 Why doesn't the Major want McIvers to scout ahead?
Brightside Crossing by Alan E. Nourse JAMES BARON was not pleased to hear that he had had a visitor when he reached the Red Lion that evening. Across to the right was a group that Baron knew vaguely—Andean climbers, or at least two of them were. I’d always liked the Major—he was big and quiet and cool, the sort of guy who always had things figured a little further ahead than anyone else and always knew what to do in a tight place. Four thousand miles of butcherous heat, just to have some joker come along, use your data and drum you out of the glory by crossing at perihelion forty-four days later? “I want to make a Crossing at perihelion and I want to cross on the surface.
 The Major thinks it's safer if they stay together.
 The Major thinks McIvers is up to something. The Major wants McIvers close, so he can keep an eye on him.  The Major thinks it's safer if they stay together.  The Major doesn't want McIvers to steal the glory by completing the crossing first.  The Major doesn't want to be responsible if McIvers dies.