In less than three years, astronauts will return to the moon for the first time since the Apollo era. The Artemis program not only aims to send crewed missions back to the surface of the moon to explore and collect samples. This time there is also the goal of establishing an important infrastructure (such as the moon gate and a base camp) that enables “sustainable lunar exploration”.
A key requirement for this ambitious plan is the provision of electricity, which can be difficult in regions such as the South Pole Aitken Basin – a crater region that is permanently shaded. To remedy this, a NASA Langley Research Center researcher named Charles Taylor proposed a novel concept known as a “light bender”. With the help of telescope optics, this system would capture and distribute the sunlight on the moon.
The Light Bender concept was one of 16 proposals selected for Phase I of NASA’s Innovative Advanced Concepts (NIAC) 2021 program, overseen by NASA’s Directorate for Space Technology Mission (STMD). As with previous NIAC submissions, the selected proposals represent a wide range of innovative ideas that could help advance NASA’s space exploration goals.
Conceptual illustration of permanently shaded, flat ice craters near the moon’s south pole. Credits: UCLA / NASA
In this case, the Light Bender proposal addresses the needs of astronauts who will be part of the Artemis missions and the subsequent “long-term presence of the human lunar surface”. The design for Taylor’s concept was inspired by the heliostat, a device that adjusts to compensate for the sun’s apparent movement across the sky so that sunlight continues to reflect on a target.
In the case of the Light Bender, Cassegrain telescope optics are used to capture, concentrate, and focus sunlight, while a Fresnel lens is used to direct beams of light for distribution to multiple sources located at distances of 1 km or more. This light is then received by photovoltaic arrays 2 to 4 m (~ 6.5 to 13 ft) in diameter, which convert the sunlight into electricity.
In addition to living spaces, the Light Bender can power cryocoolers and mobile devices such as rovers. This type of array could also play an important role in creating a vital infrastructure by providing power to ISRU (In-Situ Resource Utilization) elements (e.g. building surface structures). As Taylor described in his NIAC Phase I Proposal Statement:
“This concept is superior to alternatives such as the highly inefficient laser power beaming, as it only converts light into electricity once, as well as conventional power distribution architectures based on mass-intensive cables. Light Bender’s value proposition is a ~ 5-fold reduction in mass compared to conventional technological solutions such as laser power beaming or a distribution network based on high-voltage cables. “
Illustration of a conceptual fissure surface energy system on the moon. Credits: NASA
But perhaps the greatest benefit of such a system is the way it can distribute power systems to permanently shadowed craters on the lunar surface, which are common in the southern polar region of the moon. In the coming years, several space agencies – including NASA, ESA, Roscomos, and the China National Space Agency (CNSA) – hope to create long-term habitats in the region due to the presence of water ice and other resources.
The performance of the system is also comparable to the Kilopower concept, a proposed nuclear fission system that enables long stays on the moon and other bodies. This system should deliver an output of 10 kilowatts (kWe) – this corresponds to an electrical output of 1000 watts.
“In the first draft, the primary mirror captures nearly 48 kWe of sunlight,” writes Taylor. “The electrical performance of the end user depends on the distance to the primary collection point. However, the analyzes on the back of the shell suggest that within 1 km at least 9 kW of continuous power is available. “
Additionally, Taylor emphasizes that the overall power the system can produce is scalable. Basically, it can be increased by simply changing the size of the primary collection element, the size of the receiver elements, the spacing between nodes, or simply by increasing the total number of solar collectors on the surface. Over time, and as more infrastructure is added to a region, the system can scale to accommodate it.
Illustration of NASA astronauts at the Moon South Pole. Photo credit: NASA
As with all proposals selected for Phase I of the NIAC 2021 program, Taylor’s concept will receive a NASA grant of up to $ 125,000. All Phase I fellows are now in an initial nine-month feasibility study, during which the designers evaluate various aspects of their designs and address foreseeable issues that could affect the operation of the concepts once they operate in the South Pole Aitken Basin.
Taylor will particularly focus on how to improve the optical lens based on various designs, materials, and coatings that would result in acceptable light propagation. He will also examine how the lens can be constructed so that it can unfold autonomously once it reaches the surface of the moon. Possible methods for an autonomous use will be the subject of subsequent studies.
Following the design / feasibility study, an assessment will be made of the architectural alternatives for Light Bender in the context of a lunar base near the south pole of the moon during ongoing lunar surface operations. The main figure of merit will be the minimization of the land mass. Comparisons are made with known energy distribution technologies such as cables and laser radiation.
After completing these feasibility studies, the Light Bender and other Phase I fellows can apply for Phase II awards. Jenn Gustetic, director of innovation and early-stage partnerships within NASA’s Directorate for Space Technology Mission (STMD), said:
“NIAC fellows are known to dream big, suggesting technology that borders on science fiction and is different from research funded by other agency programs. We don’t expect them all to come to fruition, but we do recognize that providing a small amount of seed capital to NASA’s early research could bring great benefits in the long run. “
Further reading: NASA, NASA-JPL
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