165 lines
5.6 KiB
Python
Executable File
165 lines
5.6 KiB
Python
Executable File
#!/usr/bin/python3
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# tle2ssc
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# Convert a TLE into an .ssc file for Celestia
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#
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# Usage:
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# tle2ssc [filename]
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# Example:
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# tle2ssc foo-tle.txt
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# Check:
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# https://pypi.org/project/sgp4/
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# https://rhodesmill.org/skyfield/earth-satellites.html
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# https://github.com/ivanstan/tle-api
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# https://github.com/TruSat/trusat-orbit
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import os
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import skyfield
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import math
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from datetime import datetime
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from skyfield.api import load, wgs84
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from skyfield.api import EarthSatellite
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from sgp4.api import Satrec, WGS72
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satnum=37846
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satradius=0.005
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satname = 'GSAT0101'
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#satellites_url = 'http://celestrak.com/NORAD/elements/galileo.txt'
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satellites_url = './extras/galileo-gnss/galileo.txt'
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satellites = load.tle_file(satellites_url)
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#print('Loaded', len(satellites), 'satellites')
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ts = load.timescale()
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#t = ts.now()
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# 2022-05-20 02:17:30
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t = ts.utc(2022, 5, 20, 2, 17, 30)
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xpdotp = 1440.0 / (2.0 * math.pi)
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by_number = {sat.model.satnum: sat for sat in satellites}
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satellite = by_number[satnum]
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# Two different ways to get Epoch...
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#satepoch=(t.tdb)
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satepoch=satellite.model.jdsatepoch
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satellite_name=satname
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satellite_radius=satradius
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satellite_epoch=satepoch
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# ALLLLL XXX
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# The unique satellite NORAD catalog number given in the TLE file.
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satellite_number=satellite.model.satnum
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# Satellite classification, or else 'U' for “Unknown”
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satellite_classification=satellite.model.classification
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# International designator
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satellite_intldesg=satellite.model.intldesg
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# Full four-digit year of this element set’s epoch moment.
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satellite_epochyr=satellite.model.epochyr
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# Fractional days into the year of the epoch moment.
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satellite_epochdays=satellite.model.epochdays
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# Julian date of the epoch (computed from epochyr and epochdays).
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satellite_jdsatepoch=satellite.model.jdsatepoch
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# First time derivative of the mean motion (ignored by SGP4).
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satellite_ndot=satellite.model.ndot
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#print('satellite_ndot', satellite_ndot)
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# Second time derivative of the mean motion (ignored by SGP4).
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satellite_nddot=satellite.model.nddot
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#print('satellite_nddot', satellite_nddot)
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# Ballistic drag coefficient B* in inverse earth radii.
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satellite_bstar=satellite.model.bstar
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#print('satellite_bstar', satellite_bstar)
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# Ephemeris type (ignored by SGP4 as determination now automatic)
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satellite_ephtype=satellite.model.ephtype
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# Element number
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satellite_elnum=satellite.model.elnum
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# Inclination in radians. Convert radians to degrees.
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satellite_inclination=math.degrees(satellite.model.inclo)
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satellite_obliquity=math.degrees(satellite.model.inclo)
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# Right ascension of ascending node in radians. Convert to degrees.
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satellite_ascending_node=math.degrees(satellite.model.nodeo)
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satellite_equator_ascending_node=math.degrees(satellite.model.nodeo)
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# Eccentricity.
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satellite_eccentricity=satellite.model.ecco
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# Argument of perigee in radians.
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satellite_arg_of_pericenter=math.degrees(satellite.model.argpo)
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# Mean anomaly in radians.
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satellite_mean_anomoly=math.degrees(satellite.model.mo)
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# Mean motion in radians per minute.
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satellite_no_kozai=satellite.model.no_kozai
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satellite_period=(1 / (satellite.model.no_kozai * xpdotp))
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# Revolution number at epoch [Revs]
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satellite_revnum=satellite.model.revnum
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# 'i', # 'a' = old AFSPC mode, 'i' = improved mode
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# 5, # satnum: Satellite number
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# 18441.785, # epoch: days since 1949 December 31 00:00 UT
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# 2.8098e-05, # bstar: drag coefficient (/earth radii)
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# 6.969196665e-13, # ndot: ballistic coefficient (revs/day)
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# 0.0, # nddot: second derivative of mean motion (revs/day^3)
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# 0.1859667, # ecco: eccentricity
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# 5.7904160274885, # argpo: argument of perigee (radians)
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# 0.5980929187319, # inclo: inclination (radians)
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# 0.3373093125574, # mo: mean anomaly (radians)
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# 0.0472294454407, # no_kozai: mean motion (radians/minute)
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# 6.0863854713832, # nodeo: right ascension of ascending node (radians)
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# Create SSC
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# From TLE:
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# GSAT0101 (PRN E11)
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# 1 37846U 11060A 22140.09549104 -.00000093 00000+0 00000+0 0 9998
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# 2 37846 56.9858 22.1062 0004117 28.0726 331.9949 1.70474933 65739
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# Satellite name: GSAT0101
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# Satellite number: 37846U
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# Satellite number: 37846
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# International designator: 11060A
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# Inclination: 56.9858
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# Epoch year and Julian day fraction: 22140.09549104
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# Right ascension of ascending node: 22.1062
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# Eccentricity: 0004117
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# First derivative of mean motion or ballistic coefficient: -.00000093
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# Argument of perigee: 28.0726
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# Second derivative of mean motion: 00000+0
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# Mean anomaly: 331.9949
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# Drag term or radiation pressure coefficient: 00000+0
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# Mean motion: 1.70474933
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# Ephemeris type: 0
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# Element number and checksum: 9998
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# Revolution number at epoch and checksum: 65739
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# Convert epoch from TLE to SSC
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# Convert TLE to Julian Day
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# C47 = Epoch Year = 2022
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# =1721424.5-INT((C47-1)/100)+INT((C47-1)/400)+INT(365.25*(C47-1))+C49
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print('"', satellite_name, '-', satellite_number, '" ','"Sol/Earth" {',sep="")
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print(' Class "spacecraft"')
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print(' # Mesh "foo.3ds XXX"')
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print(' radius', satellite_radius)
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print()
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print(' EllipticalOrbit {')
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print(' Epoch', satellite_epoch)
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print(' Period', satellite_period)
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print(' SemiMajorAxis 29600.181 XXX')
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print(' Eccentricity', satellite_eccentricity)
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print(' Inclination', satellite_inclination)
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print(' AscendingNode', satellite_ascending_node)
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print(' ArgOfPericenter', satellite_arg_of_pericenter)
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print(' MeanAnomaly', satellite_mean_anomoly)
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print(' }')
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print(' Obliquity', satellite_obliquity)
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print(' EquatorAscendingNode', satellite_equator_ascending_node)
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print(' RotationOffset 312.7348 XXX')
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print(' # Orientation [ ]')
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print('}')
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