"A good example is that of Mount Everest — the atmospheric pressure at the top of Everest is 400 millibars, as opposed to around 1,000 millibars at sea level, and therefore water boils at 72 degrees Celsius [161 degrees Fahrenheit] rather than 100 degrees C [212 degrees F], meaning mountaineers cannot make a decent cup of tea," study co-author Susan Conway, a planetary geomorphologist at the University of Nantes in France and France's National Center for Scientific Research, said in an email. "On the Martian surface, the pressure is 5 to 10 millibars, meaning that liquid water boils no matter what the temperature is.