AccelEarthRad

class ssapy.accel.AccelEarthRad(**defaultkw)[source][source]

Bases: Accel

Acceleration due to Earth radiation pressure.

This is a very simple model in which the direction of the acceleration is directly away from the Earth and the magnitude is modulated by a single solar radiation pressure coefficient CR. The coefficient is 1.0 for purely absorbed light, and 2.0 for purely reflected light. Rough typical values for a variety of different satellite components are

~ 1.2 for solar panels ~ 1.3 for a high gain antenna ~ 1.9 for a aluminum coated mylar solar sail.

The radiation pressure at the Earth’s surface is given as (230 + 459*k) W/m^2, where 230 is from the thermal radiation of the earth, and 459 is the reflected sunlight. k is the illuminated fraction of the earth as seen from the satellite, assuming the earth is point-like (i.e., neglecting that the satellite will see less than a full hemisphere for LEO objects). The radiation pressure goes down like 1/r^2 as an object moves away from the earth.

This is a simplification of the more complex model presented in MG 3.7.1, neglecting spatial variation in the emitted light and the different angles to different parts of the earth.

Parameters:

defaultkw (dict) – default parameters for kwargs passed to __call__, (area, mass, CR)

Methods Summary

__call__(r, v, t, **kwargs)

Evaluate acceleration at particular place/moment.

Methods Documentation

__call__(r, v, t, **kwargs)[source][source]

Evaluate acceleration at particular place/moment.

Parameters:

  • r (array_like, shape(3, )) – Position in meters in GCRF frame.

  • v (array_like, shape(3, )) – Velocity in meters per second. Unused.

  • t (float) – Time as GPS seconds

  • area (float) – Area in meters^2.

  • mass (flat) – Mass in kg.

  • CR (float) – Radiation pressure coefficient.

Returns:

accel – Acceleration in meters per second^2

Return type:

array_like, shape(3,)