New Mars Forums

A very profitable attitude to take.  I’ll play devil’s advocate.

The lowest bidder?  I don’t see them being at an economic disadvantage compared to completely manufactured thin-shell habitats.  If a thin-shell habitat can economically disassemble an asteroid for materials, then so can aquaoid.  I think artificial island manufacturing costs will be lower.

But isn’t this an improvement over the minerals being under 100s of kilometers of ice?

Is soil required for growing crops?  There was a hydroponics movement at one point.  If soil is required, then it can be imported from C-type asteroids, same as for thin-shell habitats.

I think artificial islands would be sufficient.  Tethered to the core if necessary.

I think you mentioned that the deep atmosphere would help keeping the asteroid warm – especially if it were enhanced with super-greenhouse gases.  For a given solar input, I think this gives the advantage to the aerolith.

Light for crops is a huge issue for both scenarios.  Plants are very inefficient users of solar energy, and I have no idea how efficient they can be made.  I can imagine a fungi or algae based food system.  Sea food seems a natural for aquaoids.

An idea for delivering solar energy to trans-Jupiter aeroliths is a series of large (100 km radius) Fresnel lenses.  The first one close in to gather the energy, others in the series to refocus the beam until it reaches it’s destination.  This paper ( see http://www.llnl.gov/tid/lof/documents/pdf/241039.pdf ) describes gossamer lenses made of solar sail type material, but we might be able to use even lower mass plasma rings.

Actually, I don’t think large meteorites are the main threat.  If they are big enough you’ll spot them and divert them in time.  Perhaps the bigger threat is a swarm of smaller meteorites that overwhelms the thin-shell habitat’s defense and/or repair systems, or maybe a huge burst of gamma radiation from a nearby supernova.  The aerolith has the advantage in both these cases.  You’ve also ignored deliberate attacks by people, which might be the biggest threat of all.

Even if you prefer an ice worldlet instead of a water worldlet (perhaps we could just leave the poles frozen for those who have some special phobia of artificial islands) your construction costs are going to be lower for just insulation vs. insulation and pressure.

Artificial island in atmosphere vs. artificial island in vacuum.  The atmosphere costs more at first, but it may be a good long term investment.

It would help if there were a technical write up a little more substantial than this IAC paper ...

http://www.askmar.com/ConferenceNotes/2 … 0Paper.pdf

The harshest criticism I've seen is that this guy ...

# Todd H. Rider, "A general critique of inertial-electrostatic confinement fusion systems", M.S. thesis at MIT, 1994.
# Todd H. Rider, "Fundamental limitations on plasma fusion systems not in thermodynamic equilibrium", Ph. D. thesis at MIT, 1995.
# Todd H. Rider, "Fundamental limitations on plasma fusion systems not in thermodynamic equilibrium" Physics of Plasmas, April 1997, Volume 4, Issue 4, pp. 1039-1046.

... says no system of the type Bussard is talking about can work.  Tom Ligon says that Bussard has addressed the issues raised by Rider, but it'd be helpful if it were described in enough detail that an expert could say "that sounds plausible."  I'm not sure that's happened yet.

Hi Antius, welcome to newmars.

I think the main reason for considering putting atmospheres around small bodies is long term stability. 

I'm a fan of O'Neill cylinders but they have an inherent instability: a high pressure (i.e., 1 bar) atmosphere separated from vacuum by a relatively thin skin.  I have no doubt we can engineer systems that cope with this instability in the vast majority of circumstances, but eventually the cylinder will encounter the astronomical equivalent of the hundred year wave.  Even if the design can be made immune to natural menaces, the instability is there to be exploited by malicious actors (internal and external).  The necessary docking ports are at least cumbersome, if not a point of special vulnerability.

If the magnetic field around an atmosphered small body is disabled, the atmosphere will eventually be lost, but your time to repair can probably be measured in years rather than hours.  Also, atmospheric entry shouldn't be a huge issue in low gravity environments, particularly since aerobraking can be a big fuel saver, because then any mods required for atmospheric entry can be justified by fuel savings.

Some notes w.r.t. your other points:

- see the "Moving Ammonia Asteroids" section of Zubrin's _Technological Requirements for Terraforming Mars_
   http://www.users.globalnet.co.uk/~mfogg/zubrin.htm
   for an idea of economically bringing volatiles to small bodies

- if we can engineer the other stuff, I'm sure we can engineer an atmosphere transparent in the important regions for plants, however, as you say the sunlight may be too faint in any case, in which case we may first want to use the small bodies' own volatiles to change it's orbit to something more viable

- an ocean world with artificial islands is not an unappealing habitat.  Everyone gets beachfront

Each post is dated.  The threads of each forum are sorted by last post.  Simply ignore those that don't meet your personal criteria for age limit.

I don't think you get the genius designation until you show a design that beats the LLMT by an order of magnitude or two ...

A Lunar Liquid Mirror Telescope (LLMT) for deep-field infrared observations near the lunar pole
http://www.optics.arizona.edu/loft/Publ … 206265.pdf

You might though.  They've got dust issues.

http://news.uns.purdue.edu/x/2007a/0705 … rogen.html

It's an aluminum/gallium alloy so the aluminum oxide doesn't form a skin that prevents further oxidation.  You're basically burning the aluminum in water to create hydrogen for fuel.  Then you take the waste aluminum oxide and "recycle" it at a nuclear power plant to recreate the aluminum.  Essentially the aluminum acts as an energy storage mechanism - 2 kWh per pound vs. 6 kWh per pound for gasoline - not too bad.  The reaction also releases another 2 kWh per pound as heat.  I wonder if that is useful or just waste heat.

A vivid analogy.

Re-emphasizes how important that is at the top level.  A little bit of good healthy competition just does wonders.

You're basically right StarDreamer.  It's actually very complicated because pressure depends on temperature and as soon as you added a significant amount of CO2 to Mars you would raise the global average temperature and probably melt the poles, etc, etc.  But to a first approximation, it's just

delta P_mars = delta P_venus * g_mars / g_venus * surface_area_venus / surface_area_mars

So 1 bar of Venus' atmosphere -> 1.32 bar on Mars

It is a waste of energy to lift gas out of Venus' gravity well, however.  A more efficient source of millibars (as well as much needed nitrogen) is ammonia asteroids, some of which have a delta-v to Mars as low as 0.5 km/s, see ...

http://www.users.globalnet.co.uk/~mfogg/zubrin.htm

Investors and "the public" are totally different audiences.  Investors keep an eye on public sentiment, but they know that things change and that is when you make money.  High end investors all have theories, and if your pitch meshes with one of their theories, you are in the running - then it comes down to ROI and risk.  Right here is why "manned mission to Mars" and "Martian settlement" don't get a look.  The risk is way past the redline, but worse, there is no attempt to answer the question "if I give you $x now, how much will you give me back in 5 years?"  Asking private investors to look beyond 5 years is a nonstarter.  Low and Middle market investors go for hypersafe stuff like real estate and franchises.  If they want to live on the edge they fund gold prospectors (you could try that: “Gold ... in the sky!”).

I don't think it is immoral to ask the public for money, but here you have to be sophisticated in a different way.  Once you start to compete for public attention, you will be targeted by your competitors if you are at all successful.  You could easily generate a backlash that puts you behind where you started.  I think the Fund for Martian Settlement is a nonstarter with practical types (“A one in a million chance for my unborn children to travel to Mars in 2050, huh?  How ‘bout we lobby to have the local crack house turned into a dog park instead?”), so you have to go after the dreamers. 

Here’s your first problem, ‘cause the dreamers are in the minority (I seem to recall a 60/40 bias in the West, and a little worse in the US because of their puritan streak), but worse, there is a pretty powerful movement that has caught up most of the dreamer/intuitive types – you’ve probably noticed it, it’s the one that currently equates anyone questioning the immanent threat of 60 foot sea level rises with holocaust deniers.  It’s also actively hostile – at an ideological level - to realizing the solar system as a resource base, because it fatally undermines its “limits to growth” dogma, and generally grates against its obsession with romantic primitivism.  For whatever reason, there is a left/right split here, so now you’re down to pitching to 20% - dreamers who aren’t actively hostile to you.  (You can try for Mars = Green, but I think there is going to be some pushback).

I could go on (dreamers with disposable income whose dreams don’t revolve around the local cocktail circuit and/or their modeling career, etc, etc), but I think the point is made.  You’re not really pitching to “the public,” you’re pitching to a very particular demographic set which almost certainly already includes the vast majority of current advocates.  I honestly believe that efforts should be focused on networking style expansion from that base rather than any vague “Mars = Everything Good.  Vote Mars!” advertising campaign.

http://www.physorg.com/news97779197.html

...
The researchers developed the agent by attaching a portion of the Bcl-xL protein already known to block cell death - a snippet called BH4 - to the HIV protein TAT, which can deftly carry other molecules into cells. They gave the agent intravenously to mice exposed to 5 Grays of radiation. In humans, this level of exposure would cause a sharp drop in blood cells, leaving individuals with an increased risk of infection and bleeding.

They found the treatment helped protect rapidly dividing T cells and B cells in the spleen - immune system cells that are prone to radiation damage - whether it was given 30 minutes before radiation exposure or 30 minutes afterward.
...

[ great news for intense exposure, but I wonder if it effects the long term increased risk of cancer? ]

I finally get it that you are talking about FMARS.  But this is exactly the sort of thing a PR firm would advise you to do.  See that Discovery Channel logo on the side?  They have 90 million subscribers.  Discovery Channel is sponsoring the thing, and is going to run a documentary over and over again showing young happy people "on Mars."  It doesn't get better than that.  If it were a marsdrive project you would be proud as punch.

What do you think a PR firm is going to advise you to do?  Graffiti on subway walls?  (Actually, that'd be kinda cool === Mars Now ===)  An Ad Council style TV campaign?  This is your brain.  This is your brain on Mars.  Direct Mail campaign?  Dear Friend, please ignore the other beg letters you got today about buying 1/10th of a cow for an impoverished family in Somalia ("Now that my family has a cow to carry water, I can go to school") and the Campaign to End Airtravel ("Because flying costs the Earth!") and send $35 to help improve public perception of Mars ("Mars: it's less crowded there ... but not so sparsely populated that you'd be lonely or anything ... and they have cable ... and FREE BEER!").

No.  It has to be all intrepid explorer and "one step closer to Mars."  FMARS, X-Prize, Rocket Racing, Yuri's Night - all good stuff.  The film/TV/game projects should fund themselves.

The only thing I could find in English was this Nature article ...

http://www.nature.com/news/2007/070416/ … 6847a.html

What are your priorities for space?

M. Sarkozy: The Galileo project has become bogged down in national quarrels that are petty compared with the stakes on the table, and breaking the current deadlock is a matter of urgency.

I'm keen on greater European cooperation in space. France should be ready to make the extra effort to lead the way, if needs be, as it has done in the past. The main goal must be to maintain and reinforce our basic civil, military and scientific skills. If, after that, we can together develop more ambitious manned flight and planetary-exploration missions, then why not?