QUESTION:
What is the boiling temperature of water on Mars at its pressure?

ANSWER from Bob Haberle on October 28, 1997:
Average Mars surface pressure is about 6-7 mb which is very close to the
triple point.  So boiling would technically begin at about 0 degrees Celsius
(32 F). However, the vapor pressure of water is so low in the Martian
atmosphere that liquid water is not stable.

Robert M. Haberle
Space Science Division