[ExI] Why no space colonies or lunar bases? was Mooon. (Keith Henson)

[Keith Henson]

On Sat, Jul 23, 2011 at 5:00 AM,  Giovanni Santostasi
<gsantostasi at gmail.com> wrote:
>
> If one does this cost analysis to Columbus or Magellan's missions what would
> obtain?
> Were economical missions in the short range?

"The expedition eked out a small profit, but the crew was not paid
full wages.[22]"

(From Wikipedia on Magelan's voyage.)

John Grigg <possiblepaths2050 at gmail.com> wrote:

> Keith, I would think the answer is to let technology mature to the point
> where we can built an effective space elevator, circa 2030 or 2040.  And
> then the price of going into space plunges downward to I believe around $100
> a pound!

You can get to that price, which is where power satellites make sense,
with externally heated hydrogen.

It's not at all clear that the strength of the molecular bond permits
space elevators off earth.  Another problem is that everything in
orbit around earth eventually hit the elevator cable.

The moon is a different situation.  Denial floss (Spectra) is strong
enough for an elevator out through L1.  Such an elevator looks like it
could lift its own mass in 100 days.

> Our competition with China will get us there...

It's not clear we are even in the game.

Samantha Atkins <sjatkins at mac.com> wrote:

> On 07/22/2011 02:39 PM, Keith Henson wrote:

snip

>> Chemical fuels just won't do it.
>
> So why not bring up Orion and its relative clean variants for putting
> large payloads in GEO or on the moon?  At the very least space tugs with
> fission power plants and space platforms with reasonable sized fission
> plant and fission plants on the moon seem obvious.

Firing off a large number of fusion bombs is not reasonable politically.

Fission power plants are heavy.  If you have beamed energy you leave
all the heavy stuff on the ground.

>> But in recent years other ways have opened up, relatively low cost,
>> high efficiency, solid state laser diodes and low cost microwave
>> generators.  It's not entirely clear how to best exploit such beamed
>> energy sources, but they both offer exhaust velocity up in the same
>> range as the 9 km/s needed to get into orbit.
>
> These can't do the trick of lifting from LEO to GEO or into lunar
> insertion efficiently today.

Lunar insertion might be a bit dicey, but efficient transport to GEO
is the main thing I have been working on recently.
http://www.theoildrum.com/node/7898  See figures 3, 4, 5 and Read the
Appendix:  Into Orbit—Sideways

>> It's still too expensive for self funded space colonies, but if this
>> works out, it will only be 2 orders of magnitude too expensive rather
>> than 4.
>
> Go with space nukes and you can conceivably do this today.

Please advise how to get around the engineering and political problems.

David Lubkin <lubkin at unreasonable.com> wrote:

snip

> I would be very dubious about a space elevator on this planet.
> There are too many loons who'd want to destroy it, and too
> much uncertainty about what would happen if they tried.

If you could build them at all, they would not be easy to destroy and
there is not much uncertainty about what would happen.

Keith