For electric accelerator, we geometrically much more limited by height, than by length (highest mountain is about 9km, but in horizontal direction we can use up ...
SPACE TRANSPORT INFRASTRUCTURE: Supplementary materials Here we give some preliminary quantitative estimations for a version of a Space transport, based on infrastructure with extra-high construction cost .
1. Electric launch accelerator on Earth. For electric accelerator, we geometrically much more limited by height, than by length (highest mountain is about 9km, but in horizontal direction we can use up to hundreds km.) And we are limited by absolute value of acceleration. It means that optimal geometry of accelerating way having two parts: on first part there is horizontal straight line, on the last part there is a parabola. With this geometry, we can organize horizontal acceleration without vertical acceleration and vertical velocity, all on zero height, and then: maximal vertical acceleration, with constant horizontal velocity (Fig. 1, both coordinates: kilometers). 10
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Fig 1 For acceleration limit 4.5 g, this accelerator give horizontal velocity 3 km/sec, and vertical velocity 0.9 km/sec (if height is 9 km). It is not optimal, if taking into account atmosphere (Fig 2): at height 9 km we still have 27% of atmosphere higher (and, unfortunately, penetrating it with low angle), it will be significant losses on aerodynamic drag. But electric accelerator: it is no fuels, only electricity (may be used energy, accumulated from solar batteries nearby): absolutely different economical and ecological costs. 1.4
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On the next (rocket) stage we need to increase horizontal velocity on 2 km/sec (to 5 km/sec), and to reach height not less than 160 km ( low near-Earth orbit). To reach it by inertia, we need on height 10 km vertical velocity about 1.8 km/sec: twice bigger that we have after accelerator. So on rocket stage: we need to add by horizontal direction 2 km/sec, and by vertical 0.9 km/sec: by absolute value it will be about 2.2 km/sec. It is absolutely not difficult: but we did not take into account aerodynamic drug. We can try to increase height of final point of accelerator, using a huge aerostats. But there will be a problem with different wind on different heights (and we need a very stable construction with precise geometry, for our hypersonic velocities). Another option (I can't find in Internet similar approaches, but also can't guarantee that it is new): - For velocity over 3 km/sec, efficient temperature is up to 30000°. So, if we preliminary create a channel in an air, with much lower density (but may be high, for example 3000°, temperature): it still be less problem with hitting by the aerodynamic drug, than for original air. How to create the channel (may be in order 10 m in diameter, and up to dozens of kilometers by length). We can use a strong impulse beam of light (with proper coefficient of absorption in air: it may be special infrared light). It is not too much energy: 1 square m in section and one kilometer of length in atmosphere: it is compatible with energy for boiling of 1 cubic meter of water. Technically, it looks applicable, if a rocket already have hypersonic velocity (our case). Using light, we can try "to blow up" atmosphere on the way of the rocket. In an accelerator, can be vacuum, and no aerodynamic drug- if we can solve problem of "striking" on exterior air after it. Some other problems - it can be not too fatal. We already have "electric artillery" with hypersonic velocity. Electric launch accelerator: it definitely cannot be new. We only discussed it.
2. Orbital Space landing pad. In Space, our rocket must land on a pad, with relative velocity up to 3 km/sec. If the pad is horizontal, landing will be with a relative gravity in order 0.5 g: but in Space we easy can vary it, changing position and/or geometry of the pad. It is a vacuum: no wind instability problems. Current record of velocity of landing (it was a passenger flight(!), emergency situation, USSR): only 0.115 km/sec, or 30 time slower. Record of velocity for car (for nearest future) may be in order 0.5 km/sec. Interesting, that ( according data by super flywheels) not extraordinary by sizes wheels formally applicable to velocities in few km/sec. Magnetic cushions, intensively developing, may be preferable.
Electronics much faster than a human: so, automatic landing in vacuum, for the high velocity: it does not looks impossible. We can decrease angle of glide path from about 3° till 0.1°, using automatics. Rocket can be landing on a preliminary accelerated sub pad: but, may be, these more complicated options will be unnecessary. The Space landing pad will lose velocity, with each landing. Also it will be losses of velocity, for low orbit. But returning rocket on Earth, using Space pad, we need to decrease rocket's velocity relatively Earth (may be for velocity even lower than on start): it mean increasing velocity for landing pad. For 3 km/sec, length of Space landing pad, for acceleration 4.5 g, will be 100 km.
3. Outer electric Space launch and landing pads. In Space, to increase/decrease radius of a ring orbit to a small value (for example on 10%), we need to increase and decrease velocity twice, in both cases on a quarter of relative changing of radius (to increase on 2.5% in perigee, and to decrease when apogee will reached). 2.5% of 8 km/sec it is 0.2 km/sec. The pad with length 0.5 km can be enough (for acceleration 4.5 g). Only problem: launch and landing pads must be in proper positions; if their velocities are similar: it means that proper positions will be rare. Space electric pads can be used for transport from low orbit to geostationary orbit. It all can be used for Moon, Mars, Phobos and Deimos. Without dense atmosphere and high gravity: electric launch and landing pads are much easier to apply.
4. Very far future. Let imagine that everything going to blowing of Sun. And even after few billions years our physics in general the same as now. What can be done? We can build (using matter from few planets) a huge accelerator ring or line (with sizes compatible with Neptune orbit). It allow (for acceleration g) to reach velocity up to few % of light velocity. If we built landing pad, near the other star (robots built it, as an options): many humans (or their genes: it is much cheaper) can change their location, before the blowing. It will be a long way, till thousands years. But physically possible. Can we build it? Immediately: not. For billions years of constructions- why not? If to discuss only genome's transport: it can be done even easier. Enough to have only one good robot, near new star. Which can synthesize organisms by gene code. Genetic and other information can be getting by radio, with the velocity of light. Even with our physics: we can leave the Sun, before the blowing. And animals and plants (their genetic information, but partially not only)- too. Space expansion, in theory: it is possible even with our physics. And It can be ONLY option, if we REALLY want to save Earth' biological life forever.
