Earth Parameters¶
| Symbol | Value | Units | Description |
|---|---|---|---|
| \(R_E\) | 6,371,000 | m | Mean Earth radius |
| \(\mu\) | 3.986004418 × 10¹⁴ | m³/s² | Gravitational parameter |
| \(g_0\) | 9.80665 | m/s² | Standard gravity |
| \(M_E\) | 5.972 × 10²⁴ | kg | Earth mass |
| \(\omega_E\) | 7.2921 × 10⁻⁵ | rad/s | Earth rotation rate |
Atmosphere (Sea Level)¶
| Property | Value | Units |
|---|---|---|
| Pressure | 101,325 | Pa |
| Density | 1.225 | kg/m³ |
| Temperature | 288.15 | K |
| Speed of Sound | 340.3 | m/s |
Unit Conversions¶
| Conversion | Value |
|---|---|
| 1 km → m | 1,000 |
| 1 deg → rad | π/180 = 0.01745 |
| 1 kN → N | 1,000 |
| 1 tonne → kg | 1,000 |
Orbital Velocities¶
For circular orbits at altitude \(h\):
\[
v = \sqrt{\frac{\mu}{R_E + h}}
\]
| Altitude | Velocity | Period |
|---|---|---|
| 160 km | 7,808 m/s | 87.5 min |
| 200 km | 7,784 m/s | 88.4 min |
| 400 km (ISS) | 7,668 m/s | 92.7 min |
Implementation¶
# apogee_physics/types.py
@dataclass(frozen=True, slots=True)
class EarthParams:
r_e: float = 6_371_000.0 # Earth radius [m]
mu: float = 3.986004418e14 # Gravitational parameter [m³/s²]
g0: float = 9.80665 # Standard gravity [m/s²]