Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site seismo.UUCP Path: utzoo!linus!philabs!seismo!flinn From: flinn@seismo.UUCP (E. A. Flinn) Newsgroups: net.space Subject: re: G.K. O'Neill's satellite plan Message-ID: <567@seismo.UUCP> Date: Sun, 29-Jan-84 11:19:44 EST Article-I.D.: seismo.567 Posted: Sun Jan 29 11:19:44 1984 Date-Received: Tue, 31-Jan-84 02:03:13 EST References: <16109@sri-arpa.UUCP> Organization: Center for Seismic Studies, Arlington, VA Lines: 21 Two potentially important uses for GPS are in civil surveying and in geophysical research. Texas Instruments and a small company in Massachusetts have developed and are already beginning to market backpack units which can determine position to a few centimeters in a geocentric coordinate system (i.e., the coordinate system defined by the GPS satellite orbits), although they do not work in real time. These units are not much more expensive than the usual doppler geoceiver rigs, which are accurate to a meter or so. NASA is also developing small GPS receivers for two purposes: (1) to locate altimeter satellites to a few centimeters (the altimeters have 2-cm accuracy and require similar knowledge of orbital position), and to monitor crustal deformation and movement of the tectonic plates. The NASA and competing units are now being field-tested in California, and there should be papers given at the next meeting of the American Geophysical Union on the results of this comparison study. For further information on geophysical applications of this kind of space technology, see an article I wrote for Science in June 1981, and the references cited there.