P19127: XHab Deployable Crew Lock Structure
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Problem Definition

Table of Contents

Team Vision for Problem Definition Phase

During the problem definition phase, our team’s goal was to determine project scope, ensure that the project aligned with the customer’s needs, and establish the core team structure. In order to accomplish these tasks, the team began by discussing the PRP, creating a problem definition, and forming a list of questions that were necessary to better understand the project and the customer’s expectations. These questions were successfully answered during an in-person meeting with the customer, and this information was then used to create a list of customer and engineering requirements. The team also created Use Scenarios in order to better understand the various situations that the end product must be able to function in. Lastly, in order to develop a team structure, the group created a list of positions & their affiliated responsibilities critical for project success, and then distributed these responsibilities among the group.

Project Definition

A Lunar Orbital Platform-Gateway (LOP-G) is a proposed intermediate platform for future NASA expeditions into deeper space. Short-term, the gateway will be used as an astronaut training station. Long-term, it will serve as a deployment site for spacecraft transporting crew to the lunar surface and deep space locations. A critical element to the LOP-G is the crew-lock structure which allows crew members to go between the pressurized environment of a spacecraft to the vacuum of space. Currently, crew-locks have rigid designs affixed to the outside of the station; however, NASA would like proposals for an inflatable/deployable crew-lock.

The goal of the project is to design, build, and test a 1/4 - 1/6 scale version of a two-man inflatable/deployable crew-lock for performance in a low-G environment. The design should consider human factors such as stowable handrails, and internal and external attachment points for equipment, crew tethers, and outfitting. The resulting crew-lock should be capable of integrating with the LOP-G hatch, and should comply with NASA requirements for a pressure vessel in an outer space environment. This project will help further NASA’s research and understanding of soft, deployable structures for deep-space travel.

For a condensed document outlining this page, please download the Project Summary Document.

Project Goals and Key Deliverables

Project Goals

Key Deliverables

Stakeholders

Customer

Faculty guide

End Users

Project Summary

Project Summary Document

Project Summary Document

Use Cases

The scope of this project limits the amount of scenarios in which this design could be implemented and used. Therefore, the space crew-member of the LOP-G is the only perceivable user which is projected to utilize the inflatable crew-lock.

Below is a generalized example of the scenario in which this design will be used.

Deployment and EVA Use Scenario

Deployment and EVA Use Scenario

Customer Requirements (Needs)

Listed below are the Customer Requirements for this project, which have been confirmed by our customer.
Customer Requirements - 10/12/2018

Customer Requirements - 10/12/2018

Customer Interview

Interview Date Interviewee Interview Subject Interview Notes
08/29/2018 Dr. Lamkin-Kennard Initial Customer Requirements and Introductions
09/11/2018 Dr. Lamkin-Kennard Confirmation of Customer Requirements and Engineering Requirements
  • All Customer Reqs must have associated Engineering Reqs
  • "Human elements" needs further definition
  • Rest of Customer Reqs and Engineering Reqs look good

Engineering Requirements (Metrics & Specifications)

Listed below are the Engineering Requirements based on the Customer Requirements given to us by our customer.
Engineering Requirements - 10/12/2018

Engineering Requirements - 10/12/2018

Engineering Requirements Sources

The sources seen in the image below can be found in the Engineering Requirements excel workbook on the sheet named "Tabulated Sources. This workbook can be downloaded at the bottom of this page in the "Design Review Materials" section.
Engineering Requirements Sources - 10/12/2018

Engineering Requirements Sources - 10/12/2018

Benchmarking

Below is a table of benchmarks for existing product sin the realm of deployable structures and deployable space modules. There are not many products in this realm with easily available information. All information was obtained from sources mentioned in the Engineering Requirements Sources section above.
Benchmarking Table

Benchmarking Table

House of Quality

Below is our House of Quality. This House of Quality is how we weighted the priority for each of our Engineering and Customer Requirements.

Through this analysis, we have concluded that the most important elements to this crew-lock are the depressurized and pressurized modes of pressure, structural deployment and integrity, simulated equipment inside and outside of the crew-lock, and the EVA hatch.

House of Quality - 09/10/2018

House of Quality - 09/10/2018

Constraints

Listed below are our constraints. These are not requirements or risks; however they are factors we must consider when designing our system.

For a list of team-member skills, which can be considered restraints, please visit the Planning & Execution page.

Constraint Category Constraint Description Comments
Economic Cost Limitations - Only given $500 for the project Can apply for National or State Level Space Grants
Economic Material Limitations - low budget requires use of cheap and readily available components Innovative use of available materials and components is needed so that the scope and cost of the project does not increase dramatically. (e.g. Don't design our own air compressor)
Resource Time Limitations - 8 months to complete project Keep a focused scope on the project
Resource Knowledge Limitations - limited knowledge base between team members Work with Dr. Lamkin-Kennard to obtain advisers and subject matter experts
Resource Fabrication Limitations - high-precision fabrication is not possible at current budget Obtain more funding or meet minimum requirements using innovative and cheap solutions
Design Design Limitations - Must be 1/4 - 1/6 size of existing full-size crew-lock (as seen in the Engineering Requirements) Scaling can be larger, but not smaller
Design Pressure Limitations - Pressures are standard on the ISS (as seen in the Engineering Requirements) Hold and vacuum pressures are the most important
Design Testing Limitations - Lack of vacuum testing environment. Use gauge pressure (atmospheric plus added pressure) to test structure
Safety Safety Limitations - All movement of the crew-lock and equipment on/in the crew-lock must account for human presence Design for human interaction, human error, and ergonomics

Plans For Next Phase

Below is the Condensed Gantt Chart for our next 3-weeks. A more detailed Gantt Chart (named "Master Schedule") with task breakdowns and responsibilities can be downloaded in the Design Review Materials Section at the bottom.
Condensed Gantt Chart - Systems Design Phase Plan

Condensed Gantt Chart - Systems Design Phase Plan

Conclusions for this Phase

During this phase, we have concluded that this project will require more than the resources we currently have available to us. The scope and requirements for this project far outreach our current capabilities as a team. Many of the ideal and marginal values for requirements we originally thought of have been relaxed substantially, or have been left up to the team to decide upon. These design relaxations are both a help and a hindrance. This is a help because we have creative freedom for the design of the entire crew-lock; however, this is a hindrance because we now have to deal with scope-creep, lack of expertise, and lack of direction; all of these are also compounded by a lack of funding. To solve these shortcomings, we are working with Dr. Lamkin-Kennard about obtaining more expertise in the domain of Aerospace and Space, and also working with her to obtain more funding from groups within and outside of RIT. We are also looking through many research papers, books, and manuals about the current NASA crew-lock and the International Space Station in order to expand our knowledge base on the crew-lock.

Problem Definition Phase Review Notes

Starting Date Ending Date Meeting Notes
August 2018 September 2018 Design Review Notes - Problem Definition Phase

Design Review Materials


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