Complex sentence: The two then use the thruster pack to make their way back to "Explorer," which they discover has been damaged far beyond usability, the rest of the crew dead from explosive decompression and hypoxia.
Split into simpler sentences: The two then use the thruster pack to make their way back to "Explorer," which they discover has been damaged far beyond usability. The rest of the crew is dead from explosive decompression and hypoxia.