Still River

By Hal Clement

A mixed group of young scientists consisting of one human woman and four nonhumans are sent to the planet Enigma for what is, in effect, their final exam for what we would call their doctorates. The planet is called Enigma because it is very small, too small to retain its atmosphere, but it does. The young scientists must determine why Enigma has an atmosphere.
From the get-go there are problems. While Enigma has an atmosphere, since it is small, it hasn't much gravity. But it does have wind, as Joe, the first scientist off the ship, discovers when he is quickly blown away. Fortunately, he was unharmed as was the next person to run afoul of Enigma's treacherous environment, Carol, who was briefly buried in a sand pit. What the scientists didn't know was that the numerous sand pits on the surface of Enigma were bottomless, with sand blown by the gale force surface winds and into an extensive network of caves and tunnels.
Joe has designed a group of levitating robots meant to track Enigma's wind patterns. But one of the robots ends up down in the cave system and Molly (the only human), trying to reclaim the robot, falls way down into the cave system too. She latches on to the robot because its power supply can also power her space suit. She can't stop the robot from travelling with the cave winds because her fingers are too big to reach inside the control panel. (Joe, who built the robots, is a tiny creature compared to Molly.) So she has no choice but to go where the robot takes her and hope that her teammates are able to effect a rescue. So everyone puts their planned research aside in order to figure out how to find Molly in the extensive labyrinth of caves with which the planet is riddled.

The main thing I liked about this story is the interactions between the members of the team. All of the are different species and of an assortment of body types consisting of a human, a small humanoid, a centipede-like being, and two spherical beings, one small and one large. Despite their differences and occasional misunderstandings and a few disasters, they manage to come together to save Molly and Carol and even figure out the riddle of Enigma.
The traverse through the cave system of Enigma was less interesting. The book has a lot of physics and chemistry and I think someone who understood that stuff better than I do would get a lot more from the story than I did. At times it seemed like the story would never reach its conclusion, as Molly and Carol wandered endlessly through the dark, monotonous caves. Also, for a bunch of people in line for advanced degrees, they sure made a lot of stupid mistakes! But, overall, I think I liked the story pretty well, Enigma is a strange and interesting place and I liked the characters.