Build The Enterprise.

An advantage of terraforming is that you can let organisms do the work on their own time. Just stick the right bacteria and plants on the ground and they'll do the rest.

Originally posted by googlefudge
Again why should we seriously consider thermoforming Venus or Mars?

On the other hand building space habitats ....

I think the cost/benefit of both approaches should be considered.
I tend to see large spaceship habitats as both less desirable to live on and more fragile (ie at higher risk of total disaster).
I do not know what it would take to terraform Mars, but at first glance it looks like an easy way to get a lot of living space as opposed to building all that living space out in space.

Originally posted by AThousandYoung
An advantage of terraforming is that you can let organisms do the work on their own time. Just stick the right bacteria and plants on the ground and they'll do the rest.

Fantastic. Except that there is absolutely no guarantee that these 'organisms' will create an
environment suitable for humans (the earth's atmosphere has been significantly different for
most of its history and quite toxic or unsuitable for humans for most of it).
And your terraforming will take millennia at the very least.

If you want to do it in centuries not millennia and to actually make it suitable for humans you
need to take an active role in terraforming.

You need to build and operate massive numbers of terraforming machines to make the initial
atmosphere, and you need to drop huge amounts of biomatter on the surface.
And also you will probably need to drop huge amounts of water as well, Mars and Venus famous
for NOT having huge amounts of water as in both cases it's been ionised and blown off by the sun.

You still have the problem that neither planet has a magnetic shield so both suffer heavily from
solar radiation and atmosphere loss/ionisation.

Venus has an intolerably long day night cycle. And being 30% closer to the sun is very hard to keep cool.

Mars has weak gravity (likely to be detrimental to health) and is hard to keep warm.

And when you say 'just stick the right bacteria and plants on the ground...'

To have an significant effect in sub million year periods you need to dump trillions of tons of biomatter on
the ground, and you need to alter the atmosphere and water content enough before you do that so
that this biomatter doesn't all just die.

Shifting that much biomatter from earth is prohibitively expensive and just plain stupid.

What you do is build giant space greenhouses (habitats) in orbit around the planet you want to terraform,
and in those habitats grow your plants/algae/bacteria from small samples of seeds/spores you took from earth.

These habitats would provide the huge supply of biomatter needed and all you have to do is drop it down
from orbit not ferry it all the way from earth.


But again, why bother? You get vastly more liveable area in more conducive conditions (lower radiation, more
suitable gravity, normal earth day length) for vastly less effort in a much shorter timescale by living in space
habitats than you get from terraforming planets.
And you have to build space habitats in any serious terraforming operation anyway.

Why waste all that plant production capacity trying to terraform a planet, when you can just use it to feed people
straight off the bat?

Originally posted by twhitehead
I think the cost/benefit of both approaches should be considered.
I tend to see large spaceship habitats as both less desirable to live on and more fragile (ie at higher risk of total disaster).
I do not know what it would take to terraform Mars, but at first glance it looks like an easy way to get a lot of living space as opposed to building all that living space out in space.

I think the cost/benefit of both approaches should be considered.

Sure... But I have spent a long time thinking about this and am at the end of considering both approaches.

So barring any of you coming up with some completely new angle I haven't already thought of I am going to
stay firmly in the space habitats camp... however it's entirely possible that you might come up with something I
haven't thought of so feel free to continue to try to change my mind if you disagree.

I tend to see large spaceship habitats as both less desirable to live on and more fragile (ie at higher risk
of total disaster).

Why?

I don't know why you would think habitats are less desirable to live on but here are some pros/cons for habitats vs planets.

Pros

Humans have evolved to live in very specific conditions currently only found on earth, we are not evolved to live in
zero or low gravity and there are detrimental health effects for prolonged exposure to low or zero gravity.

Habitats can be spun to produce whatever gravity desired, with planets you are stuck with the gravity you start with.

Habitats have whatever day length you desire, planets you are stuck with whatever rotational period they currently have.

Habitats don't have natural disasters.

Habitats are designed to be nice places to live, planets are not designed.

http://en.wikipedia.org/wiki/Space_habitat

Now it may be a personal thing but looking at space habitat designs including the many (viable) ones in Science fiction I
find them very desirable places to live but that might be personal taste.

The only cons I can currently think of are that they don't have as much space as a planet does*, and don't have as large a
population... However I don't have a problem living somewhere with a total population on the order of a small to medium
sized city, (or even a giant city on some of the larger habitat designs).

*individually, as a totality they have vastly more.


As for safety...

Issues planets [potentially] have....

Solar radiation. You live on the surface with just the atmosphere and magnetic field to protect you.
Mars and Venus have no magnetic field.
On a space habitat you live on the inside with many meters of solid radiation shielding and an artificially generated
magnetic field of great strength which combined give vastly more radiation protection than on a planet.

Earthquakes planets can have them, man made space habitats don't. (also tsunamis)

Volcanoes See Earthquakes.

Apocalyptic disease outbreak Can happen on both, but habitats are vastly easier to quarantine than
cities on a planet.

Asteroid impact Again can happen to both, but space habitats are built FROM asteroids and thus any species
that builds them has by default the technology to detect, track and deflect asteroids.
Habitats are designed to withstand micrometeorite impacts, (Whipple shielding/thick armour) and have powerful lasers
to deflect destroy anything larger. Really big stuff has already been swept up by the building of space habitats and by
the asteroid miners. However if a big roid does come along (which is very unlikely due to the fact that habitats are vastly
smaller than the earth and lack its gravitational pull, they can see the asteroid coming a long way off and unlike the earth
where we have to go off to alter the asteroids course, space habitats can move themselves out of the way.

Climate Change/ice age/sea level rise Controlling a planets climate is very hard to do and almost impossible to predict so
on long time scales you can expect things like ice ages and large sea level changes as temperatures go up and down
and as the climate shifts the amount and location of suitable crop growing land moves.
On space habitats however climate control is much easier as the volume and area is much smaller and crucially the amount
and duration of sunlight is completely controlled allowing the maintaining of the desired climate indefinitely.

I do not know what it would take to terraform Mars, but at first glance it looks like an easy way to get a lot of living
space as opposed to building all that living space out in space.

Well all I can say to this is that 'first glances' are not always particularly accurate.

I really don't know why you would think that terraforming an entire planet would be easy by any definition of the word.

Building space habitats and terraforming them is also not easy, however individual habitats are vastly smaller than a planet,
meaning that the work needed to make an individual habitat liveable is vastly less than that of a planet.
And also much faster than terraforming a planet, which means that you can start living in habitats much much faster than planets.
And you can start to make money from them from the get go by selling some of the highly valuable rare earth minerals found in
asteroids in abundance.

Unlike terraforming which simply costs money all the way to completion which will take at least a century in even the most wildly
optimistic estimates.

Originally posted by sonhouse
I heard about this. It might LOOK like the Enterprise and it might even work as an in-system ship, it will never leave the Solar System, won't be able to even get close to 0.1 c. More like 0.001c, if that.

forget leaving the solar system, it might never leave low earth orbit.

Originally posted by VoidSpirit
forget leaving the solar system, it might never leave low earth orbit.

If they ever managed to build this it would have no trouble leaving earth orbit...

It would just do so very slowly.

There are plenty of issues with this proposed ship, and it's a very impractical design
for a real ship of the kind described, but I don't see any reason why it wouldn't work.

It will never get built (or not any time cost and practicality are issues) not because it
wouldn't work, but because it's a crappy inefficient design and you could make something
that would work an awful lot better for less money/resources.
Inspiring people by making a ship that looks like the space ship from a popular science fiction
tv series is not a good enough excuse for the design flaws inherent in this project.


If you wanted to build a ship on that scale with all the features this ship has you need to
go even more retro than the enterprise and look at the stuff they were doing in the 50's.



The primary problem with current rocket propulsion is propellent used per unit thrust, and the
overriding factor that determines this is rocket exhaust velocity.

You want to make it as high as possible thus getting maximum thrust per unit weight propellent.

The space shuttles main engines are about as good as you will ever get with a chemical rocket
with a velocity of around 4400m/s.

Ion drives (or more funky torch drives) have vastly higher exhaust velocities than chemical rockets.

The extra energy comes from either solar power, or a nuclear battery/reactor.

For a ship this size you use a nuclear reactor.

Assuming you haven't mastered fusion yet you go with a Liquid thorium reactor system as that gives you
the highest power per unit mass of fuel (note fuel and propellent not the same on nuclear rockets) and
the lightest weight reactor (liquid thorium reactors don't operate at high pressure so you don't need such
a heavy containment vessel)

For a ship this size you have a couple of reactor cores putting out a total of 3~4 Gw electrical.

The actual design of the ship would be a classical pointy rocket with the centrifugal ring mounted around the
central axis about a third of the way up held on with a number of struts.
Reactors and fuel/propellent are at the base/stern of the rocket stack, with living accommodation in the centre and
then hangers and cargo storage at the top/bow.

This design is much lighter and stronger than the proposed enterprise design, it's also aerodynamically stable during
air breaking manoeuvres with the cargo mass up front and high drag to the rear. It also has high ablative environment
survivability should it have to air break or in an absolute emergency land on a planet with an atmosphere.

The ring being mounted perpendicular to the axis of acceleration is still usable during acceleration as the direction
of acceleration is always in the same direction as opposed to on the enterprise design where it's rotating constantly
from directly underneath to strait up via sideways and then back again.



As for any discussion of 'manoeuvring'.... rockets like these measure their turning times in hours. A ship this long probably can't
do a 180 degree flip in less than 12 hours and would more likely take the whole day.

You don't need struts or components made of unobtainium or incredibly strongium... steel would do... although carbon fibre and
other more modern materials vastly outperform it in terms of strength to weight ratio.

And metal/steel has a tendency to become radioactive when bombarded with radiation... which is an issue on long space flights.


This design also means that you only need a shadow plate to protect the ship above from radiation from your reactors and drive
and don't need pretty much all encompassing shielding you would need for the enterprise reactors.



Anyhow, it's not that the enterprise wouldn't work.... it would... It just wouldn't work well.

Originally posted by googlefudge
If they ever managed to build this it would have no trouble leaving earth orbit...

It would just do so very slowly.

There are plenty of issues with this proposed ship, and it's a very impractical design
for a real ship of the kind described, but I don't see any reason why it wouldn't work.

It will never get built (or not any time cost and prac that the enterprise wouldn't work.... it would... It just wouldn't work well.

it's a nice concept, but like i said, it would never leave low earth orbit and it won't do this because the enterprise concept (or any other design for that matter) depends on shielding technology that has not yet been developed.

Originally posted by VoidSpirit
it's a nice concept, but like i said, it would never leave low earth orbit and it won't do this because the enterprise concept (or any other design for that matter) depends on shielding technology that has not yet been developed.

Um... what?

You are going to have to elaborate on that.

Originally posted by googlefudge
And also you will probably need to drop huge amounts of water as well, Mars and Venus famous
for NOT having huge amounts of water as in both cases it's been ionised and blown off by the sun.

The wikipedia page:
http://en.wikipedia.org/wiki/Terraforming_of_Mars
says there is quite a lot of water, what is required is a bit of heat to melt it all.

You still have the problem that neither planet has a magnetic shield so both suffer heavily from
solar radiation and atmosphere loss/ionisation.
But how fast is that really? Sure its a problem if left alone for millennia, but is it a problem short term? Is it more loss than we can replace with basic terraforming mechanisms?

Venus has an intolerably long day night cycle. And being 30% closer to the sun is very hard to keep cool.
I think the temperature has more to do with the amount of green house gasses. All three planets (Mars, Earth, Venus) can have their temperature adjusted quite significantly (and well within human limits) by changing the components of the atmosphere.

Mars .... is hard to keep warm
Again, greenhouse gasses can solve that problem.

To have an significant effect in sub million year periods you need to dump trillions of tons of biomatter on
the ground,
I disagree. Bio-matter can reproduce remarkably fast given the right conditions.

and you need to alter the atmosphere and water content enough before you do that so
that this biomatter doesn't all just die.
I suspect that there are life forms that would survive quite well in the current Martian atmosphere. The main missing ingredients is a bit of warming (for which a number of solutions are suggested on the Wikipedia page).

What you do is build giant space greenhouses (habitats) in orbit around the planet you want to terraform,
and in those habitats grow your plants/algae/bacteria from small samples of seeds/spores you took from earth.

These habitats would provide the huge supply of biomatter needed and all you have to do is drop it down
from orbit not ferry it all the way from earth.
Why not grow it on the surface and save all that ferrying? Your plan makes no sense at all. After all, all the raw material is on the surface. Your plan requires either harvesting raw material from asteroids or ferrying it up from the surface (for no apparent reason whatsoever, there are no benefits to working in zero gravity and zero atmospheric pressure that I can think of).

But again, why bother? You get vastly more liveable area in more conducive conditions (lower radiation, more
suitable gravity, normal earth day length)
Anything you use to lower the radiation would be just as effective on the surface, plus you get the added benefit of the atmosphere providing most of the shielding for you. Similarly earth day length could easily be simulated on the surface in enclosed habitats.

And you have to build space habitats in any serious terraforming operation anyway.
I don't believe that you do. I see no reason whatsoever for doing so. Why not do it all on the surface?

Originally posted by googlefudge
Why?

I don't know why you would think habitats are less desirable to live on .....

I work from home and spend most of my time indoors. Sometimes I just need to get out. Being constricted to a space ship, even a large one, seems to me far worse even than being constricted to a surface building with at least windows opening onto nice scenery. Though I suppose with modern high definition screens all that could be simulated.

Habitats can be spun to produce whatever gravity desired, with planets you are stuck with the gravity you start with.
Presumably spinning is also achievable, though it might be more costly.

Habitats have whatever day length you desire, planets you are stuck with whatever rotational period they currently have.
How does a habitat have a 'day length' that can't equally be achieved with lighting on a planet?

Habitats don't have natural disasters.
Yes they do, and they can be far more serious. Mars is extremely geologically stable, and has an atmosphere that projects from most meteorites. A spaceship on the other hand can be totally destroyed by a meteorite.

Originally posted by twhitehead
I work from home and spend most of my time indoors. Sometimes I just need to get out. Being constricted to a space ship, even a large one, seems to me far worse even than being constricted to a surface building with at least windows opening onto nice scenery. Though I suppose with modern high definition screens all that could be simulated.

[b]Habitats ...[text shortened]... from most meteorites. A spaceship on the other hand can be totally destroyed by a meteorite.[/b]

I work from home and spend most of my time indoors. Sometimes I just need to get out.
Being constricted to a space ship, even a large one, seems to me far worse even than being
constricted to a surface building with at least windows opening onto nice scenery. Though I suppose
with modern high definition screens all that could be simulated.

Why would the 'nice scenery' need to be simulated?

Have you looked at the pictures of the kind of thing I am talking about on wiki that I linked?

http://en.wikipedia.org/wiki/Space_habitat

http://www.google.co.uk/search?q=space+habitats&num=100&hl=en&safe=off&complete=0&site=webhp&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=roTQT5miEo-U0QWY_5HKCw&ved=0CKMEELAE&biw=1280&bih=854&sei=sYTQT_HeE4210QW49OjKCw

I am not talking about building a glorified ISS here.

These habitats can have multi kilometre (multi tens/hundreds of kilometre) dimensions.

Habitats can be spun to produce whatever gravity desired, with planets you are stuck with the gravity you start with.
Presumably spinning is also achievable, though it might be more costly.

Um what?????? Are you suggesting altering the rate of spin of a planet? And can I have some of whatever it is you are smoking?

Habitats have whatever day length you desire, planets you are stuck with whatever rotational period they currently have.
How does a habitat have a 'day length' that can't equally be achieved with lighting on a planet?

I think you are missing the point... multiply missing the point really.

The 'day length' on Venus (Mars is pretty earth like so that's ok) is 233.5 days (116.75 days light, followed by 116.75 days night)
Which means you spend nearly half an earth year with a 30% bigger sun beating down on you raising the temperatures then followed
by an equal period of time in darkness slowly freezing your ass off.

If your idea of making these planets habitable is to build self contained habitats on the surface then what's the point?

You can build self contained habitats in space and save yourself all the trouble and grief of getting in and out of a socking great gravity well.

Which means your space ships don't need inefficient high thrust engines to get you in and out of an atmosphere and don't need heavy
heat shields to withstand re-entry.

Habitats don't have natural disasters.
Yes they do, and they can be far more serious. Mars is extremely geologically stable, and has an atmosphere that projects from most meteorites.
A spaceship on the other hand can be totally destroyed by a meteorite.[/b]

A space habitat is approximately equivalent in size and population (assuming not building ones that need to be made from stuff like carbon
nano tubes or graphene) to a town or city on earth.

A town or city on earth can easily be totally destroyed by an asteroid. And an impact on the earth could very well devastate many such towns.

An impact on a habitat destroys just that habitat, all the others are unaffected. there is no ocean spanning tidal wave for example.

And again, you make space habitats out of asteroids, you use up threatening asteroids when making them.

You can also move space habitats out of the path of any rouge asteroid which is a pretty trivial exercise compared to trying to shift an asteroid
so that it doesn't hit the earth. Because unlike the earth space habitats are not thousands of miles across and don't have deep gravity wells
that attract asteroids in.

And as for small asteroids that burn up in an atmosphere, space habitats have lasers and armour to deal with those.

Originally posted by twhitehead
The wikipedia page:
http://en.wikipedia.org/wiki/Terraforming_of_Mars
says there is quite a lot of water, what is required is a bit of heat to melt it all.

[b]You still have the problem that neither planet has a magnetic shield so both suffer heavily from
solar radiation and atmosphere loss/ionisation.
But how fast is that really? Sure its a p ...[text shortened]... elieve that you do. I see no reason whatsoever for doing so. Why not do it all on the surface?[/b]

Why not grow it on the surface and save all that ferrying? Your plan makes no sense at all. After all, all the raw material is on the surface. Your plan requires either harvesting raw material from asteroids or ferrying it up from the surface (for no apparent reason whatsoever, there are no benefits to working in zero gravity and zero atmospheric pressure that I can think of).

Yes lets build giant green houses on the surface of the planet we are bombarding with asteroids to heat up....

And where did I say zero gravity or zero atmosphere??? Again I am talking about large spun habitats that have earth gravity [simulated] and earth atmosphere.

However there are benefits to not being down a planets gravity well which I am about to explain...

Why not do it all on the surface?

Energy cost.

landing on a planet requires slowing down (fuel), heat shields (weight), landing systems (high thrust engines, fuel, aerodynamic surfaces, landing legs, weight),
Your space craft has to withstand the forces of re-entry and high acceleration (increased strength, weight) and you have to ferry all this extra weight from the earth.

This makes launching more expensive and your cargo smaller so you need more ships all of which are more expensive.

Going to planets costs vastly more than going to asteroids, both in terms of cash and in terms of energy.

Also if you want to send people on a non one way mission you need to have the capability to get back to the earth.

Now you can refuel on both Mars/Venus and an asteroid so I wont penalise either by asking them to carry their return fuel...

But the mission to the planet (with the atmosphere and deep gravity well) needs the extra delta V to get out of the planets gravity well (battling air resistance on the
way up) and using high thrust inefficient engines to do so.

NASA is currently considering a mission to Mars' moon Phobos especially because it would be vastly cheaper and faster than actually going to Mars.



Building habitats in space is low energy cost compared to building them on planets.

They are more accessible which means you can reasonable have transport networks between them, you don't have to send people off on one way trips with
no reasonable expectation of being able to come back.



And again, a point you haven't dealt with... You can make money mineral mining asteroids while building your habitat.

You can't do the same terraforming a planet.

You haven't dealt with the ethics of terraforming either, or the loss of scientific information in the terraforming process.

Also if there is life on Mars or Venus you could send your colonists down to discover some exciting new plague... (unlikely but possible)

Originally posted by googlefudge
Um... what?

You are going to have to elaborate on that.

shielding technology for solar and cosmic radiation as well as micro meteorites does not yet exist.

Originally posted by VoidSpirit
shielding technology for solar and cosmic radiation as well as micro meteorites does not yet exist.

nonsense.

multiply nonsense.

And certainly nonsense on a ship the size discussed here.

There are many materials that shield against radiation the issue is one of thickness and weight.
Which is much less of an issue on a big nuclear powered space ship.


And as for micro meteorites... Whipple armour... look it up.

Originally posted by googlefudge
nonsense.

multiply nonsense.

And certainly nonsense on a ship the size discussed here.

There are many materials that shield against radiation the issue is one of thickness and weight.
Which is much less of an issue on a big nuclear powered space ship.

so you say, but that's not very convincing. the enterprise site itself confesses that the shielding technology does not yet exist.

And as for micro meteorites... Whipple armour... look it up.

various HVIT are currently in testing and analysis.