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| from __future__ import division
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| from visual import *
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| from visual.graph import *
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| scene.width=1024
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| scene.height=760
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|
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| # CONSTANTS
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| G = 6.7e-11
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| mEarth = 6e24
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| mcraft = 15000
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| deltat = 60
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| t = 0
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| mMoon = 7e22
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| scale = 800000
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| c=2.99792e8
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|
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| #OBJECTS AND INITIAL VALUES
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| Earth = sphere(pos=vector(0,0,0), radius=15e6, material = materials.BlueMarble)
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| # Add a radius for the spacecraft. It should be BIG, so it can be seen.
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| craft = sphere(pos=vector(-60160000,-192000,0), radius=2e6, material = materials.marble)
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| Moon = sphere(pos=vector(4e8,0,0), radius=1.75e6, material = materials.marble)
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| vcraft = vector(735,2849,0)
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| pcraft = mcraft*vcraft
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|
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| trail = curve(color=craft.color) # This creates a trail for the spacecraft
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| #scene.autoscale = 1000000 # And this prevents zooming in or out
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|
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| pscale = Earth.radius / mag(pcraft)
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| fscale = Earth.radius/ ((G*mEarth*mcraft)/mag(craft.pos-Earth.pos)**2)
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| dpscale = 500 * Earth.radius/mag(pcraft)
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|
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| r_EarthMoon = Moon.pos - Earth.pos #Relative position vector from Earth to Moon
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| r_EarthMoon_mag = mag(r_EarthMoon)
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| F_EarthMoon_mag = (G*mcraft*mEarth)/(r_EarthMoon_mag**2)
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| r_EarthMoon_hat = r_EarthMoon/r_EarthMoon_mag
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|
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| Force_EarthMoon = (-r_EarthMoon_hat)*F_EarthMoon_mag #Force on Moon due to Earth
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| pMoon = Force_EarthMoon / deltat
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|
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| # CALCULATIONS
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| print("p=", pcraft)
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| while t < (10e10):
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| rate(500) # This slows down the animation (runs faster with bigger number)
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| rE = craft.pos - Earth.pos
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| rEmag = mag(rE)
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| FEmag = (G*mcraft*mEarth)/(rEmag**2)
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| rEhat = rE/rEmag
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| FEnet = (-rEhat)*FEmag
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|
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| rM = craft.pos - Moon.pos
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| rMmag = mag(rM)
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| FMmag = (G*mcraft*mMoon)/(rMmag**2)
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| rMhat = rM/rMmag
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| FMnet = (-rMhat)*FMmag
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|
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| Fnet = FMnet+FEnet
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|
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| pcraft_i = pcraft + vector(0,0,0)
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| pcraft_ii = mag(pcraft_i)
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| pcraft = pcraft + ((Fnet)*deltat)
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| pcraft_f = pcraft
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| pcraft_ff = mag(pcraft)
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| vavg = pcraft/mcraft
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| speedcraft = mag(vavg)
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| craft.pos = craft.pos + vavg*deltat
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|
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| Fnet_tangent = ((pcraft_ff-pcraft_ii)/deltat)*(pcraft/mag(pcraft))*pscale
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| Fnet_perp = Fnet - Fnet_tangent
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|
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| r_EarthMoon = Moon.pos - Earth.pos #Relative position vector from Earth to Moon
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| r_EarthMoon_mag = mag(r_EarthMoon)
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| F_EarthMoon_mag = (G*mcraft*mEarth)/(r_EarthMoon_mag**2)
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| r_EarthMoon_hat = r_EarthMoon/r_EarthMoon_mag
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|
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| r_craftMoon = Moon.pos - craft.pos#Relative position vector from spacecraft to Moon
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| r_craftMoon_mag = mag(r_craftMoon)
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| F_craftMoon_mag = (G*mcraft*mEarth)/(r_craftMoon_mag**2)
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| r_craftMoon_hat = r_craftMoon/r_craftMoon_mag
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|
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| Force_EarthMoon = (-r_EarthMoon_hat)*F_EarthMoon_mag #Force on Moon due to Earth
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| Force_craftMoon = (-r_craftMoon_hat)*F_craftMoon_mag#Force on Moon due to spacecraft
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| Fnet_Moon = Force_EarthMoon + Force_craftMoon #Net force on Moon
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|
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| momentum_Moon = pMoon + Fnet_Moon*deltat#Update momentum of Moon
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| vavg_Moon = momentum_Moon/mMoon
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| Moon.pos = Moon.pos + vavg_Moon * deltat #Update momentum of Moon
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|
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| trail.append(pos=craft.pos)
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| t = t+deltat
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| pcraft = pcraft_f
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| deltap = pcraft - pcraft_i
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