I'm the author of the ASHFALL three-and-a-half-ology: ASHFALL, ASHEN WINTER, SUNRISE, and DARLA'S STORY.
Absolutely loved this one. Read it without stopping for anything but coffee and food. I laughed harder at page 129 than I've laughed at anything I've read in years. Scared my cats so badly they poofed their tails and fled. If you enjoy sci-fi yarns in the vein of the movie Gravity, read The Martian stat!