Sunday, November 22, 2015

Mars and natural satellites

Mars is the fourth planet from the sun, and the second smallest planet after Mercury.  It's believed that in its past it could have harbored life, and may still, which seems more likely since the discovery of flowing water on Mars.

The house would probably fall victim to wild temperature swings (20 Celsius to -153 Celsius) or just be covered by dust.
Normal airplanes can't fly on Mars, because that it's atmospheric density is 100 times less than Earth's, and because that there isn't enough oxygen in the air to support combustion.  However, specially designed planes could fly on Mars.
There isn't enough liquid on Mars for a boat to float in.
The human is more interesting.  The atmosphere is mostly carbon dioxide, and extremely thin, and that, combined with the temperature changes, would make some kind of space suit necessary.  Food could possibly be farmed in a green house, or just carried along.  Water could be mined from the ground in places in the form of ice.  Rocket fuel could be refined in-situ.  A trip to Mars is much farther than a trip to the Moon, so it has to be much longer because of transfer windows, which only happens approximately every two years.  Plus, travel time:
This image shows why a faster trajectory is less efficient and requires more efficient engines:
You can read more about interplanetary trajectories here: 
And here's a handy spreadsheet:
Of course, all that time in zero-g causes muscle atrophy and osteoporosis, so many Mars mission proposals involve some kind of centrifuge, to create artificial gravity.

Finally, I want to add this: List of rocks on Mars.
Phobos and Deimos are the two moons of Mars.  It is believed that they are captured asteroids.  In most respects, they are like the Moon, except for gravity.  Deimos' escape velocity is 5.6 m/s, and Phobos' is 11.4 m/s, so it probably wouldn't be quite possible to reach escape velocity by running on Phobos, but maybe on Deimos.  With a bicycle, though, it probably would be possible.