Title: Optimized Bucket Wheel Design for Asteroid Excavation,
Abstract: Current spacecraft need to launch with all of their required fuel for travel.
This limits the system performance, payload capacity, and mission flexibility.
One compelling alternative is to perform In-Situ Resource Utilization (ISRU) by
extracting fuel from small bodies in local space such as asteroids or small
satellites. Compared to the Moon or Mars, the microgravity on an asteroid
demands a fraction of the energy for digging and accessing hydrated regolith
just below the surface. Previous asteroid excavation efforts have focused on
discrete capture events (an extension of sampling technology) or whole-asteroid
capture and processing. This paper proposes an optimized bucket wheel design
for surface excavation of an asteroid or small-body. Asteroid regolith is
excavated and water extracted for use as rocket propellant. Our initial study
focuses on system design, bucket wheel mechanisms, and capture dynamics applied
to ponded materials known to exist on asteroids like Itokawa and Eros and small
satellites like Phobos and Deimos. For initial evaluation of
material-spacecraft dynamics and mechanics, we assume lunar-like regolith for
bulk density, particle size and cohesion. We shall present our estimates for
the energy balance of excavation and processing versus fuel gained.
Conventional electrolysis of water is used to produce hydrogen and oxygen. It
is compared with steam for propulsion and both show significant delta-v. We
show that a return trip from Deimos to Earth is possible for a 12 kg craft
using ISRU processed fuel.