CONSUMPTION RATE 6.045 G/S at 1.5 g; '540 trillion watts' (ch. 4, 6); a 100,000 kg ship with 2×10⁶ kg of fuel (ch. 6, 24); 'thirteen years' / 'three years and nine months' (ch. 15, 26); 0.9 g home in 'five and a half' (ch. 26); 10 ly in '6.64 years' (ch. 19); 120 kg per beetle (ch. 24)

6.045 g/s = 543 TW; F = P/c = 1.81 MN; at 1.5 g that is a 123,200 kg ship against the book's own 120,906 kg ledger, a 1.9% lock across three chapters

The 1.5 g brachistochrone: 13.1 Earth yr / 3.89 ship yr (book: 13 / 3¾) but total rapidity 6.03 → mass ratio e^6.03 = 415 against a tank of 21; the tank runs dry seven days past the flip; squaring the claims needs exhaust at 1.98 c

RS-25 exhaust 4.4 km/s; DS1/NSTAR 30 km/s; Project Daedalus 10,600 km/s (Bond & Martin 1978, INST-40); Starshot's sail carries no reaction mass (INST-20)

The Eridian surplus (consumption on the trip clock, the book's own framing), the ~6 m nozzle behind the ship, the beetles' dry mass

Whether a novel whose every clock is exact but whose tank pays for a different trip deserves Reading A (the clocks are honest) or Reading B (fiction pays no bills)