The Long Rain is a science-fiction story by Ray Bradbury, published in 1950 and collected in R is for Rocket. It is about a dozen pages long.
Like many Bradbury stories, the setting and science behind "The Long Rain" are not explained in detail. The story involves a half-dozen soldiers from Earth, lost on Venus, a planet clouded in perpetual rain. (Which was, in 1950, a common scientific view of what Venus would be like.) The soldiers are at war with the Venusians, and are seeking a "sun dome" for physical and psychological relief from the environment. All but one of the soldiers go insane and die before a "sun dome" is found.
An unavoidable thought that occurred to me while reading the story is the parallels with the Vietnam War. The soldiers are in a guerrilla war in a jungle, with low morale and in-fighting. While these are fairly vague parallels, the story still seems to be about the breakdown of the optimistic sense of expansion against the grinding realities of foreign worlds. But the story was written in 1950, when (in general), America was optimistic about both the morality and feasibility of its foreign policy, and when technological progress was mostly unquestioned. So the story's pessimistic, even surreal take on exploration may have been a stroke of foresight on the part of Ray Bradbury, may have just been an artistic experiment.