Other Current Conditions on Mars
The composition and pressure of the Mars, Earth and Venusian atmosphere:
| Pressure (Bars) |
CO2 | N2 | H2O |
O2 | |
| Venus | 100 | 96% | 3.5% | 0.00001% | 0 % |
| Earth | 1 |
0.0003% (0.35 mbars) | 77% (770 mbars) | 0.01% | 21% (210 mbar) |
| Mars | 1/100 | 95% (6.2 mbars) | 0.027%
(0.18 mbars) | 0 % | 0 % |
| Plants | 0.15 mbars | > 1 mbars | 20 mbars | ||
| Humans | 1/2 | 130 mbars |
What should be immediately obvious is the differences in CO2.
Secondly, the presence of O2---indicative of life on Earth,
and its absence on the other planets.
To increase the temperature, increase the level
of greenhouse gases in the atmosphere. Greenhouse gases important
on Earth: CO2, NH4, NO, CO and
CFCs (ChloroFluoroCarbons) and H2O. They increase the
Earth temperature by an 60 F. Mars' atmosphere is already mostly
CO2. Why is it still so cold?
Low pressure. Low pressure means there is very little mass in the atmosphere. The amount of CO2 is too little to keep the planet very warm--it's working alone, where Earth uses a number of gases, most important H2O). Though it is doing something. Without its CO2 , Mars would be even colder (by about 10F). To get the warming needed for liquid water, we'd need to increase the amount (mass) of CO2 in the atmosphere by 100 times (620 mbars!). But more than 10 mbars is TOXIC to humans!
Plants need 0.15 mbars CO2 to breath, which Mars can provide. But plants need O2 and N2, 20 mbar and 1-10 mbar, respectively. Humans need 130 mbars of O2, and additional gas (N2 or other) to bring the total pressure to 500 mbar (about the pressure of the highest mountains on Earth) to survive without pressure suits.