test Preparation, and “Better/Nicer” Tasks Once all construction work is complete, the team will spend several days completing the final integration of all hardware and subassemblies into the mockup, cleaning up the workspace, and engaging in any other necessary preparations in advance of human factors internal and beta testing. Additionally, during this time, certain members of the team will work on specific optional tasks that fall outside of the scope of the project Statement of Work but that add to and improve the mockup overall. This includes the improvement of the cabin interior ventilation system (which proved largely ineffective last semester), fixing of the door mechanisms or removal of the door and replacing it with a forced-perspective image of the main habitat module interior which would be placed on a poster on the exterior of the door frame, fixing and improving the two functional CTBs which will be handled frequently during the human factors testing, and 3D-printing new bezels for the dual monitors on the robotics work station. The final layout of the mockup is depicted in Figure 42, showing all the hardware that will be built inside and integrated into the main module interior. The final integration phase of the project is expected to begin on March 22nd and conclude on or before March 26th.
Figure 42. The layout of the mockup with all major and volume intensive components
9. Human Factors Testing
9.0 Progress to Date This semester, the human factors team began the semester with an existing mockup in place, which was in need of a variety of modifications. While the conceptual design of the habitat went on (Phase I of the semester), the human factors team began preparing for the eventual transition to on-campus work (Phase II). This beginning period included a thorough review of the previous semester’s human factors tests and evaluations, as well as supporting educational materials such as human factors literature and guidelines from both the customer and pasta NASA documentation.
55 As we transitioned to in-person learning, we held a human factors briefing, led by an experienced subject matter expert, and began to hone in on what we wanted to evaluate in the human factors testing this semester. From here, the team formulated a list of mockup features to test and a rough day-in-the-life scenario, based on the Statement of Work. The team identified the pool of individuals from which the subjects would be recruited, scheduled internal and external dry runs, and scheduled out the testing and data analysis periods for the rest of the semester. Finally, the human factors team produced a full test plan, complete with five appendices: test procedures, pre-test questionnaire, post-test questionnaire, test monitor evaluation form, and safety plan. These documents were sent out to the human factors senior advisor and the senior engineer on the CU SHEDS team for review, and several edits were suggested. The team is currently in the process of implementing these edits and will send out another version for review in the coming days.
9.1 Test Goals and Evaluations The goals for the limited human factors testing this semester were laid out in the statement of work. The team is to evaluate: • Reach and visibility of the robotics workstation • Adequacy of crew accommodations • Suitability of the module as an airlock • Adequacy of the interior volume for expected tasks • Operational tasks (combined into crew accommodations for our test) The human factors team has constructed a day-in-the-life test scenario that will allow participants to interact with and evaluate different aspects of the module. The purpose of this testing structure is to immerse the subject in a contextualized scenario so they can provide accurate feedback on the module, which in reality would be in a microgravity environment and part of a much larger habitat.
9.2 Test Procedure Summary The day-in-the-life scenario starts the subject in a repair situation, wherein the subject is informed by the habitat there is a small issue with an RCS thruster. The subject will use the robotic workstation to assess and diagnose the issue via the external robotic arm, at which point it is deemed an EVA is needed to perform the repair. The subject then goes through part of their daily exercise routine before performing a brief xEMU maintenance task to prepare for the next day’s repair EVA. An abridged summary of the test procedure is shown below.
Activity Assessment Area Test subject arrives N/A COVID-19 safety briefing N/A Test subject completes liability forms and N/A undergoes anthropometric measurements Test subject completes pre-test N/A questionnaires Test subject enters airlock mockup N/A Test subject is briefed on day-in-the-life N/A repair situation and relevant context
56 Test subject performs robotics workstation display and controls reach and visibility Robotics Workstation testing Test subject unstows clothes in preparation Crew Accommodations for exercise Test subject deploys and uses ROCKY Crew Accommodations Test subject accesses xEMU tools and spare Crew Accommodations part Test subject accesses EVA suit and EVA conducts maintenance task Test subject exits airlock mockup N/A Test subject completes second set of N/A questionnaires and interview Test subject leaves N/A
9.3 Test Subject Recruitment Plan The participant selection process of the Spring 2021 semester has been greatly impacted by the COVID-19 global pandemic. Safety concerns and the desire to limit contact with external groups to the greatest extent possible has led the CU Boulder Human Spaceflight Graduate Project team to limit participation to the following groups: HOME personnel, CU SHEDS project advisors and senior management, CU SHEDS team members, former and future CU SHEDS team members, CU Boulder Bioastronautics professors, and BioServe Space Technologies employees. The selection of the HOME personnel is driven by HOME’s role as the customer and their desire for participation in human factors testing must be accommodated. The selection of the other groups (CU SHEDS project advisors and team members, CU Boulder Bioastronautics professors, and BioServe employees) was driven by the proximity of these groups to team members, and their relevant professional experience. Since the team already has regular face-to-face interaction with each other, project advisors, CU Bioastronautics professors, and the employees of BioServe, there is no perceived increase in the threat of COVID-19 transmission from the baseline of current activities. Additionally, these groups work in the bioastronautics field, many with direct relation to microgravity habitat design and development, and thus will be able to provide relevant and meaningful feedback. As experience increases the utility of the participant’s feedback, ideal participants for these evaluations would include those with flight experience and those who have proximity to the design and development of spacecraft and space habitats, due to their ability to make more informed evaluations of the design. The Human Factors team will actively seek participants with this background in the identified testing groups, however, participants outside of these backgrounds who may have less experience with flight and/or spacecraft design will still be used to help fulfill the goal of spanning a wide range of anthropometric sizes. Potential test participants will fill out a recruitment form (selected questions from Appendix B) which will be used for participant scheduling. This recruitment form will request the participant’s demographic information and flight experience in order to better classify participants. According to Virzi (1992), for general usability evaluations, 5 participants can identify 80% of severe usability problems in a design while 20 participants can detect nearly 100% of all low-, mid-, and high-severity issues in a design. Also, in general, to provide statistically significant data from human factors testing of the mockup using a participant-reported Likert scale for evaluation, a minimum of 30 data points is required. Recruitment of test participants with variances in anthropometry is desired due to NASA’s design criteria of accommodating 57 humans with body dimensions from the 5th percentile Japanese female to the 95th percentile American male. It is understood that if we are unable to gather test participants spanning this anthropomorphic range, the data will be skewed and/or the results would not reflect the entire anthropomorphic range. Therefore, measurements of each test participant will be taken to provide a better understanding of the results, and participant selection will be focused on filling the anthropomorphic range, if the number of participants who responded allows us to do so. The range of related experience of participants poses challenges for the interpretation of the statistical analysis. The participants discussed include a diverse group of people ranging from undergraduate students to former astronauts. The feedback from the former group is less valuable than the latter, as participants with any flight experience have a better reference frame for evaluating the HOME ARL mockup. In order to ensure the feedback of experienced fliers is not hidden by statistical noise, the level of relevant experience of each test participant will be accounted for by assigning weights to their responses. Test participants will be divided into the following five categories in order the weight their responses:
• Category 5: Test participants with relevant technical and environmental experiences. This includes flown astronauts. Responses from these participants will be weighted the highest, as their responses will draw from knowledge of functional space and/or flight systems. • Category 4: Test participants with relevant applied technical experiences. This category includes professional experience in aerospace engineering (specifically design and operation of pilots or spaceflight systems), cockpit design, human factors evaluations, spaceflight operations and training, or parabolic flight experience as a test subject or test monitor. This includes unflown astronauts and career professionals in human spaceflight design and operation. • Category 3: Test participants with related technical experiences. This includes certified pilots with greater than 250 hours of pilot in command time, experience in aerospace engineering (specifically in piloted aviation or spaceflight systems), cockpit design, human factors. • Category 2: Test participants with non-related technical experience. This includes general engineering experience or certified pilots with less than 250 hours of pilot in command time. • Category 1: Test participants with no technical or related experiences. Responses from these participants will be weighted the lowest. • The response of a more experienced test subject will be weighted by counting their responses more than once, depending on the additional level of experience they have over the average level present.
9.4 Test Data Analysis Plan Table 7 is a collective list of the data gathered during each portion of the test. However, further information on data collected can be found in Human Factors Test Plan Appendices B, C and D.
58 Table 7. Data collected from the pre- and post-test questionnaires Pre-Test Data Post-Test Data • Participant demographics • Post-test questionnaire (Appendix B) (Appendix C)
• Anthropometric data (Appendix A: specific measurements taken)
Test participant pre- and post-test data will be compiled with the observations and comments taken during testing to properly analyze the data collected. Open ended responses will be evaluated and included in the final testing report. The post-test questionnaire will survey participants on their experiences in the mockup during the day-in-the-life scenario using Likert scale questions, such as in Figure 43. These questions allow a participant to choose on a scale from 1 to 6, with 1 exhibiting undesirable characteristics and 6 desirable.
Figure 43. Example of a Likert-style question
In response to the COVID-19 global pandemic, additional health information will also be collected and recorded prior to eligibility for human factors testing participation. Each participant will be required to fill out the CU Boulder Daily Health Questionnaire and Illness Reporting Form which asks four brief questions about symptoms, temperature, recent close contact with a probable COVID-19 case, and testing history. Participants will also have their temperature taken by a test conductor prior to entering the testing space and will be required to alert the human factors team if any COVID-19 symptoms develop in the 14 days following testing so proper contact tracing can be performed. The data gathered in the pre-test questionnaire and anthropometric data will be used to determine the participant weighting for data analysis. Primary weighting factors are listed in Section 9.3 and an analysis of variance and post-hoc pairwise comparisons will be conducted to analyze the difference in data sets. The evaluations will return a set of quantitative and qualitative data for each test subject. This data will be analyzed with basic statistical methods, including, but not limited to, the following: mean, standard error, median, standard deviation, variance, and visually, with box and whisker plots, histograms, and scatter plots. Further statistical tools, such as ANOVAs, chi-squared tests, Pearson correlation tests, and least- squares regression may also be used. This will enable the Human Factors team to determine if the ARL design is adequate as portrayed in the mockup, or if an adjustment range is necessary.
59 If adjustment is necessary, this basic statistical analysis will determine the range of adjustment that will be adequate for the given test population. Test result data will be used with test conductor/monitor observational comments and the data gathered from the post-test questionnaire to properly analyze the data collected. Recommendations to inform the design will be made to the senior management team and the HOME team.
9.5 Future Work Remaining work for the human factors team includes the following major items: • Test plan revision and reassessment by human factors senior advisor and senior engineer • Internal dry runs with CU SHEDS team members to refine test procedure • External dry runs with human factors senior advisor and senior engineer • Human subject testing period (aiming for 20 participants) • Data analysis and reporting These items are all on schedule to be complete by the end of the semester, and the human factors team has been in close communication with the mockup team to ensure a smooth transition from building to testing.
10. Overall Status Update
10.0 Task and Deliverable Status
10.1 Hours Worked Between January 6th and March 12th 2021 the CU SHEDS team has worked a total of 1618.7 hours. Divided amongst 9 team members this comes out to an average of 22.4 hours per week per person. If each of our team members was paid at a rate of $35/hour, the total estimated cost for project labor thus far would be $56,653.
10.2 Spending Summary As of 03/17/2021 the below breakdown is the amount spent by the CU SHEDS, the majority of the spending has been focused on mock-up costs and administrative costs.
60 Table 8 Semester Spending
ALLOCATED SPENT REMAINING MOCK-UP $3,033.18 $368.75 $2,664.43 SAFETY $275.50 $6.87 $268.63 HUMAN FACTORS $100.00 $0.00 $100.00 ADMINISTRATION $385.00 $271.66 $113.34 SUB TOTAL $3,793.68 MARGIN $206.32 TOTAL $4,000.00 $647.28 $3,146.40
Figure 44. Purchased Items
10.3 Issues and Concerns The CU SHEDS team has run into some minor issues this semester. Most of these issues have been related to technology, personnel problems, and some logistics issues. For example, the team ran into some logistical issues in procuring a purchasing card to use for our project. This caused some minor delays in purchasing materials for in-person work. The personnel issues have mostly related to COVID restrictions that prevented certain team members from working in-person. Technology problems have also caused some data loss, and issues with corrupted files that made it difficult for multiple team members to edit the same document. The CU SHEDS team is aware of the potential for these issues to occur again and is actively trying to mitigate the risk of these issues occurring again. The major concern throughout the semester thus far has been remaining in close communication with the HOME team. It is a priority of the CU SHEDS team to ensure that the HOME team is aware of the details of the project, and that the work being done meets the needs of the HOME team. The CU SHEDS team continues to be concerned about COVID-related concerns such as restrictions, potential campus closure, or personnel loss. All concerns are being actively monitored by the CU SHEDS team, and work is being done to prevent these concerns from becoming problems in the future.
61 11. References
ECLSS Anderson, M. S., Ewert, M. K., & Keener, J. F. (2018). Life Support Baseline Values and Assumptions Document. National Aeronautics and Space Administration; NASA Technical Reports Server. https://ntrs.nasa.gov/citations/20180001338 Banerjee, N., & Dekarske, J. (2020). RT3 DESIGN REFERENCE SCENARIO. Brandon, D. (2013, August 25). Current Status of the Nitrogen Oxygen Recharge System. 41st International Conference on Enviromental Systems, Portland, Oregon. https://ntrs.nasa.gov/citations/20110012004 Carter, D. L., & Gleich, A. F. (2016, July 10). Selection of a Brine Processor Technology for NASA Manned Missions. 46th International Conference on Environmental Systems, Vienna, Austria. Curley, S., Stambaugh, I., Swickrath, M., Anderson, M., & Rotter, H. (2012, July 15). Deep Space Habitat ECLSS Design Concept. 42nd International Conference on Environmental Systems. 42nd International Conference on Environmental Systems, San Diego, California. https://doi.org/10.2514/6.2012-3417 Garrod, S., Bollard, M. E., Nicholls, A. W., Connor, S. C., Connelly, J., Nicholson, J. K., & Holmes, E. (2005). Integrated Metabonomic Analysis of the Multiorgan Effects of Hydrazine Toxicity in the Rat. Chemical Research in Toxicology, 18(2), 115–122. https://doi.org/10.1021/tx0498915 Gormly, S., & Flynn, M. (2006). Alternative Physical and System Architectures for Membrane Based Advanced Regenerative Space Life Support System Water Processing. SAE Transactions, 115, 193–199. JSTOR. Guo, B., Holder, D. W., & Tester, J. T. (2005). Two-Phase Oxidizing Flow in a Volatile Removal Assembly Reactor under Microgravity Conditions. AIAA Journal, 43(12), 2586–2592. https://doi.org/10.2514/1.12267 Hintze, P., & Guardado, H. (2018, August 21). Sabatier Subsystem Thermal Managment [Technical Presentation]. https://tfaws.nasa.gov/wp- content/uploads/5_ISRU-Sabatier-Reactor-for-TFAWS-2018.pdf Holder, D. W., & Hutchens, C. F. (2003). Development Status of the International Space Station Urine Processor Assembly. Society of Automotive Engineers, Inc. Jones, H. (2011, July 17). Carbon Dioxide Reduction System Trade Studies. 41st International Conference on Environmental Systems. 41st International Conference on Environmental Systems, Portland, Oregon. https://doi.org/10.2514/6.2011-5099 Limero, T., Brokenshire, J., Cumming, C., Overton, E., Carney, K., Cross, J., Eiceman, G., & James, J. (1992). A Volatile Organic Analyzer for Space Station: Description and Evaluation of a Gas Chromatography/Ion Mobility Spectrometer. SAE Transactions, 101, 1416–1424. Loeffelholz, D., Baginski, B., Patel, V., MacKnight, A., Schull, S., Sargusingh, M., & Callahan, M. (2014, July 13). Unit Operation Performance Testing of Cascade Distillation Subsystem. 44th International Conference on Environmental Systems, Tucson, Arizona.
62 Nabity, J. (2021, January 28). Atmosphere Management [Lecture]. Space Craft Life Support Class, CU Boulder Smead Aerospace. O’Neill, J., Bowers, J., Corallo, R., Torres, M., & Stapleton, T. (2019). Environmental Control and Life Support Module Architecture for Deployment across Deep Space Platforms. https://ttu- ir.tdl.org/handle/2346/84509 Perry, J. L., Abney, M. B., Conrad, R. E., Frederic, K. R., Greenwood, Z. W., Kayatin, M. J., Knox, J. C., Newton, R. L., Parrish, K. J., Takada, K. C., Miller, L. A., Scott, J. P., & Stanley, C. M. (2015). Evaluation of an Atmosphere Revitalization Subsystem for Deep Space Exploration Missions. ICES. https://ttu-ir.tdl.org/handle/2346/64383 Reysa, R., Granahan, J., Steiner, G., Ransom, E., & Williams, D. E. (2004). International Space Station (ISS) Major Constituent Analyzer (MCA) On- Orbit Performance. SAE Transactions, 113, 1283–1293. JSTOR. Schaezler, R. N., & Cook, A. J. (2015, July 12). Report on ISS O2 Production, Gas Supply & Partial Pressure Management. 45th International Conference on Environmental Systems, Bellevue, Washington. https://ttu- ir.tdl.org/bitstream/handle/2346/64417/ICES_2015_submission_146.pdf?seq uence=1&isAllowed=y Simon, M. A., Walker, S. A., & Clowdsley, M. (2013, July 14). Habitat Design Considerations for Implementing Solar Particle Event Radiation Protection. 43rd International Conference on Environmental Systems. 43rd International Conference on Environmental Systems, Vail, CO. https://doi.org/10.2514/6.2013-3403 Singh, S. K., & Xu, Q. (2010). Bimetallic Ni−Pt Nanocatalysts for Selective Decomposition of Hydrazine in Aqueous Solution to Hydrogen at Room Temperature for Chemical Hydrogen Storage. Inorganic Chemistry, 49(13), 6148–6152. https://doi.org/10.1021/ic1007654 Stapleton, T. J., Broyan, J. L., Baccus, S., & Conroy, W. (2013, July 14). Development of a Universal Waste Management System. 43rd International Conference on Environmental Systems. 43rd International Conference on Environmental Systems, Vail, CO. https://doi.org/10.2514/6.2013-3400 Takada, K. C., Ghariani, A., & Van Keuren, S. (2014, July 12). Advancing the Oxygen Generation Assembly Design to Increase Reliability and Reduce Costs for a Future Long Duration Mission. 45th International Conference on Environmental Systems, Bellevue, Washington. Takada, K. C., Velasquez, L. E., Van Keuren, S., & Baker, P. S. (2019, July 7). Advanced Oxygen Generation Assembly for Exploration Missions. 49th International Conference on Environmental Systems, boston, Massachusetts. Turner, E. H., Son, C. H., Smirnov, E. M., Ivanov, N. G., & Telnov, D. S. (2004). Air Circulation and Carbon Dioxide Concentration Study of International Space Station Node 2 with Attached Modules. SAE Transactions, 113, 1150–1154. Volpin, F., Badeti, U., Wang, C., Jiang, J., Vogel, J., Freguia, S., Fam, D., Cho, J., Phuntsho, S., & Shon, H. K. (2020). Urine Treatment on the International Space Station: Current Practice and Novel Approaches. Membranes, 10(11). https://doi.org/10.3390/membranes10110327 Weiland, P. O. (1998). Living Together in Space: The Design and Operation of the Life Support Systems on the International Space Station. National
63 Aeronautics and Space Administration; NASA Technical Reports Server. https://ntrs.nasa.gov/citations/19980037427 Weiland, P. O. (1998). Living Together in Space: The Design and Operation of the Life Support Systems on the International Space Station. National Aeronautics and Space Administration; NASA Technical Reports Server. https://ntrs.nasa.gov/citations/19980037427 Wieleand, P. O. (1994). Designing for a Human Presence in Space: An Introduction to Environmental Control and Life Support Systems. National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program. Structures
Arnold, J., Christiansen, E. L., Davis, A., Hyde, J., Lear, D., Liou, J., . . . Giovane, F. (2009). Handbook for Designing MMOD Protection. NASA.
Crew Accommodations
Garcia, M. (2017). Exercise Device for Orion to Pack Powerful Punch. National Aeronautics and Space Administration. https://www.nasa.gov/feature/exercise-device-for-orion-to-pack-powerful- punch. Polk, J.D (2019). NASA-STD-3001-Vol-2-Rev-b. National Aeronautics and Space Administration. https://www.nasa.gov/sites/default/files/atoms/files/nasa- std-3001_vol_2_rev_b.pdf Larson, W. J., & Pranke, L. K. (1999). Human spaceflight: mission analysis and design.
Power, Propulsion, Thermal, Avionics
Burns, J. O., Mellinkoff, B., Spydell, M., Fong, T., Kring, D. A., Pratt, W. D., Cichan, T., and Edwards, C. M. “Science on the Lunar Surface Facilitated by Low Latency Telerobotics from a Lunar Orbiting Platform – Gateway”.” p. 15. California State Polytechnic University. Lunar Base Outfitted With Interchangeability and Expandability. 2020 AIAA Lunar Base Camp Design Competition, 2020. Dumoulin, J. Reaction Control System. 1988. NSTS Shuttle Reference Manual Herman, D. A.; Gray, T.; Johnson, I.; Kerl, T. Lee, T.; Silva, T. The Application of Advanced Electric Propulsion on the NASA Power and Propulsion Element (PPE). 2019. 36th International Electric Propulsion Conference. IPEC-2019-651 Gurrisi, C.; Seidel, R.; Dickerson, S.; Disziulis, S.; Frantz, P.; Ferguson, K. Space Station Control Moment Gyroscope Lessons Learned. 2010. NASA Istanbul Technical University. Miluti-Use Lunar Transportation vehicle Utilizing Deep Space Gateway. 2019 AIAA Undergraduate Spacecraft Design Competition Submission, 2019. Juhasz, A. J.; Peterson, G. P. Review of Advanced Radiator technologies for Spacecraft Power Systems and Space Thermal Control. 1994. NTRS 64 Larson, W. J.; McQuade, P.D.; Pranke, L. K. Human Spaceflight Mission Analysis and Design, Second Edition. 2015. Space Technology Series. ISBN 978-1-7331679-0-1 Ottavi, M., Gizopoulos, D., and Pontarelli, S., Eds. Dependable Multicore Architectures at Nanoscale. Springer International Publishing, Cham, 2018. Sutton, G. P.; Biblarz, O, Rocket Propulsion Elements, Ninth Edition. 2017. John Wiley and Sons. ISBN 9781118753651 Timmons, K., Coderre, K., Pratt, W. D., and Cichan, T. The Orion Spacecraft as a Key Element in a Deep Space Gateway. Presented at the 2018 IEEE Aerospace Conference, Big Sky, MT, 2018.
Human Factors
Gordon et. al. “2012 Anthropometric Survey of U.S. Army Personnel: Methods and Summary Statistics,” U.S. Army Natick Soldier Research, Development and Engineering Center, December 2014. Human Spaceflight Graduate Program: Human Factors Test Plan, Fall 2018 Human Spaceflight Graduate Program: Human Factors Test Plan, Fall 2019 Human Spaceflight Graduate Program: Human Factors Test Plan, Fall 2020 Human Spaceflight Graduate Program: Human Factors Test Plan, Spring 2018 Human Spaceflight Graduate Program: Human Factors Test Plan, Spring 2019 Human Spaceflight Graduate Program: Human Factors Test Plan, Spring 2020 M. C. Dorneich, C. Hamblin, R. DeMers and O. Olofinboba, "A task-based reach-zone analysis of the Orion Crew Exploration Vehicle controls," 2011 IEEE International Conference on Systems, Man, and Cybernetics, Anchorage, AK, 2011, pp. 2082-2086. NASA Human Integration Design Handbook (NASA/SP-2010-3407) NASA Space Flight Human Systems Standards Volume 1 (NASA-STD-3001) Virzi, Robert A. “Refining the Test Phase of Usability Evaluation: How Many Subjects Is Enough?” Human Factors: The Journal of the Human Factors and Ergonomics Society, vol. 34, no. 4, 1992, pp. 457–468., doi:10.1177/001872089203400407. Winter, David A, Biomechanics and Motor Control of Human Movement, 4th Edition, John Wiley and Sons, Inc. Hoboken, NJ, 2009.
65 12. Acronyms and Abbreviations Term Definition ADCS Attitude Determination and Control System BIOASTRO University of Colorado Bioastronautics Group CA Crew Accommodations CDH Command and Data Handling CONOPS Concept of Operations CU University of Colorado Crewed and Uncrewed Semi-autonomous Habitat for the Exploration of Deep CU SHEDS Space 4BMS Four Bed Molecular Sieve AOGA Advanced Oxygen Generator ARS Atmosphere Revitalization Subsystem BEB Brine Evaporation Bag BP Brine Processor BVAD Baseline Values and Assumptions Document CDRA Carbon Dioxide Removal Assembly CHX Condensing Heat Exchanger DOF Degrees of Freedom DSH Deep Space Habitat ECLSS Environmental Control and Life Support System EVA Extravehicular Activity FOBD Forward Osmosis Brine Dryer GNC Guidance, Navigation, and Control HDPE High Density Polyethylene HOME Habitats Optimized for Missions of Exploration IDSS Internal Docking System Standard ISS International Space Station ITCS Internal Thermal Control System ITLL Integrated Technology Learning Laboratory IWP Ionomer Water Processor kJ Kilojoules kPa Kilopascals MLI Multi Layered Insulation MMOD Micrometeoroids and Orbital Debris NASA National Aeronautics and Space Administration NASA-SP NASA Special Publication NASA-STD NASA - Standard NASA-TM NASA Technical Manual NORS Nitrogen/Oxygen Resupply System OGA Oxygen Generator Assembly ORU Orbital Replacement Unit OSHA Occupational Safety and Health Administration PCA Pressure Control Assembly PI Proportional Integral PPE Power Propulsion Element psia Pounds per Square Inch
66 PWB Potable Water Bus STRI Space Technology Research Institute SSER Space to Space Station Radio RCS Reaction Control System TALOS The Artemis Lunar Operating System TCCS Trace Contaminant Control Subassembly TCCV Temperature Control Check Valve TDRSS Tracking and Data Relay Satellite System THCA Temperature and Humidity Control Assembly TRL Technology Readiness Level UIA Umbilical Interface Assembly UWMS Universal Waste Management System VOA Volatile Organic Analyzer VCDS Vapor Condensation and Distillation System WB Wastewater Bus WMS Waste Management System WP Water Processor
67 13. Appendix A – Mass, Power, and Volume Estimates Table 9 shows the total mass of the CU SHEDS habitat broken up by subsystem. The mass of components internal to the pressurized volume can be found in the “Internal Mass” column while masses external to the pressurized volume can be found in the “External Mass” column. The total for each subsystem can be found in the “Subsystem Total” column. While this table only details the masses of subsystems as a whole, mass estimates for individual components can be found in the Master Equipment List in Appendix A. Table 9 Habitat Mass Estimates Internal External Subsystem Mass [kg] Mass [kg] Total [kg] ECLSS 4139 0 4139 CA 385 0 385 Structures 5865 0 5865 Robotics 136 286 422 EVA 669 0 669 Avionics 300 0 300 Thermal 269 9946 10215 Prop 0 11012 11012 Power 6 4200 4206 Comms 42 0 42 TOTAL 11,811 25,444 37,254
Figure 45 shows the total mass of the CU SHEDS habitat broken up by subsystem and showing the allocation of the DSH itself and the PPE.
Total Mass [kg] ECLSS CA ECLSS Structures CA Structures Robotics Robotics EVA EVA Avionics Avionics Thermal Thermal PPE Power Power Comms Comms
Figure 45. Total Mass Breakdown 68
Figure 46 and Table 10 Internal Volume Estimatesdisplay the breakdown of the subsystem volume allocations of the internal pressurized volume. In general, these volume estimations attempt to be indicative of both the technology itself and the unusable area the technology creates around it with wiring, ducting, pipes, or simply a lack of efficient packing to represent the true volume the subsystems encompass. Adding all of these subsystem volumes yields a total volume of 19.19 m3, leaving 103.14 m3 of habitable volume, as seen in Figure 47.
Total Internal Volume [m3]
EVA, 1.82 Avionics, 1.50 Power, 0.01 Robotics, 0.11 Comms, 0.06 ECLSS Structures, CA 3.65 Structures Robotics EVA Avionics Thermal Prop Power Comms ECLSS, 8.15 CA, 3.89
Figure 46. Internal Volume Broken up by Subsystem
Table 10 Internal Volume Estimates Total Volume (Volume Estimate + Consumable 3 Volume) [m ] ECLSS 8.15 CA 3.89 Structures 3.65 Robotics 0.11 EVA 1.82 Avionics 1.5 Thermal 0 Prop 0 Power 0.01 Comms 0.06 TOTAL 19.19 69
Figure 47. Summary of Pressurized Volume Table 11 Power Estimatesshows the power estimates for the DSH. Here, positive numbers show the power draw of a subsystem while negative numbers indicated power generation. The negative number in the total power consumption column shows that we have more than enough power to operate our DSH as currently designed.
Table 11 Power Estimates Internal Power External Power Total Power Consumption [W] Consumption [W] Consumption [W]
ECLSS 3985 0 3985 CA 340 0 340 Structures 0 0 0 Robotics 371 3681 4052 EVA 120 0 120 Avionics 170 0 170 Thermal 0 2200 2200 Prop 0 54400 54400 Power 0 -85400 -85400 Comms 144 0 144 TOTAL 5130 -25119 -19989
70 14. Appendix B – Trade Studies
14.0 Radiation Protection:
14.1 Brine Processing Table 12. Parameters and values for brine processor trade study.
Technology CapiBRIC IWP BEB FOBD Mass (kg) 17.3 14.1 52.8 67.8 Volume (m^3) 0.11 0.15 0.14 0.16 System Power (W) 134 142 360 191 Total Mass (kg/1100 days) 411 53 85.7 112 Total Volume (m^3/1100 0.57 0.71 0.8 1.2 days) Water Recovery (%) 98 80 95 92 Production Rate (L/day) 2 1.3 2.8 1 Reliability 2 8 5 5
Table 13. Parameter weighting for brine processor trade study.
Parameter Value Rational Mass (kg) 1 PUT A RATIONAL HERE Volume (m^3) 2 A favorable Component volume will maximize space for other subsystems System Power 2 A favorable Component mass will minimize launch costs Total Mass (kg/1100 4 Consumable mass is critical to the mission days) Total Volume 4 Consumable volume is critical to the mission (m^3/1100 days) Water Recovery 1 All technologies have adequate values Production Rate 1 All technologies have adequate values Reliability 3 Reliability is key on long duration missions 71
Table 14. Brine processor trade study results.
Technology CapiBRIC IWP BEB FOBD Mass (kg) 10 10 6 5 Volume (m^3) 16 16 18 16 System Power 18 18 8 16 Total Mass (kg/1100 days) 12 40 40 36 Total Volume (m^3/1100 24 16 12 4 days) Water Recovery 10 1 8 7 Production Rate (L/day) 6 2 10 1 Reliability 2 8 5 5 Sum 98 111 107 90
14.2 Power
Static Solar Parameter Weight Score Weighted Score Power 0.2 2 0.4 produced Mass 0.3 4 1.2 Operational 0.2 4 0.8 life Versatility 0.3 3 0.9 3.3 Rotating Solar Parameter Weight Score Weighted Score Power 0.2 3 0.6 produced Mass 0.3 3 0.9 Operational 0.2 4 0.8 life Versatility 0.3 4 1.2 3.5 RTGs Parameter Weight Score Weighted Score Power 0.2 4 0.8 produced Mass 0.3 2 0.6 Operational 0.2 4 0.8 life Versatility 0.3 3 0.9 72
3.1 Fission Reactor Parameter Weight Score Weighted Score Power 0.2 5 1 produced Mass 0.3 1 0.3 Operational 0.2 4 0.8 life Versatility 0.3 1 0.3 2.4 Fuel Cells Parameter Weight Score Weighted Score Power 0.2 3 0.6 produced Mass 0.3 2 0.6 Operational 0.2 3 0.6 life Versatility 0.3 2 0.6 2.4
14.3 Propulsion
Hall Effect Thrusters Parameter Weight Score Weighted Score Efficiency 0.3 5 1.5 Mass 0.1 4 0.4 Power 0.2 2 0.4 Applicability 0.4 4 1.6 3.9
Bipropellant Thrusters Parameter Weight Score Weighted Score Efficiency 0.3 3 0.9 Mass 0.1 3 0.3 Power 0.2 4 0.8 Applicability 0.4 2 0.8 2.8
73
Nuclear Thermal Thruster Parameter Weight Score Weighted Score Efficiency 0.3 4 1.2 Mass 0.1 1 0.1 Power 0.2 4 0.8 Applicability 0.4 2 0.8 2.9
14.4 ADCS
Reaction Wheels Parameter Weight Score Weighted Score Fine Control 0.4 4 1.6 Desaturation Frequency 0.2 2 0.4 Maintenance 0.2 3 0.6 Mass 0.1 3 0.3 Latent Stability 0.1 2 0.2 3.1
Control Moment Gyros (Gyrodynes) Parameter Weight Score Weighted Score Fine Control 0.4 4 1.6 Desaturation Frequency 0.2 4 0.8 Maintenance 0.2 2 0.4 Mass 0.1 3 0.3 Latent Stability 0.1 4 0.4 3.5
Bias-Momentum Wheels Parameter Weight Score Weighted Score Fine Control 0.4 4 1.6 Desaturation Frequency 0.2 3 0.6 Maintenance 0.2 2 0.4 Mass 0.1 3 0.3 Latent Stability 0.1 4 0.4 3.3
14.5 Thermal 74
Double Sided (Rotating, Collapsible Vane) Parameter Weight Score Weighted Score Mass 0.2 4 0.8 Heat Dissipation 0.3 5 1.5 Versatility 0.3 5 1.5 Complexity 0.2 4 0.8 4.6
Single Sided Parameter Weight Score Weighted Score Mass 0.2 5 1 Heat Dissipation 0.3 4 1.2 Versatility 0.3 4 1.2 Complexity 0.2 5 1 4.4
Ammonia - Water Parameter Weight Score Weighted Score Heritage 0.3 5 1.5 Safety 0.2 4 0.8 Effectiveness 0.2 5 1 Familiarity 0.3 5 1.5 4.8
Propylene Glycol Parameter Weight Score Weighted Score Heritage 0.3 4 1.2 Safety 0.2 5 1 Effectiveness 0.2 5 1 Familiarity 0.3 4 1.2 4.4
75 15. Appendix C – Master Equipment List The Master Equipment List (MEL) details the technology selection which fulfills each of the requirements for the DSH. The full list of requirements for the DSH can be found in the red columns on the far left of the table. Next to these is the “Assigned Subsystem” column which designates the subsystem that selected the technology associated with that requirement. Additional information regarding the selection and details of the technology can be found in the corresponding subsystem section of the CU SHEDS Concept Definition Review Document and this CU SHEDS Preliminary Design Review Document, respectively. Each requirement has its proposed technology in the green column adjacent to the requirement. The number of units required to fulfill the requirement is listed in the gray “Quantity” column while the yellow “Module Designation” records which module the technology must be placed in. The blue columns detail the mass, power, and volume estimates for each of the specific technologies chosen, while the orange columns detail the mass of the consumable that go along with that technology. The purple “Total” columns are an addition of the blue and orange columns to show the final. The source of the information detailed in the main body of the table can be found in the gray “reference/source” column. Any additional information that may be relevant but does not fit in the other columns will be found listed in the gray “General Notes” column. It should be noted that full mass, power, and volume estimates for each subsystem were not always able to be obtained, so best estimates are recorded here. Any specific assumptions made in these estimations are detailed in the blue “Mass, Volume, Power Estimate Assumptions” and the orange “Consumable Assumptions” columns.
76