--- In spacesettlers@egroups.com, "bill t" wrote:
> >
> The resource in the asteroid are vast, but so are the ones on
earth.
> The earth represents at least 9 orders of magnitude more material
than
> all the asteroid combined.

Yes, but here on Earth we're limited in how deep we can mine before
pressures and temperatures become problematic. Not so in asteroids.

> If you can effectively mine the first
> kilometer of the surface you will get everything you need, assuming
an
> energy source can be found.

Yes, but think about what's being said here. Imagine the
environmental disruption of even developing half of that. One of the
advantages of any kind of space mining is that it can take place at
any scale with 0 disturbance of the Earthly biosphere.

> Again, no. If you are looking for a continuous acceleration engine
for
> interplanetary travel, you can achieve this by using solar powered
> electric generators, to charge dust particles, then accelerate the
> dust using an electric field.

There are lots of proposals out there for all kinds of low-
thrust/high-efficiency drives. This writer happens to have a soft
spot for mass driver engines, but it might be too early to say that
it's definitely going to be this or that.

My only criticism of fusion drives might be that we don't know how to
do fusion yet, so it might be better to first concentrate on the
proposals which would use technologies already in hand.

Mike,

So, what would you power your mass driver with? Nuclear fission? Chemical? Solar? What diameter projectile? What velocity do you anticipate achieving for the projectile?

Keeping alternatives on the table helps with comparative analysis later when more options are available.

Being more pragmatic, I think that we are many decades away from space colonization and asteroid mining due to critical "missing technological links" in the chain of tools that are needed. Chiefly, these are:

1) Reduction in cost to achieve LEO and beyond,

2) Advanced remote technology to mine and to maintain mining equipment on an asteroid that may be far far away. Neural net ethnology will be crucial IMO along with VR and machines able to repair themselves.

3) Design and test viable life support systems for space colonies.

The above steps will open the frontier to space colonization IMO. Am I missing any steps? Comments?

Cheers,

Tom

From: Mike Combs
To: spacesettlers@egroups.com
Sent: Wednesday, December 27, 2000 6:49 AM
Subject: [spacesettlers] High efficiency drives

--- In spacesettlers@egroups.com, "bill t" wrote:
> >
> The resource in the asteroid are vast, but so are the ones on
earth.
> The earth represents at least 9 orders of magnitude more material
than
> all the asteroid combined.

Yes, but here on Earth we're limited in how deep we can mine before
pressures and temperatures become problematic. Not so in asteroids.

> If you can effectively mine the first
> kilometer of the surface you will get everything you need, assuming
an
> energy source can be found.

Yes, but think about what's being said here. Imagine the
environmental disruption of even developing half of that. One of the
advantages of any kind of space mining is that it can take place at
any scale with 0 disturbance of the Earthly biosphere.

> Again, no. If you are looking for a continuous acceleration engine
for
> interplanetary travel, you can achieve this by using solar powered
> electric generators, to charge dust particles, then accelerate the
> dust using an electric field.

There are lots of proposals out there for all kinds of low-
thrust/high-efficiency drives. This writer happens to have a soft
spot for mass driver engines, but it might be too early to say that
it's definitely going to be this or that.

My only criticism of fusion drives might be that we don't know how to
do fusion yet, so it might be better to first concentrate on the
proposals which would use technologies already in hand.

So, what would you power your mass driver with? Nuclear fission? Chemical? Solar? What diameter projectile? What velocity do you anticipate achieving for the projectile?

Keeping alternatives on the table helps with comparative analysis later when more options are available.

Being more pragmatic, I think that we are many decades away from space colonization and asteroid mining due to critical "missing technological links" in the chain of tools that are needed. Chiefly, these are:

1) Reduction in cost to achieve LEO and beyond,

2) Advanced remote technology to mine and to maintain mining equipment on an asteroid that may be far far away. Neural net ethnology will be crucial IMO along with VR and machines able to repair themselves.

3) Design and test viable life support systems for space colonies.

The above steps will open the frontier to space colonization IMO. Am I missing any steps? Comments?

Cheers,

Tom

From:
Mike Combs
To:
spacesettlers@egroups.com
Sent:
Wednesday, December 27, 2000 6:49 AM
Subject:
[spacesettlers] High efficiency drives
--- In
spacesettlers@egroups.com
, "bill t" <
qwerty172@e
...> wrote:
> >
> The resource in the asteroid are vast, but so are the ones on
earth.
> The earth represents at least 9 orders of magnitude more material
than
> all the asteroid combined.
Yes, but here on Earth we're limited in how deep we can mine before
pressures and temperatures become problematic. Not so in asteroids.
> If you can effectively mine the first
> kilometer of the surface you will get everything you need, assuming
an
energy source can be found.
Yes, but think about what's being said here. Imagine the
environmental disruption of even developing half of that. One of the
advantages of any kind of space mining is that it can take place at
any scale with 0 disturbance of the Earthly biosphere.
> Again, no. If you are looking for a continuous acceleration engine
for
> interplanetary travel, you can achieve this by using solar powered
> electric generators, to charge dust particles, then accelerate the
> dust using an electric field.
There are lots of proposals out there for all kinds of low-
thrust/high-efficiency drives. This writer happens to have a soft
spot for mass driver engines, but it might be too early to say that
it's definitely going to be this or that.
My only criticism of fusion drives might be that we don't know how to
do fusion yet, so it might be better to first concentrate on the
proposals which would use technologies already in hand.

If you want a more comprehensive list, go to the file section and
download a file called evacuation.tar.gz. In there you will find a
file called details.html. This has a more comprehensive list.

To your list add,
space agriculture
power management (heating, cooling, microwave beaming, electrical
discharging etc...)
search and rescue
space ship production
asteroid discovery program
asteroid retrieval program
information system (expert system)
advanced robotics

Bill

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Mike,
>
> So, what would you power your mass driver with? Nuclear fission?
Chemical? Solar? What diameter projectile? What velocity do you
anticipate achieving for the projectile?
>
> Keeping alternatives on the table helps with comparative analysis
later when more options are available.
>
> Being more pragmatic, I think that we are many decades away from
space colonization and asteroid mining due to critical "missing
technological links" in the chain of tools that are needed. Chiefly,
these are:
>
> 1) Reduction in cost to achieve LEO and beyond,
>
> 2) Advanced remote technology to mine and to maintain mining
equipment on an asteroid that may be far far away. Neural net
ethnology will be crucial IMO along with VR and machines able to
repair themselves.
>
> 3) Design and test viable life support systems for space colonies.
>
> The above steps will open the frontier to space colonization IMO.
Am I missing any steps? Comments?
>
> Cheers,
>
> Tom
>
> From: Mike Combs
> To: spacesettlers@egroups.com
> Sent: Wednesday, December 27, 2000 6:49 AM
> Subject: [spacesettlers] High efficiency drives
>
> --- In spacesettlers@egroups.com, "bill t" wrote:
> > >
> > The resource in the asteroid are vast, but so are the ones on
> earth.
> > The earth represents at least 9 orders of magnitude more
material
> than
> > all the asteroid combined.
>
> Yes, but here on Earth we're limited in how deep we can mine
before
> pressures and temperatures become problematic. Not so in
asteroids.
>
> > If you can effectively mine the first
> > kilometer of the surface you will get everything you need,
assuming
> an
> > energy source can be found.
>
> Yes, but think about what's being said here. Imagine the
> environmental disruption of even developing half of that. One of
the
> advantages of any kind of space mining is that it can take place
at
> any scale with 0 disturbance of the Earthly biosphere.
>
> > Again, no. If you are looking for a continuous acceleration
engine
> for
> > interplanetary travel, you can achieve this by using solar
powered
> > electric generators, to charge dust particles, then accelerate
the
> > dust using an electric field.
>
> There are lots of proposals out there for all kinds of low-
> thrust/high-efficiency drives. This writer happens to have a soft
> spot for mass driver engines, but it might be too early to say
that
> it's definitely going to be this or that.
>
> My only criticism of fusion drives might be that we don't know how
to

Bill,

Thanks for the input. This may come as a shock to you, but some of us do not use unix and so we have no way of uncompressing the .tar. file you are referencing. Can you unpackage PKZip files? I wonder if this wouldn't be a more universal archive?

My list's goal was to identify "missing technological links" preventing the deployment of space colonies. Some of your items appear to be "nice to have" rather than essential.
From: bill t
To: spacesettlers@egroups.com
Sent: Thursday, December 28, 2000 8:00 AM
Subject: [spacesettlers] Re: High efficiency drives

If you want a more comprehensive list, go to the file section and
download a file called evacuation.tar.gz. In there you will find a
file called details.html. This has a more comprehensive list.

To your list add,
space agriculture (covered under #3)
power management (heating, cooling, microwave beaming, electrical
discharging etc...) (Also convered under #3)
search and rescue (future nice idea)
space ship production (NASA already does a pretty good job)
asteroid discovery program (inprocess, but may take decades to complete)
asteroid retrieval program (future goal)
information system (expert system) (future nice idea)
advanced robotics (covered under #2)

Please explain your rational why the balance of your list above are critical and not amenities that can be developed after deployment of a space colony?

Cheers,

Tom

Bill

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Mike,
>
> So, what would you power your mass driver with? Nuclear fission?
Chemical? Solar? What diameter projectile? What velocity do you
anticipate achieving for the projectile?
>
> Keeping alternatives on the table helps with comparative analysis
later when more options are available.
>
> Being more pragmatic, I think that we are many decades away from
space colonization and asteroid mining due to critical "missing
technological links" in the chain of tools that are needed. Chiefly,
these are:
>
> 1) Reduction in cost to achieve LEO and beyond,
>
> 2) Advanced remote technology to mine and to maintain mining
equipment on an asteroid that may be far far away. Neural net
ethnology will be crucial IMO along with VR and machines able to
repair themselves.
>
> 3) Design and test viable life support systems for space colonies.
>
> The above steps will open the frontier to space colonization IMO.
Am I missing any steps? Comments?
>
> Cheers,
>
> Tom
>
> From: Mike Combs
> To: spacesettlers@egroups.com
> Sent: Wednesday, December 27, 2000 6:49 AM
> Subject: [spacesettlers] High efficiency drives
>
> --- In spacesettlers@egroups.com, "bill t" wrote:
> > >
> > The resource in the asteroid are vast, but so are the ones on
> earth.
> > The earth represents at least 9 orders of magnitude more
material
> than
> > all the asteroid combined.
>
> Yes, but here on Earth we're limited in how deep we can mine
before
> pressures and temperatures become problematic. Not so in
asteroids.
>
> > If you can effectively mine the first
> > kilometer of the surface you will get everything you need,
assuming
> an
> > energy source can be found.
>
> Yes, but think about what's being said here. Imagine the
> environmental disruption of even developing half of that. One of
the
> advantages of any kind of space mining is that it can take place
at
> any scale with 0 disturbance of the Earthly biosphere.
>
> > Again, no. If you are looking for a continuous acceleration
engine
> for
> > interplanetary travel, you can achieve this by using solar
powered
> > electric generators, to charge dust particles, then accelerate
the
> > dust using an electric field.
>
> There are lots of proposals out there for all kinds of low-
> thrust/high-efficiency drives. This writer happens to have a soft
> spot for mass driver engines, but it might be too early to say
that
> it's definitely going to be this or that.
>
> My only criticism of fusion drives might be that we don't know how
to
> do fusion yet, so it might be better to first concentrate on the
> proposals which would use technologies already in hand.
>

Thanks for the input. This may come as a shock to you, but some of us do not use unix and so we have no way of uncompressing the .tar. file you are referencing. Can you unpackage PKZip files? I wonder if this wouldn't be a more universal archive?

My list's goal was to identify
"missing technological links" preventing the deployment of space colonies. Some of your items appear to be "nice to have" rather than essential.
From:
bill t
To:
spacesettlers@egroups.com
Sent:
Thursday, December 28, 2000 8:00 AM
Subject:
[spacesettlers] Re: High efficiency drives
If you want a more comprehensive list, go to the file section and
download a file called evacuation.tar.gz. In there you will find a
file called details.html. This has a more comprehensive list.
To your list add,
space agriculture (covered under #3)
power management (heating, cooling, microwave beaming, electrical
discharging etc...) (Also convered under #3)
search and rescue (future nice idea)
space ship production (NASA already does a pretty good job)
asteroid discovery program (inprocess, but may take decades to complete)
asteroid retrieval program (future goal)
information system (expert system) (future nice idea)
advanced robotics (covered under #2)
Please explain your rational why the balance of your list above are critical and not amenities that can be developed after deployment of a space colony?

Cheers,

Tom

Bill
--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
> Mike,
>
> So, what would you power your mass driver with? Nuclear fission?
Chemical? Solar? What diameter projectile? What velocity do you
anticipate achieving for the projectile?
>
> Keeping alternatives on the table helps with comparative analysis
later when more options are available.
>
> Being more pragmatic, I think that we are many decades away from
space colonization and asteroid mining due to critical "missing
technological links" in the chain of tools that are needed. Chiefly,
these are:
>
> 1) Reduction in cost to achieve LEO and beyond,
>
> 2) Advanced remote technology to mine and to maintain mining
equipment on an asteroid that may be far far away. Neural net
ethnology will be crucial IMO along with VR and machines able to
repair themselves.
>
> 3) Design and test viable life support systems for space colonies.
>
> The above steps will open the frontier to space colonization IMO.
Am I missing any steps? Comments?
>
> Cheers,
>
> Tom
>
> From: Mike Combs
> To: spacesettlers@egroups.com
> Sent: Wednesday, December 27, 2000 6:49 AM
> Subject: [spacesettlers] High efficiency drives
>
> --- In spacesettlers@egroups.com, "bill t"
> > >
> > The resource in the asteroid are vast, but so are the ones on
> earth.
> > The earth represents at least 9 orders of magnitude more
material
> than
> > all the asteroid combined.
>
> Yes, but here on Earth we're limited in how deep we can mine
before
> pressures and temperatures become problematic. Not so in
asteroids.
>
> > If you can effectively mine the first
> > kilometer of the surface you will get everything you need,
assuming
> an
> > energy source can be found.
>
> Yes, but think about what's being said here. Imagine the
> environmental disruption of even developing half of that. One of
the
> advantages of any kind of space mining is that it can take place
at
> any scale with 0 disturbance of the Earthly biosphere.
>
> > Again, no. If you are looking for a continuous acceleration
engine
> for
> > interplanetary travel, you can achieve this by using solar
powered
> > electric generators, to charge dust particles, then accelerate
the
> > dust using an electric field.
>
> There are lots of proposals out there for all kinds of low-
> thrust/high-efficiency drives. This writer happens to have a soft
> spot for mass driver engines, but it might be too early to say
that
> it's definitely going to be this or that.
>
> My only criticism of fusion drives might be that we don't know how
to

What is funny is I have no way of complying with your request at the
moment. I have no windows machines at my house, and the zip program on
unix doesn't produce a file that pkzip can uncompress.

I'll get it into a zipfile and post it.

To give you an idea of what I was trying to accomplish, imagine what
infrastructure you will need to move half a million people into space
a day.

This included things like ground transportation/storage large scale
launch facilities, construction requirements for housing, factories,
ships, power equipment.

With half a million people to huase in space every day, you have to
build a Oneil cylinder every day.

Bill

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Bill,
>
> Thanks for the input. This may come as a shock to you, but some of
us do not use unix and so we have no way of uncompressing the .tar.
file you are referencing. Can you unpackage PKZip files? I wonder if
this wouldn't be a more universal archive?
>
> My list's goal was to identify "missing technological links"
preventing the deployment of space colonies. Some of your items
appear to be "nice to have" rather than essential.
> From: bill t
> To: spacesettlers@egroups.com
> Sent: Thursday, December 28, 2000 8:00 AM
> Subject: [spacesettlers] Re: High efficiency drives
>
> If you want a more comprehensive list, go to the file section and
> download a file called evacuation.tar.gz. In there you will find a
> file called details.html. This has a more comprehensive list.
>
> To your list add,
> space agriculture (covered under #3)
> power management (heating, cooling, microwave beaming, electrical
> discharging etc...) (Also convered under #3)
> search and rescue (future nice idea)
> space ship production (NASA already does a pretty good job)
> asteroid discovery program (inprocess, but may take decades to
complete)
> asteroid retrieval program (future goal)
> information system (expert system) (future nice idea)
> advanced robotics (covered under #2)
>
> Please explain your rational why the balance of your list above
are critical and not amenities that can be developed after deployment
of a space colony?
>
> Cheers,
>
> Tom
>
> Bill
>
> --- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
> wrote:
> > Mike,
> >
> > So, what would you power your mass driver with? Nuclear fission?
> Chemical? Solar? What diameter projectile? What velocity do you
> anticipate achieving for the projectile?
> >
> > Keeping alternatives on the table helps with comparative
analysis
> later when more options are available.
> >
> > Being more pragmatic, I think that we are many decades away from
> space colonization and asteroid mining due to critical "missing
> technological links" in the chain of tools that are needed.
Chiefly,
> these are:
> >
> > 1) Reduction in cost to achieve LEO and beyond,
> >
> > 2) Advanced remote technology to mine and to maintain mining
> equipment on an asteroid that may be far far away. Neural net
> ethnology will be crucial IMO along with VR and machines able to
> repair themselves.
> >
> > 3) Design and test viable life support systems for space
colonies.
> >
> > The above steps will open the frontier to space colonization
IMO.
> Am I missing any steps? Comments?
> >
> > Cheers,
> >
> > Tom
> >
> > From: Mike Combs
> > To: spacesettlers@egroups.com
> > Sent: Wednesday, December 27, 2000 6:49 AM
> > Subject: [spacesettlers] High efficiency drives
> >
> >
> > --- In spacesettlers@egroups.com, "bill t"
> > > >
> > > The resource in the asteroid are vast, but so are the ones
on
> > earth.
> > > The earth represents at least 9 orders of magnitude more
> material
> > than
> > > all the asteroid combined.
> >
> > Yes, but here on Earth we're limited in how deep we can mine
> before
> > pressures and temperatures become problematic. Not so in
> asteroids.
> >
> > > If you can effectively mine the first
> > > kilometer of the surface you will get everything you need,
> assuming
> > an
> > > energy source can be found.
> >
> > Yes, but think about what's being said here. Imagine the
> > environmental disruption of even developing half of that. One
of
> the
> > advantages of any kind of space mining is that it can take
place
> at
> > any scale with 0 disturbance of the Earthly biosphere.
> >
> > > Again, no. If you are looking for a continuous acceleration
> engine
> > for
> > > interplanetary travel, you can achieve this by using solar
> powered
> > > electric generators, to charge dust particles, then
accelerate
> the
> > > dust using an electric field.
> >
> > There are lots of proposals out there for all kinds of low-
> > thrust/high-efficiency drives. This writer happens to have a
soft
> > spot for mass driver engines, but it might be too early to say
> that
> > it's definitely going to be this or that.
> >
> > My only criticism of fusion drives might be that we don't know
how
> to
> > do fusion yet, so it might be better to first concentrate on
the

Bill,

I see. Your scenario is way out there in the future, and I am looking a the near future to see how we can build the 1st colony.

Since the earth's population only increases at 80 million/year, why move 1/2 million per day? Why not 1/4 million or 1 million while we are on the topic?

How much of the infra-structure would be build in space and how much supplied from earth? What is your presumed launch cost per KG? Presumably this would be low enough for the average person to afford, say around $1/KG?

Tom
From: bill t
To: spacesettlers@...m
Sent: Sunday, December 31, 2000 9:19 AM
Subject: [spacesettlers] Re: High efficiency drives

What is funny is I have no way of complying with your request at the
moment. I have no windows machines at my house, and the zip program on
unix doesn't produce a file that pkzip can uncompress.

I'll get it into a zipfile and post it.

To give you an idea of what I was trying to accomplish, imagine what
infrastructure you will need to move half a million people into space
a day.

This included things like ground transportation/storage large scale
launch facilities, construction requirements for housing, factories,
ships, power equipment.

With half a million people to huase in space every day, you have to
build a Oneil cylinder every day.

Bill

snip

I see. Your scenario is way out there in the future, and I am looking a the near future to see how we can build the 1st colony.

Since the earth's population only increases at 80 million/year, why move 1/2 million per day? Why not 1/4 million or 1 million while we are on the topic?

How much of the infra-structure would be build in space and how much supplied from earth? What is your presumed launch cost per KG? Presumably this would be low enough for the average person to afford, say around $1/KG?

Tom
From:
bill t
To:
spacesettlers@egroups.com
Sent:
Sunday, December 31, 2000 9:19 AM
Subject:
[spacesettlers] Re: High efficiency drives
What is funny is I have no way of complying with your request at the
moment. I have no windows machines at my house, and the zip program on
unix doesn't produce a file that pkzip can uncompress.
I'll get it into a zipfile and post it.
To give you an idea of what I was trying to accomplish, imagine what
infrastructure you will need to move half a million people into space
a day.
This included things like ground transportation/storage large scale
launch facilities, construction requirements for housing, factories,
ships, power equipment.
With half a million people to huase in space every day, you have to
build a Oneil cylinder every day.
Bill
snip

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Mike,
>
> So, what would you power your mass driver with? Nuclear fission?
Chemical? Solar?

It was proposed that the lunar catapult be solar powered. At an
earlier point of these studies there was a small, buried nuclear
reactor at the moonbase. Later on, the reactor was gone, and there
were only solar panels. I think they had decided that solar was OK
for the mass driver, even if it meant that it could only opperate 2
weeks out of every four (you'd need some downtime for repair and
maintenance anyway). I would assume some storage method was used to
get the moonbase through the 2 week long night. I think there was a
push to eliminate the nuclear reactor due to people's concerns about
launch accidents. Given the difficulties faced by the much more
modest Cassini probe, that's probably just being realistic.

A mass driver being used as an inter-orbital tug would most certainly
be solar powered since it would have continuous solar power available
to it (except for when it was in LEO).

> What diameter projectile?

O'Neill assumed spheres of sintered lunar soil about the diameter of
a softball.

> What velocity do you anticipate
> achieving for the projectile?

The lunar mass driver catapult was launching at about lunar escape
speed, which is 2.4 km/sec. I think the interorbital tug would eject
its reaction mass even faster. Seems like someone said the exhaust
velocity would be in excess of Earth escape, so that reaction mass
would not contribute significantly to orbital debris.

> Keeping alternatives on the table helps with comparative analysis
later when more options are available.

Oh, sure. I've had people advocate slingshots and lunar skyhooks to
me over mass drivers. I still tend to favor mass drivers, but I'm
for whatever turns out to work best in the end.

> Being more pragmatic, I think that we are many decades away from
space colonization and asteroid mining due to critical "missing
technological links" in the chain of tools that are needed. Chiefly,
these are:
>
> 1) Reduction in cost to achieve LEO and beyond,

I'd agree that we wouldn't even want to get started before we had at
least a 10-fold reduction in launch costs. Maybe more.

> 2) Advanced remote technology to mine and to maintain mining
equipment on an asteroid that may be far far away. Neural net
ethnology will be crucial IMO along with VR and machines able to
repair themselves.

Telepresence may help us out in HEO and even as far out as the moon.
But you are correct that we would need actual AI for asteroids due to
their distance. I'm sure robotics will come into play. But what mix
of humans and robots we can expect is open to controversy, and
depends powerfully on how rapidly technology advances, and when we
get started.

The 70's studies assumed we could do it with 70's technology. Of
course they assumed a human to robot ratio which will probably turn
out to be higher than the eventual reality.

> 3) Design and test viable life support systems for space colonies.

Absolutely.

Regards,
Mike Combs

It wasn't so much a near verses far future problem. The assumption was
that the planet was to be evacuated within a "reasonable" time period.

The time period I chose was 200 years. I assumed the first fifty the
population exodus would be negliable since the infrastructure would be
built.

After that to get 5 billion people off a planet in 150 years you need
to move about 600 000 people every day.

Let me run you through a typical scenerio.
Land transportation to the launcher.
Launcher is a 5 minute ride at 5 g then twenty minutes to one of the
capture tethers.
2 day elevator ride to the top of the tether.
from the top of the tether:
1 month or so ride to a colony at l4 or l5 or high orbit.
1 month ride to the moon transfer point to the moon.
1 month ride to a habitat in a parallel orbit with the earth for
transfer into a "transfer city", an asteroid in a two-1 orbit with
the earth and mars, or the asteroid belt.

Before you get on the launcher you have a whole procedure to organize
health checks, final destination, your personal finances, etc...

I took the model of a person emigrating to another country for that.

Please remember that much of what I wanted to do is not complete.

Almost all the infrastructure would be built in space. The parts that
would be planetbound would be built and maintained on the planet. The
only "expendable" part of the planetary infrastructure, is the
capsules being shot by the launchers.

I may in the future write a short story or a novel based on the idea.

Bill

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Bill,
>
> I see. Your scenario is way out there in the future, and I am
looking a the near future to see how we can build the 1st colony.
>
> Since the earth's population only increases at 80 million/year, why
move 1/2 million per day? Why not 1/4 million or 1 million while we
are on the topic?
>
> How much of the infra-structure would be build in space and how much
supplied from earth? What is your presumed launch cost per KG?
Presumably this would be low enough for the average person to afford,
say around $1/KG?
>
> Tom
> From: bill t
> To: spacesettlers@egroups.com
> Sent: Sunday, December 31, 2000 9:19 AM
> Subject: [spacesettlers] Re: High efficiency drives
>
> What is funny is I have no way of complying with your request at
the
> moment. I have no windows machines at my house, and the zip
program on
> unix doesn't produce a file that pkzip can uncompress.
>
> I'll get it into a zipfile and post it.
>
> To give you an idea of what I was trying to accomplish, imagine
what
> infrastructure you will need to move half a million people into
space
> a day.
>
> This included things like ground transportation/storage large
scale
> launch facilities, construction requirements for housing,
factories,
> ships, power equipment.
>
> With half a million people to huase in space every day, you have
to

Tom Tucker (Olympia) wrote:

> Being more pragmatic, I think that we are many decades away from space
> colonization and asteroid mining due to critical "missing technological
> links" in the chain of tools that are needed. Chiefly, these are:
>
> 1) Reduction in cost to achieve LEO and beyond,

The cost of mining is going to be a couple of billion+,
the cost of launching is only a ~hundred mil. I mean
sure, its not inconsiderable, but its not the biggest
part. R&D, fabrication, deployment and maintenance are the
big ticket items.

> 2) Advanced remote technology to mine and to maintain mining equipment
> on an asteroid that may be far far away. Neural net ethnology will be
> crucial IMO along with VR and machines able to repair themselves.

Possibly. I think that lunar mining is easier- teleoperation there
is just about possible. Also, radiation issues are much better
(short flight). And the moon seems to have one crucial ingredient-
hydrogen.

> 3) Design and test viable life support systems for space colonies.

Lots of plants? Incidentally you can buy closed life support
systems off the shelf see: www.eco-sphere.com.

Mike,

Two comments:
1) Whether solar of nuclear are used, I recommend that you evaluate the use of an energy storage system because the mass driver will constitute a peak load that is likely to be over 10x the nominal power capacity of the power plant. Hence, using the solar or nuclear reactor to charge up the storage medium for peak loading will make better use of the resources. If solar is used, then it makes sense to up-grade the storage system to provide power for the two weeks of darkness. A flywheel generator/motor is one I would recommend.

2) Mass drivers work according to the equation MV, and so the way to maximize the effect is to use the highest possible velocity. Why not look beyond throwing rocks and consider a plasma drive like the VASIMR which was recently described in Scientific American (Nov. 2000)? It too would require solar or nuclear power. Large take-off thrusts would not be practical, however, but perhaps you can think of a way around this?

Cheers,

Tom
From: Mike Combs
To: spacesettlers@egroups.com
Sent: Monday, January 01, 2001 6:57 PM
Subject: [spacesettlers] Re: High efficiency drives

--- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
wrote:
> Mike,
>
> So, what would you power your mass driver with? Nuclear fission?
Chemical? Solar?

It was proposed that the lunar catapult be solar powered. At an
earlier point of these studies there was a small, buried nuclear
reactor at the moonbase. Later on, the reactor was gone, and there
were only solar panels. I think they had decided that solar was OK
for the mass driver, even if it meant that it could only opperate 2
weeks out of every four (you'd need some downtime for repair and
maintenance anyway). I would assume some storage method was used to
get the moonbase through the 2 week long night. I think there was a
push to eliminate the nuclear reactor due to people's concerns about
launch accidents. Given the difficulties faced by the much more
modest Cassini probe, that's probably just being realistic.

A mass driver being used as an inter-orbital tug would most certainly
be solar powered since it would have continuous solar power available
to it (except for when it was in LEO).

> What diameter projectile?

O'Neill assumed spheres of sintered lunar soil about the diameter of
a softball.

> What velocity do you anticipate
> achieving for the projectile?

The lunar mass driver catapult was launching at about lunar escape
speed, which is 2.4 km/sec. I think the interorbital tug would eject
its reaction mass even faster. Seems like someone said the exhaust
velocity would be in excess of Earth escape, so that reaction mass
would not contribute significantly to orbital debris.

> Keeping alternatives on the table helps with comparative analysis
later when more options are available.

Oh, sure. I've had people advocate slingshots and lunar skyhooks to
me over mass drivers. I still tend to favor mass drivers, but I'm
for whatever turns out to work best in the end.

> Being more pragmatic, I think that we are many decades away from
space colonization and asteroid mining due to critical "missing
technological links" in the chain of tools that are needed. Chiefly,
these are:
>
> 1) Reduction in cost to achieve LEO and beyond,

I'd agree that we wouldn't even want to get started before we had at
least a 10-fold reduction in launch costs. Maybe more.

> 2) Advanced remote technology to mine and to maintain mining
equipment on an asteroid that may be far far away. Neural net
ethnology will be crucial IMO along with VR and machines able to
repair themselves.

Telepresence may help us out in HEO and even as far out as the moon.
But you are correct that we would need actual AI for asteroids due to
their distance. I'm sure robotics will come into play. But what mix
of humans and robots we can expect is open to controversy, and
depends powerfully on how rapidly technology advances, and when we
get started.

The 70's studies assumed we could do it with 70's technology. Of
course they assumed a human to robot ratio which will probably turn
out to be higher than the eventual reality.

> 3) Design and test viable life support systems for space colonies.

Absolutely.

Regards,
Mike Combs

Two comments:
1) Whether solar of nuclear are used, I recommend that you evaluate the use of an energy storage system because the mass driver will constitute a peak load that is likely to be over 10x the nominal power capacity of the power plant. Hence, using the solar or nuclear reactor to charge up the storage medium for peak loading will make better use of the resources. If solar is used, then it makes sense to up-grade the storage system to provide power for the two weeks of darkness. A flywheel generator/motor is one I would recommend.

2) Mass drivers work according to the equation MV, and so the way to maximize the effect is to use the highest possible velocity. Why not look beyond throwing rocks and consider a plasma drive like the VASIMR which was recently described in Scientific American (Nov. 2000)? It too would require solar or nuclear power. Large take-off thrusts would not be practical, however, but perhaps you can think of a way around this?

Cheers,

Tom
From:
Mike Combs
To:
spacesettlers@egroups.com
Sent:
Monday, January 01, 2001 6:57 PM
Subject:
[spacesettlers] Re: High efficiency drives
--- In
spacesettlers@...m
, "Tom Tucker (Olympia)"
<
tntucker@c
...> wrote:
> Mike,
>
> So, what would you power your mass driver with? Nuclear fission?
Chemical? Solar?
It was proposed that the lunar catapult be solar powered. At an
earlier point of these studies there was a small, buried nuclear
reactor at the moonbase. Later on, the reactor was gone, and there
were only solar panels. I think they had decided that solar was OK
for the mass driver, even if it meant that it could only opperate 2
weeks out of every four (you'd need some downtime for repair and
maintenance anyway). I would assume some storage method was used to
get the moonbase through the 2 week long night. I think there was a
push to eliminate the nuclear reactor due to people's concerns about
launch accidents. Given the difficulties faced by the much more
modest Cassini probe, that's probably just being realistic.
A mass driver being used as an inter-orbital tug would most certainly
be solar powered since it would have continuous solar power available
to it (except for when it was in LEO).
> What diameter projectile?
O'Neill assumed spheres of sintered lunar soil about the diameter of
a softball.
> What velocity do you anticipate
> achieving for the projectile?
The lunar mass driver catapult was launching at about lunar escape
speed, which is 2.4 km/sec. I think the interorbital tug would eject
its reaction mass even faster. Seems like someone said the exhaust
velocity would be in excess of Earth escape, so that reaction mass
would not contribute significantly to orbital debris.
> Keeping alternatives on the table helps with comparative analysis
later when more options are available.
Oh, sure. I've had people advocate slingshots and lunar skyhooks to
me over mass drivers. I still tend to favor mass drivers, but I'm
for whatever turns out to work best in the end.
> Being more pragmatic, I think that we are many decades away from
space colonization and asteroid mining due to critical "missing
technological links" in the chain of tools that are needed. Chiefly,
these are:
>
> 1) Reduction in cost to achieve LEO and beyond,
I'd agree that we wouldn't even want to get started before we had at
least a 10-fold reduction in launch costs. Maybe more.
> 2) Advanced remote technology to mine and to maintain mining
equipment on an asteroid that may be far far away. Neural net
ethnology will be crucial IMO along with VR and machines able to
repair themselves.
Telepresence may help us out in HEO and even as far out as the moon.
But you are correct that we would need actual AI for asteroids due to
their distance. I'm sure robotics will come into play. But what mix
of humans and robots we can expect is open to controversy, and
depends powerfully on how rapidly technology advances, and when we
get started.
The 70's studies assumed we could do it with 70's technology. Of
course they assumed a human to robot ratio which will probably turn
out to be higher than the eventual reality.
> 3) Design and test viable life support systems for space colonies.
Absolutely.
Regards,
Mike Combs

From: Ian Woollard
To: spacesettlers@egroups.com
Sent: Tuesday, January 02, 2001 5:56 PM
Subject: Re: [spacesettlers] High efficiency drives

Tom Tucker (Olympia) wrote:

> Being more pragmatic, I think that we are many decades away from space
> colonization and asteroid mining due to critical "missing technological
> links" in the chain of tools that are needed. Chiefly, these are:
>
> 1) Reduction in cost to achieve LEO and beyond,

The cost of mining is going to be a couple of billion+,
the cost of launching is only a ~hundred mil. I mean
sure, its not inconsiderable, but its not the biggest
part. R&D, fabrication, deployment and maintenance are the
big ticket items.

Tom - I predict that space colonization will take-off when we finally aquire the technology to use robots or telerobots to produce useful metallic fabrications with only remote involvement by humans. Only then will it make sense to mine the asteroids for colonies.

> 2) Advanced remote technology to mine and to maintain mining equipment
> on an asteroid that may be far far away. Neural net ethnology will be
> crucial IMO along with VR and machines able to repair themselves.

Possibly. I think that lunar mining is easier- teleoperation there
is just about possible. Also, radiation issues are much better
(short flight). And the moon seems to have one crucial ingredient-
hydrogen.

Tom - If telerobots are used, then the radiation problem should be minimal. Only when humans are in space will radiation and shielding be a major concern.

> 3) Design and test viable life support systems for space colonies.

Lots of plants? Incidentally you can buy closed life support
systems off the shelf see: www.eco-sphere.com.

Tom - Great! Perhaps we should all grow gills? The energy required per person is likley to asound most. The BiosphereII required about 100KW per person/day. We will need both biological as well as mechanical systems for safety.

> The above steps will open the frontier to space colonization IMO. Am I
> missing any steps? Comments?
>

> Tom

From:
Ian Woollard
To:
spacesettlers@egroups.com
Sent:
Tuesday, January 02, 2001 5:56 PM
Subject:
Re: [spacesettlers] High efficiency drives
Tom Tucker (Olympia) wrote:
> Being more pragmatic, I think that we are many decades away from space
> colonization and asteroid mining due to critical "missing technological
> links" in the chain of tools that are needed. Chiefly, these are:
>
> 1) Reduction in cost to achieve LEO and beyond,
The cost of mining is going to be a couple of billion+,
the cost of launching is only a ~hundred mil. I mean
sure, its not inconsiderable, but its not the biggest
part. R&D, fabrication, deployment and maintenance are the
big ticket items.
Tom - I predict that space colonization will take-off when we finally aquire the technology to use robots or telerobots to produce useful metallic fabrications with only remote involvement by humans. Only then will it make sense to mine the asteroids for colonies.

> 2) Advanced remote technology to mine and to maintain mining equipment
> on an asteroid that may be far far away. Neural net ethnology will be
> crucial IMO along with VR and machines able to repair themselves.
Possibly. I think that lunar mining is easier- teleoperation there
is just about possible. Also, radiation issues are much better
(short flight). And the moon seems to have one crucial ingredient-
hydrogen.
Tom - If telerobots are used, then the radiation problem should be minimal. Only when humans are in space will radiation and shielding be a major concern.
> 3) Design and test viable life support systems for space colonies.
Lots of plants? Incidentally you can buy closed life support
systems off the shelf see:
www.eco-sphere.com
.
Tom - Great! Perhaps we should all grow gills? The energy required per person is likley to asound most. The BiosphereII required about 100KW per person/day. We will need both biological as well as mechanical systems for safety.

From: Ian Woollard [mailto:ian.woollard@...]

The cost of mining is going to be a couple of billion+,
the cost of launching is only a ~hundred mil. I mean
sure, its not inconsiderable, but its not the biggest
part. R&D, fabrication, deployment and maintenance are the
big ticket items.

I hope you're not saying that it would only cost 100 million to launch as
many tons as might could be mined from an asteroid for a 2 billion dollar
effort. Even a modest asteroid mining mission could retrieve several times
as many tons of material to HEO as could be launched even over the course of
several years. I'll be the first to agree that asteroid mining may only
make sense in the context of some enormous space-based construction project,
but I hope we can get to that before very much of the century is done.

While agreeing that R&D and the rest are pretty big slices of the pie,
launch costs still dominate, and it's launch costs that use of space
resources is trying to circumvent.

Possibly. I think that lunar mining is easier- teleoperation there
is just about possible.

SSI agrees. They've experimented with a small time-delayed remote control
vehicle, and they say all it takes is a little practice.

Also, radiation issues are much better
(short flight). And the moon seems to have one crucial ingredient-
hydrogen.

If we pick a Carbonaceous Chondrite type asteroid, it could be 10-20% water.

Regards,

Mike Combs

From:
Ian Woollard [mailto:ian.woollard@...]
The cost of mining is going to be a couple of billion+,
the cost of launching is only a ~hundred mil. I mean
sure, its not inconsiderable, but its not the biggest
part. R&D, fabrication, deployment and maintenance are the
big ticket items.

I hope you're not saying that it would only cost 100 million to launch as many tons as might could be mined from an asteroid for a 2 billion dollar effort. Even a modest asteroid mining mission could retrieve several times as many tons of material to HEO as could be launched even over the course of several years. I'll be the first to agree that asteroid mining may only make sense in the context of some enormous space-based construction project, but I hope we can get to that before very much of the century is done.

While agreeing that R&D and the rest are pretty big slices of the pie, launch costs still dominate, and it's launch costs that use of space resources is trying to circumvent.
Possibly. I think that lunar mining is easier- teleoperation there
is just about possible.

SSI agrees. They've experimented with a small time-delayed remote control vehicle, and they say all it takes is a little practice.

Also, radiation issues are much better
(short flight). And the moon seems to have one crucial ingredient-
hydrogen.

If we pick a Carbonaceous Chondrite type asteroid, it could be 10-20% water.

Regards,
Mike Combs

From: Tom Tucker (Olympia) [mailto:tntucker@...]

1) Whether solar of nuclear are used, I recommend that you evaluate the use
of an energy storage system because the mass driver will constitute a peak
load that is likely to be over 10x the nominal power capacity of the power
plant.

If by "the nominal power capacity of the power plant" you're referring to
just what's needed to power the moonbase, then I'm sure you're right. One
must look at the mass driver as having its own dedicated power supply. I
think the mass driver solar array was sized to keep the mass driver
continuously operating (at least for two weeks out of every four). The
power needs of the moonbase are very different: a much lower level of power,
but a need throughout the lunar night. Totally different power supply
systems may be used, since the requirements are so different.

Hence, using the solar or nuclear reactor to charge up the storage medium
for peak loading will make better use of the resources. If solar is used,
then it makes sense to up-grade the storage system to provide power for the
two weeks of darkness. A flywheel generator/motor is one I would recommend.

Even assuming the mass driver is off-line during the lunar night, we do need
some kind of storage method to get the base through the lunar night. I'm
not sure if they were assuming flywheels, fuel cells, or what.

2) Mass drivers work according to the equation MV, and so the way to
maximize the effect is to use the highest possible velocity. Why not look
beyond throwing rocks and consider a plasma drive like the VASIMR which was
recently described in Scientific American (Nov. 2000)? It too would require
solar or nuclear power.

I have nothing against VASIMR, or any of the other high efficiency/low
thrust drive proposals. But one thing I like about the mass driver is that
it can use anything for fuel: initially, ground up chunks of Space Shuttle
ET, then raw lunar or asteroidal soil or slag. Then for ongoing routine
operation, liquefied oxygen.

freetrader2300@... at the Free
Trader's Space Station website (
http://www.geocities.com/Area51/Dunes/8426/high/md.html
) has likened the
mass driver to the old paddle-wheeled steamboats that plied the mighty
Mississippi River during America's frontier days: able to come ashore,
dispatch crews to the woods to cut down trees, stock up on firewood, and
then proceed, fueled by locally obtained fuel. VASIMR and other types of
plasma and ion drives will always require specially manufactured fuel.

Large take-off thrusts would not be practical, however, but perhaps you
can think of a way around this?

I think for large-thrust applications (like lunar takeoff for example),
we'll probably fall back to chemical rockets, at least for the foreseeable
future.

Regards,

Mike Combs

From:
Tom Tucker (Olympia) [mailto:tntucker@...]

1) Whether solar of nuclear are used, I recommend that you evaluate the use of an energy storage system because the mass driver will constitute a peak load that is likely to be over 10x the nominal power capacity of the power plant.

If by "the nominal power capacity of the power plant" you're referring to just what's needed to power the moonbase, then I'm sure you're right. One must look at the mass driver as having its own dedicated power supply. I think the mass driver solar array was sized to keep the mass driver continuously operating (at least for two weeks out of every four). The power needs of the moonbase are very different: a much lower level of power, but a need throughout the lunar night. Totally different power supply systems may be used, since the requirements are so different.

Hence, using the solar or nuclear reactor to charge up the storage medium for peak loading will make better use of the resources. If solar is used, then it makes sense to up-grade the storage system to provide power for the two weeks of darkness. A flywheel generator/motor is one I would recommend.

Even assuming the mass driver is off-line during the lunar night, we do need some kind of storage method to get the base through the lunar night. I'm not sure if they were assuming flywheels, fuel cells, or what.

2) Mass drivers work according to the equation MV, and so the way to maximize the effect is to use the highest possible velocity. Why not look beyond throwing rocks and consider a plasma drive like the VASIMR which was recently described in Scientific American (Nov. 2000)? It too would require solar or nuclear power.

I have nothing against VASIMR, or any of the other high efficiency/low thrust drive proposals. But one thing I like about the mass driver is that it can use
anything
for fuel: initially, ground up chunks of Space Shuttle ET, then raw lunar or asteroidal soil or slag. Then for ongoing routine operation, liquefied oxygen.

freetrader2300@...
at the Free Trader's Space Station website (
http://www.geocities.com/Area51/Dunes/8426/high/md.html
) has likened the mass driver to the old paddle-wheeled steamboats that plied the mighty Mississippi River during America's frontier days: able to come ashore, dispatch crews to the woods to cut down trees, stock up on firewood, and then proceed, fueled by locally obtained fuel. VASIMR and other types of plasma and ion drives will always require specially manufactured fuel.

Large take-off thrusts would not be practical, however, but perhaps you can think of a way around this?

I think for large-thrust applications (like lunar takeoff for example), we'll probably fall back to chemical rockets, at least for the foreseeable future.

Regards,
Mike Combs

Combs, Mike wrote:

>
> *From:* Ian Woollard [mailto:ian.woollard@...]
>
> The cost of mining is going to be a couple of billion+,
> the cost of launching is only a ~hundred mil. I mean
> sure, its not inconsiderable, but its not the biggest
> part. R&D, fabrication, deployment and maintenance are the
> big ticket items.
>
> I hope you're not saying that it would only cost 100 million to launch
> as many tons as might could be mined from an asteroid for a 2 billion
> dollar effort.

Correct. Quite the contrary. I'm saying that one estimate
of a lunar mining mission came in at the 2+ billion mark.
The costs of lifting the necessary equipment I estimated were
perhaps 300 million or less, using todays prices. So
its only 15%. Launch costs aren't the problem in fact.
The fact that everyone thinks they are the problem might
be part of the problem.

Still I would expect that asteroid mining would require much
more launch costs because:
a) you have to lift life support for humans
b) you have to lift the humans
c) you have to lift the fuel for the equipment
d) you have to lift the fuel for the above

> Even a modest asteroid mining mission could retrieve
> several times as many tons of material to HEO as could be launched even
> over the course of several years. I'll be the first to agree that
> asteroid mining may only make sense in the context of some enormous
> space-based construction project, but I hope we can get to that before
> very much of the century is done.

Asteroid missions are very likely to be long term optimal.
However short term optimal... lunar poles look better
right now to me. That can change with asteroid surveying.
Or with a fantastic plan and funding ;-)

> While agreeing that R&D and the rest are pretty big slices of the pie,
> launch costs still dominate,

I challenge you to find a commercial space project
where the incremental launch costs dominate.

> and it's launch costs that use of space resources is trying to
> circumvent.

Kindof. I prefer to think that its possible to make money from
the difference between $1300 and pennies per pound.
Money->profit->growth->space stations kinda thing. In the
short run you need a market. Unless you reenter stuff you
need to sell stuff to people who are on the earth who want
stuff on orbit and then move it there from the moon or an
asteroid. Stuff like fuel. Or services.

> Possibly. I think that lunar mining is easier- teleoperation there
> is just about possible.
>
> SSI agrees. They've experimented with a small time-delayed remote
> control vehicle, and they say all it takes is a little practice.

Sounds right. I've experienced packet delays of a second or so
myself to Australia.

From: Combs, Mike
To: 'spacesettlers@egroups.com'
Sent: Wednesday, January 03, 2001 6:04 AM
Subject: RE: [spacesettlers] Re: High efficiency drives

From: Tom Tucker (Olympia) [mailto:tntucker@...]

1) Whether solar of nuclear are used, I recommend that you evaluate the use of an energy storage system because the mass driver will constitute a peak load that is likely to be over 10x the nominal power capacity of the power plant.
If by "the nominal power capacity of the power plant" you're referring to just what's needed to power the moonbase, then I'm sure you're right. One must look at the mass driver as having its own dedicated power supply. I think the mass driver solar array was sized to keep the mass driver continuously operating (at least for two weeks out of every four). The power needs of the moonbase are very different: a much lower level of power, but a need throughout the lunar night. Totally different power supply systems may be used, since the requirements are so different.

Mike, what I was getting at is the duty cycle of a mass driver is probably going to require lots of power for a few seconds, and then very little for a few minutes while re-loading happens. This power spike can and should be averaged using an energy storage device. On the otherhand, perhaps you envision your mass driver working continuously like a machine gun?
Hence, using the solar or nuclear reactor to charge up the storage medium for peak loading will make better use of the resources. If solar is used, then it makes sense to up-grade the storage system to provide power for the two weeks of darkness. A flywheel generator/motor is one I would recommend.
Even assuming the mass driver is off-line during the lunar night, we do need some kind of storage method to get the base through the lunar night. I'm not sure if they were assuming flywheels, fuel cells, or what.
2) Mass drivers work according to the equation MV, and so the way to maximize the effect is to use the highest possible velocity. Why not look beyond throwing rocks and consider a plasma drive like the VASIMR which was recently described in Scientific American (Nov. 2000)? It too would require solar or nuclear power.
I have nothing against VASIMR, or any of the other high efficiency/low thrust drive proposals. But one thing I like about the mass driver is that it can use anything for fuel: initially, ground up chunks of Space Shuttle ET, then raw lunar or asteroidal soil or slag. Then for ongoing routine operation, liquefied oxygen.

freetrader2300@... at the Free Trader's Space Station website (http://www.geocities.com/Area51/Dunes/8426/high/md.html) has likened the mass driver to the old paddle-wheeled steamboats that plied the mighty Mississippi River during America's frontier days: able to come ashore, dispatch crews to the woods to cut down trees, stock up on firewood, and then proceed, fueled by locally obtained fuel. VASIMR and other types of plasma and ion drives will always require specially manufactured fuel.

Most any ionizable gas would be suitible, but H2 would be best.
Large take-off thrusts would not be practical, however, but perhaps you can think of a way around this?
I think for large-thrust applications (like lunar takeoff for example), we'll probably fall back to chemical rockets, at least for the foreseeable future.

Regards,

Mike Combs

From:
Combs, Mike
To:
'spacesettlers@egroups.com'
Sent:
Wednesday, January 03, 2001 6:04 AM
Subject:
RE: [spacesettlers] Re: High efficiency drives
From:
Tom Tucker (Olympia) [mailto:tntucker@connectcorp.net]

1) Whether solar of nuclear are used, I recommend that you evaluate the use of an energy storage system because the mass driver will constitute a peak load that is likely to be over 10x the nominal power capacity of the power plant.

If by "the nominal power capacity of the power plant" you're referring to just what's needed to power the moonbase, then I'm sure you're right. One must look at the mass driver as having its own dedicated power supply. I think the mass driver solar array was sized to keep the mass driver continuously operating (at least for two weeks out of every four). The power needs of the moonbase are very different: a much lower level of power, but a need throughout the lunar night. Totally different power supply systems may be used, since the requirements are so different.

Mike, what I was getting at is the duty cycle of a mass driver is probably going to require lots of power for a few seconds, and then very little for a few minutes while re-loading happens. This power spike can and should be averaged using an energy storage device. On the otherhand, perhaps you envision your mass driver working continuously like a machine gun?

Hence, using the solar or nuclear reactor to charge up the storage medium for peak loading will make better use of the resources. If solar is used, then it makes sense to up-grade the storage system to provide power for the two weeks of darkness. A flywheel generator/motor is one I would recommend.

Even assuming the mass driver is off-line during the lunar night, we do need some kind of storage method to get the base through the lunar night. I'm not sure if they were assuming flywheels, fuel cells, or what.

2) Mass drivers work according to the equation MV, and so the way to maximize the effect is to use the highest possible velocity. Why not look beyond throwing rocks and consider a plasma drive like the VASIMR which was recently described in Scientific American (Nov. 2000)? It too would require solar or nuclear power.

I have nothing against VASIMR, or any of the other high efficiency/low thrust drive proposals. But one thing I like about the mass driver is that it can use
anything
for fuel: initially, ground up chunks of Space Shuttle ET, then raw lunar or asteroidal soil or slag. Then for ongoing routine operation, liquefied oxygen.

freetrader2300@...
at the Free Trader's Space Station website (
http://www.geocities.com/Area51/Dunes/8426/high/md.html
) has likened the mass driver to the old paddle-wheeled steamboats that plied the mighty Mississippi River during America's frontier days: able to come ashore, dispatch crews to the woods to cut down trees, stock up on firewood, and then proceed, fueled by locally obtained fuel. VASIMR and other types of plasma and ion drives will always require specially manufactured fuel.

Most any ionizable gas would be suitible, but H2 would be best.

Large take-off thrusts would not be practical, however, but perhaps you can think of a way around this?

I think for large-thrust applications (like lunar takeoff for example), we'll probably fall back to chemical rockets, at least for the foreseeable future.

Regards,
Mike Combs

From: Ian Woollard [mailto:ian.woollard@...]

I challenge you to find a commercial space project
where the incremental launch costs dominate.

You're probably right in thinking that I can't. But that might only be
because of the small scale of present space operations. In small scale
operations, R&D and other development costs are going to be comparable to
same for much larger projects, and will outweigh launch costs, because there
aren't really that many launches. But if we look at a project like SPS or
the building of orbital habitats, then launch costs will dominate. It's
then that use of space resources becomes attractive.

Regards,

Mike Combs

From:
Ian Woollard [mailto:ian.woollard@...]
I challenge you to find a commercial space project
where the incremental launch costs dominate.

You're probably right in thinking that I can't. But that might only be because of the small scale of present space operations. In small scale operations, R&D and other development costs are going to be comparable to same for much larger projects, and will outweigh launch costs, because there aren't really that many launches. But if we look at a project like SPS or the building of orbital habitats, then launch costs will dominate. It's then that use of space resources becomes attractive.
Regards,
Mike Combs

From: Tom Tucker (Olympia) [mailto:tntucker@...]

Mike, what I was getting at is the duty cycle of a mass driver is probably
going to require lots of power for a few seconds, and then very little for a
few minutes while re-loading happens. This power spike can and should be
averaged using an energy storage device. On the otherhand, perhaps you
envision your mass driver working continuously like a machine gun?

Well, O'Neill certainly did. He spoke in terms of firing at a rate of
around one per second. He was envisioning the launch of small pellets of
ore. You might be visualizing a much larger mass driver launching finished
products.

Regards,

Mike Combs

From:
Tom Tucker (Olympia) [mailto:tntucker@...]
Mike, what I was getting at is the duty cycle of a mass driver is probably going to require lots of power for a few seconds, and then very little for a few minutes while re-loading happens. This power spike can and should be averaged using an energy storage device. On the otherhand, perhaps you envision your mass driver working continuously like a machine gun?

Well, O'Neill certainly did. He spoke in terms of firing at a rate of around one per second. He was envisioning the launch of small pellets of ore. You might be visualizing a much larger mass driver launching finished products.

Regards,
Mike Combs

Tom Tucker (Olympia) wrote:

> Mike, what I was getting at is the duty cycle of a mass driver is
> probably going to require lots of power for a few seconds, and then
> very little for a few minutes while re-loading happens. This power
> spike can and should be averaged using an energy storage device.

I know for rail guns they use a large, heavy, fast rotating coil.
And then you stop it by letting some windings conduct. The huge
current produced is enough to shoot metal off at a good few km/s.

You can use the same thing for coil guns, although coil guns are
slightly more gentle. All electromagnetic launchers need some
form of temporary energy storage.

> On the otherhand, perhaps you envision your mass driver working
> continuously like a machine gun?

It has to really, otherwise you will never break even cost-wise.