Calculator Inputs
Example Data Table
These sample cases are illustrative. Values reflect the same screening assumptions used by this page.
| Scenario | Diameter | Density | Speed | Angle | Estimated Energy | TNT Equivalent | Estimated Crater |
|---|---|---|---|---|---|---|---|
| Small stony body | 10 m | 3,000 kg/m³ | 20 km/s | 45° | 2.403e14 J | 0.057 Mt | 134 m |
| Medium iron body | 50 m | 7,800 kg/m³ | 17 km/s | 50° | 6.798e16 J | 16.247 Mt | 959 m |
| Porous carbonaceous body | 120 m | 1,800 kg/m³ | 22 km/s | 35° | 2.217e17 J | 52.986 Mt | 1,171 m |
| Large rocky impactor | 300 m | 3,200 kg/m³ | 19 km/s | 60° | 6.761e18 J | 1,615.951 Mt | 4,935 m |
Formula Used
1) Projectile volume: V = (4/3) × π × r³
2) Effective density: ρeff = ρ × (1 − porosity)
3) Mass: m = V × ρeff
4) Retained impact speed: vi = v × √R
5) Vacuum kinetic energy: KE = 0.5 × m × v²
6) Retained impact energy: Eimpact = KE × R
7) Momentum: p = m × vi
8) TNT equivalent: Mt TNT = Eimpact / 4.184 × 1015
9) Simplified crater screening relation: D ≈ C × 18 × d × (ρi/ρt)1/3 × (vi/20000)0.44 × sin(θ)1/3 × η0.2
The crater expression is a practical scaling estimate for comparison. It is not a substitute for hydrocode or mission-grade impact modeling.
How to Use This Calculator
- Enter asteroid diameter and select the correct length unit.
- Choose a material preset or type a custom bulk density.
- Add entry velocity, impact angle, and porosity.
- Set atmospheric retention to reflect energy lost before impact.
- Set target density, coupling efficiency, and crater coefficient.
- Press Calculate Impact Energy to show the summary above the form.
- Review mass, velocity components, energy, TNT yield, and crater estimates.
- Use the CSV or PDF buttons to save your result set.
Frequently Asked Questions
1) What does this calculator estimate?
It estimates projectile mass, retained impact energy, TNT equivalent, momentum, velocity components, and a simplified crater size from user-defined physical inputs.
2) Why does velocity change the answer so much?
Kinetic energy scales with the square of speed. Doubling velocity roughly quadruples energy, so even modest speed differences can strongly change destructive potential.
3) Does angle affect total energy?
Total retained energy depends mostly on mass and speed, but angle changes vertical coupling, crater efficiency, and how strongly the impact transfers energy into the ground.
4) Are the crater results exact?
No. The crater values are fast screening estimates based on scaling behavior. Real outcomes depend on geology, fragmentation, atmosphere, target layering, and water content.
5) What density should I use?
Use stony values near 3,000 kg/m³, iron values near 7,800 kg/m³, carbonaceous bodies near 1,800 kg/m³, or enter custom data from your source.
6) What is atmospheric energy retention?
It represents the fraction of entry energy that remains available at impact after losses from heating, ablation, fragmentation, and atmospheric braking.
7) Can I use this for hazard planning?
Use it for first-pass comparisons only. Serious hazard work needs validated atmospheric entry models, target data, uncertainty ranges, and professional scenario analysis.
8) Why show TNT equivalent?
TNT equivalent converts joules into a more familiar explosive scale, which helps compare impact severity across very different asteroid sizes and velocities.