Taking inspiration from a butterfly, GE⊕-LPS feature V-shaped solar panels with integrated antennas, deployed in a helix configuration extending more than a square kilometre end to end. The design would yield continuous 23 megawatts of energy for lunar surface operations. The solar panels themselves are based on iron pyrite monograin-layer solar cells produced on the Moon.
The GE⊕-LPS concept has gone through a series of geometrical design iterations. After examining various geometric configurations for the GE⊕-LPS, we arrived at an optimized helical design concept with an integrated phased-array transmitter and an optimized photovoltaic deployment using a solid-state V-Shaped photovoltaic design inspired by the heat collection of butterflies with a V-shaped wing position. As such, this biomimicry-inspired design is called the ‘Butterfly’ concept. It consists of a spherical habitat in the center, from where two axes deploy. The longer axis forms the longitudinal rotation axis for a helix shape. The rotation from end to end is 180 degrees and forms a ring beam. Between the longitudinal axis and the ring beam the hybrid PV-Antenna elements are spanned. The helix-based shape has the advantage, that no matter how the inclination angle to the Sun changes, always the same amount of solar energy is received. At the same time the beam-forming antenna elements can directly face the rectenna and therefore do not need to be switched continuously.
As a baseline for power supply to the lunar surface we have established a requirement for the GE⊕-LPS of 1.5 MW of continuous power for initial operations, allowing some margin for additional storage. To deliver this amount of power, the solar collector of the GE⊕-LPS would require a diameter of 300 m giving an optimized PV surface area of 29,339 m2. Using PVs with an efficiency of 91W/m2 this would generate 3.6 MWe at the SPS and deliver 2.0 MWe at the rectenna. However, since a smaller antenna in space requires a much larger rectenna on the Moon, a larger SPS may be considered economically and technically advantageous, as more power can always be used to increase mining and production.
To provide power to the lunar surface from EM-L1 is a trade-off between antenna size and rectenna size, i.e., the smaller the transmission antenna the larger the rectenna on the surface and vice versa. A SPS with a diameter of 900-1,200 meters at EM-L1 will require a rectenna on the Moon with a diameter of 4-5 kilometers, assuming use of 5.8 GHz microwaves. With the rectenna located near the base station of the LSE at Sinus Medii, continuous power can be supplied for lunar beneficiation and fabrication operations. A GE⊕-LPS located near the EM-L1 hub would also benefit from station keeping and maintenance. Beaming power from lower lunar orbits would require more satellites.
EM-L1から月面に電力を供給するためには、アンテナサイズとレクテナサイズがトレードオフになる。すなわち、送信アンテナが小さければ小さいほど月面上のレクテナは大きくなり、その逆もまた然りとなる。EM-L1で直径900-1,200 m のSPSを運用する場合、5.8 GHz のマイクロ波を用いると仮定すると、月面には直径4-5 km のレクテナが必要となる。レクテナを「中央の入江（Sinus Medii）」の月宇宙エレベーター（Lunar Space Elevator；LSE）基地近傍に設置することで、月の選鉱・加工作業に継続的な電力を供給することができる。EM-L1ハブの近くに設置されたGE⊕-LPSは、ステーションの維持と保守にも役立つ。もっと低い月周回軌道から電力を供給するには、もっと多くの衛星が必要となる。
The helical shape optimizes the orientation aspect of the GE⊕-LPS by minimizing the need to constantly point the solar collectors toward the Sun. The reduction of about 33.3％ in utilisation of the solar panels as a result of the geometry is offset via the use of V-Shaped photovoltaic arrays which increase both the surface area and efficiency of the photovoltaics, resulting in a higher power output (+ 1.35) than a flat PV surface.
