Other Designations: Lunar Exploration System for Apollo. Class: Manned. Type: Lunar Base. Destination: Moon. Nation: USA. LESA (Lunar Exploration System for Apollo) represented the ultimate lunar base concept studied by NASA prior to the cancellation of further Saturn V production in June 1968. LESA would use a new Lunar Landing Vehicle to land payloads of from10,500 kg to 25,000 kg on the lunar surface with a single Saturn V launch. Extended CSM and LM Taxi hardware derived from the basic Apollo program would allow crews to be rotated to the ever-expanding, and eventually permanent lunar base. A nuclear reactor would provide power. Evolution to a lunar base would go from the basic Apollo hardware to AES (Apollo Extension Systems) to ALSS (Apollo Logistics Support System using the LEM Truck), and then ultimately to LESA (Lunar Exploration System for Apollo). Modules developed for ALSS or LEM Truck could be used in LESA systems for commonality and to reduce development costs. The end result would be ever-expanding permanent stations on the moon.
A typical vision of post-Apollo lunar exploration envisioned the following phases: :
- 2 men/2 days - Apollo
- 2 men/14 days - AES - LEM Shelter (2050 kg surface payload - LEM Shelter)
- 2 men/14 to 30 days - ALSS with shelter or MOLAB (4100 kg surface payload)
- 3 men/90 days - LESA I (10,500 kg surface payload)
- 3 men/90 days - LESA I + MOLAB (12,500 kg surface payload)
- 6 men/180 days - LESA II with shelter and extended range roving vehicle (25,000 kg surface payload)
In a comparison lf lunar base approaches, the basic Apollo hardware scenario for thorough exploration of a single location would consist of a single manned lunar reconnaissance landing of the selected base site, followed by six Apollo launches over the next six quarters - total, 14 man-days on the moon for 7 Saturn V launches. The AES or ALSS approach would follow the single reconnaissance flight by three pairs of cargo landings and manned landings, resulting in a total of 86 man-days on the moon for the same number of Saturn V launches. The LESA approach, with a cargo lander followed by two manned landings in sequence to the same large shelter and rover, would allow 542 man-days on the moon. ALSS development would cost around $500 million, and LESA cost $1.45 billion. In terms of cost per man-day on the moon, either approach would pay off on the very first mission.
For LESA a "clean sheet of paper" direct lunar lander, the Lunar Landing Vehicle (LLV) was conceived, which would take full advantage of the Saturn V trans-lunar payload capability. The LLV would have a payload of 12,700 kg, which would include life support systems and consumables, a shelter, and a Lunar Roving Vehicle. The shelter was designed for six crew, but only three would use it in the early missions. It consisted of an airlock, a cylindrical domed center structure, and an outer toroid work area. Adequate space existed in the toroid for suited astronauts to function and operate the controls in case of an emergency depressurization. Net LLV translunar injection mass was 41,000 kg (equivalent to a 43,000 kg mass payload for the Saturn V, including fairings). Landed mass was 18,000 kg, including 11,5000 to 13,500 kg payload (depending on whether a one or two stage LLV was developed), 900 to 1,000 cu m of living area, and access platforms 1.6 to 3.0 m above the surface, depending on the staging concept. Engines for the LLV would be modifications of the RL10-A3 Lox/LH2 engine.
A nuclear reactor based on SNAP technology would power later LESA bases, producing 100 kWe to 200 kWe, with a mass of 11,700 to 13,500 kg, including integral shielding (it would not have to be buried under regolith). Tube radiators folded within the nose fairing during flight and deployed after landing on the surface. It would have to be located one to two kilometers from the shelter to keep personnel radiation doses within acceptable levels. The reactor would have a 10,000-hour lifetime and was expected to be ready by the mid-1970's. Landed atop a 4.72 m - 5.59 m diameter LLV stage, it would have a basic height of 2.54 m, a diameter of 6.22 m, and a height with the radiators folded of 8.89 m.
A comparison of the merits of various modes of building up the base on the lunar surface indicated that the least costly base to deploy would involve leaving the modules on their lunar landing vehicles, and having integrated meteoroid shielding on the modules rather than towing them off the landing vehicles and burying them under lunar soil. However this least-costly base also involved burying the reactor so that it could be located nearer to the base and not interfere with operations by imposing a 3 km radius 'no-go' zone around it. Finally NASA concluded that it would still be preferable to remove the elements from the landing stages and cluster them closer together so that the various shelters would be accessible to one another in a shirtsleeve environment.
One aspect of lunar communications noted early was that the moon's small size made line-of-sight communications between the base and rovers unfeasible beyond 30 km from the base. The best solution seemed to be to accept relay of communications from earth, despite the 3-second delay involved.
First generation rovers would be similar to MOLAB, a driving cab towing a fuel trailer. This would have a range of up to 300 km. Emergency return in the even of breakdown would be using a Lunar Flying Vehicle. Later more elaborate expeditions would use rovers consisting of two cabs from the earlier design, joined to tow a larger fuel trailer. This could range up to 800 km. In case of breakdown, one of the cabs, with its own fuel supply, could be separated and driven back to base. For additional redundancy, the rovers would travel in pairs.
LESA would provide the payload to allow a 90-day exploration mission by thee astronauts, including 1500 miles of exploratory traverses. An early target would be the Kepler region, with the base located southeast of the crater. First the LESA would be landed on the surface. A second Saturn V launch would deliver three astronauts to the landing site aboard a LEM Taxi. They would place the LESA shelter in operation, install a semi-permanent geophysical monitoring station, and deploy the roving vehicle. Two of the crew would embark on an exploratory traverse while the third remained at the shelter. Three or more such traverses would be undertaken during the mission, covering 14 geological features of interest as much as 400 km from the base. Later Model 4 LESA systems would allow an 18-man installation to be built, manned over 24 months by a series of 8 Saturn V launches. Crew Size: 6. Design Life: 180 days. Associated Launch Vehicle: Saturn V. - Apollo LM Taxi. Other Designations: LM Taxi. Class: Manned. Type: Lunar Lander. Destination: Moon. Nation: USA. Manufacturer: Grumman.
The LM Taxi was essentially the basic Apollo LM modified for extended lunar surface stays. This was expected to be the workhorse of both Apollo Applications Extended Lunar Surface Missions beginning in 1970 and still be used to shuttle crews to the surface to larger LESA (Lunar Exploration System for Apollo) in the mid- to late- 1970's. Changes included additional water, oxygen, LH2, and Lox tankage in the descent stage in the payload bays; fuel cells in the ascent stage; a redundant Lox tank in the ascent stage over the back of the LM; and additional micrometeorite and radiation shielding. This would permit the LM to accommodate a crew of three with the capability for a 14-day quiescent (inactive) lunar stay time, in addition to 3 days (active) operational time. The LM Taxi would land near the previously-landed LM Shelter or LESA Shelter, where the crew would spend most of its time during surface explorations lasting from 14 days to three months. Crew Size: 3. Design Life: 14 days. Length: 6.37 m (20.89 ft). Maximum Diameter: 4.27 m (14.00 ft). Habitable Volume: 6.65 m3. Mass: 14,700 kg (32,400 lb). Main Engine Thrust: 44.041 kN (9,901 lbf). Main Engine Propellants: N2O4/Aerozine-50. Main Engine Propellants: 10,500 kg (23,100 lb). Main Engine Isp: 311 sec. Spacecraft delta v: 3,700 m/s (12,100 ft/sec). Electrical System: Fuel Cells. Associated Launch Vehicle: Saturn V.
- LLV. Other Designations: Lunar Landing Vehicle. Manufacturer's Designation: Lunar Logistics Vehicle. Class: Manned. Type: Lunar Logistics. Destination: Moon. Nation: USA.
Many versions of new Lunar Logistic Vehicles (LLV's) using several possible candidate propellants were studied by NASA and its contractors in the mid-1960's for post-Apollo lunar base support. By the time budget cutbacks ended such thoughts, NASA was favoring a two-stage version powered by throttleable RL10 engines burning liquid oxygen/liquid hydrogen propellants. Limiting the propellant candidates to those being used in active NASA programs (earth storables of the N204/Aerozine 50 and cryogens of the L0X/LH2 type), the choice revolved about a tradeoff between 33% better Isp performance, poorer length to diameter configurations, and more extensive ground support requirements of LOX/LH 2 compared to N204/Aerozine 50. However, the performance increase did provide significantly larger payload capabilities, and accordingly, the cryogenic combination was chosen by NASA for the new LLV's. In addition to the conventional one stage configurations, two stage versions were also of interest. A typical two stage LLV consisted of a braking stage (LI) and a landing stage (LII). The advantages of staging were (i) payload improvement, (2) the landed vehicle had a lower center-of-gravity (reducing possible cargo unloading problems and landing gear requirements), and (3) the braking stage (LI) could be a general use propulsion stage for integration into earth orbital or planetary programs (Multi-Mission Module Concept). Length: 7.90 m (25.90 ft). Maximum Diameter: 6.70 m (21.90 ft). Span: 21.30 m (69.80 ft). Mass: 41,000 kg (90,000 lb). Payload: 13,700 kg (30,200 lb). Main Engine Thrust: 131.210 kN (29,497 lbf). Main Engine Propellants: Lox/LH2. Main Engine Propellants: 23,500 kg (51,800 lb). Main Engine Isp: 444 sec. Electrical System: Batteries.
- LESA Shelter. Other Designations: Lunar Exploration System for Apollo. Class: Manned. Type: Lunar Habitat. Destination: Moon. Nation: USA.
LESA (Lunar Exploration System for Apollo) was an advanced lunar surface shelter. It would provide the maximum Saturn V-launched lunar base module by using a high efficiency LLV Lunar Landing Vehicle which used RL10 Lox/LH2 engines for the direct landing on the lunar surface. The LESA consisted of a circular inner cabin and annular outer cabin with control stations, bunks, and an airlock. The LLV would deliver the LESA together with a Molab lunar rover on the surface of the moon. Crews to man the base would be landed in 3-man LM Taxis. The crews would use the LESA Shelter for quarters, and the pressurized Molab for mobility. Initially the shelter would be manned by 3 crew members for 90 days. Follow-on flights would build up the base to six residents for indefinite lunar operations. Crew Size: 6. Design Life: 90 days. Length: 4.30 m (14.10 ft). Maximum Diameter: 6.70 m (21.90 ft). Habitable Volume: 80.00 m3. Mass: 9,700 kg (21,300 lb). Associated Launch Vehicle: Saturn V.
- Molab. Other Designations: Moderate Capacity Mobile Laboratory. Manufacturer's Designation: Mobile Lunar Laboratory. Class: Manned. Type: Lunar rover. Destination: Moon. Nation: USA.
The moderate capacity mobile laboratory (MOLAB) concept was studied in two NASA/MT contracts to determine configurations and capabilities of vehicles in the 2950 to 3850 kg class. Designed for delivery by the LM Truck, MOLAB was to be capable of surviving six months quiescent storage on the lunar surface, and then be activated to support two men in a pressurized cabin on a 14-day mission with a 7-day stay time contingency in a stationary mode. A typical configuration consisted of a four wheel vehicle having an internal pressurized volume of 12.8 m3 plus an additional 3.46 m3 airlock. The MOLAB would take advantage of any subsystem improvements evaluated in the Early Lunar Shelter studies such as cryogenic gas storage systems. In essence, a MOLAB related to an Early Lunar Shelter as the MOLEM to the LM shelter. Stay time or experimental payload was traded for mobility. Although the MOLAB was sized for a two man, 14 day mission, the concept could to establish tradeoffs of crew size and stay time in terms of weight and subsystem requirements. A three man 21 day 900 km traverse would require a MOLAB weighing 3810 kg. Average speed would be 10 kph and 320 kg of scientific experiments drawing 112 kW-hr of power could be accommodated. Mass breakdown was as follows: Fixed Equipment
- Structure: 636 kg
- Power supply: 220 kg
- Mobility: 1,485 kg
- EC/LSS: 324 kg
- Astrionics: 320 kg
- Subtotal: 2985 kg
Expendables
- Hydrogen for power: 88 kg
- Oxygen for power: 347 kg
- Oxygen for crew: 216 kg
- Others (food, LiOH, etc): 174 kg
- Subtotal: 825 kg
Total: 3810 kg
Another variant would take two men up to a total range of 396 km at a maximum velocity of 16 km/hr on compacted soils, 9.8 km/hr on maria. Turn radius 7 m; locomotion energy .39 k2-hr/km in uplands. 3,732 kg total mass breakdown: 1,036 kg cabin systems; 825 kg mobility; 282 kg power; 210 kg electronics; 340 kg scientific equipment; 466 kg for Lunar Flying Vehicle (rocket platform for emergency return to LM Taxi); 126 kg for tie downs; and 437 kg for expendables (fuel cell propellants and crew oxygen). Crew Size: 2. Design Life: 30 days. Length: 6.15 m (20.17 ft). Maximum Diameter: 3.18 m (10.43 ft). Habitable Volume: 5.66 m3. Mass: 3,732 kg (8,227 lb). Electrical System: Fuel Cells. Electric System: 160.00 kWh.
Bibliography and Further Reading
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