The 2010 space elevator conference is coming soon to Microsoft. It turns out there is also a space elevator event coming to The Seattle Library (on getting a space elevator to the moon). Coincidence? Probably not. But it got me researching, and thinking I might just see a wire to orbit in my lifetime. Continue reading Riding the Wire: Space Elevators
Following on from solar sails we have a discussion of that other science fictional bastion of propellantless propulsion – the space elevator – it turns out that space elevators and space tethers can be used for more than just getting into orbit:
A series of bolo tethers, each tether passing a spacecraft onto the next, could be used to achieve even larger orbit changes than a single system. For example, one tether system could catch a spacecraft from a very low orbit and swing it into a somewhat higher orbit. Another bolo picks it up from there and puts the satellite into a geosynchronous transfer orbit (GTO). A third tether catches the load again and imparts sufficient velocity to it so that it reaches escape velocity. A satellite initially orbiting just above the atmosphere could thus be slung all the way into an interplanetary orbit around the Sun, and all this without using any rocket propulsion and propellant…
This is in the context of a review by Centauri Dreams of Space Tethers and Space Elevators by Michel van Pelt, which explores tethers and space elevator concepts in some detail.
Golubović and Knudsen have introduced the Rotating Space Elevator (RSE), a rotating system of a floppy string that forms an ellipse-like shape. Unlike the traditional Linear Space Elevator (LSE) made of a single straight cable at rest, the RSE rotates in a quasi-periodic state.
“The idea came by itself,” Golubović told PhysOrg.com. “I was thinking how to make things move easily and quickly up the traditional Tsiolkovsky-type space elevators. In my kitchen, I was mixing coffee in my cup too vigorously and the centrifugal force on the rotating coffee won over gravity to make some of the coffee lift and splash out the cup. This was my ‘eureka’ that lead to adding a similar conceptual feature to the old space elevator idea…
A classic Big Dumb Object is discussed in Short Sharp Science: a space elevator combined with a maglev launcher to propel prospective lunar colonists into orbit:
The lunar elevator doesn’t actually reach the regolith. Instead, the elevator ribbon ends 10 kilometres shy of the lunar surface so that no lunar mountain peaks hit the end, or terminus, of the orbiting elevator.
So how do astronauts make that 10 km jump to the elevator’s dangling tail? Easy: as the terminus passes overhead, they are fired in a magnetically levitated train along a track that’s been laid across the lunar plain and which gradually eases upwards to become vertical.
If they are fired at just the right time – and I wouldn’t like to be the person specifying or writing the software to do that, they are caught by some kind of robotic grappler at the terminus, which attaches the train to the ribbon.
Space elevator prospects have improved with the development by Cambridge scientists of a method for creating longer, less brittle carbon nanotubes by combining multiple nanotube strands:
Currently, the Cambridge team can make about 1 gram of the new carbon material per day, which can stretch to 18 miles in length. Alan Windle, professor of materials science at Cambridge, says that industrial-level production would be required to manufacture NASA’s request for 144,000 miles of nanotube. Nevertheless, the web-like nanotube material is promising.
“The key thing is that the process essentially makes carbon into smoke, but because the smoke particles are long thin nanotubes, they entangle and hold hands,” Windle said. “We are actually making elastic smoke, which we can then wind up into a fiber.”
Also worth checking out some of the alternatives to traditional space elevators that aren’t so demanding of tensile strength, like Keith Lofstrom’s launch loop, an electromagnetically “inflated” orbital launch system. [thanks to Bruce Cohen (SpeakerToManagers)]
It’ll be fun to see which of these designs actually gets off the ground: just as long as they don’t get off the ground then return unexpectedly.