Quote 22
It's kind of silly if you think about it. I'm in my space suit on Mars and I'm navigating with sixteenth-century tools. (22.34)
Actually, that doesn't sound silly at all. Throughout The Martian, Mark is forced to use some seriously lo-fi solutions for some big time problems—problems usually caused by complex modern technology. That newfangled stuff can be nice, but sometimes you just have to go back to basics.
Quote 23
People have speculated on how to make crop soil out of Martian dirt for decades. I'll just be putting it to the test for the first time. (2.46)
That's a tall order. Learning how to farm was an important step in the development of civilization, and now Mark is trying to make the leap all by himself. If he can do it, he'll be one step closer to taming this barren Martian wasteland.
Quote 24
This sort of farming [...] would turn their land into a dust bowl within twelve years. It's not sustainable. But who cares? I just need to survive for four years. (3.17)
At this point, Mark just wants to survive. Maybe the work he's doing now will set the stage for future human colonization of Mars, creating the guidebook that later explorers will follow. That would actually be pretty awesome. Still, Mark has no desire to stay on Mars any longer than he has to.