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The fleet

Eight vehicles, one design family, five kinds of propulsion.

Every vehicle number below is computed by a script from stated inputs, and the same data file drives the simulation. Each vehicle's propulsion has its own colour in the experience: fusion violet, nuclear-thermal rose, methalox blue, ion blue and radiator orange.

The colony ship is 650 m long; the Enceladus sampling drone is 2.5 m. At this scale the drone is a dot. design

Each leg of the network is flown by the engine whose exhaust speed suits it. When the needed speed change is far above the exhaust speed, the propellant mass explodes (the rocket equation), so the fastest leg needs the fastest engine. physics design

Long Passage V1 · 650 m × 122 m

Colony transport, inner system to Saturn. Arriving on her fourth crossing of about a year, with settlers and the habitat modules for the next Titan wing. Her radiators glow orange, her reactor rides far behind a shadow shield, and her two counter-rotating drums give her passengers 0.56 g.

Propulsion: D-3He fusion, magnetic nozzle, hydrogen mass addition.

Input	Value	Basis
Exhaust velocity, km/s	200	challenge
Mission Δv, km/s	100	design
Departure mass, t	10,000	design
Acceleration, g	0.001	design
Jet efficiency	0.6	challenge
Hot waste fraction	0.2	challenge
Radiator temperature, K	1,200	challenge
Habitat drum radius, m	56	design
Habitat spin, rpm	3	design

Derived	Value
Mass ratio	1.649
Dry mass, t	6,065.3
Reaction mass LH₂, t	3,934.7
LH₂ volume, m³	58,354
Tanks	6 x 18 m diameter, 44 m long
Thrust, kN	63.7
Jet power, GW	6.37
Fusion power, GW	10.62
Total burn, days	142.9
Fusion fuel burned, kg	371
Fuel energy density, J/kg	3.531e+14
Hot radiator area, m²	10,630
Tank count	6
Tank diameter, m	18
Tank length, m	44.2
Radiator wings	4
Radiator wing length, m	150
Radiator wing chord, m	17.7
Trip estimate, days	366
Spin gravity, g	0.56

How it works · See it in the tour

Gateway shuttle V2 · 45 m × 9 m

Crew and cargo between the Gateway and Titan orbit. A descendant of the Meridian-class shuttles built in Concordia's yard. The reactor heats propellant that never burns, so the exhaust is nearly invisible and the nozzle glows white-hot. On Titan it refuels with local methane.

Propulsion: Nuclear-thermal, Titan methane propellant (hydrogen option).

Input	Value	Basis
Isp s methane	600	challenge
Isp s hydrogen option	900	physics
Dry mass with payload, t	180	design
Thrust, kN	300	design
Titan parking altitude, km	1,500	design
Design Δv, km/s	4.5	design
Chamber pressure mpa	3	physics
Nozzle expansion ratio	100	design

Derived	Value
Gateway departure Δv, km/s	0.81
Titan arrival v∞, km/s	1.53
Titan capture Δv, km/s	1.12
One way propulsive Δv, km/s	1.92
Mass ratio	2.149
Methane, t	206.7
Methane volume, m³	514
Tanks	2 x 6 m diameter, 11 m long
Reactor thermal, MW	929
Mass flow kg, s	51
Characteristic velocity, m/s	3,114
Throat diameter, m	0.26
Nozzle exit diameter, m	2.6
Methane tank diameter, m	6
Methane tank length, m	11.1

How it works · See it in the tour

Titan entry capsule V3 · 6 m × 8 m

Titan orbit to atmosphere; releases the rotorcraft or lands. An aeroshell and a parachute. Titan's thick air and low gravity make entry gentle: the capsule glows during the plunge, then drifts down under a parachute almost 20 m wide.

Propulsion: Aeroshell and parachutes.

Input	Value	Basis
Mass, kg	12,000	design
Surface air density, kg/m³	5.4	physics
Surface gravity, m/s²	1.352	physics
Touchdown speed, m/s	5	design
Parachute cd	0.8	physics

Derived	Value
Main parachute area, m²	300
Main parachute diameter, m	19.6

How it works · See it in the tour

Titan rotorcraft V4 · 18 m × 18 m

Regional flight; the free-flight vehicle. The regional aircraft and the one vehicle visitors fly themselves. Dense cold air and weak gravity make hovering cheap, so the rotorcraft carries 8 tonnes on four 7 m rotors for about forty times less power than on Earth.

Propulsion: Electric quad-rotor, reactor-charged battery.

Input	Value	Basis
Mass, kg	8,000	design
Rotors	4	design
Rotor diameter, m	7	design
Figure of merit	0.7	physics
Air density, kg/m³	5.4	physics
Gravity, m/s²	1.352	physics

Derived	Value
Disc area, m²	153.9
Hover power Titan, kW	39.4
Hover power same craft on Earth, kW	1,616
Earth to Titan power ratio	41
Battery for 2h, kWh	95

How it works · See it in the tour

Titan ascent vehicle V5 · 26 m × 4.5 m

Cargo and crew from the Kraken Shore pad to Titan orbit. Methane from the sea, oxygen from electrolysed ice, power from the reactors, then fire. The ascent vehicle carries cargo and crew from the Kraken Shore pad to orbit, with shock diamonds in the thick air fading to blue-violet as it climbs out of the haze.

Propulsion: Methalox, propellant made on Titan.

Input	Value	Basis
Isp average, s	345	physics
Dry mass with payload, t	45	design
Oxidiser fuel ratio	3.6	physics
Drag and gravity losses, km/s	0.5	design
Design Δv, km/s	3	design
Lift off thrust to weight	1.5	design
Engines	1	design
Chamber pressure mpa	10	design
Characteristic velocity, m/s	1,800	physics
Isp sea level, s	330	physics
Ambient pressure bar	1.467	physics
Tank diameter, m	4.3	design

Derived	Value
Ideal Δv to 1500km orbit, km/s	2.25
Titan escape speed, km/s	2.64
Mass ratio	2.427
Lift off mass, t	109.2
Methane, t	14
Oxygen, t	50.3
Methane volume, m³	35
Oxygen volume, m³	46
Lift off thrust, kN	221
Mass flow kg, s	68.4
Nozzle expansion ratio	8.9
Throat diameter, m	0.125
Nozzle exit diameter, m	0.37
Oxygen tank barrel, m	1.75
Methane tank barrel, m	0.96

How it works · See it in the tour

Sea barge V6 · 42 m × 11 m

Methane and ethane transfer on Kraken Mare. Marine hardware on a methane sea: electric screws, cryogenic hoses and ISO 14726 pipe colours. Barges load liquid hydrocarbons at the jetty and carry them along the coast.

Propulsion: Electric screw drive.

Input	Value	Basis
Cargo, t	500	design
Liquid density, kg/m³	550	physics
Drive power, kW	300	design
Lightship, t	200	design
Block coefficient	0.72	design
Cargo tanks	3	design
Cargo tank diameter, m	6	design

Derived	Value
Cargo volume, m³	909
Displacement, t	700
Draft, m	3.83
Cargo tank length, m	11.7

How it works · See it in the tour

Inter-moon cargo tug V7 · 70 m × 40 m

Slow spirals between Titan, the Gateway and Enceladus. Gentle and patient. A fission reactor feeds Hall thrusters that push very hard in speed and very softly in force, spiralling cargo between Titan, the Gateway and Enceladus over months.

Propulsion: Nuclear-electric: fission reactor, Brayton conversion, Hall thrusters.

Input	Value	Basis
Isp, s	2,500	physics
Dry mass with payload, t	100	design
Trip, days	120	design
Thruster efficiency	0.6	physics
Conversion efficiency	0.3	physics
Radiator temperature, K	500	physics
Propellant	xenon, imported	design

Derived	Value
Spiral Δv Titan to Enceladus, km/s	7.05
Mass ratio	1.358
Xenon, t	35.8
Xenon volume, m³	23
Thrust, N	85
Electric power, MW	1.74
Reactor thermal, MW	5.8
Radiator area, m²	790
Radiator wings	2
Radiator wing length, m	18.5
Radiator wing chord, m	21.4
Hall thrusters	16
Power per thruster, kW	109
Thrust per thruster, N	5.3
Xenon tanks	4
Xenon tank diameter, m	2.24

How it works · See it in the tour

Enceladus sampling drone V8 · 2.5 m × 3 m

Robotic plume sampling runs from the station. Robotic: people stay at the station. Small puffs from green monopropellant thrusters carry the drone to the plumes and back, because on Enceladus the speed needed to escape is only 239 m/s.

Propulsion: Green monopropellant thrusters.

Input	Value	Basis
Isp, s	250	physics
Dry mass, kg	300	design
Hop distance, km	110	design
Design Δv, m/s	500	design

Derived	Value
Enceladus circular speed at surface, m/s	169
Enceladus escape speed, m/s	239
Mass ratio	1.226
Propellant, kg	68
Propellant volume, L	46
Propellant tanks	2
Propellant tank diameter, m	0.35

How it works · See it in the tour