Lunar Resources proposes a novel dual-use in-space deposition process to join/bond materials via in-space vacuum deposition. Developed during the WSF program, in-space vacuum deposition technology is currently considered at TRL 8 and consists of depositing materials atomic layer-by-atomic layer to fabricate functional thin films in the vacuum of space.
The concept consists of depositing a thick film layer of an element onto a material(s) through a physical vacuum deposition process in the vacuum of space. Considering the constraints for space flight (mass, volume, power, etc.) Lunar Resources has developed a specialized thermal deposition process to deposit coatings on-orbit which would be ideal for joining as it is low-power and is deployed by an autonomous, low-mass, space deposition system. The thermal deposition process coats the substrate (in this case the material to be joined) creating a bond between the substrate/material and the deposited coating. Lunar Resources has adapted the traditional terrestrial thermal deposition process to account for microgravity and overspray. The space deposition system is able to create thick-films (>10microns) to join materials for bonding, repairing or replacing applications. and able to deposit a wide range of elements with vaporization temperatures up to 2000 oC. For joining applications, Lunar Resources foresees the benefit to deposit numerous coatings depending on the required strength of the bond and its application. For example, for joining two joints that will not need to be unjoined, Lunar Resources could deposit a thick titanium coating. However, for joints that may need to be replaced or whose lifetimes are less than the structures which they are joining, we could deposit a lower melting temperature material such as indium to be able to unjoin and replace the joint by melting the deposited joining coating.
Lunar Resources space deposition system is a dual-use universal material fabrication facility. Its general capability of fabricating atomically structured materials, layer-by-layer, can fabricate coatings and thin films for a variety of applications. For joining applications, it is able to join, repair, replace and manufacture materials on-orbit. Specific NASA applications include: joining, rigidization, and repair of aerospace grade metals and themoplastics for habitat modules, trusses, solar arrays, and antenna reflectors.
Potential Non-NASA applications of on-orbit joining through space deposition include satellite servicing and assembly involving the joining of components (habitat modules, trusses, solar arrays and antenna reflectors) on-orbit and the repair/replacement of components by melting previously deposited thick film coatings without the need to cut materials on-orbit.