This research will employ modern developments of Additive Manufacturing (AM) technology to design a Simple Sample Return (SSR) spacecraft providing an automated and very near-term low-cost method of returning a lunar regolith sample to earth. SSR will be built using AM technology to combine the propellant tank, pressure system, feed system, injector, and combustion chamber in a single component. This coupling will not only reduce weight, but will enable an advanced regenerative cooling geometry in which the fuel tanks circumferentially surround the rocket combustion chamber to directly transfer heat into the propellant. With off-the-shelf valve integration and limited assembly/connections, SSR will reduce connections (and therefore possible failure points), cost, build time, and dry-mass. SSR will use storable hypergolic propellants MMH and MON-25 which carry the advantage of not needing an ignition system nor cryogenic systems while still haveing a extended temperature range compared to other storable propellants. This propellant selection further improves restart reliability while adding pulse modulation capability. The single greatest contribution to the field of space exploration from SSR will be demonstrating the feasibility of a design space which currently does not exist.
The Phase I effort will study the capabilities and limitations of SSR, which will be linked to limitations in AM technology. Studies will be conducted on powder bed versus powder fed products, and implications of spatial resolution and smoothness as a function of part/channel size. Phase I will study specific designs and work with AM companies to thoroughly vet details pertaining to manufacturing, and rocket engine performance. Research will also be conducted on the strength and material implications of an AM-built engine.
AGILE's SSR addresses needed sample return missions, as well as broader applications to NASA spacecraft propulsion systems that can benefit from improved cost savings with better material management and build time. The introduction of a new design space by demonstrating the feasibility of a fully-integrated system such as SSR will potentially impact not only current thruster technology but future engine designs produced predominantly from AM technology, bringing NASA closer to a ‘build on-site’ return vehicle.
The need for low-cost and high-performance space engines is led by the growth of new spacecraft missions that employ the economies of scale and quantity, and which can tolerate new technologies. Commercial missions in this space include remote site communication, earth observation, environmental monitoring, asteroid resource and commercialization, deep space and long duration exploration missions.