Doctor Who_ So Vile a Sin - Ben Aaronovitch [36]
‘What do you think they are?’ asked the Doctor.
‘Well,’ said Chris, ‘they’re small enough not to occlude any stars and they’ve got very shallow emission signatures. The random deceleration is a typical military-style approach. At a guess I’d say they were a pair of Whirlwinds.’
‘Fighters?’ asked Zatopek.
Chris punched up another tactical display. ‘From the Victoria,’
he said, ‘a carrier in orbit around Orestes.’
Emil said, ‘What do they want with us?’
‘Let’s hope it isn’t target practice,’ said the Doctor. ‘What kind of weapons package will they have?’
Chris tried to remember his model-building days. ‘Assuming they’re loaded for space intercept, four ASDAC missiles for high delta V, two Roscoes for low V and a proton cannon for knife work.’
‘Which means?’ asked the Doctor patiently.
‘If they drop within a delta-V range of about twenty kps we’re probably all right.’
‘Unless they use their cannons,’ said Iaomnet.
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‘If they’re intercepting us,’ said Zatopek, ‘why are they slowing down?’
‘Space combat isn’t like dogfighting a flitter,’ said the Doctor.
‘There’s no point arriving at your target and then zipping past it.
You’ve got to be slow enough, relative to your target, for your weapons to hit it.’
It was more complicated than that, Chris knew. The high-V
weapons like the ASDACs traded off warhead for engine size. If you launched while on an intercept vector they could rip apart a ship just with the kinetic energy of their impact, much less effective at low or negative closure.
The low-V missiles like the Roscoes traded the other way: big warhead for a proximity hit, but the engine was smaller. Each weapon had its own effective envelope based on the absolute distance from launch to target and the relative velocity. The fighters were on a relatively simple intercept from behind and above, simple enough for even the Hopper’s navigation computer to make the necessary calculations.
The fighters were closing at less than seventy kilometres per second. Too late, Chris reckoned, for them to bother with their ASDACs. Once they were below twenty kilometres per second they would be at minimum effective V for the Roscoes. Which would mean that they were going for a visual inspection and a little bit of cursory intimidation.
Unless they used their proton cannons. In which case the Hopper didn’t stand a chance.
‘Chris,’ said the Doctor, ‘I think you should stop broadcasting Jimmy Somerville now – we don’t want to get them annoyed.’
Chris winced and unplugged the Walkman from the navigation console, which immediately began to bleep at him. He’d forgotten all about it.
Iaomnet turned to the Doctor. ‘If this is just an inspection, why haven’t they hailed us?’
‘They probably wondered who was strangling the cat,’ said the Doctor.
Chris flipped a switch and the bleeping stopped. ‘Hello, unidentified Hopper,’ said a speaker. ‘Do please reply. We’re becoming a little anxious.’
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Chris tapped a control. ‘Hello there,’ he said. ‘Sorry to keep you waiting, we had a minor communications glitch.’
‘Not a problem, unidentified Hopper, we were enjoying the music. This is the interceptor Albert Edward, out of the ISN
Victoria. Could we please have your ident code?’
‘Yes, ma’am. We’re an intersystem Hopper out of Earth, bound for Iphigenia, Ident X181/481.’
‘And so you are. Many thanks for your assistance, and a safe journey.’
‘And you. Thanks.’ Chris closed the link.
Everyone in the cockpit let out the breath they’d been holding.
The Hopper slid into orbit around Iphigenia at 07.00 hours, ship’s time, a tiny dot swinging around Clytemnestra’s innermost moon. The gas giant was a massive, faintly glowing ball, cutting off the sunlight, filling the bridge with soft reddish shadows.
Chris and Iaomnet were sitting side by side. She was keeping an eye on navigation while he watched the sensor array. Zatopek had given him a series of diagnostics to run, comparing the close-range data with the long-range scans they’d done en route. Two days’ worth of recordings, all of the wrong