The GRACE satellite twins are circling the Earth, and are monitoring each others' position with extreme accuracy in an attempt to (in part) more precisely measure the differences in Earth's gravity field. My question is this: could the same data be acquired by very closely monitoring the orbit(s) of satellite(s) at many ground stations around the world (perhaps you could also measure the Doppler shifts of its radio signals) ? But I suppose there is also the question of an unknown atmospheric density to the required degree of precision; the GRACE satellites will both be affected by the atmosphere essentially equally. Drag could conceivably be confused with a gravimetric gradient. --------------------------------------------------------- Jonathan Wojack tlj18@juno.com ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/sat/seesat/seesatindex.html
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