tag:blogger.com,1999:blog-23000001.post9151252064090615000..comments2023-08-10T22:16:51.246+08:00Comments on The Bosonic State: Building a Space ElevatorJackson Tanhttp://www.blogger.com/profile/02267650599398779304noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-23000001.post-81891727425145024572008-09-29T19:22:00.000+08:002008-09-29T19:22:00.000+08:00Bleh! Of course, you're right! So long as the cent...Bleh! Of course, you're right! So long as the centre of mass of the entire structure (satellite + cable) is in an equatorial geostationary orbit, that'll do.<BR/><BR/>Oops! What a blunder! Thanks for correcting it!Jackson Tanhttps://www.blogger.com/profile/02267650599398779304noreply@blogger.comtag:blogger.com,1999:blog-23000001.post-76258776030515449472008-09-29T16:31:00.000+08:002008-09-29T16:31:00.000+08:00Sure it will work, even with a non-rigid cable. I...Sure it will work, even with a non-rigid cable. If the cable were weightless, then it is easy -- we are just tethering a point on geostationary orbit with an arbitrary point on the ground, even if it is off-equator. If the cable has no weight, then no problem. <BR/><BR/>Now let's look at the case of a weighted cable. You mentioned that there would be a "horizontal force" that tries to pull the satellite off its geostationary orbit. That is correct - for the cable to be in tension, the geostationary satellite would have to pull back on the cable with equal and opposite force as the ground pulling on the cable. From your response, it seems that you are puzzled how the satellite can exert a horizontal force. This is because a geostationary satellite alone will not work with a weighted cable (not even with a cable tied to the equator) -- the weight of the cable would pull it down from its orbit. So you need a counterweight BEYOND geostationary orbit to pull the cable outwords by centrifugal force. If the base station is off equator to the North, then the counterweight will lie beyond geostationary orbit and towards the South (instead of directly above the geostationary point). The cable is pulled tight because of the counterweight, and the center of mass of the counterweight-satellite-cable system will not drift from the geostationary point as long as they initially coincide.<BR/><BR/>If we use the space elevator to launch mass out of earth orbit, we are actually getting the energy from the earth's rotational inertia. If we do it too often, the earth will stop spinning! Haha...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-23000001.post-13618753316531052022008-09-24T21:47:00.000+08:002008-09-24T21:47:00.000+08:00Daniel:What I meant was that a geostationary orbit...Daniel:<BR/><BR/>What I meant was that a geostationary orbit that is at an angle to the equator will trace out a sinusoidal curve on Earth's surface.<BR/><BR/>I don't think an equatorial geostationary orbit and an off-equator base station will work. Think of it this way: the satellite is directly above the equator, and the cable is diagonal to an off-equator base station (and assuming that the centre of gravity is at the geostationary orbit). Then there is a horizontal force that pulls the satellite away from the equator.<BR/><BR/>Moreover, this will require the cable to be rigid, which is not necessary the case.Jackson Tanhttps://www.blogger.com/profile/02267650599398779304noreply@blogger.comtag:blogger.com,1999:blog-23000001.post-77848335905015026172008-09-24T20:13:00.000+08:002008-09-24T20:13:00.000+08:00The base station wouldn't have to be on the equato...The base station wouldn't have to be on the equator. If the base is north or south of the equator, the cable would just need to be longer and hence heavier and more expensive. The cable would extend from the base station to a point on geostationary orbit, and would hence intersect the ground at an angle off-vertical. A space elevator could even be anchored at the North Pole, with a cable tied parallel with the ground. You would need a counterweight beyond geostationary orbit to balance the weight of the cable.Anonymousnoreply@blogger.com