Here is a space systems architecture for repeatedly transporting payloads between low Earth orbit and the surface of the moon without significant use of propellant. This architecture consists of one rotating tether in elliptical, equatorial Earth orbit and a second rotating tether in a circular low lunar orbit. The Earth-orbit tether picks up a payload from a circular low Earth orbit and tosses it into a minimal-energy lunar transfer orbit. When the payload arrives at the Moon, the lunar tether catches it and deposits it on the surface of the Moon. Simultaneously, the lunar tether picks up a lunar payload to be sent down to the Earth orbit tether. By transporting equal masses to and from the Moon, the orbital energy and momentum of the system can be conserved, eliminating the need for transfer propellant. http://www.tethers.com/papers/CislunarAIAAPaper.pdf
Drs. Hoyt and Forward of Tethers Unlimited proposed the idea over 10 yrs ago. Bob Forward has passed on, RIP, but Bob Hoyt is still offering the plan. http://www.tethers.com
Hoyt has said that the system would pay for the up front investment after nine usage cycles. After that, the operating costs is minimal.
Now consider the tether in Earth orbit, suppose the tips of this tether are rotating at a speed equal to the orbital speed of the center of gravity of the whole tether system. The tips are rotating in a direction such that when they enter the atmosphere, they will slow with respect to the atmosphere because they will be moving in a direction opposite to the orbital speed. The tip will continue to slow with respect to the atmosphere until it's speed is nearly zero when it is in a vertical position.
So, the question that needs to be researched is: Just how far into the atmosphere can the tether come without causing damage to itself. If it can reach 300,000ft, then a Spaceship One could deliver cargo - 100,000ft many jet fighters can reach that altitude - 40 to 50 thousand ft. and most jet airliners could deliver cargo - or maybe 10 - 20 thousand ft. where a mountain top would work.
If the system could be used to lift automated factories to high Earth orbit to turn out components for SSP satellites from material brought from the Moon, the problem of lift cost for SSP satellites would be solved.
Drs. Hoyt and Forward of Tethers Unlimited proposed the idea over 10 yrs ago. Bob Forward has passed on, RIP, but Bob Hoyt is still offering the plan. http://www.tethers.com
Hoyt has said that the system would pay for the up front investment after nine usage cycles. After that, the operating costs is minimal.
Now consider the tether in Earth orbit, suppose the tips of this tether are rotating at a speed equal to the orbital speed of the center of gravity of the whole tether system. The tips are rotating in a direction such that when they enter the atmosphere, they will slow with respect to the atmosphere because they will be moving in a direction opposite to the orbital speed. The tip will continue to slow with respect to the atmosphere until it's speed is nearly zero when it is in a vertical position.
So, the question that needs to be researched is: Just how far into the atmosphere can the tether come without causing damage to itself. If it can reach 300,000ft, then a Spaceship One could deliver cargo - 100,000ft many jet fighters can reach that altitude - 40 to 50 thousand ft. and most jet airliners could deliver cargo - or maybe 10 - 20 thousand ft. where a mountain top would work.
If the system could be used to lift automated factories to high Earth orbit to turn out components for SSP satellites from material brought from the Moon, the problem of lift cost for SSP satellites would be solved.
Posted by jplspace
at 9:42 PM EDT
