“Space may be silent, but it’s easy to tell how the ship’s maneuvering from the noise inside. Cold-gas thrusters hiss. Hypergolics hiss too, with a harsher metallic note, bangs and pings. Hydroxy rockets, they roar. Solid packs are similar, but rougher, with underlying stutters and clicks. Fusion torches purr like giant cats – unless they’re Nucleodyne-made and running at hard burn1, when the afterburner resonance mode makes ’em howl like damned souls. Mass-driver launch is eerily silent, nothing but air whispering over the hull until the lasers cut in, and then it’s endlessly rolling thunder, dwindling behind you.”
“Nuclear pulse-drive? You don’t hear a pulse-drive, not with your ears and live t’talk about it. You hear it with your bones.”
1. Hard burn, in the jargon, refers to the practice of injecting (a limited supply of) antiprotons into the exhaust of a fusion torch for short, high-power bursts.