Specific Orbital Energy
Evaluate specific two-body orbital energy v²/2−μ/r in consistent units; this does not determine angular momentum or collision safety.
Description
Specific orbital energy is mechanical energy per unit mass in a two-body gravity model.
Specific orbital energy is mechanical energy per unit mass in a two-body gravity model. Its sign separates bound and unbound energy regimes, but radius and speed alone do not establish angular momentum or a safe orbit.1
Evaluate specific two-body orbital energy v²/2−μ/r in consistent units; this does not determine angular momentum or collision safety.
When to use Specific Orbital Energy
Use this tool to evaluate specific two-body orbital energy v²/2−μ/r in consistent units; this does not determine angular momentum or collision safety.
Prepare the orbital state or model parameters in one reference frame. Use compatible distance/time units and the stated angular and gravitational-parameter conventions.
How to use Specific Orbital Energy and understand its results
- Prepare the orbital state or model parameters in one reference frame. Use compatible distance/time units and the stated angular and gravitational-parameter conventions.
- Enter mu, radius, orbitalSpeed using the field table and calculation rules, then run the tool.
- Read specificEnergy, energyClass. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| mu | Gravitational parameter, using the same distance and time units throughout; km³/s² for km and seconds. | number | Required |
| radius | Radius | number | Required |
| orbitalSpeed | Orbital speed | number | Required |
Enter positive μ and radius and a nonnegative speed in consistent distance/time units. For km and seconds, μ is km³/s² and the result is km²/s². The tool subtracts gravitational potential from the kinetic term and labels a negative value bound, a positive value unbound, and exact zero parabolic-boundary.
specificEnergy = orbitalSpeed²/2 − μ/radius Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| specificEnergy | Specific energy | number |
| energyClass | Energy class | string |
{
"input": {
"mu": 1,
"radius": 1,
"orbitalSpeed": 1
},
"output": {
"specificEnergy": -0.5,
"energyClass": "bound"
}
}Limitations and assumptions
No tolerance, uncertainty or perturbations are modeled. A bound flag can describe a radial falling trajectory and is not a guarantee of a closed collision-free orbit. It does not return orbital orientation or angular momentum.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use State Eccentricity Vector: Derive the eccentricity vector and mathematical conic class from a nonradial two-body Cartesian state; floating values near one require physical uncertainty assessment. For a complementary task, use Semimajor Axis From Period: Invert Kepler third law for a positive elliptic semimajor axis using total gravitational parameter and period in compatible units.
References
-
Specific Orbital Energy — tool.io
Similar or alternative tools
- State Eccentricity Vector
Derive the eccentricity vector and mathematical conic class from a nonradial two-body Cartesian state; floating values near one require physical uncertainty assessment.
- Semimajor Axis From Period
Invert Kepler third law for a positive elliptic semimajor axis using total gravitational parameter and period in compatible units.