XPost: rec.arts.sf.science, sci.space.policy   
   From: smithm@SPAMBLOCKnetapps.com.au.retro.com   
      
   On 9 Feb 2005 07:51:12 -0800   
   "WLM"  wrote:   
      
   > I'm wondering if this idea has occurred anywhere else:   
   >   
   > If humans need a full one Earth gravity after all, a lunar   
   > settlement could provide that, at least part of the time.  Build a   
   > circular track on the surface, with a radius of 1 km. and tilted.   
   > Then have cars travel around the track at the appropriate speed, and   
   > one has full Earth gravity on the Moon.   
      
   Yes, you can do that but personally I wouldn't want to go to the moon if I had   
   to live on a train all the time.   
      
   > There will be no atmospheric drag, so no energy is required to keep   
   > the cars going due to this.   
      
   There would be normal mechanical friction which would result in some energy   
   loss.   
      
   > During the lunar day, photovoltaics on   
   > top of the cars could provide the energy to keep them going. During   
   > the lunar night, temperatures are low enough that they could be   
   > levitated on superconducting magnets.   
      
   I doubt it gets cold enough for superconductors to work reliably when exposed   
   on the lunar surface. Remember that heat will radiate out from the surface and   
   tend to keep things warm. And there will still be some energy and momentum   
   lost.   
      
   > An alternative way to building a track would be to have a tower with   
   > the cars travelling around, suspended by wires (two at opposite   
   > ends).  This could be cheaper to build than a track.   
      
   > These could be built on all the other planet-like bodies, too.   
   > Possibly including Mars...its atmosphere might be thin enough.   
      
   No. The atmosphere of mars is denser than you think because of all that CO2.   
   Any moving object will need some energy behind it.   
      
   I think people will learn to live with low gravity. Similar to the way that   
   other mammals learnt to live in the ocean.   
   --   
   Michael Smith   
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