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Terraforming the Solar System
Dr. Jay Maron

Mars

Mars topography

Mars needs water, nitrogen, and carbon dioxide. All three can be provided by crashing a comet into it. Comets have water and nitrogen, and the impact will liberate carbon dioxide from Mars' crust.


Atmospheres

Mars north pole
Mars Hellas Basin
Mars south pole

The objects in the solar system with meaningful atmospheres are:


      Density    Column   Pressure  Atmos.   Escape  Gravity  Atmos.  Temp  Adiabatic
     at surface  density             mass    speed            Height        lapse
      kg/m3      tons/m2     Bar    Earth=1   km/s     m/s2     km      K    K/km 

Venus   67      1000.     92.1       93.2     10.36   8.87      16     735  10.5
Titan    5.3      73.      1.46       1.19     2.64   1.35     130      94   1.3
Earth    1.2      10.      1          1       11.2    9.78       8     287   9.8
Mars      .020      .16     .0063     .0045    5.03   3.71      11     210   4.5
Hellas    .037      .29     .0116              5.03   3.71             240
The Hellas basin on Mars is a crater 7.12 km deep. The above data for "Hellas" is for the environment at the bottom of the crater, where the air is warmer and more dense than at the surface.

"Lapse" is the adiabatic lapse rate, the characteristic decrease in temperature with altitude.

Earth atmosphere mass = 5.15⋅1018 kg
Mars  atmosphere mass = 2.32⋅1016 kg

Plants

Pressure requirements for plants and humans. Pressures in millibars.

          Plant      Human    Mars    Earth

Pressure   >10       >500     6.3     1000
N2         > 1                 .27     780
O2         > 1       >130      .008    210
CO2        >  .15    < 10     6.0         .39
The highest cities on the Earth are at at atmospheric pressure of ~ 600 millibars.
                   Pressure    T
                   (Bar)    (Kelvin)

Earth                1        288
Mars                 .006     210
Mars Hellas Basin    .010     225    7 km deep. Value for the environment at the bottom
Titan               1.46       94
Minimum for plants   .1       273
If Mars were warmed to room temperature, CO2 would evaporate from the poles and double the atmospheric pressure.
Temperature  Water vapor
(C)          pressure (Bar)
 0        0.0061
10        0.0121
20        0.0230
30        0.0418
40        0.0727
50        0.122
At room temperature, the pressure from water vapor is almost enough for planet growth.

Mars has abundant ice. If the ice on the polar caps were distributed evenly over the surface it would create a layer 11 meters deep. This is more than enough to supply water vapor for the atmosphere if Mars were warmed to room temperature.

Radiation is an obstacle. Mars' atmosphere isn't thick enough to block cosmic rays and there is no ozone to block UV. Being at the bottom of the Hellas Basin doesn't help.

Mars can be warmed with orbital mirrors. Metal can be mined from Phobos and Deimos, where it is easily lifted into space.

       Escape speed (km/s)
Earth     11.2
Mars       5.0
Deimos      .0056
Phobos      .0113

Natural resources

Lunar crust
Mars atmosphere

            Moon   Mars
Hydrogen     y      y     From ice
Oxygen       y      y     From ice
Nitrogen     n      y     Mars' atmosphere is 1.9% nitrogen
Carbon       ?      y
Iron         y      y
Phosphorus   y      y
Potassium    y      y
Helium-3     y      n     Fuel for nuclear fusion energy.  The Earth is poor in Helium-3

Earth without CO2

If the Earth is an ideal blackbody,

Solar heating ~ Blackbody radiation ~ Stefan_Boltzmann_constant * Area * Temperature4

1361 Watts/m2 π Earth_radius2  ~  5.67⋅108 W/m2/K4 4 π  Earth_radius2
Temperature4

Temperature ~ 278 Kelvin
The Earth's average temperature is 287 Kelvin.

The sun's luminosity is increasing and in ~ 1 billion years the oceans will boil off even if the Earth has zero CO2. In ~ 5 billion years the sun will become a red giant and consume the Earth.


Ice

21 Lutetia (metallic asteroid)
Ceres (icy asteroid)

      Radius   Mass     H2O    H2O    Escape  Perihelion  Apehelion
       (km)             Mass   frac   speed     (AU)        (AU)

Earth  6371  59700      14    .00025   11.2      .98       1.02
Mars          6420                      5.03    1.38       1.67
Ceres   487      9.43    2.0  .21        .51    2.55       2.99
Themis   99       .2     ?     ?         .087   2.72       3.54
Europa         480     250    .5        2.02
Ganymede      1480     700    .5        2.74
Callisto      1080     500    .5        2.44
Titan         1350     700    .5        2.64
Triton         214    ~ 40   ~.25       1.46
Masses in 1020 kg

Ceres has as much H2O as the Indian ocean and it has a small escape speed.

The asteroid Themis has been found to have ice.
http://en.wikipedia.org/wiki/24_Themis


Carbon dioxide toxicity

mg/m3

  370   CO2 density in Earth air
10000   Onset of drowsiness if not already acclimated
20000   CO2 density on Mars
30000   Tolerable for 1 month
40000   Tolerable for 1 week
Humans can adapt to high concentrations of CO2
Carbon monoxide toxicity
mg/m3

     .1 Level of carbon monoxide on Earth
   12   Level of carbon monoxide on Mars
   35   Dizziness within six to eight hours of constant exposure
  100   Slight headache in two to three hours
  200   Slight headache within two to three hours; loss of judgment
  400   Frontal headache within one to two hours
  800   Headache and dizziness, nausea, and convulsions within 45 min; insensible
        within 2 hours
 1600   Headache, tachycardia, dizziness, and nausea within 20 min; death in less
        than 2 hours
 3200   Headache, dizziness and nausea in five to ten minutes. Death within 30 minutes.
 6400   Headache and dizziness in one to two minutes.
        Convulsions, respiratory arrest, and death in less than 20 minutes.
12800   Unconsciousness after 2–3 breaths. Death in less than three minutes.

Hydrogen sulfide toxicity (H2S)
mg/m3

   10   Eye irritation
   50   Eye damage
  100   The olfactory nerve is paralyzed after a few inhalations, and the sense
        of smell disappears, often together with awareness of danger
  320   Leads to pulmonary edema with the possibility of death.
  530   Causes strong stimulation of the central nervous system and rapid breathing,
        leading to loss of breathing.
  800   lethal concentration for 50% of humans for 5 minutes exposure
 1000   Immediate collapse with loss of breathing, even after inhalation of a single
        breath.
Methane is not toxic.
Nitrogen atmosphere

The closest source of nitrogen for an atmosphere is the moons of Neptune.

              Mean
           Temperature  Min   Max    Parent   Albedo
                (K)     (K)   (K)    planet

Mercury         340     100   700
Venus           735     735   735
Earth           288     184   330
Moon            220     100   390
Mars            210     130   308
Ceres           168       ?   235
Europa          102      50   125    Jupiter
Ganymede        110      70   152    Jupiter
Callisto        134      80   165    Jupiter
Titan            94                  Saturn
Titania          70      60    89    Uranus
Oberon           75                  Uranus
Nitrogen freeze  63
Oxygen freeze    54
Triton           38                  Neptune   .76
Nereid           50                  Neptune   .155
Pluto            44      33    55              .58
Hydrogen freeze  14
The boundary between rocky and icy objects is at Ceres' orbit.

The boundary for frozen nitrogen is at Neptune's orbit.


Moons of Neptune
         Diameter    Mass    Orbit   Orbit   Orbit
          (km)     (e16 kg)  (km/s)  (Mm)    (days)

Naiad       66       19     11.9       48.2      .294
Thalassa    82       35     11.7       50.1      .311
Despina    150      210     11.4       52.5      .335
Proteus    420     5035      7.6      117.6      1.122
Sao         44        6       .55   22228     2913
Laomedeia   42        5       .54   23567     3171
Psamanthe   40        4       .39   48096     9074
Neso        60       15       .37   49285     9741

Neptune orbit speed  =  5.43 km/s


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