On 21 July 1969, during the first manned lunar mission, Apollo 11, the first retroreflector array was placed on the moon, enabling highly accurate measurements of the Earthmoon separation by means of laser ranging. Lunar laser ranging (LLR) turns the Earthmoon system into a laboratory for a broad range of investigations, including astronomy, lunar science, gravitational physics, geodesy, and geodynamics. Contributions from LLR include the three-orders-of-magnitude improvement in accuracy in the lunar ephemeris, a several-orders-of-magnitude improvement in the measurement of the variations in the moon's rotation, and the verification of the principle of equivalence for massive bodies with unprecedented accuracy. Lunar laser ranging analysis has provided measurements of the Earth's precession, the moon's tidal acceleration, and lunar rotational dissipation. These scientific results, current technological developments, and prospects for the future are discussed here.
Science, founded by Thomas A. Edison in 1880 and published by AAAS, today ranks as the world's largest circulation general science journal. Published 51 times a year, Science is renowned for its highly cited, peer-reviewed research papers, its special strength in life science disciplines, and its award-winning coverage of breaking science news. The online edition includes not only the full text of current issues, but also Science archives dating back to Edison's first edition in 1880. Science Careers, found in print and online, provides relevant career articles published weekly, thousands of job postings updated several times a week, and other career related services. The online Science Multimedia Center features Science Podcasts, images and slide shows, videos, seminars, and other interactive features. For more information, access www.sciencemag.org.
AAAS, founded in 1848, has evolved into the world's largest multidisciplinary scientific society with nearly 130,000 members and subscribers. The mission, to "advance science, engineering, and innovation throughout the world for the benefit of all people," has propelled the organization to the forefront of national and international initiatives. Global efforts include programs and partnerships worldwide, from Asia to Europe to Africa, and extensive work in human rights using geospatial technology to corroborate abuses. Science and policy programs include the major annual forum on Science & Technology policy, S&T policy fellowships within the US Congress and government agencies, and the tracking of US funding for R&D research. Science education initiatives have laid the groundwork for standards-based learning and provide web-based support tools for teachers. Public engagement activities are creating an open dialogue with scientists on societal issues such as global climate change. AAAS also acts as an umbrella organization for a federation of more than 270 affiliated scientific groups. An extended series of websites includes comprehensive career development resources. For more information, access www.aaas.org.
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© 1994 American Association for the Advancement of Science