User:Skyhook1/sandbox
From Wikipedia, the free encyclopedia
A skyhook is a proposed space transportation concept, which its promoters claim will make Earth-to-orbit and interplanetary spaceflight affordable, thereby opening the way for the commercial development of lunar mining, asteroid mining, space-based solar power stations, space colonies, and colonies on the Moon, Mars, and in the asteroids. Skyhooks are often confused with an Earth surface to geostationary orbit space elevator, but they are different. A skyhook is a much shorter version of the space elevator that does not reach down to the surface of the Earth, is much lighter in mass, and can be affordably built with existing materials and technology. It works by starting from a relatively low altitude orbit and hanging a cable down to just above the Earth’s atmosphere. Since the lower end of the cable is moving at less than orbital velocity for its altitude, a launch vehicle flying to the bottom of the skyhook can carry a larger payload than it could otherwise carry to orbit on its own. When the skyhook is long enough and the lower endpoint velocity is low enough, single stage to skyhook flight with a reusable sub-orbital launch vehicle becomes possible.
The most important difference between a skyhook and a space elevator is that a skyhook can be built with presently available materials,[1] while a space elevator cannot.[2][3][4][5][6]
The following is a direct quote from "Hypersonic Airplane Space Tether Orbital Launch System" (HASTOL), a NASA funded study on rotating and non-rotating skyhooks.[1]
"The fundamental conclusion of the Phase I HASTOL study effort is that the concept is technically feasible. We have evaluated a number of alternate system configurations that will allow hypersonic air-breathing vehicle technologies to be combined with orbiting, spinning space tether technologies to provide a method of moving payloads from the surface of the Earth into Earth orbit. For more than one HASTOL architecture concept, we have developed a design solution using existing, or near-term technologies. We expect that a number of the other HASTOL architecture concepts will prove similarly technically feasible when subjected to detailed design studies. The systems are completely reusable and have the potential of drastically reducing the cost of Earth-to-orbit space access."
The following is a quote from Keith Henson, co-founder of the L-5 Society regarding space elevators.[2]
"No current material exists with sufficiently high tensile strength and sufficiently low density out of which we could construct the cable [for a space elevator]. There’s nothing in sight that’s strong enough to do it – not even carbon nanotubes."
Skyhooks come in two types: rotating and non-rotating. While no skyhook capable of capturing an arriving spacecraft has been built so far, there have been a number of flight experiments exploring various aspects of the skyhook/space tether concept.[7]