Andre Norton 
The Defiant Agents 

An exciting sequel to 'The Time Traders’ in a series of related time- and space-travel stories and part of Norton’s 'Forerunner’ universe. The star traveling secrets brought back by time travelers have been unraveled, and both the Americans and the Russians are intent upon colonizing new worlds. In a desperate move, the U.S. government decides to use a group of Apache volunteers in an experimental attempt to colonize a primitive planet, but before they can even begin their spaceship crashes on the planet Topaz… Full of intrigue and adventure, this classic novel is a must for adventure and pulp fans!