# Shared Flashcard Set

## Details

AERO 451
Spacecraft Dynamics 1
15
Aerospace Engineering
06/04/2011

Term
 Equinox
Definition
 Twice per year -Equitorial and Orbital plane meet March 20/21 - Spring Equinox Sept 22/23 - Fall Equinox
Term
 Solstice
Definition
 Twice per year Equitorial and Orbital plan are furthest away June 20/21 - Summer Solstice Dec 22/23 - Winter Solstice
Term
 First Point of Aries
Definition
 Defined as the position of the sun @ the time of Vernal Equinox   Named for constellation where sun was when it occured
Term
 Mean Solar Time
Definition
 Kept by clocks   Assumes a circular orbit
Term
 Sidereal Time
Definition
Term
 Kepler's Laws
Definition
 Planets orbit in ellipses with sun @ 1 focus Law of Areas Equal area in equal time If A1=A2=A3 Then T1=T2=T3 P2 α a3 - Square of Period is proportional to cube of mean distance from sun.
Term
 Periapse
Definition
 When m is closest to M   Velocity is greatest
Term
 Apoapse
Definition
 When m is furthest from M   Velocity is the smallest
Term
 Newtons Law of Gravitation
Definition
 Force =     Gm1m2 r2   G=6.6742 x 10-11
Term
 Flight Path Angle
Definition
 Angle between the normal to position vector and the velocity vector
Term
 Coordinate Systems ECI
Definition
 Earth Centered Inertial   Fixed Vernal Equinox
Term
 Coordinate Systems GCRF
Definition
 Geocentric Celestial Reference Frame
Term
 Coordinate Systems ECEF
Definition
 Earch Centered Earth Fixed
Term
 Coordinate Systems Perifocal Frame
Definition
 Most Common Earth Centered Orbit Based Inertial S/C fixed - rotating   Not for circular orbits PQW unit vectors. P points towards perigee
Term
 Rules for HT vs. Bi-elliptical
Definition
 If outer target is <11.9x inner, H.T is better If outer target is >15x inner, Bi-elliptical  is better
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