Solar Radiation Pressure Orbit Drift Calculator
Orbital Perturbations & Space Debris: Model solar radiation pressure (SRP) acceleration ($a_{srp}$), long-period eccentricity oscillations, and perigee pumping for high area-to-mass satellites.
Spacecraft Area-to-Mass Properties
Orbit Sizing
SRP Perturbation & Drift Output
Solar Radiation Pressure (SRP) Orbital Perturbation Theory
Solar photon momentum transfer causes non-gravitational orbital perturbations that dominate high area-to-mass satellites and solar sails.
1. Photon Momentum & Acceleration
P_solar = Solar_Flux / c_light ≈ 4.54 μPa a_srp = C_R · ( Area / Mass ) · P_solar [m/s²]
2. Secular Eccentricity Pumping Amplitude
Δe_max ≈ ( 3 / 2 ) · [ a_srp / ( n² · a ) ] Δh_perigee = a · Δe_max
Frequently Asked Questions
What is Solar Radiation Pressure (SRP) in orbital mechanics?
Solar Radiation Pressure is the physical mechanical force exerted on a spacecraft surface by photons emitted by the Sun. Photons carry momentum ($p = E / c$). When sunlight is absorbed or specularly reflected by satellite surfaces (solar arrays, multi-layer insulation), momentum exchange creates a continuous disturbing acceleration ($a_{srp} \approx 10^{-6}\sim 10^{-4}\,\text{m/s}^2$).
Why does SRP cause orbital eccentricity to oscillate over time?
Over an orbit, SRP adds energy on the side where the satellite travels away from the Sun and removes energy on the opposite side. This asymmetry breaks the symmetry of the ellipse, driving long-period sinusoidal oscillations in orbital eccentricity (known as "eccentricity pumping"). For high area-to-mass objects (HAMR debris, CubeSats), eccentricity can increase until perigee dips into the upper atmosphere, causing premature re-entry.
What is the optical reflectivity coefficient (C_R)?
The radiation pressure coefficient $C_R = 1 + R_{refl}$ ranges from $1.0$ for a perfectly absorbing black body ($R_{refl}=0$) to $2.0$ for a perfectly reflecting mirror ($R_{refl}=1$). Most satellites with a mix of solar cells and aluminized thermal blankets exhibit an effective $C_R$ between $1.2$ and $1.5$.