To: Maurice Winn who wrote (24066 ) 8/26/2001 9:24:17 PM From: Mr. Adrenaline Read Replies (1) | Respond to of 29986 I think it was Abraham Lincoln who said that it was better to remain silent and be thought a fool than to open your mouth and remove all doubt. Thanks Mqurice, I needed that! Where to start...? Gravity is not a variable -- at least not at constant altitude. Gravity on the surface of the Earth has the same pull on a feather as it does on a 747. The force of gravity is a function of mass -- that of course is F = ma, F is the force, in Newtons, mass is in kilograms and a, the acceleration, is in this case gravity, 9.8 meters/sec^2. The acceleration of gravity is not a function of mass. The force of gravity is a function of mass. So, the gravitational pull, or the acceleration, is the same for a feather or a 747. But enough of that -- it won't make sense to the average person. If a big satellite was to be pulled from orbit at LEO altitude, the space station, which when complete will be the most massive thing ever put in to orbit, would then "get pulled out of orbit". As well as the space shuttle, which is at LEO altitudes and much more massive than a typical GEO communication satellite. There is no fundamental reason why GEO satellites are typically larger than LEOs. There are reasonable limits that make GEOs larger, which, as you state, are rooted in power. The farther RF energy travels, the more power you need. In addition at GEO you see a bigger footprint of the Earth. So a satellite is, typically, radiating a larger land mass. More power makes for larger satellites. Mq, I know you where joking when you said the photovoltaic wings kept satellites in space, but for those who don't know better, it is gravity that keeps a satellite in orbit. Yup that's right, the pull of gravity keeps a satellite up. For those who thought that there was no gravity in space because you saw an astronaut float upside down, tomorrow there may be another lesson on orbital mechanics -- like how to slow down by speeding up. Let's just finish this by saying that the effects of gravity at LEO altitudes are about 98% of what they are on your bathroom scale. Kind Regards, Mr A