This paper presents the results of illumination analyses for the lunar south and north pole regions obtained using an independently developed analytical tool and two types of digital elevation models (DEM). The first DEM was based on radar height data from Earth observations of the lunar surface and the other DEM was a combination of the radar data with a separate dataset generated using Clementine spacecraft stereo imagery. The analysis tool enables the assessment of illumination at most locations in the lunar polar regions for any time and any year. Maps are presented for the north and south lunar poles for the worst case winter period (the critical power system design and planning bottleneck) and for the more favorable best case summer period. Average illumination maps are presented to help understand general topographic trends over the regions. Energy storage duration maps are presented to assist in power system design. Average illumination fraction, energy storage duration, solar/horizon terrain elevation profiles and illumination fraction profiles are presented for favorable lunar north and south pole sites which have the potential for manned or unmanned spacecraft operations. The format of the data is oriented for use by power system designers to develop mass optimized solar and energy storage systems. More work is needed to improve the quality of the combined and filtered DEMs, but a filtered version of the radar DEM for the worst case lunar day at the best south pole site on the Crater Shackleton rim has 73 percent average illumination fraction and 71 to 113 hr required for energy storage. The worst case lunar day at the best north pole site (on the rim of a small crater near the north pole) has a 52 percent average illumination fraction and 154 to 278 required energy storage hours. The illumination at these sites vary dramatically for each lunar day during a year, with as many as three lunar days with full illumination. This paper shows that by increasing the best identified north pole site height to 100 m using a tower reduces the energy storage duration by 4 percent with 0.2 hr of energy storage duration savings per meter of tower height for heights up to 300 m. Elimination of north pole energy storage occurs with tower heights near 1500 m, quite different than has been seen with the south pole sites (>3 km). Combining two north pole sites that are separated by 3 km reduces the energy storage duration by 5 percent. IntroductionThe lunar poles have complex illumination environments in which some sites have potentially continuous darkness (offering the chance for resident ice or other volatiles) and other sites have potentially long duration illumination (quite different than regions closer to the lunar equator). Such illumination characteristics have made the polar regions key for permanently-manned base planning.Most unobstructed locations on the Moon's surface have about 15 days of illumination followed by 15 days of darkness. Near the poles, due to site terrain heights, low Sun elevation an...
This paper reviews past analyses and research related to lunar south pole illumination and presents results of independent illumination analyses using an analytical tool and a radar digital elevation model. The analysis tool enables assessment at most locations near the lunar poles for any time and any year. Average illumination fraction, energy storage duration, solar/horizon terrain elevation profiles and illumination fraction profiles are presented for various highly illuminated sites which have been identified for manned or unmanned operations. The format of the data can be used by power system designers to develop mass optimized solar and energy storage systems. Data are presented for the worse case lunar day (a critical power planning bottleneck) as well as three lunar days during lunar south pole winter. The main site under consideration by present lunar mission planners (on the Crater Shackleton rim) is shown to have, for the worse case lunar day, a 0.71 average illumination fraction and 73 to 117 hours required for energy storage (depending on power system type). The illumination at this site for each lunar day during a year varies dramatically, with as many as seven lunar days with negligible shadowing (i.e., maximal illumination/very little energy storage required). The maximum duration shadowing period for this site is primarily due to distant high terrain in the Malapert Mountain region (from 84 to 86 S, -10 to +45 E). Two potential sites with higher average illumination fraction and lower energy storage hours than the Shackleton site are shown to possibly have erroneously high site heights. In addition, a site at the Malapert Mountain peak counter-intuitively had a much lower average illumination fraction and much higher energy storage hour range, due primarily to nearby mountainous high terrain. This paper shows that by increasing the Shackleton site height by 100 m using a tower reduces the number of energy storage hours by 15 to 21 percent, although whether this is a mass optimized solution for a power system awaits further analysis. Completely eliminating energy storage through the use of practical tower heights does not appear feasible due to the nature of the shadowing terrain. Linking the Shackleton site with one ~10 km away was shown to improve the average illumination fraction from 0.71 to 0.84 and reduce the energy storage hours from 117 to 68 hours. Again, this may not be a mass optimum power system solution due to either heavy power beaming equipment or power cables (compared with simply increasing the energy storage size at the site). Linking other sites and including towers at both sites are shown to not completely eliminate the need for energy storage. IntroductionThe lunar south pole offers numerous reasons for space mission planners and designers to consider the location for unmanned and manned spacecraft deployments (e.g., robotic landers and rovers, shortterm and long-term manned bases). Apart from scientific research and anticipated in situ material resources, a critical...
This paper presents the preliminary results of a recent National Aeronautics and Space Administration (NASA) study funded under the Advanced Exploration Systems (AES) Modular Power Systems (AMPS) project. This study evaluated multiple surface locations on both the Moon and Mars, with the goal of establishing a common approach towards technology development and system design for surface power systems that use Regenerative Fuel Cell (RFC) energy storage methods. One RFC design may not be applicable to all surface locations; however, AMPS seeks to find a unified architecture, or series of architectures, that leverages a single development approach to answer the technology need for RFC systems. Early system trades were performed to select the most effective fuel cell and electrolyzer architectures based on current state-of-the-art technology, whereas later trades will establish a detailed system design to enable a near-term ground (non-flight) demonstration. This paper focuses on the initial trade studies, presents the selected fuel cell and electrolyzer architectures for follow-on system design studies, and suggests areas for further technology investment.
A multi-discipline team of experts from the National Aeronautics and Space Administration (NASA) developed Mars surface power system point design solutions for two conceptual missions. The primary goal of this study was to compare the relative merits of solar-versus fission-powered versions of each surface mission. First, the team compared three different solar power options against a fission power system concept for a sub-scale, uncrewed demonstration mission. The 4.5 meter (m) diameter pathfinder lander's primary mission would be to demonstrate Mars entry, descent, and landing techniques. Once on the Martian surface, the lander's In Situ Resource Utilization (ISRU) payload would demonstrate liquid oxygen propellant production using atmospheric resources. For the purpose of this exercise, location was assumed to be at the Martian equator. The three solar concepts considered included a system that only operated during daylight hours (at roughly half the daily propellant production rate of a round-the-clock fission design), a batteryaugmented system that operated through the night (matching the fission concept's propellant production rate), and a system that operated only during daylight, but at a higher rate (again, matching the fission concept's propellant production rate). Including 30% mass growth allowance, total payload masses for the three solar concepts ranged from 1,116 to 2,396 kg, versus the 2,686 kg fission power scheme. However, solar power masses are expected to approach or exceed the fission payload mass at landing sites further from the equator, making landing site selection a key driver in the final power system decision. The team also noted that detailed reliability analysis should be performed on daytime-only solar power schemes to assess potential issues with frequent ISRU system on/off cycling. Next, the team developed a solar-powered point design solution for a conceptual four-crew, 500-day surface mission consisting of up to four landers per crewed expedition mission. Unlike the demonstration mission, a lengthy power outage due to the global dust storms that are known to occur on Mars would pose a safety hazard to a crewed mission. A similar fission versus solar power trade study performed by NASA in 2007 concluded that fission power was more reliable-with a much lower mass penalty-than solar power for this application. However, recent advances in solar cell and energy storage technologies and changes in operational assumptions prompted NASA to revisit the analysis. For the purpose of this exercise a particular landing site at Jezero Crater, located at 18 o north latitude, was assumed. A fission power system consisting of four each 10 kW Kilopower fission reactors was compared to a distributed network of Orion-derived Ultraflex solar arrays and Lithium ion batteries mounted on every lander. The team found that a solar power system mass of about 9,800 kg would provide the 22 kilowatts (kW) keep-alive power needed to survive a dust storm lasting up to 120-days at average optical depth of 5, an...
This paper presents illumination analyses using the latest Earth-based radar digital elevation model (DEM) of the lunar south pole and an independently developed analytical tool. These results enable the optimum sizing of solar/energy storage lunar surface power systems since they quantify the timing and durations of illuminated and shadowed periods. Filtering and manual editing of the DEM based on comparisons with independent imagery were performed and a reduced resolution version of the DEM was produced to reduce the analysis time. A comparison of the DEM with lunar limb imagery was performed in order to validate the absolute heights over the polar latitude range, the accuracy of which affects the impact of long range, shadow-casting terrain. Average illumination and energy storage duration maps of the south pole region are provided for the worst and best case lunar day using the reduced resolution DEM. Average illumination fractions and energy storage durations are presented for candidate low energy storage duration south pole sites. The best site identified using the reduced resolution DEM required a 62 hr energy storage duration using a fast recharge power system. Solar and horizon terrain elevations as well as illumination fraction profiles are presented for the best identified site and the data for both the reduced resolution and high resolution DEMs compared. High resolution maps for three low energy storage duration areas are presented showing energy storage duration for the worst case lunar day, surface height, and maximum absolute surface slope. I. IntroductionContinuing interest in the southern lunar polar region as a location for long-term manned activities has made it important to accurately quantify the amount of solar illumination that can be expected for surface operations. The sizing of various spacecraft systems, particularly power/energy storage systems, are key drivers in the mass feasibility of lunar architectures. Unmanned assets, including landers and rovers, require illumination data for proper sizing. Due to the low Sun angles near the poles, especially during the worst case sizing winter period, it is important to include topographic effects in any assessment of illumination. The large number of craters and mountains result in random-appearing, time-varying shadowing onto potential sites. Although prior analysts have focused on average illumination estimates using spacecraft imagery, these are of limited value to designers. It is the knowledge of the maximum shadow period duration that dictates the energy storage size, a large power system mass contributor. Assessing this duration requires the characterization of the illumination profile at each operational site.Prior papers (refs. 1 and 2) by the author reviewed past data and analyses relevant to the topic of lunar illumination. These papers documented illumination analyses for the lunar north and south pole using radar-derived (from terrestrial radar) lunar digital elevation models (DEM), combined radar/stereoimagery-derived ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.