Delta-V Budgets

Delta-V as Currency

In spaceflight, delta-V is everything:

Delta-V = capability

More delta-V means: - Higher orbits achievable - More destinations reachable - More maneuvers possible - Greater flexibility

Every mission has a delta-V budget - the total velocity change available given your fuel and engines.

Example budgets: - LEO → GEO: ~4,000 m/s - LEO → Moon: ~4,000 m/s - LEO → Mars: ~6,000 m/s - LEO → Jupiter: ~9,000 m/s

Calculating Your Budget

The Tsiolkovsky rocket equation tells you your total delta-V:

Δv_total = Isp × g₀ × ln(m_initial / m_final)

Where: - Isp = specific impulse (engine efficiency) - g₀ = 9.81 m/s² (standard gravity) - m_initial = spacecraft + fuel mass - m_final = spacecraft mass (after fuel used)

Example: Spacecraft: 5000 kg Fuel: 1500 kg Isp: 300 s

Δv = 300 × 9.81 × ln(6500/5000) = 786 m/s

That's your entire budget!

Budget Planning Strategy

How to plan within your budget:

1. Calculate total available delta-V Use Tsiolkovsky equation

2. List all mission requirements - Orbit changes - Plane changes - Rendezvous maneuvers - Contingency margins

3. Estimate each maneuver - Use Hohmann transfer equations - Add plane change costs - Include circularization burns

4. Add margins - Always reserve 10-15% for contingencies - Account for execution errors - Allow for corrections

5. Optimize if needed - Combine maneuvers - Choose efficient transfer types - Time burns optimally

Common Delta-V Values

Memorize these approximate values:

Earth Orbit Changes: - 200 → 400 km altitude: 100 m/s - 200 → 800 km altitude: 225 m/s - LEO → GEO: 4,000 m/s - Plane change (1 degree): 133 m/s at LEO

Interplanetary: - Earth → Mars: 5,800 m/s - Earth → Venus: 5,000 m/s - Earth → Jupiter: 9,000 m/s

Special Maneuvers: - Circularization: varies, ~50-200 m/s - Rendezvous: 50-150 m/s - Landing (Moon): 2,000 m/s