What is primarily responsible for the surface conditions on Mars?

The primary factor responsible for the surface conditions on Mars is the low atmospheric pressure. Mars has a very thin atmosphere, with a surface pressure less than 1% that of Earth’s. This low pressure affects various surface conditions, including the boiling point of water, which is significantly lower on Mars than on Earth, meaning that liquid water cannot exist for long periods. The thin atmosphere also results in less insulation from solar radiation and cosmic radiation, making the surface conditions harsher.

In addition, because of the low pressure, Mars experiences considerable temperature fluctuations that can lead to extreme cold at night. While temperature extremes and high solar radiation do play a role in Martian conditions, they are consequences of the low atmospheric pressure rather than primary factors. Similarly, the presence of ice contributes to surface conditions but is more of a component within the context of Mars' geology and climactic cycles rather than the fundamental cause of its overall surface environment. Thus, the low atmospheric pressure is indeed the key factor influencing Mars' surface conditions.