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Drop a pack of 128 automated rovers with the antennas and let them crawl out to their designated grid Which brings up the thought that someday hundreds of year

by ck2 5y ago

Drop a pack of 128 automated rovers with the antennas and let them crawl out to their designated grid Which brings up the thought that someday hundreds of years from now someone is going to install GPS on the moon (and mars) and ruin radio silence I wonder how they precisely position things on the moon now.

shagie 5y ago
Moon orbiters have the difficulty that there "mascons" (mass concentrations) on the moon that make its gravitational field very lumpy. https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)#Lunar_mascons https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)... That makes an orbital GPS difficult. > Lunar mascons alter the local gravity above and around them sufficiently that low and uncorrected satellite orbits around the Moon are unstable on a timescale of months or years. The small perturbations in the orbits accumulate and eventually distort the orbit enough that the satellite impacts the surface. > Because of its mascons, the Moon has only four "frozen orbit" inclination zones where a lunar satellite can stay in a low orbit indefinitely. Lunar subsatellites were released on two of the last three Apollo manned lunar landing missions in 1971 and 1972; the subsatellite PFS-2 released from Apollo 16 was expected to stay in orbit for one and a half years, but lasted only 35 days before crashing into the lunar surface. It was only in 2001 that the mascons were mapped and the frozen orbits were discovered. > ... At that time, one of NASA's highest priority "tiger team" projects was to explain why the Lunar Orbiter spacecraft being used to test the accuracy of Project Apollo navigation were experiencing errors in predicted position of ten times the mission specification (2 kilometers instead of 200 meters). You could still do things with atomic clocks on tops of mountains - but it is unlikely that we'll ever see something like StarLink or GPS on the moon. I suspect they do the positioning today via a really good map. https://moon.nasa.gov/resources/87/high-resolution-topographic-map-of-the-moon/ https://moon.nasa.gov/resources/87/high-resolution-topograph... > NASA's Lunar Reconnaissance Orbiter science team released the highest resolution near-global topographic map of the Moon ever created to date. This topographic map shows the surface shape and features over nearly the entire moon with a pixel scale close to 328 feet. https://www.lpi.usra.edu/planetary_news/2020/05/26/the-most-complete-map-of-the-moon/ https://www.lpi.usra.edu/planetary_news/2020/05/26/the-most-... > The geologic map makes use of LRO Lunar Orbiter Laser Altimeter data with 100-meter resolution for the polar regions and Kaguya terrain camera data with 60-meter resolution for the equatorial regions. This global map, combined with future high-resolution maps of local regions on the Moon, can be used to prioritize potential landing areas for robotic and crewed spacecraft. To download it - https://astrogeology.usgs.gov/search/map/Moon/Geology/Unified_Geologic_Map_of_the_Moon_GIS_v2 https://astrogeology.usgs.gov/search/map/Moon/Geology/Unifie...

by ck2 5y ago

shagie 5y ago

Moon orbiters have the difficulty that there "mascons" (mass concentrations) on the moon that make its gravitational field very lumpy. https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)#Lunar_mascons https://en.wikipedia.org/wiki/Mass_concentration_(astronomy)... That makes an orbital GPS difficult. > Lunar mascons alter the local gravity above and around them sufficiently that low and uncorrected satellite orbits around the Moon are unstable on a timescale of months or years. The small perturbations in the orbits accumulate and eventually distort the orbit enough that the satellite impacts the surface. > Because of its mascons, the Moon has only four "frozen orbit" inclination zones where a lunar satellite can stay in a low orbit indefinitely. Lunar subsatellites were released on two of the last three Apollo manned lunar landing missions in 1971 and 1972; the subsatellite PFS-2 released from Apollo 16 was expected to stay in orbit for one and a half years, but lasted only 35 days before crashing into the lunar surface. It was only in 2001 that the mascons were mapped and the frozen orbits were discovered. > ... At that time, one of NASA's highest priority "tiger team" projects was to explain why the Lunar Orbiter spacecraft being used to test the accuracy of Project Apollo navigation were experiencing errors in predicted position of ten times the mission specification (2 kilometers instead of 200 meters). You could still do things with atomic clocks on tops of mountains - but it is unlikely that we'll ever see something like StarLink or GPS on the moon. I suspect they do the positioning today via a really good map. https://moon.nasa.gov/resources/87/high-resolution-topographic-map-of-the-moon/ https://moon.nasa.gov/resources/87/high-resolution-topograph... > NASA's Lunar Reconnaissance Orbiter science team released the highest resolution near-global topographic map of the Moon ever created to date. This topographic map shows the surface shape and features over nearly the entire moon with a pixel scale close to 328 feet. https://www.lpi.usra.edu/planetary_news/2020/05/26/the-most-complete-map-of-the-moon/ https://www.lpi.usra.edu/planetary_news/2020/05/26/the-most-... > The geologic map makes use of LRO Lunar Orbiter Laser Altimeter data with 100-meter resolution for the polar regions and Kaguya terrain camera data with 60-meter resolution for the equatorial regions. This global map, combined with future high-resolution maps of local regions on the Moon, can be used to prioritize potential landing areas for robotic and crewed spacecraft. To download it - https://astrogeology.usgs.gov/search/map/Moon/Geology/Unified_Geologic_Map_of_the_Moon_GIS_v2 https://astrogeology.usgs.gov/search/map/Moon/Geology/Unifie...