Preliminary Infrastructure Development for Altair Sortie Operations
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Preliminary Infrastructure Development for Altair Sortie Operations Madhu Thangavelu * and Eshete Mekonnen. † Department of Astronautics, University of Southern California, Los Angeles, CA 90089 -1191 NASA’s Exploration Systems Architecture Study ( ESAS) rep ort envisions humans returning to the Moon in the 2020 timeframe. However, many factors still need to be addressed in depth. They include site selection, materials, and design of inhabitable and survivable infrastructure elements. One of the most important issues dealing with a manned return mission to the Moon is lunar dust. Dust suppression is a critical issue with regard to Altair operations as well as surface vehicles in the proximity of the habitat. Dust and debris thrown up by vehicles can also degrad e exposed payloads such as telescope elements and photovoltaic arrays. This paper explores several architectural concepts relating to developing essential preliminary infrastructure for humans on the lunar surface during the first several missions. Concept s discussed include certain selection criteria aspects for lunar habitat location as well as a variety of architectural elements, which can ameliorate the effects of lunar dust during Altair operations and routine surface vehicle movement around the primar y lunar settlement. Specifically, these elements include a microwave sintered landing zone around a hard, paved and topped landing pad for repeated service use, inflatable structures for blast aprons, a light rail system with pallet, winch and gantry suppo rt for lander and payload transport from landing pad to hangar or habitat location, a hard, topped dust -free platform on which to erect the habitat and allied structures, and a built -up access road from the habitat area to the hangar and the landing pad. A n emergency exit route from habitat to a standby escape vehicle is also depicted as well as a dust monitoring system and a dust cleaning rover attachment is suggested as well. I. Introduction HE USC ASTE 527 team project of Fall 2008 “Return to the Moon: L ooking Glass 204” explored a variety of Tconcepts for NASA’s plan to return people, first on one week surface stays, extending them to 14 days and eventually up to six months. The USC team was tasked specifically to go beyond NASA’s Mars Forward technology development program to propose on two more fronts, namely to commission a variety of permanent assets that are useful not only to the scientists but also for the public and to look at how this specific project might be employed to inspire a new generation of explorers. This project is envisioned to happen between 2020 and 2040. Assuming two or three Altair missions every year, we expect between 50 -60 Altair derived landers to be serviced around the lunar globe, with at least 50 of them in the vicinity of a south polar lunar settlement. They include both crew sortie and cargo missions. The other 10 landers would primarily be cargo landers with specialized payloads to be commissioned in remote locations of the lunar globe. Substantial international participati on is foreseen in all a spects including Earth to Moon t ransportation, landers and payloads. It is in this context that the preliminary infrastructure development concepts proposed in this paper are portrayed. * Conductor, ASTE527 Space Concepts Studio, Department of Astronautics, Viterbi School of Engineering, Graduate Thesis Adviser, School o f Architecture, University of Southern California, Los Angeles, CA, AIAA Member † Graduate Student, Department of Astronautics, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, AIAA Student Member 1 American Institute of Aeronautics and Astronautics II. Lunar Settlement in Polar Region While satellit es are still gathering crucial data, there is some consensus building within the space community which suggests that polar regions might offer a better initial location for manned lunar operations. The South Polar Region is shown in figure 1. 1 The Malaper t mountain range, the Malapert crater and environs have been discussed in recent literature as potential regions of interest to locate a lunar settlement 2. The Shackleton crater and environs, almost directly at the South Pole has also been targeted as a si te of interest 1. The distance to the Schrodinger crater is also shown in figure 1, primarily because it is an ideal location to setup sensitive radio telescopes. This far -side location of the Moon would effectively block any interference from radio -noise g enerated on Earth. Eventually, an advanced far -side settlement would also better simulate conditions on a planetary base without the Earth -disc in view for the crew. Pending more specific data from missions in progress including the Lunar Reconnaissance Or biter/ Lunar Crater Observation and Sensing Satellite ( LRO/LCROSS), these two locations were adopted as the sites of interest for the Fall 2008 USC project. Figure 1: Image of Lunar Map of the South Pole 3, 4 . Lunar map shows regions of interest for the lunar colony; Mons Malapert and Shackleton, and their distances between each location. The distance to the Schrodinger crater is shown as it is a good location for situating certain observator ies away from Earth noise using robots and crew in extra -vehicular activities (EVA). III. Preliminary Infrastructure (PI) Elements Generally, besides offering ample opportunity for exploration and technology development, a site must provide a safe zone for crew to operate in. It must present a viable route for logistics support and emergency abort operations and rescue missions. The polar regions of the Moon also offer longer periods of solar illumination 2, 5 , allowing the quick and straightforward deployment of photovoltaic power plants for near -continuous electricity generation. If water and volatiles are confirmed there, this will be a boon to the settlement by providing liquids and gases to replenish power, consumption and other losses. Sulfur has been propos ed as a binder for lunar concrete 6. Water could also make a good binding agent, allowing straightforward regolith stabilization and dust suppression, through sublimation -deposition process, in permanently shadowed lunar development. 2 American Institute of Aeronautics and Astronautics For Altair operations, the following site attributes and systems are considered essential: A. Topography suitable for direct line -of -sight visual acquisition of landing zone for Altair pilot, preferably both during lunar day as well as lunar night, aided by Earth shine. B. Dust suppr ession employed around approach and ascent zone. C. A well lit, sturdy and dust free landing pad. D. A simple and easy to deploy system for transporting Altair lander and payload from landing pad to hangar and habitat. E. A safe and reliable means to transfer crew and cargo to and from habitat. F. A similar way to conduct lift -off operations. G. A quick and reliable exit to abort or rescue crew in the event of an emergency. H. Allied structures to support these activities. I. Other Systems for PI depicted in Looking Glass 204 P roject Figure 2 depicts the main preliminary infrastructure design of the proposed lunar colony. Figure 2: Preliminary Infrastructure (PI) design. Design and dimensions of lunar base, top view (drawing not to scale), which includes the emergency e sc ape vehicle, the cable/winch system for moving equipment easily out of the landing pad area as well as shows the var ious regolith rock outcrop show depending on location . *Note the landing pad and dust suppression zone is on top of an elevated surface. A. Di rect Visual Acquisition of Landing Zone and Pad - Earth Shine The shallow insulation angles in the polar regions tend to present a dimly lit lunar surface with stark relief and stretched shadows. However, since Malapert range faces the Earth, a carefully s elected landing site in this region would also be illuminated by the Earth disc for most of the lunar night 2. Earthlight would allow for visual acquisition of landing zone for Altair pilots. Even though the Altair lander would be assisted by instrumental l anding aids, the ability for the pilot to take the controls at any time during descent and touchdown is considered essential. Earth shine would also allow for enhanced lunar surface operations, alleviating thermal loads on operational systems across the bo ard. B. Dust Suppression As the Altair lander descends towards the landing pad, the main engines and reaction control system (RCS) will kick up a large amount of lunar dust 7 as shown in the images of figure 3. To minimize this effect caused by Altair descent engines, it is proposed to deploy the landing pad atop a natural hill or mound with a slope of between 1:12 to 1:20. To further prevent this dust scattering, the regolith surface around in an area about 3 km in diameter surrounding the landing pad, called the landing zone, will be stabilized. 3 American Institute of Aeronautics and Astronautics Figure 3: Effects of lunar dust disturbance and Altair thruster ejecta on various landing terrain. Top images depicts landing on an elevated surface. Middle image depicts landing on a level/flat terrain. Bottom image depicts landing on a concave, crater surface. Detailed studies are needed to verify that an elevated pad on the lunar surface would show diminished dust disturbance than the other two alternatives depicted. C. Landing Pad The reusable landing pad should be easy to identify within the landing zone for the Altair pilot. It will have a resilient surface for repeated operations as well as all the supporting elements to assist in quickly moving the lander and payload in and out of this zone of activity. Infla table aprons to contain or curtail lander ejecta are suggested. By locating the habitat directly east from the landing pad and a possible expansion of the settlement located due west, the two -stage descent module of the Altair could approach and touch -dow n from the south and the ascent stage module could lift -off to the north when the astronauts depart the settlement, as seen in figure 4.