IBEX spacecraft detects fast neutral hydrogen coming from the moonJune 19, 2009Research also provides insight to particle 'recycling' processes in space NASA's Interstellar Boundary Explorer (IBEX) spacecraft has made the first observations of very fast hydrogen atoms coming from the moon, following decades of speculation and searching for their existence. During spacecraft commissioning, the IBEX team turned on the IBEX-Hi instrument, built primarily by Southwest Research Institute (SwRI) and the Los Alamos National Laboratory, which measures atoms with speeds from about half a million to 2.5 million miles per hour. Its companion sensor, IBEX-Lo, built by Lockheed Martin, the University of New Hampshire, NASA Goddard Space Flight Center, and the University of Bern in Switzerland, measures atoms with speeds from about one hundred thousand to 1.5 million mph. "Just after we got IBEX-Hi turned on, the moon happened to pass right through its field of view, and there they were," says Dr. David J. McComas, IBEX principal investigator and assistant vice president of the SwRI Space Science and Engineering Division. "The instrument lit up with a clear signal of the neutral atoms being detected as they backscattered from the moon." The solar wind, the supersonic stream of charged particles that flows out from the sun, moves out into space in every direction at speeds of about a million mph. The Earth's strong magnetic field shields our planet from the solar wind. The moon, with its relatively weak magnetic field, has no such protection, causing the solar wind to slam onto the moon's sunward side. From its vantage point in space, IBEX sees about half of the moon -- one quarter of it is dark and faces the nightside (away from the sun), while the other quarter faces the dayside (toward the sun). Solar wind particles impact only the dayside, where most of them are embedded in the lunar surface, while some scatter off in different directions. The scattered ones mostly become neutral atoms in this reflection process by picking up electrons from the lunar surface. The IBEX team estimates that only about 10 percent of the solar wind ions reflect off the sunward side of the moon as neutral atoms, while the remaining 90 percent are embedded in the lunar surface. Characteristics of the lunar surface, such as dust, craters and rocks, play a role in determining the percentage of particles that become embedded and the percentage of neutral particles, as well as their direction of travel, that scatter. McComas says the results also shed light on the "recycling" process undertaken by particles throughout the solar system and beyond. The solar wind and other charged particles impact dust and larger objects as they travel through space, where they backscatter and are reprocessed as neutral atoms. These atoms can travel long distances before they are stripped of their electrons and become ions and the complicated process begins again. The combined scattering and neutralization processes now observed at the moon have implications for interactions with objects across the solar system, such as asteroids, Kuiper Belt objects and other moons. The plasma-surface interactions occurring within protostellar nebula, the region of space that forms around planets and stars -- as well as exoplanets, planets around other stars -- also can be inferred. IBEX's primary mission is to observe and map the complex interactions occurring at the edge of the solar system, where the million miles per hour solar wind runs into the interstellar material from the rest of the galaxy. The spacecraft carries the most sensitive neutral atom detectors ever flown in space, enabling researchers to not only measure particle energy, but also to make precise images of where they are coming from. Around the end of the summer, the team will release the spacecraft's first all-sky map showing the energetic processes occurring at the edge of the solar system. The team will not comment until the image is complete, but McComas hints, "It doesn't look like any of the models." Southwest Research Institute |
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| Related Solar Wind Current Events and Solar Wind News Articles A special issue on the International Workshop of the 2008 Solar Total Eclipse On August 1, 2008 a total solar eclipse was visible within a narrow corridor that traversed from North America to China. Satellite reveals surprising cosmic 'weather' at edge of solar system The first solar system energetic particle maps show an unexpected landmark occurring at the outer edge of the solar wind bubble surrounding the solar system. IBEX satellite finds ribbon-like structure at edge of heliosphere The invisible structures of space are becoming less so, as scientists look out to the far edges of the solar wind bubble that separates our solar system from the interstellar cloud through which it flies. Cassini Helps Redraw Shape of Solar System In a paper published Oct. 15 in Science, researchers from the Johns Hopkins Applied Physics Laboratory (APL) present a new view of the region of the sun's influence, or heliosphere, and the forces that shape it. Images from one of the Magnetospheric Imaging Instrument's sensors, the Ion and Neutral Camera (MIMI/INCA), on NASA's Cassini spacecraft suggest that the heliosphere may not have the comet-like shape predicted by existing models. IBEX discovers that galactic magnetic fields may control the boundaries of our solar system The first all-sky maps developed by NASA's Interstellar Boundary Explorer (IBEX) spacecraft, the initial mission to examine the global interactions occurring at the edge of the solar system, suggest that the galactic magnetic fields had a far greater impact on Earth's history than previously conceived, and the future of our planet and others may depend, in part, on how the galactic magnetic fields change with time. How the Moon produces its own water The Moon is a big sponge that absorbs electrically charged particles given out by the Sun. These particles interact with the oxygen present in some dust grains on the lunar surface, producing water. NASA Goddard visualization team previews lunar impact At 7:30 a.m. EDT on October 9, a two-ton rocket body will slam into a crater near the moon's south pole. By studying the resulting plume of gas and dust, scientists hope this grand experiment will confirm the presence of ice in permanently shadowed craters at the lunar poles. Cosmic Rays Hit Space Age High Planning a trip to Mars? Take plenty of shielding. According to sensors on NASA's ACE (Advanced Composition Explorer) spacecraft, galactic cosmic rays have just hit a Space Age high. CU-Boulder space scientists set for final spacecraft flyby of Mercury NASA's MESSENGER spacecraft, which is toting an $8.7 million University of Colorado at Boulder instrument, will make its third and final flyby of Mercury on Sept. 29 -- a clever gravity-assist maneuver that will steer it into orbit around the rocky planet beginning in March 2011. Deep Impact and Other Spacecraft Find Clear Evidence of Water on Moon New data from the Deep Impact spacecraft and the Moon Mineralogy Mapper (M3), an instrument aboard India's recently ended Chandrayaan-1 spacecraft, provide, for the first time, clear evidence that water exists on the surface of the Moon. More Solar Wind Current Events and Solar Wind News Articles |
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