Up and Down

[stickmaker]

For the background of an SF novel, I'm assuming that even with technology approaching Clarke's "indistinguishable from magic" that one of the most awkward portions of a journey through space is the part between planetary surface and orbit. My assumption is that ships which are either very large or only expect to travel between "civilized" worlds will not be atmosphere capable. For "interface" concepts, so far I've got beanstalks, rotary tethers, accelerators (probably magnetic; on the ground, in orbit and maybe even hung from giant airships), dedicated atmospheric craft, and "antigravity." I am aware of a few other concepts - such as launch loops a the like - but consider most of them to be impractical. Neither do I want "transporters." If they have those, they don't need cargo ships.

So, any suggestions for other methods? From basic to "indistinguishable" will be welcome. Also, justifications for "antigravity" would be a help.

Comments

[kengr]

I know Keith Loftstrom, the originator of the Launch Loop concept. Frankly, it's a lot more doable than a beanstalk, especially with current materials science.

Orbital "fountains" (a series of platforms supported by the kinetic energy of a stream of material "fired" from the surface are a lot trickier but might be workable.

Laser launchers still seem doable (What can I say, I've seen Jordin Kare's presentations several times over the years). They also have the advantage of being usable as anti missile or anti-invader defenses.

And given better fission reactors, fusion, or antimatter "simple" ground to orbit rockets become a lot easier to build. Even the Old NERVA program reached an Isp of 800. Much better is likely doable.

At "merely" double the ISP of the Space Shuttle's main engines, you get a huge drop in mass ratio. You still need the same deltaV, but since the ISP (or exhaust velocity) to mass ratio function is exponential. A small improvement makes a *big* difference.

Of course higher Isp rockets have a truly spectacular exhaust.

Finally, if you want to go into super-science, there area few "variants" on anti-gravity that are interesting in that they are not much use once you get to orbit.

One "reacts" to the local gravity (or the "curvature of spacetime" if you want to look at it that way). So the weaker the local field the less use it is.

Another is a truly reactionless drive. One that has to either push on something (like the planet)or somehow converts energy into momentum.

Turns out that the energy required raises exponentially as the velocity does. (or alternatively the acceleration drops).

Makes for a fun change from the usual stuff.