New Mars Forums

When I think of what I like about particular cities it mostly comes down to climate and culture.  The premise of Clean Slate City seems to be efficiency.  Now, I'll admit that traffic jams are no fun and that cheap electricity is nice, but I wonder if you aren't planning the 21st century version of the Chicago Housing Projects.

They started out with the best of intentions - high efficiency, low cost housing  - but became pretty much hell on Earth.  There are a million arguments as to why, but it has become common to say things like "they were torn from their organic social networks and subjected to alien social networks as artificial as the structures themselves" and "the fabric of an urban community is not physical, but woven from the interrelationships of its members."

How will you prevent Clean Slate City from becoming another Chicago Housing Project?  How will you stop the government of the host nation from dumping their poor there?  How will you grow healthy social networks?  How will people feel ownership when so much is handed to them on a plate, when the place has no history?  What will stop the leadership from exploiting whatever resources the City provides for personal gain and then moving back to New York? 

Even if you are successful, won't other cities in the host nation become jealous of your efficiency and demand that the government reduce your competitiveness with tariffs and taxes?  Won't the government of the host nation seek to maximize total revenue by roughly equalizing development in each of its regions?

I tried to find some figures for back of the envelope calculations. 

Most cyanobacteria oxygen production rates were given for full sun on a clear day in the desert (they want to use them for CO2 drawdown), but from what figures I could find, there are some cyanobacteria that basically produce oxygen in proportion to the light you give them - right down to 1/100th of "noon in the desert" light. 

With that in mind, I think there are existing cyanobacteria that would generate 20 mmol of O2 per square meter per hour ( seasonal average Martian light levels, averaged over the Martian day, peaking at 80 mmol O2 m-2 h-1 ).  If you can cover 10% of the Martian surface with them, it will take 100 years to generate 2 mbar of O2.

So, optimistically, if you can find/engineer a cyanobacteria that has a production rate double that, and you could seed 20% of the Martian surface (needs to be watery & ice free), then you'd have 2 mbar of O2 in 25 years.

<cigar chompin'>'cause today's targets ain't destinations, they're networks.  And the nodes are mobile.

2 hours to combat.  Anywhere on Earth.  Almost makes you feel sorry for da bad guys.  Almost.</cigar chompin'>

<gamer>Just two.  But that's all they'll need, 'cause they'll be wearing powered armor and carrying man-portable rail guns.  Game over dude.  Game freakin' over.</gamer>  (Actually, I think it is 6-8).

These are guys who fired 400 missiles costing $2 million a piece to quote shock and awe unquote.  And suborbitals are way cheaper if you're only going to use them once.

Yep, it's still there ...

http://newmars.com/wiki/

A nice, optimistic article. 

TSTO (and later, SSTO) RLVs are a long time dream, and (as intended by the X Prize) Rutan got everyone dreaming again.

The "1000 times cheaper" claim is a little disingenuous.  First they are comparing against the space shuttle ( > $10,000/lb ) instead of, say, SpaceX's next gen heavy lifter ( ~ $1500/lb ), and then everything depends on volume (the number of flights per year).  Since for high enough volume you can ignore development costs, you are then free to set the cost at pretty much whatever you like. 

Most TSTO RLV proposals claim $2000/lb initially, $1000/lb for modest volume, and $500/lb for high volume.  The order of magnitude improvement is enough to attract interest while fending off disbelief, but if you like you could say $50/lb (for a million flights per year).  The initial shuttle proposals did exactly this, promising $120/lb at high volume.

Tech barriers I've seen highlighted include:
- hypersonics are hard when you are a rocket, they are much harder when you are also trying to generate lift
- reusable reentry shields don't really exist (inspecting and refurbishing the shuttle's heat shield is a big part of its per launch cost)
- but most of all, going from 10 launches/year -> 1000 launches/year -> 100,000 launches/year at ever decreasing marginal cost is not just a matter of logistics, but requires serious technological advance.

I think private companies will do better than NASA (profit motivator), but I think the price will come down a lot slower than the optimistic articles suggest.

dicktice, you so love a mystery.  It's just wonderful 

Just awesome data Midoshi.  I can't believe how quickly we'll be able to start establishing these bogs.  Even 2 mbar O2 won't be instantaneous though.  I looked at how much energy it would take by electrolysis: 32 terrawatts for 100 years (yikes!  current energy usage on Earth in all forms - coal, oil, nuclear, etc - is ~14 terrawatts).  Any idea how long it will take algae to get us 2 mbar?

As a follow-on to the post I made about maintaining a Lunar atmosphere, I did the same calculations for Mars.  But quite interestingly, I learned that having a high proportion of CO2 is a great way to cool your exobase.  Both Venus and Mars have exobase temperatures ~200K, whereas Earth's averages ~1500K because the high proportion of oxygen is heated by XUV radiation.  However, even Earth's exobase temperature has been cooling (~40K per century) because of the increased atmospheric concentration of CO2.

I don't know how to work out the exobase temperature for Mars given 170 mbars of oxygen, so I'll just give the loss rates and power requirements for several temperatures ...

exobase temp. (K) --- oxygen loss rate (tonnes/yr) --- Replace Power

1500 --- 4100 --- 23 MW
1300 --- 430 --- 2.4 MW
1000 --- 3.5 ---  14 kW
900 --- 0.2 ---  1.2 kW
700 --- ~1E-4 --- ~1 W
500 --- ~1E-6 ---  ~1E-6 W

I'm using 5 kWh/kg to calculate the power required to replace the lost oxygen (electrolysis of H2O).  The interesting thing is that the 500 K exobase temperature isn't entirely unreasonable for a Martian atmosphere that is, say, 170 mbars oxygen and 170 mbars CO2.  Even if the exobase temperature rises to 1000 K, 2.4 MW is entirely reasonable as a power expenditure to maintain your hard won atmosphere.

The high CO2 proportion exobase cooling effect may also work for Luna.  Maintaining 170 mbars at an exobase temperature of 300 K requires just 9.4 MW.

*** EDIT

Updated the figures.  The previous figures were way too conservative.

It's very difficult to construct a plausible scenario that relies on physical exports from Mars for bootstrap funds.

Once there is demand from offworld industry, I think Zubrin's argument is the best I've seen ...

The Economic Viability of Mars Colonization
http://www.cbqc.net/mars/docs/m_econom.pdf

... but demand has to be substantial to justify Mars infrastructure.

It is possible that religious or ethnic intolerance could reach the point where a persecuted group would fund a Mars colony.  This was the motivation for a lot of historical colonies.

It's possible that a powerful world government occurs on Earth, and they ban particular technologies as too dangerous, but that the technologies are so beneficial that entrepreneurs decide to establish production facilities on Mars.  Maybe some biotech or nanotech. 

In a similar vein, it's possible that Mars could bootstrap using unrestricted fission for cheap energy to undercut energy-intensive industries on Earth.  Anti-matter production might be one industry (I know it sounds like science fiction, but anti-matter is the ultimate energy-storage mechanism).

The only problem with these last two is that Mars is competing against Luna, so there has to be a reason that Luna is unsuitable.  Eventually, Mars' resources probably win out, but at first, Luna infrastructure is cheaper.

Virtual exports may be possible, for example if a research culture arises, but again, it is hard to see it paying for bootstrap.

BTW, Red Oasis is lookin' good - feel free to start a shameless promotion thread.

bsdwork is a spammer
http://newmars.com/forums/profile.php?m … ile&u=2785

he is making random posts each with a single link to generally objectionable sites.  I have been removing the link, but I'm sure he never checks his previous posts.

You might be interested in this paper and the web site it references ...

Mars Mineral Spectroscopy Web Site
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1356.pdf

Thinking about maintaining a Lunar atmosphere, I wanted to work out loss rates - you're going to lose some, but how much, how fast?

From what I read, Jeans escape flux gives reasonable results.  The main parameters are the exobase height and temperature.  To simplify, I assumed an all-oxygen atmosphere (say, generated by heating lunar regolith), and an exobase height that basically scales from Earth's (e.g., 500 km * 100 mbars / 1000 mbars * 9.8 / 1.6 = 300 km for a 100 mbar atmosphere).  Earth's exobase temperature varies from 1000 K (solar min) to 2500 K (solar max) mostly due to oxygen absorption of far UV[1].  I assumed the same for an atmosphered Luna, with an average value of 1500 K.

That gives the flux as a function of surface pressure, and the surface through which the flux flows is just the sphere with radius = radius_luna + exobase_height.  The exobase height has a big influence because it increases the size of the sphere, but also decreases the gravitational attraction keeping the gas close to Luna ...

surface pressure (mbar) -- mass loss per year (million tonnes) -- GW

100 -- 53 -- 300
170 -- 81 -- 460
200 -- 95 -- 540
400 -- 230 -- 1300
700 -- 540 -- 3100
1000 -- 1000 -- 5800

The last figure (GW) is how much power is required to generate the mass of oxygen lost per year from lunar regolith at 50 kWh/kg (estimates range from 20-50 kWh/kg [2]).  The 460 GW figure to maintain 170 mbar is about what the US generated in 2004[3].

Zubrin's calc's for a 10 billion tonne iceteroid calls for 20 GW and a 75 year transit time to collide with Mars[4].  If we assume 50 GW and 150 years, the same asteroid can be safely orbiting Luna.  It would provide replenishment needs for ~120 years at the 170 mbar level. 

None of this assumes an artificial magnetosphere (although exobase may be higher without a magnetosphere) or cooling of the exobase.  However, anything that can be done to cool the exobase helps tremendously.  For example dropping the exobase temperature to 1000 K drops the power requirements to 125 GW for the 170 mbar case.

[1] http://www.geosc.psu.edu/~kasting/Abiol … escape.ppt
[2] http://fti.neep.wisc.edu/neep602/LEC20/IMAGES/fig21.GIF
[3] https://www.cia.gov/library/publication … os/us.html
[4] http://www.users.globalnet.co.uk/~mfogg/zubrin.htm

*** EDIT

(Figures adjusted again, 3rd time lucky).

Note that the power requirements can be dropped an order of magnitude if you are just electrolyzing water (e.g., from an iceteroid), so that it would require 46 GW for the 170 mbar case.