In Situ Fabrication and Repair

Overview

In Situ Fabrication and Repair (ISFR) of components are essential to human exploration of distant planets in order to reduce resource requirements, spare parts inventory, reduce launch mass, cost, and enhance mission safety. Reliable in situ fabrication and repair processes and technologies must be developed, and the behavior and performance of fabrication materials in space and on extraterrestrial surfaces must be understood in order to ensure the effective accomplishment of the manned Moon and Mars exploration initiative. ISFR is composed of three sub-elements, Fabrication Technologies, Repair & NDE Technologies, and Habitat Structures.

Importance to Exploration - NASA's vision to conduct distant, long duration mission to moon and Mars introduces unique provisioning and contingency response challenges. Longer duration missions without near access to Earth will require increased maintainability of systems; component degradation and failure is inevitable. The Space Architect has identified sparing as a principal issue for reducing the mass required for long duration exploration missions. It would not be practical to carry a complete spare parts and tools inventory, nor would an extensive collection of spares necessarily fulfill every emergency need. Fabrication of new tools in situ to cover unforeseen needs and a robust suite of repair capabilities will significantly mitigate risk. This program will develop methods to allow quality controlled manufacturing processes in low-gravity space environments and on extraterrestrial surfaces.

Research Objectives - Development of reliable in situ fabrication, repair, and habitat structural technologies and processes to TRL 6.

Development Approach - Spiral development of technologies through ground demonstrations followed by ground testbeds and selected International Space Station or lunar mission demonstrations.

The ISFR Element supports both directed and competitive research efforts and will conduct multiple ISFR workshops to produce near term solutions for demonstration on the International Space Station and on Lunar Missions.

MSFC's National Center for Advanced Manufacturing has established collaborative relationships with other NASA Centers and Universities to support advanced technologies for developing, testing, and fabricating parts for exploration.

For more information, please contact:

Element Lead: Julie Bassler
(256) 544-7412
Julie.A.Bassler@nasa.gov

Element Scientist: Richard Grugel
(256) 544-9165
Richard.N.Grugel@nasa.gov

Fabrication Technologies Overview

The Fabrication Technologies sub-element will provide a means of building new parts or replacing existing parts or tools. This may include other ISFR elements or itself, fabricating newly defined parts or tools within an element of the transport vehicle, other vehicle equipment, or habitat equipment. These technologies will use available materials as provided by a logistics support function, which will include new and recycled materials. New materials will include materials delivered from Earth or fabricated in-situ. Parts will include various material types such as metals, plastics, ceramics and composites to fulfill requirements for all functioning elements used in the in-situ equipment and habitat.

Fabrication Technologies will primarily utilize shop level equipment to perform fabrication functions. Early developments will include stationary equipment, which requires the raw materials to be transported to the shop for fabrication. Later capabilities will include mobile equipment which goes to the field to build on site as would be the desired case for terrestrial missions. Several capabilities will be available in the fabrication shop. There are two basic modes of fabrication that can be used separately or in combinations.

Additive Fabrication: This technique uses raw materials as feed stock (wire, powder, liquid, etc.) and builds a part to the specifications required by adding material to achieve net shape. This includes fusion, casting, sintering, lithography, layered consolidation, etc.

Subtractive Fabrication: This mode of fabrication starts with materials larger than the end item and removes material to achieve net shape or part specifications. This is machining, grinding, ablation, and abrasive blasting.

Repair & NDE Technologies Overview

The Repair & NDE (non-destructive evaluation) Technologies sub-element will provide a means of repairing systems during transport and while on the Moon, Mars, and other extraterrestrial bodies. NDE technologies will be developed from existing techniques to support the monitoring and validation of the quality and safety integrity for the repair processes, the initial fabrication and assembly of in situ habitats and structures, and replacement parts. Self healing techniques will be developed for wire insulation and composite repairs where applicable, as well as other techniques for electrical component repair. Welding and patching/bonding techniques will be developed to provide repair process for most or all materials subject to in-situ failures. These technologies will utilize in-situ, imported, and recycled materials as provided by a logistics support function. Repairs will target the inclusion of all system and element material types utilized during transport and while on extraterrestrial bodies.

Repair & NDE Technologies will reduce/eliminate the need for spares through the utilization of in-situ, imported, and recycled materials in the restoration of system and element functionality. Repairs are considered a cheaper, better, faster mode of returning function in lieu of sparing. Repairs will utilize shop, portable, and robotic handheld equipment to perform functions.

Habitat Structures Overview

Gamma and particle radiation constitute a serious but reducible threat to long-term survival in space environments. Habitat manufacturing and assembly technologies that incorporate in situ resources provide options for autonomous, affordable, pre-positioned habitat environments with radiation shielding features and protection from micrometeorites and exhaust plumes.

The ISFR Habitat Structures subelement is focused on the development of lunar and Martian habitat structures with environmental protection features fabricated primarily of in situ resources and deployed with a high degree of automation. Current agency approaches depend on pre-fabricated habitat structures which require excessive upmass. Utilizing in situ resources for producing habitat structures in place or enhancing pre-fabricated structures as opposed to sole usage of pre-fabricated structures will significantly reduce upmass requirements.

Habitat Structures will investigate six basic structural concept categories based primarily on in situ materials. These categories of construction products are described below.

Raw Regolith: Structures formed by subsoil positioning over and around personnel and equipment enclosures or through the use of existing subsurface features such as caves or lava tubes. Regolith may also be used in conjunction with other technologies.
Blocks: Carved rock or regolith configured into construction blocks or bricks and configured into a habitat structure.
Reinforced Concrete: Structures formed from regolith based concrete.
Thin Films/Inflatables: Structural components erected by inflation or assembled as liners in other structural elements.
Deployable Metal Structures: Deployable structures which will work in concert with other components such as regolith or inflatables.
Glass Products: Structural elements or components fabricated from regolith-based glass.

Since no single technology will meet structural, radiation shielding, and minimal upmass/upvolume goals, combinations of technologies are being evaluated as integrated construction approaches.

A TRL6 sub-scale semi-autonomous capability is planned for FY09 to be compatible with the Spiral 1/2 Lunar Robotic Exploration Program (LREP) missions to demonstrate the integrated concept that evolves from the selected technologies.