Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare.
[Every body continues in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it.]
— Newton's First Law (tr. Motte)
The airlock opened, and Agent Gomez stepped into the control room of the space vessel Unyielding Judgement.
"Situation?" he asked.
"Unchanged," Agent Borodin replied.
Gomez nodded. "Stand down. I'll take over."
As Borodin left to take some well-earned rest, Gomez turned to the ship's captain.
"If they make a break for it, can we catch them?" he asked.
Captain Lupita Orlov considered the question. "We can outmanoeuvre them, out-accelerate them and outgun them. Projections show a maximum engagement time of ninety minutes. Of course, any such activity would break our cover."
"Quite. Let's remain innocuous for now. Let them make the first move."
It had long been known that stealth in space — concealing a spacecraft or probe from prying eyes — was difficult, bordering on impossible. The traffic radars scattered through the Solar System were designed to track objects large enough to be a hazard to navigation, and that would certainly include a spaceship. Even without those, the heat radiation from its life support systems — or its engines, the first time it needed to alter its course — would be unmistakeable.
For this reason, the Unyielding Judgement, in the guise of the freighter Watersmeet, had registered its routine cargo flight from Earth to Station Gamma-3, in orbit around Neptune, with all the relevant authorities. And since it was thus registered, it attracted only the most cursory attention on its journey, its humdrum identity and purpose making it far less visible than any attempt to conceal its thermal signature or obscure it from radar.
Gomez glanced at the monitor by his elbow. It was filled by the looming presence of Neptune, a dark blue sphere with a few pale streaks, and the dark blots of moon-sized storms. One of them, near the north pole, almost resembled an eye peering up from the globe. Station Gamma-3 was a tiny dot against the planet, hardly noticeable if not for the tracking glyphs surrounding it.
"Sir." Lieutenant Darius, tactical officer, had spoken. "Launch detected."
At the same moment, there had been a brief flare of light from the dot that was Gamma-3. A second set of tracking glyphs glowed into life, moving slowly away from the first.
"It is them?" Captain Orlov asked. "Not a decoy?"
"Mass and acceleration consistent with Butterfly. Transponder code match. Sir, departure profile is consistent with full emergency acceleration."
"So they do know we're here. Or suspect it." Gomez checked his seatbelt was properly fastened. "No point in hiding, then. Intercept course."
"Full power," Orlov said. "Intercept in eighty-four minutes."
A low, menacing hum ran through the Unyielding Judgement. The tracking glyphs on its monitors were joined by new data: range to target, intercept time, weapons status.
Two minutes later, a brief flicker ran across the bridge. Lights and screens winked out, then relit. The hum of the engines momentarily faltered.
"What was that?" Gomez asked.
"Checking." Darius tapped at a computer. "Electromagnetic pulse, apparently centred on Butterfly."
Orlov was hurriedly paging through screens of information on her own console. "Consistent with catastrophic reactor failure."
Sharp, clear schematics of the Butterfly appeared on the screens, overlaid with hazy patches indicating the likely areas of damage.
"Their course has changed," Darius said sharply. "Contra-orbital thrust... their course will intersect Neptune's atmosphere. Sir, is this a distress situation?"
"It is." Gomez was gripping the arms of his chair. "Can we get to that ship before it burns up?"
"Possibly," Orlov said. "But it's not sufficient to get to it: we need to grapple and decelerate it before it's destroyed. A drone fighter would stand a better chance."
"Then launch one. Launch both."
A shudder ran through the ship. Two sleek silver tubes were briefly visible on the screen, quickly shrinking to points of light.
"Drones away," Darius said. He turned back to his console. "We have further data on the Butterfly's course."
"Tell me," Gomez snapped.
"Butterfly's course will intersect Neptunian atmosphere in T plus seventy-four minutes. It will be destroyed no later than T plus seventy-seven minutes. Earliest possible drone intercept..." He swallowed. "Earliest possible drone intercept is at T plus eighty-five minutes."
"If I authorise the use of war emergency power ratings on the drones?" Gomez demanded.
"T plus eighty-one minutes."
"Four minutes too late," Orlov said. "Before the drones get anywhere near her, Butterfly will be molten slag. And when they do, they'll be scrap metal too."
Gomez, his face still maintaining an expression of rigid calm, brought his fist down on the arm of his chair, hard enough to crack it. "The little snake!" he growled.
"Sir?" Orlov asked.
"This isn't an accident. It's sabotage. She deliberately programmed the reactor to blow them out of orbit. Make sure we couldn't get our hands on them. Look at your own figures! Seventy-seven minutes versus eighty-five. A ten percent safety margin." He swallowed, trying to regain his self-control. "Keep the drones with them, for as long as you can. Check she really was on board the ship, not hiding on the station."
"Check who was on the ship, sir?" Darius asked.
Gomez shot a cold glare at him. "The Heriot girl, of course." He looked back at the radar image of the doomed ship. "There's no way she can escape, but I want to be completely certain."