Detailed Trust and Travel Time (IF)

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Solar Hard SF Setting

Rough travel times with electric (power-limited) thrust

Assumptions: straight-line distance bands
symmetric accel/decel
constant reactor power sized for ≈0.001 g with water (P/M≈125 W/kg)
v_e ≈ 25 km/s (water), 35 km/s (noble), 75 km/s (H₂ effective after tank penalty). Fuel fraction f is % of departure mass. Times rounded to days.

Travel from Earth — WATER (steam/RF/MPD)

Destination	5% fuel	10% fuel	20% fuel	40% fuel
Mars (0.6–1.0 AU)	burn 1 d coast 1620–2700 d total 1621–2702 d	burn 3 d coast 788–1314 d total 791–1317 d	burn 6 d coast 371–620 d total 377–626 d	burn 12 d coast 160–271 d total 172–283 d
Asteroid Belt (1.5–2.2 AU)	burn 1 d coast 4051–5942 d total 4052–5943 d	burn 3 d coast 1972–2894 d total 1975–2896 d	burn 6 d coast 932–1368 d total 938–1374 d	burn 12 d coast 410–604 d total 421–615 d
Jupiter (4.2–5.0 AU)	burn 1 d coast 11344–13505 d total 11345–13506 d	burn 3 d coast 5525–6578 d total 5528–6581 d	burn 6 d coast 2615–3114 d total 2621–3120 d	burn 12 d coast 1158–1379 d total 1169–1391 d

Travel from Earth — NOBLE GAS (Xe/Kr/Ar, gridded/Hall/RF)

Destination	5% fuel	10% fuel	20% fuel	40% fuel
Mars (0.6–1.0 AU)	burn 3 d coast 1156–1928 d total 1159–1931 d	burn 6 d coast 561–937 d total 567–943 d	burn 11 d coast 261–440 d total 273–451 d	burn 23 d coast 107–187 d total 130–209 d
Asteroid Belt (1.5–2.2 AU)	burn 3 d coast 2893–4243 d total 2895–4246 d	burn 6 d coast 1407–2065 d total 1413–2071 d	burn 11 d coast 662–974 d total 674–985 d	burn 23 d coast 285–424 d total 308–447 d
Jupiter (4.2–5.0 AU)	burn 3 d coast 8102–9645 d total 8105–9648 d	burn 6 d coast 3945–4697 d total 3951–4703 d	burn 11 d coast 1864–2221 d total 1876–2232 d	burn 23 d coast 820–978 d total 842–1001 d

Travel from Earth — HYDROGEN (RF/VASIMR/MPD
effective 3× water after tank penalty)

Destination	5% fuel	10% fuel	20% fuel	40% fuel
Mars (0.6–1.0 AU)	burn 13 d coast 534–894 d total 547–907 d	burn 26 d coast 250–426 d total 276–452 d	burn 52 d coast 99–182 d total 151–234 d	burn 104 d coast 3–40 d total 107–144 d
Asteroid Belt (1.5–2.2 AU)	burn 13 d coast 1344–1974 d total 1357–1987 d	burn 26 d coast 645–952 d total 671–978 d	burn 52 d coast 286–431 d total 338–483 d	burn 104 d coast 86–151 d total 191–255 d
Jupiter (4.2–5.0 AU)	burn 13 d coast 3775–4495 d total 3788–4508 d	burn 26 d coast 1829–2180 d total 1855–2206 d	burn 52 d coast 847–1013 d total 899–1065 d	burn 104 d coast 336–410 d total 440–514 d

Read this: With typical reactor power, low fuel fractions = huge coasts. H₂ buys endurance (Δv), not push
it only beats water/nobles on long legs where you can actually keep thrusting for months.