Delta-v: the currency of space
Every maneuver in space costs delta-v (Δv) — a change in velocity. Your rocket's propellant reserve sets an upper bound on the total Δv you can ever perform.
Typical budgets (LEO starting point)
| Maneuver | Δv (m/s) |
|---|---|
| LEO → GTO | ~2,440 |
| GTO → GEO (circularise) | ~1,470 |
| LEO → Lunar intercept | ~3,150 |
| LEO → Mars transfer | ~3,600 |
| Earth surface → LEO | ~9,400 (launch) |
Tsiolkovsky rocket equation
Δv = Isp · g₀ · ln(m₀ / m_f)
Where Isp is specific impulse, g₀ = 9.80665 m/s², m₀ is initial (wet) mass and m_f is final (dry) mass.
In the next lesson you'll use a Hohmann transfer calculator to compute Δv for a real orbit change.