http://www.spaceelevatorblog.com/?p=889 For scalable, inexpensive access to space... Thu, 09 Sep 2010 23:24:12 +0000 http://wordpress.org/?v=2.2.1 http://www.spaceelevatorblog.com/?p=889#comment-132500 Libor Micek Mon, 16 Jun 2008 01:48:20 +0000 http://www.spaceelevatorblog.com/?p=889#comment-132500 Just today I have come across your (not new at all) objection answered. Already in the discussion of Artusjan's original concept in the former Soviet Union in the sixties the question was asked. Put simply, Earth's rotation is imparting all the energy (you have calculated at 40MW). By each sling shot off of space elevator the Earth's rotation is slowed down a tiny bit. The 6378 km radius of Earth is serves as the sling's arm. Just today I have come across your (not new at all) objection answered. Already in the discussion of Artusjan’s original concept in the former Soviet Union in the sixties the question was asked. Put simply, Earth’s rotation is imparting all the energy (you have calculated at 40MW). By each sling shot off of space elevator the Earth’s rotation is slowed down a tiny bit. The 6378 km radius of Earth is serves as the sling’s arm.

]]> http://www.spaceelevatorblog.com/?p=889#comment-77343 Noel Hughes Thu, 17 Jan 2008 20:14:23 +0000 http://www.spaceelevatorblog.com/?p=889#comment-77343 All discussions of a space elevator ignore the basic laws of physics. Conservation of energy implies that mass moved from the Earth surface to any height must acquire potential energy equal to mgh, where m = mass, g = the acceleration due to gravity and h = altitude. If at the same time the mass is accelerated (a geosynchronous body, while it looks to be motionless, is actually traveling at roughtly 3.1 km/sec) it must also acquire kinetic energy equal to .5*mv^2, where v is the velocity imparted. Assuming a two week trip up, a 10000 kg body would require an average of about 40 megawatts of power which is, very roughly, the average generating capacity of a typical power plant in the United States. A claim of several elevator proponents is that once a body has reached the top of the elevator, getting to other planets requires only releasing from the elevator system. However, to leave the vicinity of the Earth, escape velocity must be achieved, which is approximately 11 km/sec which means that only about 8% of the kinetic energy required for Earth escape has bee imparted to a body in geosynchronous orbit. There are many other issues that I have yet to see addressed. All discussions of a space elevator ignore the basic laws of physics. Conservation of energy implies that mass moved from the Earth surface to any height must acquire potential energy equal to mgh, where m = mass, g = the acceleration due to gravity and h = altitude. If at the same time the mass is accelerated (a geosynchronous body, while it looks to be motionless, is actually traveling at roughtly 3.1 km/sec) it must also acquire kinetic energy equal to .5*mv^2, where v is the velocity imparted. Assuming a two week trip up, a 10000 kg body would require an average of about 40 megawatts of power which is, very roughly, the average generating capacity of a typical power plant in the United States.
A claim of several elevator proponents is that once a body has reached the top of the elevator, getting to other planets requires only releasing from the elevator system. However, to leave the vicinity of the Earth, escape velocity must be achieved, which is approximately 11 km/sec which means that only about 8% of the kinetic energy required for Earth escape has bee imparted to a body in geosynchronous orbit.
There are many other issues that I have yet to see addressed.

]]> http://www.spaceelevatorblog.com/?p=889#comment-76876 Stephen Steiner Tue, 15 Jan 2008 16:52:30 +0000 http://www.spaceelevatorblog.com/?p=889#comment-76876 Thanks for the publicity Ted! Thanks for the publicity Ted!

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