Cabeus (crater)
 Cabeus Crater (left) as imaged by theDivinerinstrument on theLunar Reconnaissance Orbiter. | |
| Coordinates | 84°54′S35°30′W/ 84.9°S 35.5°W |
|---|---|
| Diameter | 98 km (61 mi) |
| Depth | 4 km[1] |
| Colongitude | 45° at sunrise |
| Eponym | Niccolò Cabeo[2] |
Cabeusis alunarimpact craterthat is located about 100 km (62 mi) from thesouth poleof theMoon.[3]At this location the crater is seen obliquely fromEarth,and it is almostperpetually in deep shadowdue to lack ofsunlight.Hence, not much detail can be seen of this crater, even from orbit. Through atelescope,this crater appears near the southern limb of the Moon, to the west of the craterMalapertand to the south-southwest ofNewton.[4][5]
Description
[edit]
The crater nameCabeusfirst appeared in the 1651 workAlmagestum NovumbyGiovanni Riccioli,who named it afterNiccolò Cabeo.However, the position of the Cabeus crater was in the location later assigned toNewton crater.[6]The official name and location for this crater was adopted by theIAUCommission 17, as established in the 1935 workNamed Lunar FormationsbyMary A. Blaggand Karl Müller.[2]
This crater is a worn formation that has been eroded by subsequent impacts. The rim is eroded and uneven, with prominent ridges at the northern and southern ends. A small crater lies across the northeastern rim and there is 10–11 km crater on the interior floor near the west-southwestern rim. Near the center of the crater floor is a small ridge. The floor of the crater has an average depth of 4 km and it is 60 km across. The slope of the crater walls is 10–15°.[1]
Because of the crater's location near the lunar south pole, the main part of the crater is illuminated by the Sun during only 25% of each lunar day. The inner walls receive illumination for 30% of a lunar day, while part of the western end of the crater is in permanent shadow.[1]
Volatiles
[edit]
The south polar region of the Moon was surveyed by theLunar Prospectorspacecraft and a hydrogen signature was detected. Potential sources for this hydrogen include water deposits from comet or meteorite impacts, thesolar windor out-gassing.[7]This crater is sufficiently large that the temperature within the shaded region is below 100 K (−173 °C). This would allow water ice to remain on or near the crater surface for billions of years without sublimating.[8]
LCROSS
[edit]
TheUnited StatesNational Aeronautics and Space Administrationlaunched theLCROSS,impactor spacecraft on 18 June 2009, to look forwaterat theLunar south pole.On 28 September 2009, Cabeus proper was selected as the impact target for theLCROSSmission, switching the target from satellite crater Cabeus A. The change was made after review of the latest data gathered by other lunar exploration craft, which indicated that Cabeus proper had a higher concentration of hydrogen than Cabeus A.[9]
At 11:31UTCon 9 October 2009 theCentaurupper stage of itsAtlas Vcarrier rocket impacted Cabeus, followed shortly thereafter by the impact of the LCROSS spacecraft itself. The impact of the Centaur was intended to throw up a plume of lunar surface material to be sampled by sensors carried on the LCROSS spacecraft as it traversed the plume. But the debris plumes were smaller than predicted.[10]Preliminary data from the LCROSS spectrometer measurements of the impact plume appeared to confirm the presence of water in the crater.[11]
Analysis of the plume observations supports the presence of water in the regolith. Absorption in the near-infrared can be attributed to ice and water vapor, while emissions in the ultraviolet indicate the presence of hydroxyl radicals, which also supports the likelihood of water. The estimated total amount of water vapor and ice in the plume is up to155 ± 12 kg,or an estimated5.6 ± 2.9%by mass. The spectral signatures of other volatiles were observed, matching the signatures ofcarbon dioxide,lighthydrocarbons,andsulfur-bearing compounds.[12]
Satellite craters
[edit]By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Cabeus.[4]
| Cabeus | Latitude | Longitude | Diameter |
|---|---|---|---|
| A | 82.2° S | 39.1° W | 48 km |
| B | 82.4° S | 53.0° W | 61 km |
References
[edit]- ^abcKozlova, E. A.; et al. (March 1–5, 2010). "Crater Cabeus as Possible Cold Trap for Volatiles Near South Pole of the Moon".Proceedings, 41st Lunar and Planetary Science Conference.The Woodlands, Texas. p. 1779.Bibcode:2010LPI....41.1779K.
- ^abBlue, Jennifer (July 25, 2007)."Gazetteer of Planetary Nomenclature".USGS.Retrieved2007-08-05.
- ^Grego, Peter (2005).The Moon and How to Observe it.Birkhäuser.p. 214.ISBN978-1-85233-748-3.
- ^abBussey, B.;et al. (2004).The Clementine Atlas of the Moon.New York: Cambridge University Press.ISBN978-0-521-81528-4.
- ^Whitaker, Ewen A. (1999).Mapping and Naming the Moon.Cambridge University Press.p. 172.ISBN978-0-521-62248-6.
- ^Whitaker (1999:61, 211)
- ^Margot, J. L.; Campbell, DB; Jurgens, RF; Slade, MA (1999-06-04). "Topography of the Lunar Poles from Radar Interferometry: A Survey of Cold Trap Locations".Science.284(5420): 1658–1660.Bibcode:1999Sci...284.1658M.CiteSeerX10.1.1.485.312.doi:10.1126/science.284.5420.1658.PMID10356393.
- ^Feldman, W. C.; et al. (2001)."Evidence for water ice near the lunar poles".Journal of Geophysical Research.106(E10): 23, 231–23, 251.Bibcode:2001JGR...10623231F.doi:10.1029/2000JE001444.
- ^"NASA's LCROSS Mission Changes Impact Crater".NASA. 2009-09-28. Archived fromthe originalon 2009-10-28.Retrieved2009-09-28.
- ^"NASA's LCROSS Reveals Target Crater For Lunar South Pole Impacts".NASA. 2009-09-11.Retrieved2009-09-11.
- ^"NASA'S LCROSS Impacts Confirm Water In Lunar Crater".PR Newswire.November 13, 2009.Retrieved2009-11-13.
- ^Colaprete, Anthony; et al. (October 22, 2010)."Detection of Water in the LCROSS Ejecta Plume".Science.330(6003): 463–468.Bibcode:2010Sci...330..463C.doi:10.1126/science.1186986.PMID20966242.S2CID206525375.Retrieved2010-12-01.
External links
[edit]
- Jenner, Lynn; et al. (November 17, 2009)."Cabeus Crater".Lunar Reconnaissance Orbiter.NASA.Retrieved2010-01-27.
- USGS: Lunar south pole map
