A peak of eternal light (PEL) is a hypothetical point on the surface of an astronomical body that is always in sunlight. Such a peak must have high latitude, high elevation, and be on a body with very small axial tilt. The existence of such peaks was first postulated by Beer and Mädler in 1837. The pair said about the lunar polar mountains: "...many of these peaks have (with the exception of eclipses caused by the Earth) eternal sunshine".[1] These polar peaks were later mentioned by Camille Flammarion in 1879, who speculated that there may exist pics de lumière éternelle at the poles of the Moon.[2] PELs would be advantageous for space exploration and colonization due to the ability of an electrical device located there to receive solar power regardless of the time of day or day of the year, and the relatively stable temperature range.
Detailed lunar topography collected by the Lunar Reconnaissance Orbiter (LRO) suggests that no points on the Moon receive perpetual light during both the winter and summer, but points on crater rims exist which have very extended periods of sunlight.[3][4]
The ESASMART-1, NASAClementine and JAXASELENEspacecraft made maps of the lunar poles that have been used to identify sites receiving eternal light. The orbiting craft monitored the lighting at the poles and looked for seasonal variations, as well as mapping the relief so that peaks of eternal light could be identified topographically.
The Lunar Reconnaissance Orbiter then took a data set including 24,000 wide-area camera and 31,500 narrow-angle camera images within 2° of the poles. These were used to construct high-resolution maps that reveal illuminated terrain under varying lighting conditions.[3]
Lunar north poleEdit
Based on images from the Clementine lunar mission, a team from Johns Hopkins University suggested that four locations along the rim of the Peary crater are candidates for peaks of eternal light. This crater lies near the north pole of the Moon. Clementine's images were taken during the northern summer, however, and did not address illumination of these peaks during the winter, when the Sun is below the horizon. Further data from the SELENE spaceprobe determined that one peak at Peary Crater receives sunlight for 89% of a lunar year.[5]
Lunar south poleEdit
Lunar South Pole: four peaks are identified which are illuminated more than 80% of the time
The lunar south pole is situated in a huge depression, leading to 16 km altitude differences over the region. Careful analysis of imagery and topographic conditions on the lunar South Pole by teams from NASA and the ESA revealed a small number of illuminated ridges within 15 km of the pole, each of them much like an island of no more than a few hundred meters across in an ocean of eternal darkness, where a lander could receive near-permanent lighting (for ~70–90% of the southern lunar winter, and likely all of the southern lunar summer).[6]
The Malapert Mountain region, on the rim of the Malapert crater 122 km from the lunar south pole on the Earth-facing side, may also have high levels of illumination. One study estimates the Malapert Mountain region to receive less than full sunlight 11% of the time. Sunlight exposure varies by year due to the Moon's orbit being 1.5° off-plane with the Sun. 2005 estimates of sunlight coverage of the Malapert Mountain region found only six partially lit or unlit events that year: 0–159 hours of complete sunset per event and 41–199 hours of complete or partial sunset per event.[7] A later study using a combination of both Clementine imaging and SELENE topographical data estimated only 74% of full sunlight for the year 2020.[8] This study found that two points only ~8 km from each other along a straight ridge extending from Shackleton Crater at the Lunar South Pole are illuminated a combined ~94% of a lunar year. This is because both points cast shadows upon each other during different times of the lunar year, and only a few times of darkness occur when further peaks throw shadows over both of these points simultaneously.
The data set from Lunar Reconnaissance Orbiter shows that some sites on the rim of Shackelton remain illuminated for 94% of a lunar year. The longest all three Shackleton outposts are eclipsed is 43 h.[3]
Lighting conditions for specific southern lunar pole coordinates[8]
Approximate placement near a named feature
Lunar coordinates
Illuminated time fraction
Notes
Over lunar year 2020
Minimum per lunar day
Maximum per lunar day
On Shackleton Crater ridge: point A
089.68°S 166.0°W
081%
044%
098%
Even during the worst lunar day the longest period of darkness is ~7 Earth days, with shortest periods of light between darkness of ~3 Earth days
Peak near Shackleton Crater ridge: point B
089.44°S 141.8°W
082%
056%
100%
During worst lunar day the longest period of darkness is ~12 Earth days; has 4.5 lunar days of continuous lighting in lunar summer and only 4.5 Earth days of total darkness time in 8 lunar days.
on De Gerlache Crater ridge: point C
088.71°S 068.7°W
085%
064%
098%
Has shortest period of darkness of only ~6 days, followed by ~7 days of intermittent light and darkness periods.
Peak close to Shackleton Crater ridge: point D
088.79°S 124.5°E
086%
058%
100%
5 lunar days of continuous light, ~7 lunar days lighting with only ~2 Earth days of darkness, ~12 Earth days periods of darkness or near darkness during lunar winter.
^Beer, Wilhelm, and Mädler, Johann Heinrich (1837). Der Mond nach seinen kosmischen und individuellen Verhältissen oder allgemeine vergleichende Selenographie. Berlin, Simon Schropp and Co. (in German).
^Flammarion, Camille. Astronomie Populaire, description générale du ciel. Paris, 1879. (in French).
^ abcSpeyerer, Emerson J., and Robinson, Mark S. (2013). "Persistently illuminated regions at the lunar poles: Ideal sites for future exploration", Icarus, 222, No. 1, January, pp. 122–136.
^Gläser, P., Oberst, J., Neumann, G. A., Mazarico, E., Speyerer, E. J., Robinson, M. S. (2017). "Illumination conditions at the lunar poles: Implications for future exploration", Planetary and Space Science, vol. 162, p. 170–178.
^Noda, H. (2008). "Illumination conditions at the lunar polar regions by KAGUYA (SELENE) laser altimeter". Geophysical Research Letters. 35 (24): L24203. Bibcode:2008GeoRL..3524203N. doi:10.1029/2008GL035692.
^Kruijff, M. (2000). The Peaks of Eternal Light on the Lunar South Pole: How they were found and what they look like, 4th International Conference on Exploration and Utilization of the Moon (ICEUM4), ESA/ESTEC, SP-462, September.
^Sharpe, Burton L., and Schrunk, David G. (2002). "Malapert Mountain Revisited". Space 2002 and Robotics 2002: 129–135. Bibcode:2002spro.conf..129S. doi:10.1061/40625(203)18. ISBN978-0-7844-0625-0.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ abBussey D. B. J., McGovern J. A., Spudis P. D., Neish C. D., Noda H., Ishihara Y., Sørensen S.-A. (2010). "Illumination conditions of the south pole of the Moon derived using Kaguya topography". Icarus. 208 (2): 558–564. Bibcode:2010Icar..208..558B. doi:10.1016/j.icarus.2010.03.028.{{cite journal}}: CS1 maint: multiple names: authors list (link)
External linksEdit
Koschny, Detlef; Grieger, Björn. . Europlanet Research Infrastructure. Archived from the original on 2011-09-29. Retrieved 2009-09-24.
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A peak of eternal light PEL is a hypothetical point on the surface of an astronomical body that is always in sunlight Such a peak must have high latitude high elevation and be on a body with very small axial tilt The existence of such peaks was first postulated by Beer and Madler in 1837 The pair said about the lunar polar mountains many of these peaks have with the exception of eclipses caused by the Earth eternal sunshine 1 These polar peaks were later mentioned by Camille Flammarion in 1879 who speculated that there may exist pics de lumiere eternelle at the poles of the Moon 2 PELs would be advantageous for space exploration and colonization due to the ability of an electrical device located there to receive solar power regardless of the time of day or day of the year and the relatively stable temperature range Detailed lunar topography collected by the Lunar Reconnaissance Orbiter LRO suggests that no points on the Moon receive perpetual light during both the winter and summer but points on crater rims exist which have very extended periods of sunlight 3 4 Contents 1 On the Moon 1 1 Orbital imagery 1 2 Lunar north pole 1 3 Lunar south pole 2 See also 3 References 4 External linksOn the Moon EditOrbital imagery Edit The ESA SMART 1 NASA Clementine and JAXA SELENE spacecraft made maps of the lunar poles that have been used to identify sites receiving eternal light The orbiting craft monitored the lighting at the poles and looked for seasonal variations as well as mapping the relief so that peaks of eternal light could be identified topographically The Lunar Reconnaissance Orbiter then took a data set including 24 000 wide area camera and 31 500 narrow angle camera images within 2 of the poles These were used to construct high resolution maps that reveal illuminated terrain under varying lighting conditions 3 Lunar north pole Edit Based on images from the Clementine lunar mission a team from Johns Hopkins University suggested that four locations along the rim of the Peary crater are candidates for peaks of eternal light This crater lies near the north pole of the Moon Clementine s images were taken during the northern summer however and did not address illumination of these peaks during the winter when the Sun is below the horizon Further data from the SELENE spaceprobe determined that one peak at Peary Crater receives sunlight for 89 of a lunar year 5 Lunar south pole Edit nbsp Lunar South Pole four peaks are identified which are illuminated more than 80 of the timeThe lunar south pole is situated in a huge depression leading to 16 km altitude differences over the region Careful analysis of imagery and topographic conditions on the lunar South Pole by teams from NASA and the ESA revealed a small number of illuminated ridges within 15 km of the pole each of them much like an island of no more than a few hundred meters across in an ocean of eternal darkness where a lander could receive near permanent lighting for 70 90 of the southern lunar winter and likely all of the southern lunar summer 6 The Malapert Mountain region on the rim of the Malapert crater 122 km from the lunar south pole on the Earth facing side may also have high levels of illumination One study estimates the Malapert Mountain region to receive less than full sunlight 11 of the time Sunlight exposure varies by year due to the Moon s orbit being 1 5 off plane with the Sun 2005 estimates of sunlight coverage of the Malapert Mountain region found only six partially lit or unlit events that year 0 159 hours of complete sunset per event and 41 199 hours of complete or partial sunset per event 7 A later study using a combination of both Clementine imaging and SELENE topographical data estimated only 74 of full sunlight for the year 2020 8 This study found that two points only 8 km from each other along a straight ridge extending from Shackleton Crater at the Lunar South Pole are illuminated a combined 94 of a lunar year This is because both points cast shadows upon each other during different times of the lunar year and only a few times of darkness occur when further peaks throw shadows over both of these points simultaneously The data set from Lunar Reconnaissance Orbiter shows that some sites on the rim of Shackelton remain illuminated for 94 of a lunar year The longest all three Shackleton outposts are eclipsed is 43 h 3 Lighting conditions for specific southern lunar pole coordinates 8 Approximate placementnear a named feature Lunarcoordinates Illuminated time fraction NotesOver lunaryear 2020 Minimumper lunar day Maximumper lunar dayOn Shackleton Crater ridge point A 0 89 68 S166 0 W 0 81 0 44 0 98 Even during the worst lunar day the longest period of darkness is 7 Earth days with shortest periods of light between darkness of 3 Earth daysPeak near Shackleton Crater ridge point B 0 89 44 S141 8 W 0 82 0 56 100 During worst lunar day the longest period of darkness is 12 Earth days has 4 5 lunar days of continuous lighting in lunar summer and only 4 5 Earth days of total darkness time in 8 lunar days on De Gerlache Crater ridge point C 0 88 71 S0 68 7 W 0 85 0 64 0 98 Has shortest period of darkness of only 6 days followed by 7 days of intermittent light and darkness periods Peak close to Shackleton Crater ridge point D 0 88 79 S124 5 E 0 86 0 58 100 5 lunar days of continuous light 7 lunar days lighting with only 2 Earth days of darkness 12 Earth days periods of darkness or near darkness during lunar winter on Malapert Mountain point M1 0 86 04 S0 0 2 7 E 0 74 0 54 0 95 on Malapert Mountain point M2 0 86 00 S0 0 2 9 W 0 74 0 58 0 90 See also EditCrater of eternal darknessReferences Edit Beer Wilhelm and Madler Johann Heinrich 1837 Der Mond nach seinen kosmischen und individuellen Verhaltissen oder allgemeine vergleichende Selenographie Berlin Simon Schropp and Co in German Flammarion Camille Astronomie Populaire description generale du ciel Paris 1879 in French a b c Speyerer Emerson J and Robinson Mark S 2013 Persistently illuminated regions at the lunar poles Ideal sites for future exploration Icarus 222 No 1 January pp 122 136 Glaser P Oberst J Neumann G A Mazarico E Speyerer E J Robinson M S 2017 Illumination conditions at the lunar poles Implications for future exploration Planetary and Space Science vol 162 p 170 178 Noda H 2008 Illumination conditions at the lunar polar regions by KAGUYA SELENE laser altimeter Geophysical Research Letters 35 24 L24203 Bibcode 2008GeoRL 3524203N doi 10 1029 2008GL035692 Kruijff M 2000 The Peaks of Eternal Light on the Lunar South Pole How they were found and what they look like 4th International Conference on Exploration and Utilization of the Moon ICEUM4 ESA ESTEC SP 462 September Sharpe Burton L and Schrunk David G 2002 Malapert Mountain Revisited Space 2002 and Robotics 2002 129 135 Bibcode 2002spro conf 129S doi 10 1061 40625 203 18 ISBN 978 0 7844 0625 0 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link a b Bussey D B J McGovern J A Spudis P D Neish C D Noda H Ishihara Y Sorensen S A 2010 Illumination conditions of the south pole of the Moon derived using Kaguya topography Icarus 208 2 558 564 Bibcode 2010Icar 208 558B doi 10 1016 j icarus 2010 03 028 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link External links EditKoschny Detlef Grieger Bjorn Taking a SMART sidelong look at Peak of Eternal Light Europlanet Research Infrastructure Archived from the original on 2011 09 29 Retrieved 2009 09 24 The Peak of Eternal Light video by the European Space Agency Retrieved from https en wikipedia org w index php title Peak of eternal light amp oldid 1171835206, wikipedia, wiki, book, books, library,
