question:  Why didn’t the proton gun hurt the monsters?
context: For Click and Irish were marooned on the pirate's asteroid—their only weapons a single gun and a news-reel camera. The picture of Marnagan hunched huge over the control-console, wrenching levers, jamming studs with freckled fists. And out in the dark of the fore-part there was space and a star-sprinkling and this meteor coming like blazing fury. It made a spiked fist and knocked the rear-jets flat, and the ship spun like a cosmic merry-go-round. Hathaway only knew he was picked up and hurled against a lever-bank, and that Marnagan wasn't long in following, swearing loud words. A sweeter one still of Marnagan beating hell out of the controls and keeping his words to himself until just now. It got so quiet you could almost hear the asteroids rushing up, cold, blue and hard. "Is this what ?" yelled Marnagan inside his helmet. Hathaway felt himself grabbed; he and Marnagan rattled around—human dice in a croupier's cup. They stood in the middle of a pocked, time-eroded meteor plain that stretched off, dipping down into silent indigo and a rash of stars. Overhead, the sun poised; black and stars all around it, making it look sick. Upon the sharp meteoric rocks Hathaway saw the tangled insides of the radio, the food supply mashed and scattered. "It's not proof we need now, Click. Oh, God, this would make great news-release stuff if we ever get back to Earth. Immense crimson beasts with numerous legs and gnashing mandibles, brown-black creatures, some tubular and fat, others like thin white poisonous whips slashing along in the air. Hathaway yelled and ran, Marnagan at his heels, lumbering. Marnagan, firing his proton-gun. Hathaway made it first, Marnagan bellowing just behind him. Click's voice gasped it out, as Marnagan squeezed his two-hundred-fifty pounds beside him. Instinctively, Hathaway added, "Asteroid monsters! Marnagan raised his proton-gun dramatically.
output:  The monsters had thick, resistant skin.
options:  The monsters ran too fast.  The proton gun was damaged in the crash.  The monsters had thick, resistant skin.  Irish wanted to negotiate a peace.