 What wasn't an issue their bodies were going through?
The Twilight Lab, near the northern pole of Mercury, was the obvious jumping-off place. F. No permanent installation with a human crew could survive at either extreme. The Major was counting on Sanderson knowing something about Mercury as well as the Sun when we camped at the Lab to make final preparations. But the only way to avoid it is to travel over the Pole, which would lose us days and offer us no guarantee of less activity to the west. We knew there were active volcanoes on the Brightside—even on the Darkside, though surface activity there was pretty much slowed down and localized. There was an atmosphere and a constant atmospheric flow from Brightside to Darkside. The trick was to find a passage that avoided those upheavals as far as possible.
 malnutrition
 dehydration  malnutrition  headaches  irritation