Surviving and Operating Through the Lunar Night
Future Operations in Space (FISO) Seminar April 1, 2020
Andrew Petro NASA Headquarters
1 Workshop sponsored by the NASA Space Technology, Science, and Human Exploration and Operations Mission Directorates (STMD, SMD & HEOMD)
With support from the Solar System Exploration Research Virtual Institute (SSERVI), Lunar Exploration Analysis Group (LEAG), NASA Space Portal, and Universities Space Research Association (USRA).
Over 200 participants from industry, academia, the lunar science community, and government agencies.
2 The Lunar Day-Night Cycle 14 Earth days of sunlight followed by 14 Earth days of continuous darkness and extreme cold (with no solar power) and no moderating atmosphere presents one of the most demanding environmental challenge that will be faced in the exploration of the solar system
Rough Comparison of Temperature Ranges for Earth, Moon and Mars
Lunar Permanent Shadow Lunar Equator – Average Day to Night Range -250˚C -130˚C 120˚C
Mars Equator – Day to Night -70˚C 10˚C
Montana Winter – Day to Night -15˚C 10˚C Death Valley Summer – Day to Night 30˚C 45˚C 0˚K
3 Previous Lunar Night Experience
Surveyor Spacecraft Missions - powered by solar arrays and batteries not specifically designed to survive the night. Several did operate into the night and were revived on subsequent days.
Surveyor 1: 48 hours into the first lunar night, partial data obtained as late as the sixth lunar day
Surveyor 3: Shut down 2 hours after sunset on the first lunar night
Surveyor 5: 115 hours into the first lunar night and 215 hours into the second lunar night
Surveyor 6: 40 hours into the first lunar night
Surveyor 7: 80 hours into the first lunar night, revived on the second lunar day but contact lost before sunset
4 Previous Lunar Night Experience
Apollo Lunar Surface Experiments Packages (ALSEP’s) 1969-77 At Apollo 12, 14, 15, 16, and 17 landing sites – used 70-Watt Plutonium-238 radioisotope thermoelectric generators (RTG’s) and operated continuously for several years. (Shutdown intentionally in 1977.)
5 Previous Lunar Night Experience
Soviet Lunokhod Rovers 1970-1973 Top of the rover had a lid with solar arrays and a radiator which could be opened during daytime operations and closed at night for hibernation. Radioactive Polonium 210 source heated air circulated through a pressurized chamber containing electronics, batteries, and instruments.
In the lunar morning, the rovers waited to heat up for two days before moving. During lunar noon, movement was limited because the high sun angle made it impossible to see surface features such as craters.
Lunokhod 1 survived 11 lunar day-night cycles Lunokhod 2 survived 4 day-night cycles.
6 Recent Lunar Night Experience
Chinese Yutu Rovers - powered by solar panels for operation and battery charging during daylight, powered down at night with some heating provided by radioisotope heater units (Plutonium-238)
Yutu 1: Landed in December 2013. Stopped moving after 1 month, transmitted data for several years.
Yutu-2: Landed in January 2019 and still operational. Has operated through 15 lunar days so far.
7 Survive and Operate through the Lunar Night Potential Applications
Stationary instrument package (like ALSEP and larger) – operate in sunlight, hibernate at night – operate in sunlight, minimal operation at night – operate continuously through day/night cycle – operate continuously in permanently shadowed region (PSR) Distributed network of instruments (generally small) – operate continuously through day/night cycle Robotic rover – operate in sunlight, hibernate at night – operate in sunlight, minimal operation at night – operate continuously through day/night cycle – operate for limited periods in PSR
8 Survive and Operate through the Lunar Night Potential Applications
Pressurized rover, construction or excavation vehicle – operate in sunlight, hibernate at night – operate continuously through day/night cycle – operate for limited periods in PSR Habitat – operate continuously through day/night cycle Propellant Plant – operate in sunlight, hibernate at night – operate continuously through day/night cycle
9 Survive and Operate through the Lunar Night Potential Solutions and Strategies
Generate power continuously - fuel cells - Fission - radioactive isotope - thermo-electric – using large temperature differentials Expend stored energy - batteries or other chemical systems - fuel cells - mechanical storage (fly wheel) - electromagnetic storage (especially with superconductors) Absorb stored heat - internal heat sink - reclaim waste heat - external heat sink (wadi), - chemical reaction - radioactive isotope 10 Survive and Operate through the Lunar Night Potential Solutions and Strategies
Conserve energy - increase efficiency - thermal switches - insulation and sheltering - increase component tolerance for cold Obtain power from remote source - long distance transmission lines - power beaming – for power or heat - globally from an orbiting satellite or locally between a power source and mobile assets Minimize eclipse - through mobility - follow the sun (most practical near poles) - locate in areas of minimal eclipse (high elevations near poles) - very tall tower for solar array (near poles)
11 Survive and Operate through the Lunar Night Recommendations Develop and Advance Technology - Advanced batteries – improved performance, mass, and thermal robustness - Solar arrays for daytime power, regenerative fuels cells provide the lowest mass, non-nuclear option to supply power during the lunar night - Small fission power systems such as “Kilopower” - Potential for much larger scale fission generators - Power beaming - Novel energy storage Thermal modeling of conditions during dawn and dusk and the extreme heat of lunar noon Systematic effort to identify, certify, and document avionics and other components for the extreme thermal environment of the lunar surface.
Get Started Now Initiate survive the night efforts from the beginning and improve incrementally: hibernation to limited nighttime operations to continuous operation Use Commercial Lunar Payload Services (CLPS) missions to accelerate demonstration of new technology and capabilities 12 NOW
13 IN THE FUTURE? ......
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Survive and Operate Through the Lunar Night – Workshop Report https://www.lpi.usra.edu/leag/
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