The Delphus Paradox - End of Earth by Steven Sands
Approx. 58,770 words.
Published on October 11, 2012.
A deep space exploration team lands on a distant, uninhabited planet and discovers a ringed fortress buried deep in a mountain. They find what may be a portal to a new world. With a damaged ship that cannot fly where can they go? When placed into ever increasing, imminent, mortal danger, the humans must choose a final stand and make a desperate choice.