Design
| Enviro |
Astro | Propulsion
| Power | Thermal
| Structures | AD&C
| CDHS |
Test
Mathematical
predictions must account for these orbital disturbances
to
provide space systems engineers with accurate spacecraft
trajectory models.
Perturbations
Atmospheric
drag is
most prevalent in Low Earth Orbit (LEO) up to about
800 km. It is difficult to model, since atmospheric
density changes drastically from activity in the
magnetosphere and global temperatures that vary
with day-night and seasonal tilt.
Earth's
oblate shape
skews
gravitational force from that of a perfect sphere.
This affects the right ascension of the ascending
node and argument of perigee from the orbital elements.
Solar
radiation pressure
over
a long period of time may result in uncommanded
spacecraft rotation, which onboard attitude control
systems must then dampen.
The
Moon, Sun and planets
cause third-body gravitational effects most evident
on interplanetary transfers and orbits above LEO.
