Class: Orbit::Orbit

Inherits:
Object
  • Object
show all
Defined in:
lib/orbit/orbit.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tle) ⇒ Orbit

Returns a new instance of Orbit.



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# File 'lib/orbit/orbit.rb', line 27

def initialize( tle )
  @tle = tle


  @epoch = tle.epoch
  # puts "Orbit @epoch is now: #{@epoch}"


  @m_Inclination   = OrbitGlobals.deg_to_rad(@tle.inclination)
  @m_Eccentricity  = @tle.eccentricity
  @m_RAAN          = OrbitGlobals.deg_to_rad(@tle.raan)
  @m_ArgPerigee    = OrbitGlobals.deg_to_rad(@tle.arg_perigee)
  @m_BStar         = @tle.bstar_drag
  @m_Drag          = @tle.mean_motion_dt
  @m_MeanAnomaly   = OrbitGlobals.deg_to_rad(@tle.mean_anomaly)
  @m_TleMeanMotion = @tle.mean_motion

  # Recover the original mean motion and semimajor axis from the
  # input elements.
  mm     = tle_mean_motion
  rpmin  = mm * OrbitGlobals::TWO_PI / OrbitGlobals::MIN_PER_DAY   # rads per minute

  a1     = (OrbitGlobals::XKE / rpmin) ** (2.0 / 3.0)
  e      = eccentricity
  i      = inclination
  temp   = (1.5 * OrbitGlobals::CK2 * (3.0 * (Math.cos(i) ** 2) - 1.0) /
                  ( (1.0 - e * e) ** 1.5 ) )
  delta1 = temp / (a1 * a1)
  a0     = a1 *
                 (1.0 - delta1 *
                 ((1.0 / 3.0) + delta1 *
                 (1.0 + 134.0 / 81.0 * delta1)))

  delta0 = temp / (a0 * a0)

  @m_rmMeanMotionRec    = rpmin / (1.0 + delta0)
  @m_aeAxisSemiMajorRec = a0 / (1.0 - delta0)
  @m_aeAxisSemiMinorRec = @m_aeAxisSemiMajorRec * Math.sqrt(1.0 - (e * e))
  @m_kmPerigeeRec       = OrbitGlobals::XKMPER * (m_aeAxisSemiMajorRec * (1.0 - e) - OrbitGlobals::AE)
  @m_kmApogeeRec        = OrbitGlobals::XKMPER * (m_aeAxisSemiMajorRec * (1.0 + e) - OrbitGlobals::AE)



  @period_minutes = calculate_period_minutes

  if @period_minutes > 225
    @norad_model = NoradSDP4.new( self )
  else
    @norad_model = NoradSGP4.new( self )
  end
end

Instance Attribute Details

#epoch ⇒ Object

Returns the value of attribute epoch.



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# File 'lib/orbit/orbit.rb', line 22

def epoch
  @epoch
end

#m_aeAxisSemiMajorRec ⇒ Object

Caching variables recovered from the input TLE elements



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# File 'lib/orbit/orbit.rb', line 16

def m_aeAxisSemiMajorRec
  @m_aeAxisSemiMajorRec
end

#m_aeAxisSemiMinorRec ⇒ Object

semiminor axis, in AE units



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# File 'lib/orbit/orbit.rb', line 17

def m_aeAxisSemiMinorRec
  @m_aeAxisSemiMinorRec
end

#m_ArgPerigee ⇒ Object

Returns the value of attribute m_ArgPerigee.



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# File 'lib/orbit/orbit.rb', line 9

def m_ArgPerigee
  @m_ArgPerigee
end

#m_BStar ⇒ Object

Returns the value of attribute m_BStar.



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# File 'lib/orbit/orbit.rb', line 10

def m_BStar
  @m_BStar
end

#m_Drag ⇒ Object

Returns the value of attribute m_Drag.



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# File 'lib/orbit/orbit.rb', line 11

def m_Drag
  @m_Drag
end

#m_Eccentricity ⇒ Object

Returns the value of attribute m_Eccentricity.



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# File 'lib/orbit/orbit.rb', line 7

def m_Eccentricity
  @m_Eccentricity
end

#m_Inclination ⇒ Object

TLE caching variables



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# File 'lib/orbit/orbit.rb', line 6

def m_Inclination
  @m_Inclination
end

#m_kmApogeeRec ⇒ Object

apogee, in km



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# File 'lib/orbit/orbit.rb', line 20

def m_kmApogeeRec
  @m_kmApogeeRec
end

#m_kmPerigeeRec ⇒ Object

perigee, in km



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# File 'lib/orbit/orbit.rb', line 19

def m_kmPerigeeRec
  @m_kmPerigeeRec
end

#m_MeanAnomaly ⇒ Object

Returns the value of attribute m_MeanAnomaly.



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# File 'lib/orbit/orbit.rb', line 13

def m_MeanAnomaly
  @m_MeanAnomaly
end

#m_RAAN ⇒ Object

Returns the value of attribute m_RAAN.



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# File 'lib/orbit/orbit.rb', line 8

def m_RAAN
  @m_RAAN
end

#m_rmMeanMotionRec ⇒ Object

radians per minute



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# File 'lib/orbit/orbit.rb', line 18

def m_rmMeanMotionRec
  @m_rmMeanMotionRec
end

#m_TleMeanMotion ⇒ Object

Returns the value of attribute m_TleMeanMotion.



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# File 'lib/orbit/orbit.rb', line 12

def m_TleMeanMotion
  @m_TleMeanMotion
end

#norad_model ⇒ Object

Returns the value of attribute norad_model.



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# File 'lib/orbit/orbit.rb', line 24

def norad_model
  @norad_model
end

#period ⇒ Object

Returns the value of attribute period.



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# File 'lib/orbit/orbit.rb', line 25

def period
  @period
end

#tle ⇒ Object

Returns the value of attribute tle.



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# File 'lib/orbit/orbit.rb', line 3

def tle
  @tle
end

Instance Method Details

#apogee ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 124

def apogee
 return @m_kmApogeeRec
end

#arg_perigee ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 137

def arg_perigee
 return @m_ArgPerigee
end

#bstar ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 140

def bstar
 return @m_BStar
end

#calculate_period_minutes ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 79

def calculate_period_minutes
  if @tle.mean_motion == 0
    minutes = 0.0
  else
    minutes = (OrbitGlobals::TWO_PI / @tle.mean_motion)
  end

  minutes
end

#drag ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 143

def drag
 return @m_Drag
end

#eccentricity ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 131

def eccentricity
 return @m_Eccentricity
end

#epoch_time ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 102

def epoch_time
  @epoch
end

#get_position(minutesPastEpoch) ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 89

def get_position(minutesPastEpoch)
  # puts "Orbit.get_position( #{minutesPastEpoch} )"

  eci = @norad_model.get_position(minutesPastEpoch)

  # puts "Position: #{eci.m_Position.m_x}"

  eci.scale_pos_vector(OrbitGlobals::XKMPER / OrbitGlobals::AE)      # km
  eci.scale_vel_vector((OrbitGlobals::XKMPER / OrbitGlobals::AE) *
                    (OrbitGlobals::MIN_PER_DAY / 86400.0))      # km/sec
  return eci
end

#inclination ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 128

def inclination
 return @m_Inclination
end

#major ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 115

def major
 return 2.0 * SemiMajor
end

#mean_anomaly ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 146

def mean_anomaly
 return @m_MeanAnomaly
end

#mean_motion ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 112

def mean_motion
 return @m_rmMeanMotionRec
end

#minor ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 118

def minor
 return 2.0 * SemiMinor
end

#perigee ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 121

def perigee
 return @m_kmPerigeeRec
end

#raan ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 134

def raan
 return @m_RAAN
end

#sat_name ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 156

def sat_name
 return @tle.name
end

#sat_name_long ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 159

def sat_name_long
 return SatName + " #" + SatNoradId
end

#sat_norad_id ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 153

def sat_norad_id
 return @tle.norad_number
end

#semi_major ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 106

def semi_major
 return @m_aeAxisSemiMajorRec
end

#semi_minor ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 109

def semi_minor
 return @m_aeAxisSemiMinorRec
end

#tle_mean_motion ⇒ Object 



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# File 'lib/orbit/orbit.rb', line 149

def tle_mean_motion
 return @m_TleMeanMotion
end