re drag free satellites in article be e cpva saic com thomsonal cpva saic com writes on sat may gmt henry zoo toronto edu henry spencer said no a dragless satellite does not magically have no drag it burns fuel constantly to fight drag maintaining the exact orbit it would have if there was no drag well almost it turns out that clever orbital mechanics can engineer things so that resonant interactions with the higher order harmonics of the earth s gravitational field can pump energy into a satellite and keep it from experiencing drag effects for periods of months to years a harmonic of the earth s gravitational field what is a harmonic of the earth s gravitational field my favorite example of this is the soviet russian heavy elint satellites of the cosmos class which are in resonance in resonance with what it s not like there s any wavelength or frequency to the earth s gravitational field now there might be some interesting interactions with the moon s tidal effect is that what you re talking about this probably has little relevance to space stations since the degree orbits of the c satellites are at km which is unacceptably far into the inner van allen belt for manned platforms but it s kind of interesting from the point of view of the physics of the situation what are the physics of the situation the only way i can see gravitational effects being useful in adding energy to an object orbiting earth is some sort of interaction with the moon isaac kuo isaackuo math berkeley edu o twinkle twinkle little sig keep it less than lines big
