[extropy-chat] The 2nd IAA/ ESA/ CASI Space and Society Conference -- CfP

[Keith Henson]

At 05:40 PM 8/15/2006 +0200, you wrote:
>Esteemed colleagues,
>Dear friends,
>
>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
>to it!
>
>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/
>thematic areas.
>
>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
Abstract Text

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 
required.

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 
discussed.

http://www.liftport.com/forums/attachment.php?attachmentid=21

(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.)