Electric Thruster from eliptic Earth orbit to Lunar orbit

Using GMAT for specific types of missions.

Electric Thruster from eliptic Earth orbit to Lunar orbit

Postby jinx1984 » Sun Mar 26, 2017 11:39 am

Hello,

I've tried to design scenario in which tiny satelite is transfered from eliptycal orbit to lunar orbit with very low thrust engine in energy efficient way.

I did it in following stages:

1) Stay on orbit and wait for right alignment with a moon
2) start to increase altitiude by applying thrust near your orbit peryapsis
3) when orbit apoapsis will be far enaught from earth to make lunar influence significant apply thrust in apoapsis to go on more circular orbit
4) stay on that orbit until Luna will be considerably close (1700 km)
5) apply slow down thrust to enter lunar orbit
6) apply slow down thrust in peryapsis to make orbit more circular

I've found point 4) most unstable and here is my question.

How to make that orbiting more stable? How to apply thrust for Electric thruster in direction of my choice ?
The goal is to change the script in a way that You can start it with any date and it will handle the task I believe step 4 is crutial.




full code below. Thank You in advance for help.


this is best scenario I came up with:

Code: Select all
%General Mission Analysis Tool(GMAT) Script
%Created: 2017-03-23 10:24:38


%----------------------------------------
%---------- Spacecraft
%----------------------------------------

Create Spacecraft DefaultSC;
GMAT DefaultSC.DateFormat = UTCGregorian;
GMAT DefaultSC.Epoch = '26 Apr 2017 07:59:28.000';
GMAT DefaultSC.CoordinateSystem = EarthMJ2000Eq;
GMAT DefaultSC.DisplayStateType = Cartesian;
GMAT DefaultSC.X = 41771.0217;
GMAT DefaultSC.Y = -4556.8904;
GMAT DefaultSC.Z = -3420.096961;
GMAT DefaultSC.VX = 0;
GMAT DefaultSC.VY = 1.7;
GMAT DefaultSC.VZ = 0.6;
GMAT DefaultSC.DryMass = 20;
GMAT DefaultSC.Cd = 2.2;
GMAT DefaultSC.Cr = 1.8;
GMAT DefaultSC.DragArea = 100;
GMAT DefaultSC.SRPArea = 1;
GMAT DefaultSC.Tanks = {ElectricTank1};
GMAT DefaultSC.Thrusters = {ElectricThruster1, ElectricThruster2};
GMAT DefaultSC.PowerSystem = SolarPowerSystem1;
GMAT DefaultSC.NAIFId = -10001001;
GMAT DefaultSC.NAIFIdReferenceFrame = -9001001;
GMAT DefaultSC.OrbitColor = Red;
GMAT DefaultSC.TargetColor = Teal;
GMAT DefaultSC.EstimationStateType = 'Cartesian';
GMAT DefaultSC.OrbitErrorCovariance = [ 1e+070 0 0 0 0 0 ; 0 1e+070 0 0 0 0 ; 0 0 1e+070 0 0 0 ; 0 0 0 1e+070 0 0 ; 0 0 0 0 1e+070 0 ; 0 0 0 0 0 1e+070 ];
GMAT DefaultSC.CdSigma = 1e+070;
GMAT DefaultSC.CrSigma = 1e+070;
GMAT DefaultSC.Id = 'SatId';
GMAT DefaultSC.Attitude = CoordinateSystemFixed;
GMAT DefaultSC.SPADSRPScaleFactor = 1;
GMAT DefaultSC.ModelFile = 'aura.3ds';
GMAT DefaultSC.ModelOffsetX = 0;
GMAT DefaultSC.ModelOffsetY = 0;
GMAT DefaultSC.ModelOffsetZ = 0;
GMAT DefaultSC.ModelRotationX = 0;
GMAT DefaultSC.ModelRotationY = 0;
GMAT DefaultSC.ModelRotationZ = 0;
GMAT DefaultSC.ModelScale = 1;
GMAT DefaultSC.AttitudeDisplayStateType = 'Quaternion';
GMAT DefaultSC.AttitudeRateDisplayStateType = 'AngularVelocity';
GMAT DefaultSC.AttitudeCoordinateSystem = EarthMJ2000Eq;
GMAT DefaultSC.EulerAngleSequence = '321';

%----------------------------------------
%---------- Hardware Components
%----------------------------------------

Create ElectricTank ElectricTank1;
GMAT ElectricTank1.AllowNegativeFuelMass = false;
GMAT ElectricTank1.FuelMass = 2;

Create ElectricThruster ElectricThruster1;
GMAT ElectricThruster1.CoordinateSystem = Local;
GMAT ElectricThruster1.Origin = Earth;
GMAT ElectricThruster1.Axes = VNB;
GMAT ElectricThruster1.ThrustDirection1 = 1;
GMAT ElectricThruster1.ThrustDirection2 = 0;
GMAT ElectricThruster1.ThrustDirection3 = 0;
GMAT ElectricThruster1.DutyCycle = 1;
GMAT ElectricThruster1.ThrustScaleFactor = 1;
GMAT ElectricThruster1.DecrementMass = true;
GMAT ElectricThruster1.Tank = {ElectricTank1};
GMAT ElectricThruster1.MixRatio = [ 1 ];
GMAT ElectricThruster1.GravitationalAccel = 9.810000000000001;
GMAT ElectricThruster1.ThrustModel = ConstantThrustAndIsp;
GMAT ElectricThruster1.MaximumUsablePower = 25;
GMAT ElectricThruster1.MinimumUsablePower = 1;
GMAT ElectricThruster1.ThrustCoeff1 = -5.19082;
GMAT ElectricThruster1.ThrustCoeff2 = 2.96519;
GMAT ElectricThruster1.ThrustCoeff3 = -14.4789;
GMAT ElectricThruster1.ThrustCoeff4 = 54.05382;
GMAT ElectricThruster1.ThrustCoeff5 = -0.00100092;
GMAT ElectricThruster1.MassFlowCoeff1 = -0.004776;
GMAT ElectricThruster1.MassFlowCoeff2 = 0.05717;
GMAT ElectricThruster1.MassFlowCoeff3 = -0.09956;
GMAT ElectricThruster1.MassFlowCoeff4 = 0.03211;
GMAT ElectricThruster1.MassFlowCoeff5 = 2.13781;
GMAT ElectricThruster1.FixedEfficiency = 0.7;
GMAT ElectricThruster1.Isp = 5000;
GMAT ElectricThruster1.ConstantThrust = 0.24;

Create SolarPowerSystem SolarPowerSystem1;
GMAT SolarPowerSystem1.EpochFormat = 'UTCGregorian';
GMAT SolarPowerSystem1.InitialEpoch = ''01 Jan 2000 11:59:28.000'';
GMAT SolarPowerSystem1.InitialMaxPower = 25;
GMAT SolarPowerSystem1.AnnualDecayRate = 5;
GMAT SolarPowerSystem1.Margin = 5;
GMAT SolarPowerSystem1.BusCoeff1 = 0.3;
GMAT SolarPowerSystem1.BusCoeff2 = 0;
GMAT SolarPowerSystem1.BusCoeff3 = 0;
GMAT SolarPowerSystem1.ShadowModel = 'DualCone';
GMAT SolarPowerSystem1.ShadowBodies = {'Earth', 'Luna'};
GMAT SolarPowerSystem1.SolarCoeff1 = 1.32077;
GMAT SolarPowerSystem1.SolarCoeff2 = -0.10848;
GMAT SolarPowerSystem1.SolarCoeff3 = -0.11665;
GMAT SolarPowerSystem1.SolarCoeff4 = 0.10843;
GMAT SolarPowerSystem1.SolarCoeff5 = -0.01279;

Create ElectricThruster ElectricThruster2;
GMAT ElectricThruster2.CoordinateSystem = Local;
GMAT ElectricThruster2.Origin = Earth;
GMAT ElectricThruster2.Axes = VNB;
GMAT ElectricThruster2.ThrustDirection1 = -1;
GMAT ElectricThruster2.ThrustDirection2 = 0;
GMAT ElectricThruster2.ThrustDirection3 = 0;
GMAT ElectricThruster2.DutyCycle = 1;
GMAT ElectricThruster2.ThrustScaleFactor = 1;
GMAT ElectricThruster2.DecrementMass = true;
GMAT ElectricThruster2.Tank = {ElectricTank1};
GMAT ElectricThruster2.MixRatio = [ 1 ];
GMAT ElectricThruster2.GravitationalAccel = 9.810000000000001;
GMAT ElectricThruster2.ThrustModel = ConstantThrustAndIsp;
GMAT ElectricThruster2.MaximumUsablePower = 7.266;
GMAT ElectricThruster2.MinimumUsablePower = 0.638;
GMAT ElectricThruster2.ThrustCoeff1 = -5.19082;
GMAT ElectricThruster2.ThrustCoeff2 = 2.96519;
GMAT ElectricThruster2.ThrustCoeff3 = -14.4789;
GMAT ElectricThruster2.ThrustCoeff4 = 54.05382;
GMAT ElectricThruster2.ThrustCoeff5 = -0.00100092;
GMAT ElectricThruster2.MassFlowCoeff1 = -0.004776;
GMAT ElectricThruster2.MassFlowCoeff2 = 0.05717;
GMAT ElectricThruster2.MassFlowCoeff3 = -0.09956;
GMAT ElectricThruster2.MassFlowCoeff4 = 0.03211;
GMAT ElectricThruster2.MassFlowCoeff5 = 2.13781;
GMAT ElectricThruster2.FixedEfficiency = 0.7;
GMAT ElectricThruster2.Isp = 5000;
GMAT ElectricThruster2.ConstantThrust = 0.24;


































%----------------------------------------
%---------- ForceModels
%----------------------------------------

Create ForceModel NearEarthProp_ForceModel;
GMAT NearEarthProp_ForceModel.CentralBody = Earth;
GMAT NearEarthProp_ForceModel.PrimaryBodies = {Earth};
GMAT NearEarthProp_ForceModel.PointMasses = {Jupiter, Luna, Mars, Mercury, Neptune, Pluto, Saturn, Sun, Uranus, Venus};
GMAT NearEarthProp_ForceModel.SRP = On;
GMAT NearEarthProp_ForceModel.RelativisticCorrection = On;
GMAT NearEarthProp_ForceModel.ErrorControl = RSSStep;
GMAT NearEarthProp_ForceModel.GravityField.Earth.Degree = 10;
GMAT NearEarthProp_ForceModel.GravityField.Earth.Order = 10;
GMAT NearEarthProp_ForceModel.GravityField.Earth.PotentialFile = 'JGM2.cof';
GMAT NearEarthProp_ForceModel.GravityField.Earth.EarthTideModel = 'None';
GMAT NearEarthProp_ForceModel.SRP.Flux = 1367;
GMAT NearEarthProp_ForceModel.SRP.SRPModel = Spherical;
GMAT NearEarthProp_ForceModel.SRP.Nominal_Sun = 149597870.691;
GMAT NearEarthProp_ForceModel.Drag.AtmosphereModel = MSISE90;
GMAT NearEarthProp_ForceModel.Drag.HistoricWeatherSource = 'ConstantFluxAndGeoMag';
GMAT NearEarthProp_ForceModel.Drag.PredictedWeatherSource = 'ConstantFluxAndGeoMag';
GMAT NearEarthProp_ForceModel.Drag.CSSISpaceWeatherFile = 'SpaceWeather-All-v1.2.txt';
GMAT NearEarthProp_ForceModel.Drag.SchattenFile = 'SchattenPredict.txt';
GMAT NearEarthProp_ForceModel.Drag.F107 = 150;
GMAT NearEarthProp_ForceModel.Drag.F107A = 150;
GMAT NearEarthProp_ForceModel.Drag.MagneticIndex = 3;
GMAT NearEarthProp_ForceModel.Drag.SchattenErrorModel = 'Nominal';
GMAT NearEarthProp_ForceModel.Drag.SchattenTimingModel = 'NominalCycle';

Create ForceModel FarEarthPropagator_ForceModel;
GMAT FarEarthPropagator_ForceModel.CentralBody = Earth;
GMAT FarEarthPropagator_ForceModel.PrimaryBodies = {Earth};
GMAT FarEarthPropagator_ForceModel.PointMasses = {Jupiter, Luna, Mars, Mercury, Neptune, Pluto, Saturn, Sun, Uranus, Venus};
GMAT FarEarthPropagator_ForceModel.Drag = None;
GMAT FarEarthPropagator_ForceModel.SRP = On;
GMAT FarEarthPropagator_ForceModel.RelativisticCorrection = On;
GMAT FarEarthPropagator_ForceModel.ErrorControl = RSSStep;
GMAT FarEarthPropagator_ForceModel.GravityField.Earth.Degree = 4;
GMAT FarEarthPropagator_ForceModel.GravityField.Earth.Order = 4;
GMAT FarEarthPropagator_ForceModel.GravityField.Earth.PotentialFile = 'EGM96.cof';
GMAT FarEarthPropagator_ForceModel.GravityField.Earth.EarthTideModel = 'None';
GMAT FarEarthPropagator_ForceModel.SRP.Flux = 1367;
GMAT FarEarthPropagator_ForceModel.SRP.SRPModel = Spherical;
GMAT FarEarthPropagator_ForceModel.SRP.Nominal_Sun = 149597870.691;

Create ForceModel LunarProp_ForceModel;
GMAT LunarProp_ForceModel.CentralBody = Luna;
GMAT LunarProp_ForceModel.PrimaryBodies = {Luna};
GMAT LunarProp_ForceModel.PointMasses = {Earth, Jupiter, Mars, Mercury, Neptune, Pluto, Saturn, Sun, Uranus, Venus};
GMAT LunarProp_ForceModel.Drag = None;
GMAT LunarProp_ForceModel.SRP = Off;
GMAT LunarProp_ForceModel.RelativisticCorrection = Off;
GMAT LunarProp_ForceModel.ErrorControl = RSSStep;
GMAT LunarProp_ForceModel.GravityField.Luna.Degree = 10;
GMAT LunarProp_ForceModel.GravityField.Luna.Order = 10;
GMAT LunarProp_ForceModel.GravityField.Luna.PotentialFile = 'LP165P.cof';

%----------------------------------------
%---------- Propagators
%----------------------------------------

Create Propagator NearEarthProp;
GMAT NearEarthProp.FM = NearEarthProp_ForceModel;
GMAT NearEarthProp.Type = RungeKutta89;
GMAT NearEarthProp.InitialStepSize = 60;
GMAT NearEarthProp.Accuracy = 1e-007;
GMAT NearEarthProp.MinStep = 0.001;
GMAT NearEarthProp.MaxStep = 2700;
GMAT NearEarthProp.MaxStepAttempts = 50;
GMAT NearEarthProp.StopIfAccuracyIsViolated = false;

Create Propagator FarEarthPropagator;
GMAT FarEarthPropagator.FM = FarEarthPropagator_ForceModel;
GMAT FarEarthPropagator.Type = RungeKutta89;
GMAT FarEarthPropagator.InitialStepSize = 60;
GMAT FarEarthPropagator.Accuracy = 9.999999999999999e-012;
GMAT FarEarthPropagator.MinStep = 0.001;
GMAT FarEarthPropagator.MaxStep = 2700;
GMAT FarEarthPropagator.MaxStepAttempts = 50;
GMAT FarEarthPropagator.StopIfAccuracyIsViolated = true;

Create Propagator LunarProp;
GMAT LunarProp.FM = LunarProp_ForceModel;
GMAT LunarProp.Type = RungeKutta89;
GMAT LunarProp.InitialStepSize = 60;
GMAT LunarProp.Accuracy = 9.999999999999999e-012;
GMAT LunarProp.MinStep = 0.0001;
GMAT LunarProp.MaxStep = 2700;
GMAT LunarProp.MaxStepAttempts = 50;
GMAT LunarProp.StopIfAccuracyIsViolated = false;

%----------------------------------------
%---------- Burns
%----------------------------------------

Create FiniteBurn FiniteBurn1;
GMAT FiniteBurn1.Thrusters = {ElectricThruster1};
GMAT FiniteBurn1.ThrottleLogicAlgorithm = 'MaxNumberOfThrusters';

Create FiniteBurn FiniteBurn2;
GMAT FiniteBurn2.Thrusters = {ElectricThruster2};
GMAT FiniteBurn2.ThrottleLogicAlgorithm = 'MaxNumberOfThrusters';

%----------------------------------------
%---------- Coordinate Systems
%----------------------------------------

Create CoordinateSystem LunaFixed;
GMAT LunaFixed.Origin = Luna;
GMAT LunaFixed.Axes = BodyFixed;

%----------------------------------------
%---------- Solvers
%----------------------------------------

Create DifferentialCorrector DefaultDC;
GMAT DefaultDC.ShowProgress = true;
GMAT DefaultDC.ReportStyle = Normal;
GMAT DefaultDC.ReportFile = 'DifferentialCorrectorDefaultDC.data';
GMAT DefaultDC.MaximumIterations = 25;
GMAT DefaultDC.DerivativeMethod = ForwardDifference;
GMAT DefaultDC.Algorithm = NewtonRaphson;

%----------------------------------------
%---------- Subscribers
%----------------------------------------

Create OrbitView DefaultOrbitView;
GMAT DefaultOrbitView.SolverIterations = Current;
GMAT DefaultOrbitView.UpperLeft = [ -0.4694589877835951 0.1647727272727273 ];
GMAT DefaultOrbitView.Size = [ 1.199825479930192 0.8428030303030303 ];
GMAT DefaultOrbitView.RelativeZOrder = 111;
GMAT DefaultOrbitView.Maximized = true;
GMAT DefaultOrbitView.Add = {DefaultSC, Earth, Luna, Sun};
GMAT DefaultOrbitView.CoordinateSystem = LunaFixed;
GMAT DefaultOrbitView.DrawObject = [ true true true true ];
GMAT DefaultOrbitView.DataCollectFrequency = 1;
GMAT DefaultOrbitView.UpdatePlotFrequency = 500;
GMAT DefaultOrbitView.NumPointsToRedraw = 0;
GMAT DefaultOrbitView.ShowPlot = true;
GMAT DefaultOrbitView.ShowLabels = true;
GMAT DefaultOrbitView.ViewPointReference = Luna;
GMAT DefaultOrbitView.ViewPointVector = [ 41771.0217 -8056.8904 6400.096961 ];
GMAT DefaultOrbitView.ViewDirection = Luna;
GMAT DefaultOrbitView.ViewScaleFactor = 1;
GMAT DefaultOrbitView.ViewUpCoordinateSystem = EarthMJ2000Eq;
GMAT DefaultOrbitView.ViewUpAxis = Z;
GMAT DefaultOrbitView.EclipticPlane = Off;
GMAT DefaultOrbitView.XYPlane = On;
GMAT DefaultOrbitView.WireFrame = Off;
GMAT DefaultOrbitView.Axes = On;
GMAT DefaultOrbitView.Grid = Off;
GMAT DefaultOrbitView.SunLine = Off;
GMAT DefaultOrbitView.UseInitialView = On;
GMAT DefaultOrbitView.StarCount = 7000;
GMAT DefaultOrbitView.EnableStars = Off;
GMAT DefaultOrbitView.EnableConstellations = Off;

Create ReportFile ReportFile1;
GMAT ReportFile1.SolverIterations = All;
GMAT ReportFile1.UpperLeft = [ 0 0 ];
GMAT ReportFile1.Size = [ 0 0 ];
GMAT ReportFile1.RelativeZOrder = 0;
GMAT ReportFile1.Maximized = false;
GMAT ReportFile1.Filename = 'C:\Users\AdamS\Desktop\adam_test2_report.csv';
GMAT ReportFile1.Precision = 16;
GMAT ReportFile1.Add = {DefaultSC.Luna.Altitude, maxLunaAlt, minLunaAlt, altDiff, DefaultSC.TotalMass, DefaultSC.ElapsedDays, DefaultSC.Luna.OrbitPeriod};
GMAT ReportFile1.WriteHeaders = true;
GMAT ReportFile1.LeftJustify = On;
GMAT ReportFile1.ZeroFill = Off;
GMAT ReportFile1.FixedWidth = true;
GMAT ReportFile1.Delimiter = ' ';
GMAT ReportFile1.ColumnWidth = 23;
GMAT ReportFile1.WriteReport = true;

Create OrbitView OrbitView1;
GMAT OrbitView1.SolverIterations = Current;
GMAT OrbitView1.UpperLeft = [ 0.005235602094240838 0 ];
GMAT OrbitView1.Size = [ 0.5008726003490401 0.4507575757575758 ];
GMAT OrbitView1.RelativeZOrder = 97;
GMAT OrbitView1.Maximized = false;
GMAT OrbitView1.Add = {DefaultSC, Earth, Sun, Luna};
GMAT OrbitView1.CoordinateSystem = EarthMJ2000Eq;
GMAT OrbitView1.DrawObject = [ true true true true ];
GMAT OrbitView1.DataCollectFrequency = 1;
GMAT OrbitView1.UpdatePlotFrequency = 50;
GMAT OrbitView1.NumPointsToRedraw = 0;
GMAT OrbitView1.ShowPlot = true;
GMAT OrbitView1.ShowLabels = true;
GMAT OrbitView1.ViewPointReference = DefaultSC;
GMAT OrbitView1.ViewPointVector = DefaultSC;
GMAT OrbitView1.ViewDirection = Luna;
GMAT OrbitView1.ViewScaleFactor = 1;
GMAT OrbitView1.ViewUpCoordinateSystem = EarthMJ2000Eq;
GMAT OrbitView1.ViewUpAxis = Z;
GMAT OrbitView1.EclipticPlane = Off;
GMAT OrbitView1.XYPlane = On;
GMAT OrbitView1.WireFrame = Off;
GMAT OrbitView1.Axes = On;
GMAT OrbitView1.Grid = Off;
GMAT OrbitView1.SunLine = Off;
GMAT OrbitView1.UseInitialView = On;
GMAT OrbitView1.StarCount = 7000;
GMAT OrbitView1.EnableStars = On;
GMAT OrbitView1.EnableConstellations = On;

%----------------------------------------
%---------- Arrays, Variables, Strings
%----------------------------------------
Create Variable OrbitParking minLunaAlt maxLunaAlt altDiff;
GMAT OrbitParking = 0;
GMAT minLunaAlt = 2000;
GMAT maxLunaAlt = 7000;
GMAT altDiff = 7000;






















%----------------------------------------
%---------- Mission Sequence
%----------------------------------------

BeginMissionSequence;
Propagate NearEarthProp(DefaultSC) {DefaultSC.ElapsedDays = 10};
While DefaultSC.Earth.Altitude < 320000
   Propagate FarEarthPropagator(DefaultSC) {DefaultSC.Earth.Altitude = 5000, OrbitColor = [255 0 0]};
   BeginFiniteBurn FiniteBurn1(DefaultSC);
   Propagate NearEarthProp(DefaultSC) {DefaultSC.Earth.Altitude = 5001, StopTolerance = 0.01, OrbitColor = [128 255 0]};
   EndFiniteBurn FiniteBurn1(DefaultSC);
   Propagate NearEarthProp(DefaultSC) {DefaultSC.Earth.Apoapsis, StopTolerance = 1, OrbitColor = [255 0 0]};
EndWhile;
BeginFiniteBurn FiniteBurn1(DefaultSC);
Propagate FarEarthPropagator(DefaultSC) {DefaultSC.ElapsedDays = 0.75, OrbitColor = [255 128 255]};
EndFiniteBurn FiniteBurn1(DefaultSC);
Propagate FarEarthPropagator(DefaultSC) {DefaultSC.Luna.Altitude = 10000};
Propagate LunarProp(DefaultSC) {DefaultSC.Luna.Altitude = 1700, StopTolerance = 1};
BeginFiniteBurn FiniteBurn2(DefaultSC);
Propagate LunarProp(DefaultSC) {DefaultSC.Luna.Energy = -0.36, OrbitColor = [255 255 0]};
EndFiniteBurn FiniteBurn2(DefaultSC);
Propagate LunarProp(DefaultSC) {DefaultSC.ElapsedDays = 20, OrbitColor = [0 255 255]};
While altDiff > 20
   GMAT maxLunaAlt = DefaultSC.Luna.Altitude;
   GMAT altDiff = maxLunaAlt - minLunaAlt;
   Propagate LunarProp(DefaultSC) {DefaultSC.Luna.Periapsis, OrbitColor = [255 0 0]};
   GMAT minLunaAlt = DefaultSC.Luna.Altitude;
   GMAT altDiff = maxLunaAlt - minLunaAlt;
   BeginFiniteBurn FiniteBurn2(DefaultSC);
   Propagate LunarProp(DefaultSC) {DefaultSC.ElapsedSecs = 500, OrbitColor = [255 0 0]};
   EndFiniteBurn FiniteBurn2(DefaultSC);
   Propagate LunarProp(DefaultSC) {DefaultSC.Luna.Apoapsis, OrbitColor = [255 0 0]};
EndWhile;
Propagate LunarProp(DefaultSC) {DefaultSC.ElapsedDays = 30, OrbitColor = [0 255 0]};

jinx1984
 
Posts: 1
Joined: Sun Mar 26, 2017 11:12 am

Nice

Postby hybugojyl » Mon Sep 10, 2018 12:15 pm

The urge of the new scheme is inducted for the individuals. It has been marginal for the use of the uk essay writing help for all possible items for the humans in life.
hybugojyl
 
Posts: 1
Joined: Mon Sep 10, 2018 12:13 pm


Return to Flight Regimes and Mission Types

Who is online

Users browsing this forum: No registered users and 2 guests

cron