Norton decides to send three of his crew down into Rama.
We learn that two of the men are married to the same woman back on Earth, and that she has had one child by each of them. The relationship is described as an equilateral triangle, which strongly implies that the two men both love the woman, who loves both of them, and that they love each other, too.
So in Clarke's future, women practice polyandry, and gays/bis can be married. He apparently sees a future where consenting adults can have the legal realtionships that work for them (remember that Norton himself is a bigamist, with wives and children on two planets).The two guys in the group marriage are Norton's second officer, Mercer (whose description makes him sound like ship's engineer), and Mercer's partner and ship's navigation officer, Joe Calvert. The third guy chosen to go into Rama with them is Willard Myron, a part time engineering professor, and mechanical genius. So two of the first three people to enter an alien space craft are engineers of one kind or another - which makes a ton of sense, when you think about it.
The three men set off down one of the three huge and long staircases which lead down into Rama - and quickly discover that the stairs were actually made for climbing upwards rather than descending downwards. So they end up sliding down the bannisters like naughty little kids.
As they get further down into Rama they discover that air pressure is going up - and might even be breathable down further. After one of them sniffs the air, they climb back out.They have been down in Rama an hour, and made it about an eighth of the way down the staircase. Another telling detail of the sheer ginormous scale of the thing.
