Moon Base L2 for Solar Sail Assembly Line

Moon Base L2
Douglas Eagleson


I read somewhere that L2 was to be usable for launching solar sails. L2 is the geostationary
lagrangian point on the far side of the moon.

I was rumaging the issue. L2 exhibits a well like location behavior. An object placed there tends to settle.

I also commented that a real lifting cable system is viable at this point. It is in fact the only viable place where cable will work.

The ascent is able to gently lift with small rockets allowed rather than a cable. My proposal is to use a real moon base at the L2 point on the moon. A remote factory system to make the ultimate solar sails. A 5 by 5 kilometer sail is easy on the surface to make. No oscillations to contend with.

Ultimate light weight is posible. Allowing true interstellar spacecraft. fyi. L2 is the exit point planned already. But a base to ground assemble is my request. Light acceleration stability is buildable into the sail.

Does any country already lay claim to this base location?

On Feb/7/2016 7:53 PM, wrote :
Moon Base L2
Douglas Eagleson


I read somewhere that L2 was to be usable for launching solar sails. L2 is the geostationary
lagrangian point on the far side of the moon.

I was rumaging the issue. L2 exhibits a well like location behavior. An object placed there tends to settle.

No. L2 is an unstable equilibrium point. An object placed there will
tend to drift away. An object can be kept there with minimal station
keeping to maintain position. Only L4 and L5 have stable equilibrium.


Alain Fournier

"Alain Fournier" wrote in message ...

On Feb/7/2016 7:53 PM, wrote :
Moon Base L2
Douglas Eagleson


I read somewhere that L2 was to be usable for launching solar sails. L2
is the geostationary
lagrangian point on the far side of the moon.

I was rumaging the issue. L2 exhibits a well like location behavior. An
object placed there tends to settle.

No. L2 is an unstable equilibrium point. An object placed there will tend
to drift away. An object can be kept there with minimal station keeping to
maintain position. Only L4 and L5 have stable equilibrium.


Alain Fournier

Wikipedia seems to indicate otherwise, and this is my recollection as well:

https://en.wikipedia.org/wiki/Lagran...ipotential.jpg




--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

On Monday, February 8, 2016 at 8:26:44 AM UTC-5, Greg (Strider) Moore wrote:
"Alain Fournier" wrote in message ...

On Feb/7/2016 7:53 PM, wrote :
Moon Base L2
Douglas Eagleson


I read somewhere that L2 was to be usable for launching solar sails. L2
is the geostationary
lagrangian point on the far side of the moon.

I was rumaging the issue. L2 exhibits a well like location behavior. An
object placed there tends to settle.

No. L2 is an unstable equilibrium point. An object placed there will tend
to drift away. An object can be kept there with minimal station keeping to
maintain position. Only L4 and L5 have stable equilibrium.


Alain Fournier

Wikipedia seems to indicate otherwise, and this is my recollection as well:

https://en.wikipedia.org/wiki/Lagran...ipotential.jpg




--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

Thanks for the reference. Just to clarify. The well field occurs when the moon is on the moon-earth-sun centerline. It is a window of usable proportions. It is a matter of the distortion of the centering forces.

L4 and L5 are also transiently existing.

L4 is also a good point to launch solar sails. Or is it? They are theory fields of enticement only. But boosting a solar sail from low earth orbit up to L4 is also the transient field usage. It is a big deal to define the points of minimal energy usage to leave the earth-moon system.

In article . com,
says...

L4 is also a good point to launch solar sails. Or is it?

Since there isn't even a McDonalds there, what is the point of staging a
launch at a LaGrange point since you'll need to spend fuel to get there,
so there are no real savings and no resources there. And bring supplies
there will cost a lot more fuel, and any EVA there also has the
radiation problem since you're above Van Allen.

Setting aside the issue of lack of a stable point or orbit around L2 for
a moment...

If you're using materials (including fuel and oxidizer) obtained from
the moon, there could be an advantage because the moon's gravity is far
less, so it ought to take much less delta-V to take materials from the
lunar surface to L2 than from the earth's surface to L2.

In LEO, you have a constant sun/dark cycle every 90 minutes. This lets
you charge batteries and then cool down 45 minutes later when it goes dark.

This also creates all sorts of cyclic thermal stresses to deal with. It
also means you need fairly heavy batteries to store electricity when
your solar arrays are in darkness. Plus, if you assemble a frail craft
like a solar sail in LEO, getting it out of LEO and through the van-
Allen radiation belts quickly is a problem.

What sort of orbital periods are we talking about at LaGrange ? What
percentage of time is spent in the dark vs sun ? Would there be issues
with cooling (long periods of sun) or battery autonomy (long periods of
dark) ?

Put it in a halo orbit around L2 and you'd have virtually no periods of
darkness. People have thought about these things and written papers on
the subject:

A Lunar L2 Navigation, Communication, and Gravity Mission
Keric Hill, Jeffrey Parker, George H. Born, and Nicole Demandante
University of Colorado, Boulder, Colorado 80309
http://ccar.colorado.edu/geryon/pape...AA-06-6662.pdf

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

Jeff Findley wrote:
Plus, if you assemble a frail craft like a solar sail in LEO,
getting it out of LEO and through the van- Allen radiation belts
quickly is a problem.

Are materials commonly considered for solar sails that sensitive to
radiation, or is it more just a slow trip through the belts in general
and the effects on the electronics whether the propulsion was solar
sail or not?

rick jones
--
a wide gulf separates "what if" from "if only"
these opinions are mine, all mine; HPE might not want them anyway...
feel free to post, OR email to rick.jones2 in hpe.com but NOT BOTH...

In article , says...

Jeff Findley wrote:
Plus, if you assemble a frail craft like a solar sail in LEO,
getting it out of LEO and through the van- Allen radiation belts
quickly is a problem.

Are materials commonly considered for solar sails that sensitive to
radiation, or is it more just a slow trip through the belts in general
and the effects on the electronics whether the propulsion was solar
sail or not?

I believe that it's mostly a problems with electronics, including solar
cells.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On Tuesday, February 9, 2016 at 11:55:35 AM UTC-5, Jeff Findley wrote:
In article . com,
says...

L4 is also a good point to launch solar sails. Or is it?

Since there isn't even a McDonalds there, what is the point of staging a
launch at a LaGrange point since you'll need to spend fuel to get there,
so there are no real savings and no resources there. And bring supplies
there will cost a lot more fuel, and any EVA there also has the
radiation problem since you're above Van Allen.

Setting aside the issue of lack of a stable point or orbit around L2 for
a moment...

If you're using materials (including fuel and oxidizer) obtained from
the moon, there could be an advantage because the moon's gravity is far
less, so it ought to take much less delta-V to take materials from the
lunar surface to L2 than from the earth's surface to L2.

In LEO, you have a constant sun/dark cycle every 90 minutes. This lets
you charge batteries and then cool down 45 minutes later when it goes dark.

This also creates all sorts of cyclic thermal stresses to deal with. It
also means you need fairly heavy batteries to store electricity when
your solar arrays are in darkness. Plus, if you assemble a frail craft
like a solar sail in LEO, getting it out of LEO and through the van-
Allen radiation belts quickly is a problem.

What sort of orbital periods are we talking about at LaGrange ? What
percentage of time is spent in the dark vs sun ? Would there be issues
with cooling (long periods of sun) or battery autonomy (long periods of
dark) ?

Put it in a halo orbit around L2 and you'd have virtually no periods of
darkness. People have thought about these things and written papers on
the subject:

A Lunar L2 Navigation, Communication, and Gravity Mission
Keric Hill, Jeffrey Parker, George H. Born, and Nicole Demandante
University of Colorado, Boulder, Colorado 80309
http://ccar.colorado.edu/geryon/pape...AA-06-6662.pdf

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

space xs lower cost to orbit may make doing things on cite more costly

In article ,
says...
space xs lower cost to orbit may make doing things on cite more costly

I have no idea what you are talking about.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

Will we even be using Solar Sails in the future, or will they be superceded by E-Sails?:

http://www.space.com/31063-electric-...ploration.html

Quote:

"The HERTS team's work suggests that e-sailing craft can continue accelerating
far beyond the point that solar-sail probes lose steam, Johnson said. For this
reason, an e-sail could get a probe out to the heliopause -- the edge of the
sun's sphere of influence, where the solar wind hits the interstellar medium --
in 10 years, twice as fast as a solar sail could, HERTS team members have said."