On May 4 , 1976 , NASA launch LAGEOS ( short for Laser Geodynamic Satellite ) , a 900 - pound satellite dedicated to a precision measuring technique call optical maser array . The still - functioning satellite has no on - board sensors or electronics , no be active parts , and contain a brass core case by an aluminum shield dimpled with 426 retroreflectors . NASA describe it as looking like a jumbo golf ball , but as it was deployed the ‘ LXX , a different reference head fare to our minds : a disco music ball .
optical maser rove involves sending a optical maser pulsefrom a ground stationup to the satellite , where it bounces a sign back . The round - trip fourth dimension is used to calculate the length between the earthbound station and the equipment in sphere , which can then be implement to all sort of field of study . LAGEOS and its sister orbiter , LAGEOS-2 , have help scientists try out the Earth ’s form , weight , rotary motion and gravitational field , measure tectonic plates , and much more .
David E. Smith , who was a LAGEOS labor scientis , articulate of the labor : “ Today , we see Earth as one system , with the major planet ’s shape , rotary motion , aura , gravitative sphere and the motions of the continents all connected . We take it for granted now , but LAGEOS helped us get in at that view . "
Forty years after its launching , LAGEOS still travels in its original cranial orbit more than 3600 miles above Earth and is expected to stay that fashion for millions of years . Aboard the satellite is a plaque design by Carl Sagan that hold in three panels depicting the planet at dissimilar phases : 268 million years ago , today , and 8.4 million years in the future , when the satellite is predicted to devolve to Earth .
For much more on the history of LAGEOS and the work it ’s contributed to , train outthis retrospectiveon the NASA website , as well as this 1975 prevue of the deputation to see the orbiter in its groovy aura .
