The scenario: There is a rotating lunar elevator that will orbit the
moon and approach the lunar surface five times per orbit. The
nearest approach is 50 feet from the surface.

The Problem: As the rotating elevator descends it may encounter high
spots in the terrain, even some mountain tops around the equator.
These will have to be cleared to allow a clear path for the rotating
elevator.

What are the solutions?

1.) Nuclear exlosive to blow the obstructing mountain top out of the
way. I think this is unlikely considering international treaties
prohibiting nuclear weapons in space.

2.) A kinetic energy mass that is fired into the mountain. How much
mass? What velocity? Do we launch the mass from earth? Do we collect
space junk? Is it cost effective to collect space junk rather than
launching inert mass from earth?

3.) A kinetic energy bomb. A combination hit of explosives and
impact of the delivery vehicle. How dangerous is it to launch
explosives? Is it necessary?

4.) Land a crew and have them plant the explosives strategically to
allow the explosives to work efficiently, where the above examples
would concentrate a lot of energy in a small space and that energy
could remove a lot more material if spread over a larger area, and
if it was buried.

So which would be the best way to clear a path for the descending
phase of the rotating lunar elevator?

From: "victoriatangoman"
To:
Sent: Wednesday, April 03, 2002 5:00 AM
Subject: [spacesettlers] Preparing lunar surface . . .

> The scenario: There is a rotating lunar elevator that will orbit the
> moon and approach the lunar surface five times per orbit. The
> nearest approach is 50 feet from the surface.
>
> The Problem: As the rotating elevator descends it may encounter high
> spots in the terrain, even some mountain tops around the equator.
> These will have to be cleared to allow a clear path for the rotating
> elevator.
>

I don't know the mechanics of a lunar rotating elevator. Does it "touch"
always the same points in the surface? If so, why not just set the lowest
altitude of the elevator high enough to avoid natural obstacles (mountain
tops, crater rims, etc) and build high towers to load and unload cargo? That
seems both cheaper and more "environmentally correct"...

[snikt]
Lucio Coelho

Um, I did a web search. The tip of the rotovator follows
a shape called a cycloid. There is an applet that shows a
cycloid at:
http://www-groups.dcs.st-and.ac.uk/~history/Java/Cycloid.html

You'll see that the tip comes in vertically; so no
nuclear weapons to level mountains are required.

victoriatangoman wrote:

> The scenario: There is a rotating lunar elevator that will orbit the
> moon and approach the lunar surface five times per orbit. The
> nearest approach is 50 feet from the surface.
>
> The Problem: As the rotating elevator descends it may encounter high
> spots in the terrain, even some mountain tops around the equator.
> These will have to be cleared to allow a clear path for the rotating
> elevator.
>
> What are the solutions?
>
> 1.) Nuclear exlosive to blow the obstructing mountain top out of the
> way. I think this is unlikely considering international treaties
> prohibiting nuclear weapons in space.
>
> 2.) A kinetic energy mass that is fired into the mountain. How much
> mass? What velocity? Do we launch the mass from earth? Do we collect
> space junk? Is it cost effective to collect space junk rather than
> launching inert mass from earth?
>
> 3.) A kinetic energy bomb. A combination hit of explosives and
> impact of the delivery vehicle. How dangerous is it to launch
> explosives? Is it necessary?
>
> 4.) Land a crew and have them plant the explosives strategically to
> allow the explosives to work efficiently, where the above examples
> would concentrate a lot of energy in a small space and that energy
> could remove a lot more material if spread over a larger area, and
> if it was buried.
>
> So which would be the best way to clear a path for the descending
> phase of the rotating lunar elevator?
>

--
- Ian Woollard (ian.woollard@...)

"Is a planetary surface the right place for an expanding
technological civilization?"
- Gerard O'Neill

The rotating system would touch down on the same points if it
followed a equatorial orbit. It could touch down from one point to
about 7 on its orbit.

Your suggestion has merit, and I'm not sure which is the best way to
go. What if there is an obstruction on a 2,000 meter mountain and we
need to clear the peak of 100 meters of material? Is it more
efficient to blast it away to give an unobstructed path so that the
system can touch down at 10-50 meters elevation at the touchdown
points, or is it more efficient to leave the mountain peak intact
and build a 2,050 meter tower at each of the touchdown points?

--- In spacesettlers@y..., Lucio de Souza Coelho wrote:
> From: "victoriatangoman"
> To:
> Sent: Wednesday, April 03, 2002 5:00 AM
> Subject: [spacesettlers] Preparing lunar surface . . .
>
> > The scenario: There is a rotating lunar elevator that will orbit
the
> > moon and approach the lunar surface five times per orbit. The
> > nearest approach is 50 feet from the surface.
> >
> > The Problem: As the rotating elevator descends it may encounter
high
> > spots in the terrain, even some mountain tops around the equator.
> > These will have to be cleared to allow a clear path for the
rotating
> > elevator.
> >
> I don't know the mechanics of a lunar rotating elevator. Does
it "touch"
> always the same points in the surface? If so, why not just set the
lowest
> altitude of the elevator high enough to avoid natural obstacles
(mountain
> tops, crater rims, etc) and build high towers to load and unload
cargo? That

Here is a movie about exactly what I'm talking about.

http://www.tethers.com/Cislunar.mov

In their papers, Tethers Unlimited researchers discuss the issue of
the payload descending vertically, but I assumed that they were
discussing the point of reference of the observer and that such an
observer standing on the lunar surface would see the payload
trajectory as described. But then I wondered what about the path of
the payload in its entire orbit not just the approach to the
landing. What if there were obstructions in that path?

In the movie I can see the vertical landing component quite clearly,
but because it is rendered to such a small scale I'm trying to
visualize the orbit of the payload if there were obstructions that
were not near the landing zone.

Take a look at the movie.

--- In spacesettlers@y..., Ian Woollard wrote:
> Um, I did a web search. The tip of the rotovator follows
> a shape called a cycloid. There is an applet that shows a
> cycloid at:
> http://www-groups.dcs.st-and.ac.uk/~history/Java/Cycloid.html
>
> You'll see that the tip comes in vertically; so no
> nuclear weapons to level mountains are required.
>
> victoriatangoman wrote:
>
> > The scenario: There is a rotating lunar elevator that will orbit
the
> > moon and approach the lunar surface five times per orbit. The
> > nearest approach is 50 feet from the surface.
> >
> > The Problem: As the rotating elevator descends it may encounter
high
> > spots in the terrain, even some mountain tops around the
equator.
> > These will have to be cleared to allow a clear path for the
rotating
> > elevator.
> >
> > What are the solutions?
> >
> > 1.) Nuclear exlosive to blow the obstructing mountain top out of
the
> > way. I think this is unlikely considering international treaties
> > prohibiting nuclear weapons in space.
> >
> > 2.) A kinetic energy mass that is fired into the mountain. How
much
> > mass? What velocity? Do we launch the mass from earth? Do we
collect
> > space junk? Is it cost effective to collect space junk rather
than
> > launching inert mass from earth?
> >
> > 3.) A kinetic energy bomb. A combination hit of explosives and
> > impact of the delivery vehicle. How dangerous is it to launch
> > explosives? Is it necessary?
> >
> > 4.) Land a crew and have them plant the explosives strategically
to
> > allow the explosives to work efficiently, where the above
examples
> > would concentrate a lot of energy in a small space and that
energy
> > could remove a lot more material if spread over a larger area,
and
> > if it was buried.
> >
> > So which would be the best way to clear a path for the
descending

From: "victoriatangoman"
To:
Sent: Wednesday, April 03, 2002 6:53 PM
Subject: [spacesettlers] Re: Preparing lunar surface . . .

[snikt]
> Your suggestion has merit, and I'm not sure which is the best way to
> go. What if there is an obstruction on a 2,000 meter mountain and we
> need to clear the peak of 100 meters of material? Is it more
> efficient to blast it away to give an unobstructed path so that the
> system can touch down at 10-50 meters elevation at the touchdown
> points, or is it more efficient to leave the mountain peak intact
> and build a 2,050 meter tower at each of the touchdown points?
>

I don't know (although I feel that tall towers will have very cheap
structural requirements in the low lunar gravity). But what about if we take
an intermediate approach:

- First, you run some optimization/lunaprocessing program in order to
maximize the "peakness" of your touch down points. (A "peaky" touchdown
point would be one located in a elevation - mountain top, crater rim - with
no taller elevations around.)

- Then you build your "spaceport towers". The tallest touchdown point in
fact will have no tower, just a spaceport platform. The other points will
have a tower going to the altitude of the tallest point. Since all points
were optimized to be locally high, I would expect the average height of the
towers to be not that big.

[snikt]
Lucio Coelho

You propose a very good suggestion and all other factors being
equal, I would favor your proposal.

But how would distance from the base effect your proposal? The road
infrastructure needed to connect the two. The electrical power that
might be required.

The one supposition in my proposal that I didn't clearly state was
that I thought that a kinetic energy projectile would be cheaper
than the engineering needed to optimize tower locations and connect
them to the base with road and utilities. To avoid a lengthy journey
every time you wanted to launch a payload. Such journeys on the moon
wouldn't be as easy as they are on earth.

If the destructive energy of the kinetic energy projectile (or
explosive) that would destroy a mountaintop is not cheaper and more
time-efficient, then of course there's little point in further
investigating that option and better to optimize the site and build
the roads, etc.

--- In spacesettlers@y..., Lucio de Souza Coelho wrote:
> From: "victoriatangoman"
> To:
> Sent: Wednesday, April 03, 2002 6:53 PM
> Subject: [spacesettlers] Re: Preparing lunar surface . . .
>
> [snikt]
> > Your suggestion has merit, and I'm not sure which is the best
way to
> > go. What if there is an obstruction on a 2,000 meter mountain
and we
> > need to clear the peak of 100 meters of material? Is it more
> > efficient to blast it away to give an unobstructed path so that
the
> > system can touch down at 10-50 meters elevation at the touchdown
> > points, or is it more efficient to leave the mountain peak intact
> > and build a 2,050 meter tower at each of the touchdown points?
> >
> I don't know (although I feel that tall towers will have very cheap
> structural requirements in the low lunar gravity). But what about
if we take
> an intermediate approach:
>
> - First, you run some optimization/lunaprocessing program in order
to
> maximize the "peakness" of your touch down points. (A "peaky"
touchdown
> point would be one located in a elevation - mountain top, crater
rim - with
> no taller elevations around.)
>
> - Then you build your "spaceport towers". The tallest touchdown
point in
> fact will have no tower, just a spaceport platform. The other
points will
> have a tower going to the altitude of the tallest point. Since all
points
> were optimized to be locally high, I would expect the average
height of the

From: "victoriatangoman"
To:
Sent: Friday, April 05, 2002 6:35 PM
Subject: [spacesettlers] Re: Preparing lunar surface . . .

[snikt]
> The one supposition in my proposal that I didn't clearly state was
> that I thought that a kinetic energy projectile would be cheaper
> than the engineering needed to optimize tower locations and connect
> them to the base with road and utilities. To avoid a lengthy journey
> every time you wanted to launch a payload. Such journeys on the moon
> wouldn't be as easy as they are on earth.
[snikt]

The cost of optimizing tower locations is nearly null. You just need a
topography map of the moon (and I think that fairly accurate maps do exist)
and a program that you may code in a day or two.

Lucio Coelho

I beg to differ. The cost of planning the tower locations may be
next to nothing but actually doing it will be substantial.

Keep in mind, we're not referring to any existing lunar
infrastructure. We're building these towers to serve as landing
platforms for a lunar elevator which will be instrumental in
building the infrastructure to support industrialization on the
lunar surface.

You'll need heavy construction equipment, life support, or with tele-
operation you'll need radio repeater towers, a source of energy,
methods to erect such towers, a means to transport the tower
material to the site from the earth. Basically, a heavy construction
project at each location, when your supply base is the earth.

What I suggested is to use kinetic energy methods from space to
replace all of the equipment on the surface. Then when the orbit of
the lunavator ground region is unobstructed, the small scale landing
platforms can be constructed by hand or by robot. When completed,
base building equipment can be transported to the lunar surface to
build the infrastructure needed for more development.

I'm still left with the feeling that KE means are more cost
effective than rocket landing all of the heavy equipment needed, but
I'd welcome a response to arguments that you think I may have
overlooked.

--- In spacesettlers@y..., Lucio de Souza Coelho wrote:
> From: "victoriatangoman"
> To:
> Sent: Friday, April 05, 2002 6:35 PM
> Subject: [spacesettlers] Re: Preparing lunar surface . . .
>
> [snikt]
> > The one supposition in my proposal that I didn't clearly state
was
> > that I thought that a kinetic energy projectile would be cheaper
> > than the engineering needed to optimize tower locations and
connect
> > them to the base with road and utilities. To avoid a lengthy
journey
> > every time you wanted to launch a payload. Such journeys on the
moon
> > wouldn't be as easy as they are on earth.
> [snikt]
>
> The cost of optimizing tower locations is nearly null. You just
need a
> topography map of the moon (and I think that fairly accurate maps
do exist)