Natural Science Forum / Physics / General Physics / July 2008

The first step in space travel would be to map the
trip and all obstacles in an absolute way, otherwise
you will be crashing into things that were not foreseen.
Part of that step would also be to create an absolute time
clock so you would have no worry of hitting things that
were not supposed to be there according to a dilated clock.
Until those two things are done,
It would be pretty stupid to just blast off out into that
absolute wilderness that one spec could blow up your ship
before you knew it was even coming at you..

On Jul 4, 3:11 pm, Will Davis <Will.Davis.2b46...@physicsbanter.com>
wrote:

Having a spaceport in orbit doesn't really help much. A low earth
orbit like where the ISS orbits means that the space station is
traveling at roughly 1000 mph, or Mach 16. Thus, to get down to the
ground from a spaceport still involves decelerating through the
atmosphere at high speed.

It is possible to orbit directly over a fixed spot on the Earth, but
that means putting the spaceport out in geosynchronous orbit, 36000 km
or 22,300 miles up. That's quite  a ways out there. If you do, though,
this raises the possibility of a "space elevator", a promising idea
originated by Arthur C Clarke. You can Google that to find out the
technical challenges of doing that, not the least of which is that a
trip up and down the elevator would take months.

PD

  The ISS is Low Earth Orbit (LEO) protected from the solar wind by
  the Earth's magnetic field... not anything close to the kind of
  thing you are envisioning.

When the LGM (little green men) find out that you haven't even colonised
Antarctica yet with its abundance of water, Earth-like gravity, perfect mix
of atmospheric gases, six months of glorious sunshine all summer long,
absolutely ideal conditions to support human life without even needing
a spacesuit, a whole damn continent still unexplored, they'll be having
a good laugh at your idiotic attempts at "the possib[i]lity of interstellar
travel hopefully" and promptly exterminate you for your disease. Stupidity
is contagious. Oops, I just caught some... forget I mentioned the LGM
and hand me back my sanity.

 We will create / adapt / improvise / expand and grow our way into the
universe at large.

 I wouldn't worry about the naysaying Dark Age physicists and Earth First
Utopians (Gibbon's mental "pygmies" updated) living today. Had Columbus and
everyone else listened to their types back in his day we more than likely
would not be advanced in energies, powers and capabilities much beyond 1492
even now. The Ottoman Turks would have conquered an inward looking, and
imploding, Europe and put its advancement back some 500 or more years. China
(less than a hundred years prior) had already been set back some 500 years
or so by its own naysaying and inward looking -- implosive -- elites,
schools and bureaucracies.

 The biggest problem is we should already have bases on the Moon, large
gravitied [general purpose] space stations in Earth orbit, capable mass
transportation system shuttles and ships plying the lanes to space and in
space, and at least the first space colony city-state complex coming on line
around L4 or L5. With all that expanding and growing frontier activity, our
(then) increasingly frontier-like economies on Earth would be doing a heck
of lot better than they -- increasingly implosively -- are doing now.

 About 230 years ago, an American farmer / writer named Crevecoeur
commented on how people immigrating into a vast new frontier environment
seemed to just naturally expand in mind, genius, energy and potential to be
creative and do, equally vastly. Edward Gibbon wrote of just the opposite
occurring in a tyrannically frontierless world imploding into itself.
Shrinking minds, genius, energy and potential producing, evolving, mental
"pygmies" -- savage mental midgets -- as the vast, the very vast, now
otherwise irresistibly immovable, mass.

 But maybe we haven't reached that point yet. A move to begin now what we
should have begun long ago (and were [tyrannically] kept from doing by
inward looking -- government, university and, in general, ideological --  
powers that be) might reverse civilization's decline and fall from the
accelerating growth of a [savage] mental midgetry. New (energetic) Worlds in
the making.....including a brand spanking new (energetic) Old World in the
making right here. Being in the presence, the environment, of an energetic
vastness expanding minds -- the mass mind and genius -- vastly, expanding
possibilities, potentials, capacities, capabilities, vision and creativity
vastly. It's not something new, it's simply the nature of the thing (simply
the nature of opening....of going nova).

GLB

Thoughts?  We have some, yes.  You should get some.

Reentry heat is solved by coming in backwards.  Rocket exhaust is much
cooler than the apparent temp of the atmosphere at the viewed relative
velocity of reentry,

http://hyperphysics.phy-astr.gsu.edu/Hbase/kinetic/kintem.html

Be clever and zoom in with not against the planet's rotation.  A blunt
ablative thermal shield bounces most of the energy back into the
plasma plume.  Sharp edges burn.  The Space Scuttle is an obscenity.

Space stations?  Conservation of enery, linear and angular momentum.
Don't be an idiot about path changing either - it doesn't.

There exist no solutions within extant physics for practical
interstellar travel,

"The Starflight Handbook" Mallove and Matloff.

There exist no solutions within extant physics for practical
intersystem travel, either.  Price 100 kg of xenon.  Mercury ion
engines short out and dissolve the spacecraft.  Solar sails are
bullshit when you go to make one.  Unless you want to ride a nuclear
reactor bareback, massive radiation shielding negates any propulsion
advanatge - and don't be one of the mainteneance crew.

Why not build this?
http://www.pacificsites.com/~snyder/Space%20Drive/SpDrive.html
Larry