It has no magnetic field, so the solar winds just evaporated the water away.
The Earth has a magnetic field because the outer shell is spinning at a different rate than the core.
I don’t know how this happens in frictionless space... but I have a theory that the molten material is slightly elastic.
And if the out shell is hit in just the right way it could cause the outer shell to shift, which could send it oscillating back and forth like a swinging door.
This would also explain the roughly cyclical 26,000 year periodic pole shift.
“It has no magnetic field, so the solar winds just evaporated the water away.”
The water didn’t simply evaporate. It froze. However, at some point the surface temperature was high enough to have running liquid water, at least for some portion of every year, and this happened for longer than it should have taken the solar wind to give Mars the atmosphere it currently has. Unless our prevailing geological models or something else are not quite right.