Orbital Power-Beaming: An Alternative for Power-Restricted Regions on the Lunar Surface

One of the biggest challenges facing the expansion of lunar surface exploration is access to a reliable power source for purposes of surviving lunar night, exploring permanently shadowed regions (PSRs), and achieving long traverses. Many landers and rovers are currently limited in their range, performance, and lifetime due to power and recharging constraints. The concept of Space-Based Solar Power (SBSP) has been studied for decades for terrestrial applications and provides an attractive solution to these lunar surface missions by enabling flexible power delivery from orbit to surface assets. The Orbital Power-Beaming Assets for Lunar Applications (OPAL) project is employing systems analysis methodologies to study the systems-of-systems relationships between the orbital power beaming spacecraft and the surface assets or “clients” and to assess the cost, benefit, and complexity of employing this technology. A preliminary Concept of Operations (ConOps) has been defined and an orbital assessment resulted in the selection of a near-polar circular orbit with an altitude of 1,175 km based on station-keeping requirements, access to the lunar south pole, and distance to the surface. Solar Electric Propulsion (SEP) has been selected as the main propulsion system of each OPAL spacecraft to minimize the amount of propellant required. A power beaming trade resulted in the selection of an optical wavelength of 1064 nm, followed by a laser technology assessment that resulted in the recommendation of a fiber laser as the optical beam source for the OPAL spacecraft. Following the definition of three “power classes” that group clients based on similar power demands, a parametric sizing of the OPAL spacecraft was completed. A case study of an OPAL-compatible Commercial Lunar Payload Services (CLPS)–type lander was then performed, which included a high-level assessment of impacts to the power system mass and the operations of the lander. This integrated approach and the results of the analyses support the decision to continue the development of a concept for a power-tunable and focusable optical power beaming system that could accommodate the power demands of current and future lunar surface missions.