Initial orbit parameters for Mars Intercept

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Initial orbit parameters for Mars Intercept

Postby Casius » Fri Apr 14, 2017 4:58 pm

Hi all, hoping someone here can help me out.

I'm currently trying to setup a mars intercept for a manned mission, and I've used the Trajectory Optimisation Tool (http://www.orbithangar.com/searchid.php?ID=5418) to give me potential outbound transfer windows. Part of this tool also computes the required outbound hyperbolic orbit for the transfer window, and the accociated dV costs. The issue I have is that when I put this information into GMAT as the initial state of my spacecraft it does not follow the same trajectory as predicted in the previous programme. Instead the orbit fails to reach mars and usually ends up closer to the sun that when it started.

The following is initial spacecraft state information I'm putting into GMAT. This was obtained from an output of TOT
Code: Select all
GMAT Maven.DateFormat = UTCGregorian;
GMAT Maven.Epoch = '26 Jun 2035 00:00:04.000';
GMAT Maven.CoordinateSystem = EarthMJ2000Ec;
GMAT Maven.DisplayStateType = Keplerian;
GMAT Maven.SMA = -39244.03530000037;
GMAT Maven.ECC = 1.167399999999999;
GMAT Maven.INC = 1.306100000000088;
GMAT Maven.RAAN = 303.2142999999999;
GMAT Maven.AOP = 359.9683099999871;
GMAT Maven.TA = 303.2142999999999;
GMAT Maven.DryMass = 850;
GMAT Maven.Cd = 2.2;
GMAT Maven.Cr = 1.8;
GMAT Maven.DragArea = 15;
GMAT Maven.SRPArea = 1;
GMAT Maven.Tanks = {MainTank};
GMAT Maven.NAIFId = -10001001;
GMAT Maven.NAIFIdReferenceFrame = -9001001;
GMAT Maven.OrbitColor = Red;
GMAT Maven.TargetColor = Teal;
GMAT Maven.EstimationStateType = 'Cartesian';
GMAT Maven.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 Maven.CdSigma = 1e+070;
GMAT Maven.CrSigma = 1e+070;
GMAT Maven.Id = 'SatId';
GMAT Maven.Attitude = CoordinateSystemFixed;
GMAT Maven.SPADSRPScaleFactor = 1;
GMAT Maven.ModelFile = 'aura.3ds';
GMAT Maven.ModelOffsetX = 0;
GMAT Maven.ModelOffsetY = 0;
GMAT Maven.ModelOffsetZ = 0;
GMAT Maven.ModelRotationX = 0;
GMAT Maven.ModelRotationY = 0;
GMAT Maven.ModelRotationZ = 0;
GMAT Maven.ModelScale = 1;
GMAT Maven.AttitudeDisplayStateType = 'Quaternion';
GMAT Maven.AttitudeRateDisplayStateType = 'AngularVelocity';
GMAT Maven.AttitudeCoordinateSystem = EarthMJ2000Ec;
GMAT Maven.EulerAngleSequence = '321';


If I propgate this orbit for 365 days I get the following trajecotry:
Image

Whereas TOT predicts the following for the same outbound orbit data:
Image

I have double checked this against NASAs Trajectory Browser, and I get a transfer window on the same date (26/4/35), with roughly the same dV requirement as TOT specifies (allowing for LEO differences).Can anyone help me out with why this trajectory is not working?

(I have attached the full mission script to this post)
Attachments
Earth to Mars GDP 3.script
(11.24 KiB) Downloaded 164 times
Casius
 
Posts: 1
Joined: Fri Apr 14, 2017 4:35 pm

Re: Initial orbit parameters for Mars Intercept

Postby Jackkevin » Wed Mar 28, 2018 8:32 am

It demonstrates that the virtual focal gravitational field technique can parameterize countless Keplerian circles utilizing parameters of virtual gravity, and Write My Essay For Me give starting speculation to more exact enhancer.
Jackkevin
 
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Joined: Thu Apr 20, 2017 7:16 am


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