 What are Hathaway and Marnagan's physiques like?
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. "Is this what ?" yelled Marnagan inside his helmet. They both waited, thrust against the shipside and held by a hand of gravity; listening to each other's breathing hard in the earphones. 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. "If we walk in opposite directions, Click Hathaway, we'd be shaking hands the other side of this rock in two hours." Hathaway felt his heart pumping slow, hot pumps of blood. Oh, God, this would make great news-release stuff if we ever get back to Earth. Marnagan said, "We're working on margin, and we got nothin' to sweat with except your suspicions about this not being an accident. We got fifty minutes to prove you're right. It's times like this when we all need words, any words, on our tongues. 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. The immense things rolled, slithered and squirmed after him. Marnagan, firing his proton-gun. Hathaway made it first, Marnagan bellowing just behind him. Instinctively, Hathaway added, "Asteroid monsters! You're doing nothing but sitting, looking like a little boy locked in a bedroom closet, so take me a profile shot of the beasties and myself." "Then," retorted Marnagan, "we'll develop it for our own benefit; while waitin' for the U.S. Cavalry to come riding over the hill to our rescue!" Marnagan raised his proton-gun dramatically.
 Both of their appearances are described to some degree, and Marnagan is often described as being a large presence.
 There isn't much discussion about how either person looks at all.  Marnagan is consistently described as feeble in comparison to Hathaway.  Both of their appearances are described to some degree, and Marnagan is often described as being a large presence.  Both are each regularly described as having similar builds.