Mission Δv Budget Ladder | mysimulator.uk

Engine

Spacecraft Mass

Initial wet mass 3200 kg

Payload / dry mass 1000 kg

Mission Legs

Mid-course correction (0.10 km/s) Surface descent & landing (0.80 km/s)

Contingency margin 10%

Δv Ladder

Live Readouts

Total Δv budget

0.00 km/s

Propellant burned

0 kg

Final mass margin vs payload

0 kg

How it works

Every burn obeys Tsiolkovsky's rocket equation. Rearranged for the mass left after a maneuver of size Δv:

Δv = Isp · g0 · ln(m0/mf)
mf = m0 · exp(−Δv / (Isp · g0))
propellant used = m0 − mf

A real mission is not one burn — it is a ladder of them. The mass left over after burn 1 becomes the starting mass m0 for burn 2, so each leg's propellant cost compounds on a lighter (or, if margin is too thin, an already-starved) vehicle. This simulator chains the four legs above — departure injection, an optional mid-course correction, orbit insertion, and an optional landing burn — plus a contingency reserve added as a percentage of the baseline total, exactly the way mission designers pad a Δv budget for navigation errors and off-nominal burns.

Engine — chemical propulsion trades a low specific impulse (Isp) for high thrust; ion propulsion needs far less propellant per unit Δv (higher Isp) but the mass savings only matter if the vehicle can afford the longer burn time.
Wet / dry mass — dry mass is the payload that must still exist after every burn. If the ladder's cumulative propellant use eats past (wet − dry), the margin readout goes negative: the mission is not flyable with this propellant budget.
Contingency margin — real missions never fly the bare-minimum Δv; a 5–15% reserve absorbs launch dispersions, navigation error and off-nominal burns.

The fuel column beside the spacecraft is a physical bar chart: each block is one increment of remaining propellant, and blocks disappear from the top as the ship burns down the ladder — a stalled or empty column mid-ladder is the visual signature of an infeasible mission.

Earth Mars Burn marker Propellant remaining

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