Radiation is probably the least important factor. Annual dose on the surface is only 240-300 mSv. An issue for humans but we’re terrible at withstanding radiat

Radiation is probably the least important factor. Annual dose on the surface is only 240-300 mSv. An issue for humans but we’re terrible at withstanding radiation. A colony of Deinococcus radiodurans is capable of withstanding an acute dose of 5,000,000 mSv (5,000 Gy) with minimal issues. Temperature is similarly less problematic than you would assume. Daily temperatures can reach well over 20C near the equator. It gets really cold, but once an organism freezes going super cold doesn’t really do anything. Thus storing human sperm at minus 196C even though they clearly weren’t evolved to deal with such temperatures. Lack of water is the major issue. So yes overall Mars is significantly worse for life but it’s surprisingly close.