Patched Conic

You are a freelance pilot working a single ship, a fragile budget, and a logbook full of jobs nobody else will fly. Haul cargo and passengers between stations, prospect bodies for ore and ice, stand up surface refineries, build out a fleet, and take on the megamissions that earn a name out past the frost line.

Every trajectory you fly is one a real spacecraft could fly. There is no "go to planet" button. The propagator never cheats on your behalf.

Real orbital mechanics, not an approximation

The simulation is built on a closed-form two-body propagator and a patched-conic sphere-of-influence model — the same baseline mission designers used in the Apollo era and still use today for first-order trajectory work.

• Kepler's equation solved every tick with a Danby starter and Newton–Raphson iteration; the hyperbolic form handles escape and flyby trajectories
  
• Lambert's problem solved with Izzo's 2015 universal-variable algorithm and a Householder iterator — a porkchop search over departure and arrival dates picks the minimum-Δv window, the same way NASA's Trajectory Browser does
  
• Hohmann transfers compute the phase angle and Δv for the cheapest two-impulse hop between circular orbits
  
• The vis-viva equation governs speed at every point on every conic, elliptic through hyperbolic
  
• The Tsiolkovsky rocket equation costs out every burn, with a two-stage form for cradle-and-ship staging
  
• Hill-sphere SOI radii decide when you leave one body's gravity well and enter another's, with nested moon SOIs taking precedence
  
• Gravity assists modeled as hyperbolic flybys with turn angle set by periapsis radius and excess velocity
  
• Solar power falls off as 1/r² from the Sun; RTG output decays on the real Pu-238 half-life of 87.7 years

What you do

• Plan and execute burns from an Apollo-style DSKY: local orbit changes, Hohmann transfers, rendezvous, circularization, interplanetary Lambert transfers, gravity assists, and full heliocentric multi-leg trajectories
  
• Run cargo, passenger, resupply, and survey contracts across the solar system; build station reputation to unlock trusted and elite tiers, then chase the eight endgame megamissions
  
• Land on planets, moons, and minor bodies; mine ore, ice, volatiles, and fissionables; deploy ISRU refineries and bioharvest plants to sustain operations past Jupiter
  
• Buy and fly a fleet of six ship classes, from the bare Scout to the ion-driven Endurance; build staged propulsion cradles for missions your ship can't reach on its own tanks
  
• Survive micrometeorite swarms in LEO, the belt, and Saturn's rings; solar flares that fry unshielded avionics; depleted batteries; and the slow decay of your RTGs over the years
  
• Install upgrades — Whipple shields, panel shrouds, flare-hardened avionics, radioisotope generators — and salvage the wrecks of pilots who didn't

Features

• Patched-conic orbital mechanics — no approximations, no autopilot
  
• Apollo DSKY flight computer interface with 20+ programs
  
• 38-body solar system: planets, moons, asteroids, and Kuiper Belt objects
  
• 8 endgame megamissions with permanent career titles
  
• 6 ship classes with distinct role bonuses
  
• Procedural SID/Amiga chiptune soundtrack
  
• Runs fully offline — no network connection required