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Extraterrestrial Surface Construction

Description:

Scope Title:

Extraterrestrial Surface Construction: Assembly of Tall Truss-Based Power Towers

Scope Description:

Assembly of truss-based structures is one of the leading candidates for establishing some of the early lunar infrastructure—for example, tall towers (50- to 80-m total height, which includes the attached payload height) for solar power generation, blast containment shields for launch and landing pads, shelters, etc. While structural assembly on Earth is a well-established construction approach, many technology gaps exist for the automated assembly of truss infrastructure on the Moon. Specifically, joining technologies and robotic tools are required to enable autonomous/automated assembly of these structures, which are often composed of hundreds of individual elements.

Proposals are invited for the development of assembly and joining concepts and the robotic tools required to assemble large-scale truss structures. The primary focus of this activity is the assembly of a tall (50- to 80-m class) truss-based tower. However, extensibility of the joining concepts and robotic tools to other structural assemblies is desirable. Joining methods can include, but are not limited to, mechanical fastening (e.g., rivets), welding, and bonding (both reversible and nonreversible approaches to joining). Proposals to the current solicitation can assume that the truss elements being assembled are between 0.75 and 1.5 m in length, with either an angle or square prismatic cross sections (cross-section dimensions listed below). It is expected that early assembly missions will use Earth-sourced truss elements and that these elements may be either aluminum or composite. However, over time, it is expected that ISRU-based aluminum truss elements will replace Earth-sourced elements for large-scale infrastructure development. Thus, concepts that support assembly of Earth-sourced and ISRU-based truss elements are favored. Finally, it is also assumed that a commercial space-capable robotic manipulating arm will be available and that proposals shall concentrate on the development of specialized robotic tooling required for assembly; however, it is desirable for proposers to specify the estimated infrastructure and robot capabilities assumed (reach, payload capacity, etc.).

Proposal elements of interest include, but are not limited to, the following:

  • Joining concepts for assembly of composite and/or aluminum truss structures (including the joining method and any necessary fittings/tooling/jigging).
  • Joint/node designs.
  • Robotic tools for assembly that are compatible with commercially available robotic manipulator arms.
  • Considerations for operating in lunar daytime environment (1/6 gravity, temperature, radiation, vacuum, lighting, power requirements).
    • Note: Proposal does not have to produce space-rated equipment; however, the processes shall be applicable to the lunar environment. Justification of design choices shall be included.
  • Concepts that maximize structural efficiency, minimize power requirements and complexity, and maintain suitable tolerances during assembly (not to exceed a 1-degree tilt when assembled on a horizontal surface).
  • Concept of operations describing process to assemble a tall tower using the robotic tools and joining methods developed.
  • Description of the assumed robotic system(s) and infrastructure necessary for the proposed approach, including reach, payload, etc., of the individual robotic agents.
  • Preliminary proof-of-concept demonstrations, methods, and equipment.
  • Outline application to other truss-based assemblies, e.g., walls, arches, and domes.

Focused application for development: Assembly of a tall tower:

  • Tower height: 50- to 80-m class.
  • Tower payload: 1,500 kg at top of tower (250 kg Earth equivalent for 1/6 gravity loads).
  • Assembly tolerance: Straight to within ±1-degree tilt when assembled on a horizontal surface.
  • Factor of safety of 5 on buckling and 10,000 psi maximum stress.
  • Assume assembly site is level to within ±2.5 degrees.
  • Assume a suitable foundation/interface is available for assembly; however, proposals are free and encouraged to provide/derive their own foundation/interface requirements.
  • NASA concept of operations (ConOps) = Module build and lift assembly approach (i.e., assemble a truss module, lift up and assemble the next module below, repeat until tower is fully erected).

Assume the following truss elements are available for use in the assembly:

  • Truss element lengths: 0.75 to 1.5 m (it can be assumed that intermediate lengths can be obtained if necessary).
  • Truss element cross section:
    • Square rod: 5 mm2, 10 mm2, 15 mm2 
      • Angle: flange length 10 mm, 20 mm, 40 mm; flange thickness 1.0 mm, 2.0 mm, 4.0 mm, 6.0 mm
  • Truss material:
    • Earth sourced = aluminum 6061, graphite-epoxy
    • ISRU-based = 98% pure aluminum (properties similar to 1-series untempered aluminum; E = 10 Msi, yield >5 ksi)

Expected TRL or TRL Range at completion of the Project: 3 to 5

Primary Technology Taxonomy:

  • Level 1 12 Materials, Structures, Mechanical Systems, and Manufacturing
  • Level 2 12.X Other Manufacturing, Materials, and Structures

Desired Deliverables of Phase I and Phase II:

  • Research
  • Analysis
  • Prototype
  • Hardware
  • Software

Desired Deliverables Description:

Phase I must include the design and test of critical elements associated with the proposed joining and robotic technologies to assemble truss-based structures, leading to a 50- to 80-m-tall tower in Phase II. For example, joint designs, structural analysis, and associated fabrication and testing must be included. Phase I must also include a concept of operations for the assembly of the tower and the design and testing of the robotic assembly system concept. Phase I proposals should result in at least TRL 4 structures and robotic assembly system.

  • NOTE: It is expected that not all element lengths or cross sections will be applicable to the design of a 50-m-tall tower; however, preference will be given to proposals with versatile approaches that accommodate larger combinations of the truss elements described above.

Phase II deliverables must include demonstration of a 50-m tower assembly. The tower is expected to be constructed using robotic systems and implements and joint designs developed in Phase I. Structures and systems must be developed to a minimum of TRL 5. Phase II assembly shall also include the integration and deployment of a surrogate 100-kWe solar array.

  • NOTE: Proposers should be aware of a complementary SBIR topic scope on outfitting of wiring harnesses and junction boxes and may take advantage of potential synergies between topics.

State of the Art and Critical Gaps:

While civil engineering and construction are well-established practices on Earth, automated lunar applications remain at low TRLs. Large-scale lunar infrastructure will require the construction of towers, landing pads, shelters, and habitats, many of which can be accomplished by the assembly of common structural elements such as trusses and panels. To date, very few activities have been conducted to develop robotic assembly of large-scale truss-based structures such as 50- to 100-m-tall towers or arches for shelters and habitats. Most assembly technologies have been proof-of-concept and developed at a small scale. Thus, to accomplish large-scale structural assembly on the lunar surface, joining technologies and robotic assembly systems are needed.

NASA Moon to Mars Objectives: LI-1 Development of a Global Power Grid, and LI-3.1 Industrial Scale Construction capabilities – Roads with autonomous navigation aids & Assembly of towers.

The NASA Space Technology Mission Directorate (STMD) STARPort database currently includes four technology gaps related to assembly of structures, for example, power towers:

  • Assemble truss-based tower.
  • Structural elements for assembly.
  • Structural joints/joining technology.
  • Autonomy and robotics to assemble the tower.

Relevance / Science Traceability:

Robotic assembly of truss-based structures directly addresses the STMD Strategic Thrust "Live: Sustainable Living and Working Farther from Earth," and the following Moon to Mars Objectives:

  • LI-1 Development of a Global Power Grid.
  • LI-3.1 Industrial Scale Construction capabilities – Roads with autonomous navigation aids and Assembly of towers.

References:

  • Doggett, William. "Robotic assembly of truss structures for space systems and future research plans." Proceedings, IEEE Aerospace Conference. Vol. 7. IEEE, 2002.
  • Belvin, Wendel K., et al. In-space structural assembly: Applications and technology. 3rd AIAA Spacecraft Structures Conference, 2016.
  • Komendera, Erik, et al. Truss assembly and welding by intelligent precision jigging robots. 2014 IEEE International Conference on Technologies for Practical Robot Applications (TePRA). IEEE, 2014.
  • Moses, R.W., and Mueller, R.P. (2021). Requirements development framework for lunar in situ surface construction of infrastructure. Earth and Space 2021, pp. 1141-1155.

Scope Title:

Foundations and Assembly Technologies for Lunar Landing/Launch Pad Structures

Scope Description:

Proposals are invited for the development of technologies for foundations and assembly of lunar landing/launch pad structures using advanced construction techniques and ISRU materials. Materials extracted from in situ lunar and planetary resources (e.g., materials extracted from the minerals in the regolith present on the surface) have the potential to radically reduce the cost and increase the scale of ambitious future space exploration activities and sustainable infrastructure. The design and fabrication of such systems and associated technologies so that construction and subsequent outfitting can be effectively accomplished locally is essential to their utilization. Design scaling for eventual outfitting should be considered.

Materials, components, and systems that would be necessary for the proposed technology must be able to operate on the lunar surface in temperatures up to 127 °C (261 °F) during sunlit periods and as low as -170 °C (-274 °F) during periods of darkness. Systems must also be able to operate for at least 1 year, with a goal of 5 years without substantial maintenance in the dusty regolith environment. Proposers should assume that operations involving other systems (e.g., robots), and later astronauts, will be ongoing not more than tens of meters away from the local fabrication, construction, and/or outfitting activities. Phase I efforts can be demonstrated at any scale; Phase II efforts must be scalable up to relevant size.

Each of the following specific areas of technology interest may be developed as a standalone technology.

  • Enabling foundation emplacement capable of withstanding the lunar seismic environment. Proposals should include the design of an interface with regolith that will allow for one or more of the following: (1) mitigation of lunar seismic activity for infrastructure element stability (e.g., flexible foundation designs and dampening); (2) “sealing” to the regolith (the physical interface between the integrated system and regolith that allows pressurization of structures placed on the foundation) to allow emplacement of a foundation material with relatively high vapor pressure in a temporary pressurized volume at a build site; (3) wear resistance of the foundation materials; and (4) structural anchoring technologies.
  • Novel structural systems: Proposals should address novel structural systems for Human Landing System (HLS) lunar lander launch/landing pads that can be fabricated from as much local extraterrestrial material as possible, can be assembled locally with robotics and/or astronaut-assisted construction, and are designed for easy and effective maintenance to maintain performance. Some materials may be transported from Earth, but these should be minimized. Proposals should address the following attributes: low and/or predictable coefficients of thermal expansion, strength, mass, reliability, radiation protection, waste heat rejection in lunar or other planetary environments, energy efficiency, and cost. Design considerations for the outfitting of landing pads are encouraged.

Expected TRL or TRL Range at completion of the Project: 3 to 5

Primary Technology Taxonomy:

  • Level 1 12 Materials, Structures, Mechanical Systems, and Manufacturing
  • Level 2 12.2 Structures

Desired Deliverables of Phase I and Phase II:

  • Analysis
  • Prototype
  • Hardware
  • Software

Desired Deliverables Description:

Phase I proposal deliverables should include a document describing appropriate materials, design, interfaces, and behavior in the lunar seismic environment, as well as a presentation describing the work and interpreting the results. Extensibility of the foundation concept to other lunar surface infrastructure elements such as tall towers, shelters, and habitats is desirable.

Phase II deliverables must be a demonstrated foundation concept to other lunar surface infrastructure element(s) in Earth 1g but should include design recommendations for mass reductions due to operations in lunar gravity (1/6 gravity) deployment.

State of the Art and Critical Gaps:

State of the Art:

  1. At present there are additively constructed concrete house neighborhoods in Austin, TX, and southern Mexico with a level of secure remote operations capability.
  2. NASA Lunar Pad Team - Subscale development of concrete landing pad printing and testing at U.S. Army Camp Swift, TX. October 2020.
  3. U.S. Army Corps of Engineers, Engineering Research and Development Center (ERDC), Construction Engineering Research Laboratory (CERL), Development of forward operating base construction technologies, Champaign, IL.

Critical Gaps:

  1. Technologies and lunar construction materials for larger scale development of Earth-based landing pads.
  2. Autonomous operations and emplacement technologies.
  3. In situ material utilization to minimize launch mass associated with raw materials capabilities: "Living off the land" and remote construction. Examples of desired infrastructure are power plants, habitats, refineries, greenhouses, launch and landing pads, and blast shields.
  4. Design criteria and civil engineering standards for these first in situ infrastructure assets.
  5. Thermal transfer of heat from plume impingement in a vacuum environment.
  6. Mitigation of regolith blast ejecta from plume impingement.
  7. Maintenance and repair for long lifetimes (>5 years).

 

Relevance / Science Traceability:

This technology is very much applicable in Space Technology Mission Directorate (STMD) support of its NASA, Government, and industry customers.

  • STMD for Science Mission Directorate (SMD) - Radio telescope structural support (back side of the Moon).
  • Exploration Systems Development Mission Directorate and Space Operations Mission Directorate (ESDMD-SOMD) Human Habitats - Space infrastructure, as in buildings, landing pads, roads, berms, radiation protection, custom building sizes and shapes.
  • Department of Defense (DoD) and Earth-based Government agencies - In situ construction capabilities both locally and remote.

 

References:

  • Gelino, N.J.; Mueller, R.P.; Moses, R.W.; Mantovani, J.G., Metzger, P.T., Buckles, B.C., and Sibille, L. (2021). Off Earth Landing and Launch Pad Construction—A Critical Technology for Establishing a Long-Term Presence on Extraterrestrial Surfaces. Earth and Space 2021, pp. 855-869.
  • Moses, Robert W.; and  Mueller, Robert P. Requirements Development Framework for Lunar In Situ Surface Construction of Infrastructure. Earth and Space 2021, pp. 1141-1155.
  • Clinton, R.G., Jr., PhD; Prater, Tracie, PhD; Edmunson, Jennifer, PhD; Fiske, Mike; and Effinger, Mike. Don’t Take It – Make It: NASA’s Efforts to Address Exploration Logistics Challenges through In Space Manufacturing and Extraterrestrial Construction for Lunar Infrastructure. Novel Orbital and Moon Manufacturing, Materials, and Mass-efficient Design (NOM4D) Kick-Off December 14-15, 2021. https://ntrs.nasa.gov/api/citations/20210025774/downloads/NOM4D%20KO%2012.15.2021.pdf
  • Mueller, R.P.; Moses, R.; Wilson, D.; Carrato, P.; and King, T. (2020). Lunar Mega Project: Processes, Work Flow and Terminology of the Terrestrial Construction Industry versus the Space Industry. ASCE Earth & Space Conference (No. KSC-E-DAA-TN78054).

 

Scope Title:

Outfitting of Lunar Surface Structures: Tall Truss-Based Power Towers

Scope Description:

The assembly and outfitting of truss-based structures, and in particular, tall solar power towers, is a leading candidate for some of the earliest lunar infrastructure in support of these Moon-to-Mars Objectives: LI-1 Development of a Global Power Grid and LI-3.1 Industrial Scale Construction Capabilities – Roads with autonomous navigation aids and Assembly of towers. The assembly of tall truss-based solar power towers is the topic of a separate SBIR Phase I scope in this subtopic. The outfitting of these tall towers with wiring harnesses and junction boxes for power, lights, and sensors is a critical gap in creating a functioning power grid.

Proposals are invited for the development of outfitting concepts and the robotic tools required to outfit a 50- to 80-m-tall truss-based tower with electrical harnesses for a 100- to 200-kWe solar power tower, as specified below. Additionally, wiring junction boxes at various harness connection locations are needed for these different outfitting applications. Making wiring harness connections is not the focus of this topic; however, proposers are strongly encouraged to understand and report on a viable connection strategy to be used during the outfitting process. For example, it is likely that Earth-sourced wiring harnesses will come complete with connectors, and approaches for managing these connectors are highly desirable. Thus, technology development and demonstration that includes the connector feature is encouraged.

Attachment methods for outfitting may include, but are not limited to, mechanical fastening (rivets, tie wraps, twist-ties, clips); however, other methods may be viable and are encouraged. Proposals to the current solicitation can assume that the various wiring harnesses will be attached to the truss elements used in the assembly. It can be assumed that the truss elements are between 0.75 and 1.5 m in length, with either an angle or square prismatic cross sections (a range of cross-section dimensions is listed below), and that the truss elements are joined together using joint elements and mechanical fasteners. It is assumed that no specific accommodations are made for the outfitting of the truss structure (i.e., truss members and joints do not have dedicated mounting features for harnesses or junction boxes pre-integrated).

Robotic systems and/or tools required to complete the outfitting are also desired. Proposers are encouraged to utilize/incorporate commercially available solutions but can also propose specialized concepts if desired. For example, it is assumed that a commercial space-capable robotic manipulating arm will be available and that proposals should concentrate on the development of specialized robotic tooling required for the outfitting. Justification for all concept elements should be made.  A description of the proposed outfitting concept of operations is requested and can be based on an outfitting strategy for any one or more stages during or after tower assembly. Additionally, concepts that are extensible to other truss-based structures, such as curved walls, arches, and domes, are also encouraged.

Proposal elements of interest include, but are not limited to:

  • Concepts for outfitting truss-based structures with electrical harnesses for applications, including:
    • Sensors and instruments stationed along the length of the tower.
    • Power transmission lines for the collection of solar energy.
    • Sun-tracking motors that rotate the solar arrays toward the sun; these can be located at the top, bottom, or midspan of the tower.
    • Communications packages located at the top of the tower.  
  • Concept of operations to outfit a tall tower using the robotic tools and outfitting methods developed.
  • Robotic tools/systems for outfitting of truss structures.
  • Considerations for operating in lunar environment (1/6 gravity, temperature, radiation, vacuum, lighting, power requirements). Note: proposal does not have to produce space-rated equipment; however, the processes shall be applicable to the lunar environment. Justification of design choices shall be included.
  • Concepts that maximize operational efficiency and minimize power requirements and complexity.
  • Preliminary proof-of-concept demonstrations, methods, equipment.
  • Suggested outfitting accommodations (i.e., suggested mounting features/aids incorporated into future truss or joint/node elements).
  • Describe possible extensions of proposed technology to outfitting of other truss-based assemblies, e.g., walls, arches, domes.
  • Describe possible application of proposed technology to management of nonwiring outfitting tasks, e.g., piping, ECLSS systems.

Assume the following truss elements are used in the tower assembly:

  • Truss element lengths: 0.75 to 1.5 m
  • Truss element cross section:
    • Square rod: 5 mm, 10 mm, 15 mm square
    • Angle: flange length 10 mm, 20 mm, 40 mm; flange thickness 1.0 mm, 2.0 mm, 4.0 mm, 6.0 mm
  • Truss material:
    • Earth sourced = aluminum 6061, graphite-epoxy
    • ISRU based = 98% pure aluminum (properties similar to 1-series untempered aluminum (E = 10 Msi, Yield > 5 ksi)

Tower details and design assumptions:

  • Tower height: 50 to 80 m.
  • Assume the truss elements are joined together using joint elements and mechanical fasteners.
  • Assume assembly site is level to within ±2.5 degrees.
  • Assume a suitable foundation/working area is available at the base of the tower to stage the outfitting process; however, proposals are free and encouraged to provide their own foundation requirements.
  • Current NASA ConOps for truss tower assembly = vertical build and lift assembly approach (i.e., assemble a truss module, lift up and assemble the next module below, repeat until tower fully erected).

Expected TRL or TRL Range at completion of the Project: 3 to 5

Primary Technology Taxonomy:

  • Level 1 12 Materials, Structures, Mechanical Systems, and Manufacturing
  • Level 2 12.2 Structures

Desired Deliverables of Phase I and Phase II:

  • Analysis
  • Prototype

Desired Deliverables Description:

Phase I must include the design and test of critical elements associated with the proposed outfitting technologies. For example, harness and junction box attachment concept design and testing must be included. Phase I must also include a concept of operations for the outfitting of the tower and the design and testing of the robotic outfitting system and tools. Phase I proposals should result in at least TRL 4 robotic outfitting system.

Phase II deliverables must include demonstration of the outfitting concept at a relevant scale. The demonstration shall be designed and justified by the proposer. The outfitting is expected to be accomplished using the robotic systems, implements, and outfitting concepts developed in Phase I. Preliminary plan for maturing the outfitting technology for a future lunar demo. All elements of the outfitting concept must be developed to a minimum of TRL 5.

State of the Art and Critical Gaps:

Lunar and planetary surface outfitting is not a current capability. The state of the art is terrestrial-based construction technology. Current technologies for outfitting robots are low TRL, application specific, and fragile with respect to environmental uncertainties. To enable the outfitting of lunar and planetary structures, these technologies must be made more resilient.

A common problem across a broad class of applications (electrical, fiber, fluids, gases, etc.) with different size, stiffness, and bend radius combinations is conductor/cable and piping/tubing line management. This area encompasses both conductors and tubing, and considerations include installation (securing, strain relief, etc.), interfaces and expansion to include splicing/connecting in the presence of environmental factors, micrometer protection, radiation shielding, and management of coefficients of thermal expansion (CTE) mismatch between the conductor or tubing and substrate. Correct design of these critical features is necessary for robust and reliable outfitting of surface infrastructure.

To date, very few activities have been conducted to develop robotic outfitting of truss-based structures. Thus, to accomplish large-scale structural outfitting on the lunar surface, a variety of new technologies and robotic systems are needed.

Outfitting of tall towers is directly applicable to the following Moon to Mars Objectives:

  • LI-1 Development of a Global Power Grid; and, more broadly,
  • LI-3.1 Demonstrate industrial-scale autonomous construction capabilities necessary to support global lunar utilization and continuous human presence, including […] roads with autonomous navigation aids, landing pads/berms, […] and assembly of structures such as towers or buildings.

Relevance / Science Traceability:

Robotic outfitting of infrastructure directly addresses the STMD Strategic Thrust “Live: Sustainable Living and Working Farther from Earth” and the following Moon to Mars Objectives:

  • LI-1 Development of a Global Power Grid.
  • LI-3.1 Industrial Scale Construction Capabilities – Roads with autonomous navigation aids and assembly of towers.

References:

  • Doggett, William. Robotic Assembly of Truss Structures for Space Systems and Future Research Plans. Proceedings, IEEE Aerospace Conference. Vol. 7. IEEE, 2002.
  • Belvin, Wendel K., et al. In-Space Structural Assembly: Applications and Technology. 3rd AIAA Spacecraft Structures Conference, 2016.
  • Komendera, Erik, et al. Truss Assembly and Welding by Intelligent Precision Jigging Robots. 2014 IEEE International Conference on Technologies for Practical Robot Applications (TePRA). IEEE, 2014.
  • Moses, R.W.; and Mueller, R.P. (2021). Requirements Development Framework for Lunar In Situ Surface Construction of Infrastructure. Earth and Space 2021, pp. 1141-1155.

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