There Comes a Time by J.J. Green

Return to classic scifi with these shorts about time travel, future Earth, interplanetary exploration, Mars colonies, strange new subterranean life forms and other futuristic, weird and horrific tales. 
 

There Comes a Time 
Corporal Elliot, the first Future Soldier, has only one mission: to find out why humanity will be wiped off the face of the Earth. But time isn’t on her side. 
The Last Days of Duane Dayton 
Brutal murderer Duane Dayton waits on Death Row for his second and final execution, hoping for a quick end. His new technician has other ideas. 
Breathing Space 
In the deepest cave ever entered by human beings, Collins searches for the body of a lost caver. But there’s something strange about a colleague of the deceased, and the patches on the cave walls she's investigating. Collins must figure out the mystery if he’s to get out alive. 
Never in Fear Fly to the Woods 
For the first colony on Perseverance to survive, Robert has to overcome his grief and fear.