Questions about "The High Frontier"

"John Savard" wrote in message
...

But the book "Space Colonies" from the Whole Earth Catalog people is one
where a *variety* of viewpoints on the project, including those that
claimed that the terrorism danger would make it a non-starter, were
presented.

Available online at
http://www.nss.org/settlement/nasa/C...ook/index.html

--


Regards,
Mike Combs
----------------------------------------------------------------------
By all that you hold dear on this good Earth
I bid you stand, Men of the West!
Aragorn

....So in other words, there is no justification for a kilometer-scale
O'Neill colony that doesn't involve either kilometer-scale SSPs (which
probably can't be built), or a national ideology based on the so-far-
unheard-of idea of "saving the human species" (which, for some reason,
forbids settling the Moon and Mars, even though to build the O'Neill
in the first place you'd have to have thousands of people on the Moon
already...).\

Forgive me if I sound frustrated.

"Logan Kearsley" wrote in message
...

The solution, of course, is to find a way to turn that 25-mile-high
launcher into a tensile structure... attach balloons to it!

Here's a hard-sf novella I wrote on that very idea:

The Bridge to Space
http://members.aol.com/howiecombs/bridge.htm


--


Regards,
Mike Combs
----------------------------------------------------------------------
By all that you hold dear on this good Earth
I bid you stand, Men of the West!
Aragorn

Pat Flannery wrote:



Wayne Throop wrote:

: Pat Flannery
: Which leads to a interesting problem... at 300 km long the rail has
a : significant curve in it to follow the curvature of the Earth's
surface. : Toward the end of the acceleration run it may try to peel
right off the : track, as from its point of view the track drops away
from its direction : of movement. To deal with air friction during
ascent at a shallow angle : it's going to have to come off the
launcher at a velocity far higher : than orbital velocity.

Well, first, you make sure the ejection end is as high as you
can get it, to minimize those losses.


That unfortunately means that the track's last 50 km or so is going to
have to be pretty much a straight incline, because if yo try to turn the
projectile into a angled launch from a horizontal rail in a few km the
transition in it's direction of movement is going to squish everyone to
the floorboards. Anyway, the desired launch angle is pretty much
straight at the horizon, allowing the curvature of the Earth to fall
away from under it as it heads for orbit.

A nearly horizontal path would mean a much longer path through the
troposphere. Thus much more delta vee losses from atmospheric drag.

More importantly, in my opinion, a longer path through the dense lower
atmosphere traveling at very high velocities. A descending space shuttle
is able to shed velocity in the more forgiving mesosphere. By the time
it reaches the troposphere, it's traveling less than orbital velocity.

The punishing environment of the lower atmosphere makes terrestial mass
drivers much less practical. Most of the mass driver proposals I've seen
are for the airless moon or asteroids.

Look at the trajectory of most conventional rockets. They don't do the
major horizontal burn until they're above the atmosphere.

Hop

John Savard wrote:

On Sun, 07 Oct 2007 14:42:32 -0500, Pat Flannery
wrote, in part:


But to deal with air drag during ascent you'll need to exceed that
velocity by a considerable amount,


Put the rail inside an evacuated tube. It shouldn't be too hard to pump
the air out, since there isn't much air at the far end anyways.

How high do you think it's plausible to build the far end?

Hop

Pat Flannery wrote:



Wayne Throop wrote:

: Pat Flannery
: If we could just make it all-electric, we would be in business.
: Maybe a giant railgun to shoot it right into orbit. Okay, so we may
need : to train the crew to handle 500 or so gs on takeoff... :-)

Nah, just use a 300 km long rail.





Which leads to a interesting problem... at 300 km long the rail has a
significant curve in it to follow the curvature of the Earth's surface.
Toward the end of the acceleration run it may try to peel right off the
track, as from its point of view the track drops away from its direction
of movement. To deal with air friction during ascent at a shallow angle
it's going to have to come off the launcher at a velocity far higher
than orbital velocity.

Pat


Space Shuttle Columbia started disintegrating at a 70 kilometer altitude
going about mach 22.5. Seems like you're talking mach 25 through a
medium 10,000 times denser.

Hop

Hop David wrote:

Space Shuttle Columbia started disintegrating at a 70 kilometer
altitude going about mach 22.5. Seems like you're talking mach 25
through a medium 10,000 times denser.

Columbia had to be as light as possible; in this case you want the
projectile to be as dense as possible so it losses velocity slower as it
drills through the atmosphere. The thing would look like a huge bullet
and probably be made of of very thick iron with some sort of ablative
nosecone on it.

Pat

Damien Valentine wrote:
...So in other words, there is no justification for a kilometer-scale
O'Neill colony that doesn't involve either kilometer-scale SSPs (which
probably can't be built), or a national ideology based on the so-far-

Which probably can be built, but probably don't actually need an O'Neill
colony to do.

unheard-of idea of "saving the human species" (which, for some reason,
forbids settling the Moon and Mars, even though to build the O'Neill
in the first place you'd have to have thousands of people on the Moon
already...).\

Well, it depends who's paying, and how expensive it is for them. If
we're talking investment by groundside capital, it's hard to find a
reason. If we're talking a dekabillionaire wanting to build his own
world, utterly free of intrusion by the hoi polloi, it makes tons of
sense. Mix of isolation, grandiosity, and dominance display. Or maybe
courtship gift.

-xx- Damien X-)

In article .com,
Johnny1a wrote:

Given the cost of launching every kilogram, _any_ space operation has
to be as unmassive and uncomplicated as we can possibly make it.

I don't really buy an argument that space missions are generally
uncomplicated, for any meaning of uncomplicated that I can think of.

I wonder whether the issue isn't more that there are about half a
dozen sizes of vehicle that can be launched (fits on a Soyuz, fits on
a Proton, fits on an Ariane 5, fits on a Delta 4, ...), and you build
the most complicated thing possible that fits on the smallest vehicle
on which an adequate thing can be launched.

Taking on hideous manufacturing difficulty in exchange for lower mass
is almost always the right answer.

Tom

Mike Combs wrote:

You might perform this experiment: Pick out about 10 friends, family
members, or coworkers. Outline your scenario, and then ask them how many
would pay 100,000 dollars (assuming they had it) to send off an embryo in
this fashion. Then ask them if they would pay 1 million dollars for a
property lot on an Island 1 habitat (along with passage for them and their
spouse).

My prediction: A fair number will say "no" to either scenario, but there
will be a big difference between those saying yes to the second scenario vs.
the first. That may provide a clue to which is most likely to come about.


Then ask them if they would spend 100,000 dollars on a really choice
beachfront condo in Belize...I'll bet you will get some takers on that
last one, because living in a really choice beachfront condo in Belize
is going to be a lot more fun than living in a space habitat. Also, if
you take a few miles walk straight away from your condo you don't end up
approaching it from the opposite direction. :-)

Pat