[extropy-chat] The 2nd IAA/ ESA/ CASI Space and Society Conference -- CfP
hkhenson at rogers.com
Thu Aug 17 19:18:15 UTC 2006
At 05:40 PM 8/15/2006 +0200, you wrote:
>I wish to call your attention to an upcoming IAA conference that may
>find your interest -- possibly to the point of motivating you to contribute
>Below I have included a summary of the official Call for Papers as you
>can find at <http://www.congrex.nl/06a12/>, or through the ESA site
><http://conferences.esa.int/>. I shall follow up in the next few days with
>a message outlining some of my own ideas for creating sessions/
>You can give me your feedback simply by replying to this message, as
>the list is moderated.
For your amusement.
2000 tonne per day space elevator
Even the most optimistic carbon nanotube materials will require some taper
to build a space elevator. Tapered cables are difficult to drive
mechanically, leading to complex systems of electrically powered climbers
and lasers to deliver energy to the climbers. This leads to slow transit
and replication times.
This paper proposes the design of a moving, non-tapered space elevator
cable threaded through a system of pulleys that increase the number of
supporting strands as the space elevator approaches geostationary orbit
(GEO). The number of pulley stations and the length of the cable will
depend on the performance of the cable--projected materials have cable
lengths of 50-500 times the distance to GEO.
The proposed design is particularly suited to rapid buildup. The up cable
goes beyond GEO before winding back down. New cable attached to the
existing one at the bottom reinforces the elevator from the top. This
design also makes cloning the elevator simple.
Cables can move much faster than climbers, perhaps as fast as 1500 km/hr,
reducing transit time to a day and replication time to 50-500 days. Maximum
velocity is uncertain because part of the cable in the earth's atmosphere
and subject to aerodynamic forces. This design also makes cable degradation
due to molecular oxygen less of a problem since any part of the cable is
only briefly exposed and the entire cable can be inspected and replaced as
The paper analyzes a mature system able to lift 2000 metric tons per day to
GEO. The mechanical power requirement is about a Gw (for scale the aircraft
carrier Enterprise is rated at 0.21 Gw). Five Gw power satellites (at
2kg/kW) would mass 10,000 metric tons each, allowing a mature space
elevator to transport parts for more than 50 power satellites a year. At 5
Gw-days to lift the parts, the lift energy would be paid back in one day of
operation of a 5 Gw power satellite.
The obvious effects of building scores of 5 Gw power satellites a year on
such matters as reducing energy costs and carbon emissions are briefly
(Photo of model. The cable on the left side of the photograph goes to the
top, stress being transferred to the other cables through the pulley stations.)
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