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Conversion from cr3bp fixed frame units to m/sec and km and seconds #47

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rslippert opened this issue Feb 6, 2024 · 0 comments
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@rslippert
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rslippert commented Feb 6, 2024

for CR3BP, NASA uses EMR as the term for Earth Moon Rotating Frame.
although I like EMB Earth Moon Barycenter or EMBR (EMB rotating)
For conversion of EMR units to m/sec and km and seconds
I'm using the following information:

27.32167 days per lunar sidereal revolution
1 EMB_days is 27.32167/2pi = 4.348378 days
1 EMB_secs = 375700. seconds (same as per radian of lunar revolution)
1 EMB distance =384400. km
1 EMB velocity = 1023.157 m/sec (Lunar rotational velocity)
1 EMB accel. = .002723335 m/sec2 EMBv/EMBsec=1023.157 / 375700.

Note: Don't forget that for EMB the location of X is the Barycenter.
So when converting EMB states to Kepler states for Lunar orbits:
The X coordinate needs to be subtracted by (1-mu) the X location of moon.
For X Earth orbits, subtract Mu from X because Earth is at [-mu, 0]
EMB_mu = .012153619
so for moon relative coordinates: X_km = ( X_EMB - (1 - .0121505845)) * 384400.
and for earth relative coordinates: X_km = ( X EMB + mu) * 384400.

@rslippert rslippert changed the title Convertion from cr3bp fixed frame units to m/sec and km and seconds Conversion from cr3bp fixed frame units to m/sec and km and seconds Mar 9, 2024
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