cheap orbital insertion

On Wed, 10 January 2001, tntucker@... wrote:

>
> --- In spacesettlers@egroups.com, "bill t" wrote:
> >
> > At 5 g the length of the mass driver is 1250 km long. The
> acceleration
> > would be constant.
> >
> > Bill
> >
> > --- In spacesettlers@egroups.com, "Ed Minchau"
> > wrote:
> > > The key factor in the development of space is the cost of moving
> > > people and cargo from the Earth's surface to orbit. I propose
> > > building a mass driver along the ridge of the Himalayas.
> > >
> > > A mass driver consists of a series of solenoids, which move a
> > charged
> > > projectile along their length by alternately turning on and off
> one
> > > by one.
> > >
> > > The mass driver I propose would consist of solenoids 100 m in
> > > diameter, made of a superconducting material. They would be
> spaced
> > > along the mountain range so that they would provide a constant 3g
> > > acceleration. The projectile would resemble a supersonic
> airplane,
> > > gliding from one solenoid to the next. A maglev track could be
> used
> > > to provide the initial velocity required for the airfoil to
> provide
> > > sufficient lift to carry the craft from one solenoid to the
> next.
> > > The craft would make a series of parabolic glides until it
> received
> > > its final boost at the end of the mass driver.
> > >
> > > I figure that such a mass driver would have to be about 1500
> miles
> > > long to achieve escape velocity at 3g.
> > >
> > > :) ed
>
> To minimize cost, you must maximize G loading. Astronauts can
> tolerate 20Gs and public passengers around 10Gs for a launch.
> Cheers,
> Tom Tucker
>
..........

The maximum acceleration a human body can take and still survive is about 200g. There has been a racecar driver who hit the wall head-on at over 200 km/h, and decellerated in about one meter; he received first aid within seconds, and prompt medical treatment. He was comatose, but eventually recovered. That was about 150 g for less than 4 tenths of a second.

Pilots (and astronauts) generally black out at 10-12 g, and maintaining blood flow to the brain requires a specialized breathing technique, something like pushing really hard when constipated. Anything above 6 g is uncomfortable.

The US Space Shuttle experiences about 2.5-3 g of acceleration, to provide protection for the sensitive life experiments they carry. As John Glen proved, this acceleration is even tolerable for senior citizens, if they are in relatively good health.

For an unmanned, strictly cargo carrying craft, I would expect a much shorter accelerator, as you could use much higher acceleration. 200g is not unfeasible.

Although the physical structure of the mass driver is only at fixed points in space, the acceleration takes place along the entire length. It is not the solenoids themselves that produce the acceleration, it is the magnetic field they produce, and that is controlled though the entire length of the mass driver, even beyond the final solenoid.

All mountain ranges are moving in several directions at once. The rings would have to be gimbal-mounted and controlled to compensate for the subtly shifting terrain.

Political considerations will always be important; I suggested the Himalayas because they are near the equator and roughly parallel to it, and because the range is long enough to support 3g acceleration. I realize that the necessary trajectory is East, through, over or near such hotspots as Nepal, Tibet, Kashmir, China, North Korea, Pakistan, etc. For Polar orbits, perhaps using the Rockies, Andes, or Urals may prove to be more politically acceptable.

There are also religious factors to consider; I can't imagine trying to tell some monk that we have to tear down his temple to make way for the mass driver.

:) ed

>

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