# A Lunar-Orbiting Satellite Constellation for Wireless Energy Supply
## 2 State of the Art Models  
One solution for the problem of lunar energy supply proposed by NASA (in collaboration with Astrobotic Technology of Pittsburgh, Honeybee Robotics, and Lockheed Martin of Littleton) is to install large vertical solar panels (as shown in Figure 1 and discussed in [9]) on the edge of the Shackleton Crater. This site was chosen for its scientific interest and for the amount of available sunlight. This solution would solve the problem of the long lunar night, but would force the installation of solar panels locally in that precise area on the surface. Several companies have proposed and studied alternative solutions to using solar panels, such as nuclear energy exploitation. Rolls Royce has recently secured the first contract with the UK Space Agency [10] to study a nuclear microreactor, as depicted in Figure 2, capable of operating in the lunar environment. Figure 1: Astrobotic vertical panel (Image credits: [[https://www.astrobotic.com/](https://www.astrobotic.com/)]([https://www.astrobotic.com/](https://www.astrobotic.com/)), accessed on 2 February 2023). Figure 2: Rolls Royce nuclear microreactor (Image credits: Rolls Royce Holdings). This paper primarily focuses on the topic of wireless power transmission (WPT) in space. The main methods of power transmission over long distances are microwave power transmission (MPT) and laser power transmission (LPT). A major challenge in lunar power systems is the extended duration of lunar nights, which results in the inability of solar panels to generate electricity due to the absence of sunlight. MPT and LPT offer an alternative solution by enabling WPT from a power source located on the Moon's surface or in orbit. This allows for a consistent power supply to lunar habitats, rovers, and other infrastructure even during the prolonged periods of darkness. Another challenge in the lunar environment is the presence of fine dust particles and surface debris that can accumulate on solar panels, reducing their efficiency over time. MPT and LPT can mitigate this issue by eliminating the need for extensive solar arrays on the lunar surface. With WPT, the power generation equipment can be located away from the dusty lunar surface, thereby reducing the impact of dust accumulation and minimizing the need for frequent maintenance. This leads to longer operational lifetimes for power systems. At the lunar poles, sunlight is not uniform because of the Moon's tilt, and some areas are constantly in shadow. MPT and LPT can overcome this challenge by transmitting power from well-illuminated regions to permanently shaded areas. This ensures a continuous power supply to potential habitats, facilities, and scientific installations located in these challenging polar environments. MPT and LPT technologies also offer enhanced efficiency and power density compared to traditional wire-based power transmission systems. They can transmit energy more efficiently over longer distances, reducing energy losses during transmission. This allows for the provision of greater amounts of power to distant lunar sites, meeting the increasing demands for power in future missions and lunar colonies. Furthermore, these technologies are scalable and adaptable, allowing for flexible adjustments to meet the evolving energy needs of the Moon. As lunar missions and settlements grow, MPT and LPT systems can be designed to scale up, providing the necessary flexibility in power distribution and facilitating expansion as needed. When comparing MPT and LPT as methods to transmit energy to the lunar surface, several factors come into play. When discussing efficiency, it is important to note that LPT systems have the potential to achieve higher levels of efficiency compared to MPT systems. Laser beams can be focused with greater precision, leading to reduced energy losses during transmission. In addition, the MPT systems could have significant path losses depending on the transmission distance. As far as the system costs, MPT systems generally have lower initial costs compared to LPT systems.