Scientists locate lunar impact crater produced by LCROSS in 2009
Taken from figure 2 of the paper. Click for
original image.
Using orbital radar and opitcal images scientists finally believe they have identified the small crater on the Moon produced when — as part of the 2009 LCROSS mission — an abandoned rocket stage crashed in a permanently shadowed section of Cabeus crater near the lunar south pole.
LCROSS was designed to study the ejecta thrown up by that impact, and found “a significant amount of water, estimated at 5.6 ± 2.9% by mass, as well as minor amounts of other volatile species.” Because the impact was in that permanently shadowed region, however, locating the new crater required new instrumentation.
Using a radar instrument on Lunar Reconnaissance Orbiter (LRO) as well as the Shadowcam instrument on South Korea’s Danuri orbiter — designed to take optical images in very low light — the scientists pinpointed that impact crater, as shown in the image to the right, overlaying both the radar and optical images. The crater is estimated to be about 22 meters across, about 25% smaller than predicted. From this the scientists conclude that the water in the ejecta plume came from close to the surface, and thus could only have been placed there in the past billion years. Before that, the location was not in shadow, and volatiles like water could not have survived if they were near the surface.
From this data the scientists believe the water was likely placed there by the “recent delivery by comets or the solar wind, rather than as a paleo-reservoir from an early volcanic atmosphere.” If so, the amount of material can be reasonably predicted, and is likely less than hoped for because it only exists in the top two meters.
Taken from figure 2 of the paper. Click for
original image.
Using orbital radar and opitcal images scientists finally believe they have identified the small crater on the Moon produced when — as part of the 2009 LCROSS mission — an abandoned rocket stage crashed in a permanently shadowed section of Cabeus crater near the lunar south pole.
LCROSS was designed to study the ejecta thrown up by that impact, and found “a significant amount of water, estimated at 5.6 ± 2.9% by mass, as well as minor amounts of other volatile species.” Because the impact was in that permanently shadowed region, however, locating the new crater required new instrumentation.
Using a radar instrument on Lunar Reconnaissance Orbiter (LRO) as well as the Shadowcam instrument on South Korea’s Danuri orbiter — designed to take optical images in very low light — the scientists pinpointed that impact crater, as shown in the image to the right, overlaying both the radar and optical images. The crater is estimated to be about 22 meters across, about 25% smaller than predicted. From this the scientists conclude that the water in the ejecta plume came from close to the surface, and thus could only have been placed there in the past billion years. Before that, the location was not in shadow, and volatiles like water could not have survived if they were near the surface.
From this data the scientists believe the water was likely placed there by the “recent delivery by comets or the solar wind, rather than as a paleo-reservoir from an early volcanic atmosphere.” If so, the amount of material can be reasonably predicted, and is likely less than hoped for because it only exists in the top two meters.
