A. Tons of material from space fall on the Earth each year -- mostly as dust. But there are Earth orbit crossing asteroids which traverse the path the Earth follows around the Sun. The odds of the Earth and one of those asteroids ever being in the same place at the same time is not zero. However, it would take an object of extraordinary size to actually destroy our planet. A larger worry is what would happen if even a 'small' asteroid were to strike the Earth. Even if the impact was far from civilized areas, material thrown into the atmosphere could reduce the amount of sunlight which reaches the surface, thus destroying or damaging the plant life which needs that sunlight. If that were to happen, it's possible that plant-eating animals would eventually perish. Then the animals which depend on those plant eaters as food would lose their source of food too.
A. Archer made the decision early on to keep to a 24-hour 'day'. She felt it was essential to have some sort of routine. Research has shown, however, that the human body and mind, deprived of any indication of time-of-day, will gradually slip into a cycle that may actually last longer than our familiar 24 hours. I wonder why?
A. Mostly they're there to help create a livable atmosphere and climate inside the craft for the flight crew. Oxygen and CO
