org.orekit.propagation.analytical.tle

Class TLE

java.lang.Object

org.orekit.propagation.analytical.tle.TLE

All Implemented Interfaces:

Serializable, TimeStamped

public class TLE
extends Object
implements TimeStamped, Serializable

This class is a container for a single set of TLE data.

TLE sets can be built either by providing directly the two lines, in which case parsing is performed internally or by providing the already parsed elements.

TLE are not transparently convertible to Orbit instances. They are significant only with respect to their dedicated propagator, which also computes position and velocity coordinates. Any attempt to directly use orbital parameters like eccentricity, inclination, etc. without any reference to the TLE propagator is prone to errors.

More information on the TLE format can be found on the CelesTrak website.

Author:

Fabien Maussion, Luc Maisonobe

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	B_STAR Parameter name for B* coefficient.
static int	DEFAULT Identifier for default type of ephemeris (SGP4/SDP4).
static int	SDP4 Identifier for SDP4 type of ephemeris.
static int	SDP8 Identifier for SDP8 type of ephemeris.
static int	SGP Identifier for SGP type of ephemeris.
static int	SGP4 Identifier for SGP4 type of ephemeris.
static int	SGP8 Identifier for SGP8 type of ephemeris.

Constructor Summary

Constructors

Constructor and Description
TLE(int satelliteNumber, char classification, int launchYear, int launchNumber, String launchPiece, int ephemerisType, int elementNumber, AbsoluteDate epoch, double meanMotion, double meanMotionFirstDerivative, double meanMotionSecondDerivative, double e, double i, double pa, double raan, double meanAnomaly, int revolutionNumberAtEpoch, double bStar) Simple constructor from already parsed elements.
TLE(int satelliteNumber, char classification, int launchYear, int launchNumber, String launchPiece, int ephemerisType, int elementNumber, AbsoluteDate epoch, double meanMotion, double meanMotionFirstDerivative, double meanMotionSecondDerivative, double e, double i, double pa, double raan, double meanAnomaly, int revolutionNumberAtEpoch, double bStar, TimeScale utc) Simple constructor from already parsed elements using the given time scale as UTC.
TLE(String line1, String line2) Simple constructor from unparsed two lines.
TLE(String line1, String line2, TimeScale utc) Simple constructor from unparsed two lines using the given time scale as UTC.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o) Check if this tle equals the provided tle.
double	getBStar() Get the ballistic coefficient.
char	getClassification() Get the classification.
AbsoluteDate	getDate() Get the TLE current date.
double	getE() Get the eccentricity.
int	getElementNumber() Get the element number.
int	getEphemerisType() Get the type of ephemeris.
double	getI() Get the inclination.
int	getLaunchNumber() Get the launch number.
String	getLaunchPiece() Get the launch piece.
int	getLaunchYear() Get the launch year.
String	getLine1() Get the first line.
String	getLine2() Get the second line.
double	getMeanAnomaly() Get the mean anomaly.
double	getMeanMotion() Get the mean motion.
double	getMeanMotionFirstDerivative() Get the mean motion first derivative.
double	getMeanMotionSecondDerivative() Get the mean motion second derivative.
ParameterDriver	getParameterDriver(String name) Get parameter driver from its name.
List<ParameterDriver>	getParametersDrivers() Get the drivers for TLE propagation SGP4 and SDP4.
double	getPerigeeArgument() Get the argument of perigee.
double	getRaan() Get Right Ascension of the Ascending node.
int	getRevolutionNumberAtEpoch() Get the revolution number.
int	getSatelliteNumber() Get the satellite id.
TimeScale	getUtc() Get the UTC time scale used to create this TLE.
int	hashCode() Get a hashcode for this tle.
static boolean	isFormatOK(String line1, String line2) Check the lines format validity.
static TLE	stateToTLE(SpacecraftState state, TLE templateTLE) Convert Spacecraft State into TLE.
static TLE	stateToTLE(SpacecraftState state, TLE templateTLE, TimeScale utc, Frame teme) Convert Spacecraft State into TLE.
static TLE	stateToTLE(SpacecraftState state, TLE templateTLE, TimeScale utc, Frame teme, double epsilon, int maxIterations) Convert Spacecraft State into TLE.
String	toString() Get a string representation of this TLE set.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

SGP

public static final int SGP

Identifier for SGP type of ephemeris.

See Also:

Constant Field Values

SGP4

public static final int SGP4

Identifier for SGP4 type of ephemeris.

See Also:

Constant Field Values

SDP4

public static final int SDP4

Identifier for SDP4 type of ephemeris.

See Also:

Constant Field Values

SGP8

public static final int SGP8

Identifier for SGP8 type of ephemeris.

See Also:

Constant Field Values

SDP8

public static final int SDP8

Identifier for SDP8 type of ephemeris.

See Also:

Constant Field Values

DEFAULT

public static final int DEFAULT

Identifier for default type of ephemeris (SGP4/SDP4).

See Also:

Constant Field Values

B_STAR

public static final String B_STAR

Parameter name for B* coefficient.

See Also:

Constant Field Values

Constructor Detail

TLE

@DefaultDataContext
public TLE(String line1,
                               String line2)

Simple constructor from unparsed two lines. This constructor uses the default data context.

The static method isFormatOK(String, String) should be called before trying to build this object.

Parameters:

line1 - the first element (69 char String)

line2 - the second element (69 char String)

See Also:

TLE(String, String, TimeScale)

TLE

public TLE(String line1,
           String line2,
           TimeScale utc)

Simple constructor from unparsed two lines using the given time scale as UTC.

The static method isFormatOK(String, String) should be called before trying to build this object.

Parameters:

line1 - the first element (69 char String)

line2 - the second element (69 char String)

utc - the UTC time scale.

Since:

10.1

TLE

@DefaultDataContext
public TLE(int satelliteNumber,
                               char classification,
                               int launchYear,
                               int launchNumber,
                               String launchPiece,
                               int ephemerisType,
                               int elementNumber,
                               AbsoluteDate epoch,
                               double meanMotion,
                               double meanMotionFirstDerivative,
                               double meanMotionSecondDerivative,
                               double e,
                               double i,
                               double pa,
                               double raan,
                               double meanAnomaly,
                               int revolutionNumberAtEpoch,
                               double bStar)

Simple constructor from already parsed elements. This constructor uses the default data context.

The mean anomaly, the right ascension of ascending node Ω and the argument of perigee ω are normalized into the [0, 2π] interval as they can be negative. After that, a range check is performed on some of the orbital elements:

     meanMotion >= 0
     0 <= i <= π
     0 <= Ω <= 2π
     0 <= e <= 1
     0 <= ω <= 2π
     0 <= meanAnomaly <= 2π
 

Parameters:

satelliteNumber - satellite number

classification - classification (U for unclassified)

launchYear - launch year (all digits)

launchNumber - launch number

launchPiece - launch piece (3 char String)

ephemerisType - type of ephemeris

elementNumber - element number

epoch - elements epoch

meanMotion - mean motion (rad/s)

meanMotionFirstDerivative - mean motion first derivative (rad/s²)

meanMotionSecondDerivative - mean motion second derivative (rad/s³)

e - eccentricity

i - inclination (rad)

pa - argument of perigee (rad)

raan - right ascension of ascending node (rad)

meanAnomaly - mean anomaly (rad)

revolutionNumberAtEpoch - revolution number at epoch

bStar - ballistic coefficient

See Also:

TLE(int, char, int, int, String, int, int, AbsoluteDate, double, double, double, double, double, double, double, double, int, double, TimeScale)

TLE

public TLE(int satelliteNumber,
           char classification,
           int launchYear,
           int launchNumber,
           String launchPiece,
           int ephemerisType,
           int elementNumber,
           AbsoluteDate epoch,
           double meanMotion,
           double meanMotionFirstDerivative,
           double meanMotionSecondDerivative,
           double e,
           double i,
           double pa,
           double raan,
           double meanAnomaly,
           int revolutionNumberAtEpoch,
           double bStar,
           TimeScale utc)

Simple constructor from already parsed elements using the given time scale as UTC.

The mean anomaly, the right ascension of ascending node Ω and the argument of perigee ω are normalized into the [0, 2π] interval as they can be negative. After that, a range check is performed on some of the orbital elements:

     meanMotion >= 0
     0 <= i <= π
     0 <= Ω <= 2π
     0 <= e <= 1
     0 <= ω <= 2π
     0 <= meanAnomaly <= 2π
 

Parameters:

satelliteNumber - satellite number

classification - classification (U for unclassified)

launchYear - launch year (all digits)

launchNumber - launch number

launchPiece - launch piece (3 char String)

ephemerisType - type of ephemeris

elementNumber - element number

epoch - elements epoch

meanMotion - mean motion (rad/s)

meanMotionFirstDerivative - mean motion first derivative (rad/s²)

meanMotionSecondDerivative - mean motion second derivative (rad/s³)

e - eccentricity

i - inclination (rad)

pa - argument of perigee (rad)

raan - right ascension of ascending node (rad)

meanAnomaly - mean anomaly (rad)

revolutionNumberAtEpoch - revolution number at epoch

bStar - ballistic coefficient

utc - the UTC time scale.

Since:

10.1

Method Detail

getUtc

public TimeScale getUtc()

Get the UTC time scale used to create this TLE.

Returns:

UTC time scale.

getLine1

public String getLine1()

Get the first line.

Returns:

first line

getLine2

public String getLine2()

Get the second line.

Returns:

second line

getSatelliteNumber

public int getSatelliteNumber()

Get the satellite id.

Returns:

the satellite number

getClassification

public char getClassification()

Get the classification.

Returns:

classification

getLaunchYear

public int getLaunchYear()

Get the launch year.

Returns:

the launch year

getLaunchNumber

public int getLaunchNumber()

Get the launch number.

Returns:

the launch number

getLaunchPiece

public String getLaunchPiece()

Get the launch piece.

Returns:

the launch piece

getEphemerisType

public int getEphemerisType()

Get the type of ephemeris.

Returns:

the ephemeris type (one of DEFAULT, SGP, SGP4, SGP8, SDP4, SDP8)

getElementNumber

public int getElementNumber()

Get the element number.

Returns:

the element number

getDate

public AbsoluteDate getDate()

Get the TLE current date.

Specified by:

getDate in interface TimeStamped

Returns:

the epoch

getMeanMotion

public double getMeanMotion()

Get the mean motion.

Returns:

the mean motion (rad/s)

getMeanMotionFirstDerivative

public double getMeanMotionFirstDerivative()

Get the mean motion first derivative.

Returns:

the mean motion first derivative (rad/s²)

getMeanMotionSecondDerivative

public double getMeanMotionSecondDerivative()

Get the mean motion second derivative.

Returns:

the mean motion second derivative (rad/s³)

getE

public double getE()

Get the eccentricity.

Returns:

the eccentricity

getI

public double getI()

Get the inclination.

Returns:

the inclination (rad)

getPerigeeArgument

public double getPerigeeArgument()

Get the argument of perigee.

Returns:

omega (rad)

getRaan

public double getRaan()

Get Right Ascension of the Ascending node.

Returns:

the raan (rad)

getMeanAnomaly

public double getMeanAnomaly()

Get the mean anomaly.

Returns:

the mean anomaly (rad)

getRevolutionNumberAtEpoch

public int getRevolutionNumberAtEpoch()

Get the revolution number.

Returns:

the revolutionNumberAtEpoch

getBStar

public double getBStar()

Get the ballistic coefficient.

Returns:

bStar

toString

public String toString()

Get a string representation of this TLE set.

The representation is simply the two lines separated by the platform line separator.

Overrides:

toString in class Object

Returns:

string representation of this TLE set

stateToTLE

@DefaultDataContext
public static TLE stateToTLE(SpacecraftState state,
                                                 TLE templateTLE)

Convert Spacecraft State into TLE. This converter uses Fixed Point method to reverse SGP4 and SDP4 propagation algorithm and generates a usable TLE version of a state. Equinocital orbital parameters are used in order to get a stiff method. New TLE epoch is state epoch.

This method uses the default data context, as well as EPSILON_DEFAULT and MAX_ITERATIONS_DEFAULT for method convergence.

Parameters:

state - Spacecraft State to convert into TLE

templateTLE - first guess used to get identification and estimate new TLE

Returns:

TLE matching with Spacecraft State and template identification

Since:

11.0

See Also:

stateToTLE(SpacecraftState, TLE, TimeScale, Frame), stateToTLE(SpacecraftState, TLE, TimeScale, Frame, double, int)

stateToTLE

public static TLE stateToTLE(SpacecraftState state,
                             TLE templateTLE,
                             TimeScale utc,
                             Frame teme)

Convert Spacecraft State into TLE. This converter uses Fixed Point method to reverse SGP4 and SDP4 propagation algorithm and generates a usable TLE version of a state. Equinocital orbital parameters are used in order to get a stiff method. New TLE epoch is state epoch.

This method uses EPSILON_DEFAULT and MAX_ITERATIONS_DEFAULT for method convergence.

Parameters:

state - Spacecraft State to convert into TLE

templateTLE - first guess used to get identification and estimate new TLE

utc - the UTC time scale

teme - the TEME frame to use for propagation

Returns:

TLE matching with Spacecraft State and template identification

Since:

11.0

See Also:

stateToTLE(SpacecraftState, TLE, TimeScale, Frame, double, int)

stateToTLE

public static TLE stateToTLE(SpacecraftState state,
                             TLE templateTLE,
                             TimeScale utc,
                             Frame teme,
                             double epsilon,
                             int maxIterations)

Convert Spacecraft State into TLE. This converter uses Newton method to reverse SGP4 and SDP4 propagation algorithm and generates a usable TLE version of a state. New TLE epoch is state epoch.

Parameters:

state - Spacecraft State to convert into TLE

templateTLE - first guess used to get identification and estimate new TLE

utc - the UTC time scale

teme - the TEME frame to use for propagation

epsilon - used to compute threshold for convergence check

maxIterations - maximum number of iterations for convergence

Returns:

TLE matching with Spacecraft State and template identification

Since:

11.0

isFormatOK

public static boolean isFormatOK(String line1,
                                 String line2)

Check the lines format validity.

Parameters:

line1 - the first element

line2 - the second element

Returns:

true if format is recognized (non null lines, 69 characters length, line content), false if not

equals

public boolean equals(Object o)

Check if this tle equals the provided tle.

Due to the difference in precision between object and string representations of TLE, it is possible for this method to return false even if string representations returned by toString() are equal.

Overrides:

equals in class Object

Parameters:

o - other tle

Returns:

true if this tle equals the provided tle

hashCode

public int hashCode()

Get a hashcode for this tle.

Overrides:

hashCode in class Object

Returns:

hashcode

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Get the drivers for TLE propagation SGP4 and SDP4.

Returns:

drivers for SGP4 and SDP4 model parameters

getParameterDriver

public ParameterDriver getParameterDriver(String name)

Get parameter driver from its name.

Parameters:

name - parameter name

Returns:

parameter driver

Since:

11.1