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What hit the Moon? New crater makes a splash

Aug. 2, 2010
Courtesy of NASA Goddard Space Flight Center
and World Science staff

NASA sci­en­tists are av­idly stu­dy­ing a new crat­er that formed on the Moon with­in the past 39 years, as pho­tographs show.

While not huge, the pit stands out among its neigh­bors as bright ma­te­ri­al splat­tered by the im­pact ra­di­ates out­ward from the site.

This crater is be­lieved to have formed some­time in the last 38 years. The new crat­er is on­ly ~10 me­ters (30 feet) across, but its bright "ejec­ta" ex­tends much far­ther, mak­ing it stand out from all the near­by crat­ers. The view is 400 meters (437 yards) across. (Cred­it: NA­SA/GS­FC/Ari­zona State U.)
Re­search­ers iden­ti­fied the crat­er by com­par­ing de­tailed new moon im­ages with his­tor­i­cal ones.

The crat­er and its bright ha­lo ap­pear in a Sept. 30 im­age from NASA’s Lu­nar Re­con­nais­sance Or­biter Nar­row An­gle Cam­era. They are ab­sent from a 1971 Apol­lo 15 im­age tak­en un­der si­m­i­lar light­ing con­di­tions.

Sci­en­tists are sur­mis­ing that the roughly 10-me­ter (30-foot) wide de­pres­sion was formed by an as­ter­oid or small com­et only about half a me­ter (20 inches) wide. The ex­act lu­nar loca­t­ion, 16.92 de­grees North lat­i­tude and 40.50 de­grees East lon­gi­tude, cor­re­spond to no known im­pact or land­ing sites of hu­man-made ob­jects, ex­perts said.

NASA re­search­ers said the crash ex­posed fresh ma­te­ri­al from be­neath the sur­face. The rays of this bright ma­te­ri­al ex­tend­ing out­ward from the cen­tral crat­er are an es­ti­mat­ed three times more re­flec­tive than the un­der­ly­ing, bas­alt sur­face.

Dis­cov­er­ies of re­cent, ap­prox­i­mately dat­a­ble im­pact crat­ers like these es­tab­lish the pre­s­ent-day im­pact crat­ering rate on the Moon, ac­cord­ing to NASA plan­e­tary sci­en­tists. This, they said, should in turn lead to bet­ter un­der­stand­ing of the rate of “bom­bard­ment” of plan­ets by rocks wan­der­ing the in­ner so­lar sys­tem 

Me­te­orites of this size are con­sid­ered a po­ten­tial haz­ard to fu­ture ex­plor­ers on the Moon or any­where in the in­ner So­lar Sys­tem where, un­like on Earth, there is no pro­tec­tive at­mos­phere. On Earth the at­mos­phere pre­vents most im­pacts by burn­ing up in­com­ing ob­jects. 

If we have a bet­ter sense of the cur­rent im­pact rate for this size of im­pactor, we can more ef­fec­tively de­sign habi­tats and hard­ware to pro­tect hu­man ex­plor­ers, re­search­ers not­ed. 

A crat­er this young, they added, has not been mod­i­fied by oth­er pro­cesses, so we can study the ap­pearance of fea­tures we know are ex­tremely fresh. In ad­di­tion, know­ing how many crat­ers are cur­rently be­ing pro­duced is ex­pected to im­prove our un­der­stand­ing of the ge­o­log­ic his­to­ry of the Moon, Mars, and oth­er plan­ets.

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NASA scientists are avidly studying a new crater that formed on the Moon within the past 38 years, as photographs show. While not huge, the puncture is no run-of-the-mill hole in the ground. Bright material splattered by the impact radiates outward from it, making it stand out among its neighbors. Researchers identified the crater by comparing detailed new moon images with historical ones. The crater and its bright halo appear in a Sept. 30 image from NASA’s Lunar Reconnaissance Orbiter Narrow Angle Camera, but are absent from a 1971 Apollo 15 image. Both pictures were taken under similar lighting conditions, with the Sun at a similar angle. Scientists are surmising that the roughly 10-meter (30-foot) wide depression was formed by an asteroid or small comet only about half a meter (20 inches) wide. The exact lunar location, 16.92 degrees North latitude and 40.50 degrees East longitude, correspond to no known impact or landing sites of human-made objects, experts said. NASA researchers said the crash exposed fresh material from beneath the surface. The rays of this bright material extending outward from the central crater are an estimated three times more reflective than the underlying, basalt surface. Discoveries of recent, approximately datable impact craters like these establish the present-day impact cratering rate on the Moon, which will lead to better understanding of the bombardment rate in the inner solar system, according to NASA planetary scientists. Meteorites of this size are considered a potential hazard to future explorers on the Moon or anywhere in the inner Solar System where, unlike on Earth, there is no protective atmosphere. On Earth the atmosphere prevents most impacts by burning up incoming objects. If we have a better sense of the current impact rate for this size of impactor, we can more effectively design habitats and hardware to protect human explorers, researchers noted. A crater this young, they added, has not been modified by other processes, so we can study the appearance of features we know are extremely fresh. In addition, knowing how many craters are currently being produced is expected to improve our understanding of the geologic history of the Moon, Mars, and other planets.