The loss of atmosphere stripped the Martian surface of warmth and pressure and since water needs both warmth and pressure to remain in liquid form, water is no longer stable on the Martian surface.

大气层的丧失剥夺了火星表面的温暖和压力，因为水需要温度和压力才能保持液态，所以在火星表面水无法保持稳定。