The Land of Crimson Clouds

A spaceship, propelled by a prototype photon engine, sets off for Venus, which at that time, is an enigmatic and unexplored planet covered by clouds. The tasks of the crew are a) to test the prototype engine in field conditions and b) to locate and set radio beacons on the s.c. "Uranium Golconda" (a place with incredibly large heavy metals deposits), presumably, found somewhere on the second planet of the Solar System.
As the crew ventures into the depths of Venus, unknown dangers take them out one by one, so only a half of them returns home after accomplishing the mission—all badly damaged, both physically and mentally. However, their feat was the first milestone in colonizing Venus and the first step into the 22nd century.