dietz@SLB-DOLL.CSNET (Paul Dietz) (02/24/86)
> The electrically-assisted shuttle launch was >an idea for a lead-in to true mass drivers. Most of the mass driver >ideas I saw four or five years ago (I haven't kept up) required >huge amounts of power in one or two seconds, to sustain hundreds >of g's to get into orbit. This stretches out the >power need to almost a minute, and lowers the g's to something >that could launch almost any payload, including people. People can be launched at hundreds or thousands of g's if they are immersed in a fluid of the same density as the body. The fluid must permeate the lungs to prevent internal damage. Fortunately, fluids such as perfluorocarbons can dissolve large amounts of oxygen, so you don't suffocate. Another idea is to use highly compressed xenon gas (it's expensive, though). Accelerations are ultimately limited by density differences between body tissues (one's bones will sink through one's body). [The perfluorocarbon idea was used in "The Forever War."]
henry@utzoo.UUCP (Henry Spencer) (02/26/86)
> People can be launched at hundreds or thousands of g's if they > are immersed in a fluid of the same density as the body. The fluid > must permeate the lungs to prevent internal damage. Fortunately, > fluids such as perfluorocarbons can dissolve large amounts of oxygen, > so you don't suffocate... This is speculation, not established fact. Nobody has yet produced such a fluid which has adequate capacity for *both* oxygen and carbon dioxide, as I recall. Getting it in (without triggering cough reflexes) and getting it out again afterwards are also problematic. > Another idea is to use highly compressed xenon gas (it's expensive, though). It's also an anesthetic even at ordinary pressures, and its physiological effects at high pressure are uncertain. There is also a potential problem with the muscular effort needed to breathe liquids or very-high-pressure gases; work has been done on this for deep-diving operations. The last report I saw estimated maximum dive depth of about 1 mile, limited by the effort needed to breathe. That would be about 160 atmospheres. This was with the lightest mix they could get -- oxygen in hydrogen (!) -- to reduce the breathing effort to the absolute minimum. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry