Units

For those inputs that do not explicitly indicate units, DU, TU, and radians are assumed by default. Sticky unit specifiers modify the default units for all following entries until updated. One DU is the scaling radius used by the gravity model (phy_const::km_per_du). It is very close to one earth radius but tied to the gravity model vs. the ellipsoid model defining the shape of the earth. One TU (Herg) is the time it would take a circular orbit with a radius of 1 DU to travel 1 DU. The gravitational parameter is equal to 1 using units of DU and TU.

DistanceUnits DU
DistanceUnits Kilometers
DistanceUnits Meters

TimeUnits TU
TimeUnits Minutes
TimeUnits Seconds

AngleUnits Radians
AngleUnits Degrees

Some input types require units to be specified. This typically occurs where it would be inconvenient to have to change the default sticky units. For example, one set of sticky units would be set to input a batch of state vectors and orbital elements (kilometers, seconds, degrees). The time sticky unit could be set to minutes at the end of the scenario definition to indicate command output rates. In the middle, various other inputs could vary greatly w.r.t. the most commonly used or readable units.

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