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Science 103 meteoroid impacts on Moon in 2.5 years
Science 103 meteoroid impacts on Moon in 2.5 years | 103 meteoroid impacts on Moon in 2.5 years |
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| by William Atkins | |
| Thursday, 22 May 2008 | |
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Science DiscussionsThe first meteoroid recorded by the MEO team hitting the moon occurred on November 7, 2005. The baseball-sized meteoroid was a piece from Comet Encke, and it hit the Mare Imbrium (Latin for “Sea of Showers” or “Sea of Rains”), a large lunar mare (“sea”) that was created when lava flooded into a giant crater. The southwestern region of this impact basin, near the Apennine Mountains (Montes Apenninus), and southwest of Mons Hadley, was the landing site for the Apollo 15 astronauts on July 30, 1971, the fourth mission to land on the Moon. This first recorded hit on the Moon by the MEO team resulted in a 7th magnitude flash of light. Since then many more explosions have been seen by the MEO astronomers. Bill Cooke, head of the MEO office (out of the Marshall Space Flight Center in Huntsville, Alabama), explains, “They're explosions caused by meteoroids hitting the Moon. A typical blast is about as powerful as a few hundred pounds of TNT and can be photographed easily using a backyard telescope." [NASA: “100 Explosions on the Moon”] (Although the title indicates "100" explosions, since the NASA article was written, another three were recorded.) A video of meteoroid impact number 86 near crater Gauss appears on the before-mentioned NASA website. It occurred on January 4, 2008—being a small piece of comet 2003 EH1 from the Quadrantid meteor shower (which we see on Earth every January). To view the video, click on the image of the Moon and, then, look in the upper-left hand corner of the short video. Team leader of the MEO team, Rob Suggs, stated, “We started our monitoring program in late 2005 after NASA announced plans to return astronauts to the Moon.” With astronauts eventually walking on the Moon and establishing colonies there, Suggs commented, “… it seemed like a good idea to measure how often the Moon was getting hit." In fact, the mission statement of the group is: “Use Earth-based observations of the dark portion of the moon to establish the rates and sizes of large meteoroids (greater than 500 grams or 1 pound in mass) striking the lunar surface.” And, these astronomers are performing this task because “U.S. Space Exploration Policy eventually calls for extended astronaut stays on the lunar surface. Spacecraft, vehicles, habitats, and EVA [Extra-Vehicular Activity] suits must all be designed to withstand the stresses posed by the harsh lunar environment over this period of time. Meteoroids, and the ejecta produced when they create impact craters, are part of this environment." As stated before, over one hundred of these impacts have been recorded by the MEO team. The team has found that these meteoroids travel over 30,000 miles (48,000 kilometers) per hour on their way to the surface of the Moon. Without an atmosphere, there is no resistance from atmospheric molecules (like here on Earth)—so they shoot toward the Moon and hit it with explosive speeds. NASA states that “even a pebble can blast a crater several feet wide.” And, when such an impact occurs, the rock and soils hit by the meteoroid are heated up so hot that they begin to glow, which produces the flash of light we can see here on Earth if our telescopes are aimed just in the right direction. Find the NASA MEO list of all 103 meteoroid impacts on the next page. |
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