Questions tagged [gmat]

Questions about the General Mission Analysis Tool, the program which is designed to model, optimize, and estimate spacecraft trajectories in flight regimes ranging from low Earth orbit to lunar applications, interplanetary trajectories, and other deep space missions.

Filter by
Sorted by
Tagged with
0 votes
0 answers
25 views

RCS Thrusters in GMAT

Is it possible to model RCS thrusters in GMAT to change the attitude of the spacecraft or use any techniques to emulate this (such as maybe chemical thrusters)?
0 votes
0 answers
17 views

GMAT Orbit View with Spacecraft at centre

Is it possible to have an orbit view with the camera always centred on the spacecraft?
0 votes
0 answers
36 views

Can we have launch trajectories in GMAT?

Is it possible to model launch trajectories from ground to a certain earth orbit in GMAT?
0 votes
0 answers
32 views

How to add an asteroid into GMAT (General Mission Analysis Tool). How to generate a reliable SPK file

I'm currently trying to use GMAT to represent a mission centered around the asteroid 523632 2009UX17. To represent the asteroid's orbit I've used the Horizons Online Ephemeris System: https://ssd.jpl....
3 votes
0 answers
83 views

New to GMAT. Where do I start to build an orrery?

The goal would be an animated, variable-speed, 2-D view from celestial north of the Sun and planets. A stretch goal would be showing photorealistic rotations of CelestialBodys as a function of time. I ...
2 votes
0 answers
60 views

Mathematical description of the flight trajectory parameters of voyager 1

I would like to run in some simulation software an end-to-end simulation replicating the flight of voyager 1. I am somewhat conversant with GMAT that I think would have this capability or perhaps ...
  • 2,242
0 votes
0 answers
26 views

Apse Line rotation maneuver in GMAT

How should I perform Apse line Rotation Maneuver in GMAT? Both orbits have same orbital elements except for the argument of periapsis. I have found out the intersection points and now and have also ...
  • 11
1 vote
1 answer
38 views

Initial Value in Vary Command (GMAT)

What number should I give as an initial value in GMAT's Vary command? I have been trying to use default values but in some missions this default value does not lead to the convergence of target or ...
  • 19
1 vote
1 answer
43 views

How to propagate satellite to orbit intersection (relative node) in GMAT? [closed]

I am trying to propagate the spacecraft to the intersection points of two orbits (relative node) in GMAT. The analytical calculations of the true anomaly of that point is done using the formulas in ...
3 votes
1 answer
156 views

Modelling ISS orbit in GMAT

I am a complete newbie in all things space related. I am trying to work out how I can model the orbit of the ISS in the NASA open source tool GMAT. I can get the TLE for ISS (ZAYRA) from space-track....
  • 121
2 votes
0 answers
75 views

Earth to Mars Transfer using GMAT

I saw a couple of people mention here that in order to change the epoch date from the given Mars transfer example on GMAT I would need to change and re-optimize initial conditions. How would I do that?...
1 vote
1 answer
59 views

Non-coplanar transfer in GMAT

I am trying to use GMAT to do a non-coplanar transfer between 2 circular orbits. In which the first orbit would have a 0º inclination, and the final orbit would have a 28º inclination. And the ...
2 votes
1 answer
46 views

GMAT: What causes the error "ArrayTemplate error : dimension error"?

I have made various scripts that work with GMAT, but once in a while I get an "ArrayTemplate error : dimension error" error. I do not know what causes it, as in this case my script appears ...
  • 329
3 votes
1 answer
93 views

GMAT Python API No Convergence

I’m currently using the GMAT Python API in order to set and run my GMAT scripts, but am running into a problem where my scripts do not converge based on certain inputs. Is there a way in the Python ...
  • 31
1 vote
0 answers
34 views

NASA GMAT Hardware in the Loop testing

We are currently evaluating various Mission Analysis & Simulation tools, one of which is NASA's GMAT (2020). One of our requirements is for the tool to support HITL testing. However, i am unable ...
  • 111
5 votes
1 answer
129 views

Low-thrust maneuver validation in GMAT

I'm working on a LEO-to-LEO transfer with low-thrust propulsion. I've generated a control sequence with a direct optimization implemented by me and I would like to use GMAT to validate the maneuver. I ...
  • 101
1 vote
2 answers
88 views

Ноw to configure mission sequence for propagate until desired date in GMAT?

In GMAT, I have a state of satellite for a date (for example, 24.04.2022). Now, I need to propagate its motion for some days forward, until selected date (say, 29.04.2022). I added Propagation into ...
2 votes
2 answers
167 views

Optimizing trajectories with GMAT: how to understand the "Vary" parameters, and how to know what values to use for them?

I've been using GMAT in my free time to optimize trajectories, and have varied burn component values and spacecraft states, usually with success. The vary command in GMAT, with the Yukon optimizer ...
2 votes
0 answers
104 views

GMAT: How do I prevent infinite propagation into the future, which causes the "requested epoch 95008.513478505 is not on the DE file" error?

I have a spacecraft I am trying to get from Earth to Mars. I use an Earth propagator until the SC is out of the Earth's sphere of influence, then a deep space propagator until Mars' sphere of ...
2 votes
1 answer
141 views

Is there any software or other resources that can find optimal launch windows and gravity assist trajectories involving Lagrange points?

I've been using GMAT to make various trajectories involving the Sun-Earth L2 point. Earth-L2-Mars, Earth-L2-Earth flyby-Mars, etc. However, the main source of optimal launch windows I've been using is ...
  • 329
2 votes
2 answers
205 views

Is there a parameter that describes the angle between the spacecraft's position and the sun angle or direction of the Earth's motion?

I am trying to design an Earth flyby for gravity assist in GMAT, and I know from theory that the spacecraft should pass in front of a planet with regard to its heliocentric direction of motion in ...
  • 329
2 votes
0 answers
119 views

GMAT: How to Access startup file variables such as PYTHON_MODULE_PATH?

I use the python interface quite frequently and read-in tables of control variables created by another standalone module. I need to be sure that a file created by the standalone python module can be ...
2 votes
1 answer
204 views

Code to generate Sun-Earth L2 halo orbits for given epoch?

I am working on a GMAT script out of personal interest (not part of a job) that involves a spacecraft orbiting the Sun-Earth L2 point. I have found some orbital state vectors for the spacecraft that ...
  • 329
1 vote
0 answers
164 views

How do I construct halo orbits around the Sun-Earth L2 point in GMAT? What should the state vector of the spacecraft be?

I am new to trajectory design, and have been using GMAT to learn it since it's free, unlike STK. I have been trying to design a script that takes a spacecraft from Earth orbit to a halo orbit around ...
  • 329
2 votes
1 answer
90 views

GMAT Sun Ephemeris Output

I need the sun's position vector for an analysis, conducted in Matlab. Thus, I let output the ephemeris files for the spacecrafts and additionally I would like to do the same with the sun. A Report ...
  • 91
4 votes
1 answer
364 views

NASA GMAT: Any good tutorials or methods to learn how to use patch points and control points to come up with viable and optimal trajectories?

I'm a beginner to trajectory design, and have to use NASA's GMAT software. It's been a few weeks now, and I have done the first four tutorials and managed to create a (very unrealistic and sub-optimal)...
  • 329
1 vote
1 answer
90 views

GMAT B-Plane to Mars different date

can anybody help me to find how to change the date to the exercise of GMAT in order to work anyway? I'm not able to solve this problem. Thanks
  • 11
4 votes
1 answer
327 views

User help forum for GMAT (General Mission Analysis Tool) users?

GMAT (General Mission Analysis Tool) is an amazing open-source tool for designing spacecraft orbits etc. The latest documentation for GMAT version 2020a says that help is available at http://forums....
  • 671
3 votes
0 answers
155 views

GMAT B-plane Transfer to Mercury

I have been fighting with GMAT for about 3 days now trying to get this transfer to converge so literally ANY assistance and advice would be greatly appreciated. I need to do a direct hohmann like ...
4 votes
0 answers
216 views

How to perform a Hohmann-like transfer to mercury on GMAT

I am trying to simulate a Hohmann-like transfer from Earth to Mercury and establish an orbit there on GMAT. I have the following values already: launch velocity (22.25 km/s) Launch burn (-7.53 km/s) ...
3 votes
1 answer
244 views

GMAT: Finite burn targeting, solving for burn duration and quaternion

I'm trying to using GMAT to design a finite burn with a fixed attitude throughout the burn. I do not know the attitude needed at the start, nor do I know the burn duration needed. I set up six ...
  • 5,985
1 vote
1 answer
110 views

Hohmann transfer using GMAT software

I am trying to plot an orbit using gmat. I fixed apogee(RadApo) and perigee(RadPer) for the inner orbit(green) and inserted an impulsive burn. I got the desired shape of the outer orbit but I am ...
  • 173
7 votes
3 answers
695 views

Differences between numerical propagators

I am a trainee who is working on a numeric orbital propagator developed in the company. I can't show you the code but I can tell you that the propagator was developed to work in Simulink. My job was ...
  • 243
1 vote
0 answers
148 views

How to propagate the trajectory in GMAT with a custom thrust profile

So basically I was trying to design a low thrust maneuver to increase the apogee of the spacecraft. I solved it separately and got some thrust profile (thrust and it's direction as a function of time)....
  • 11
0 votes
0 answers
44 views

How to use the Util and Base Code of the General Mission Analysis Tool

GMAT (General Mission Analysis Tool) provides detailed Util and Base Code, but I don't know how to use it, namely I still don't know how to access so many data of some missions. Can somebody provide ...
1 vote
1 answer
361 views

Using GMAT data to determine satellite elevation angle

I am trying to simulate a communications system between a ground station in Canberra and a satellite in LEO with a $90^{\circ}$ inclination. Specifically, I am interested in the the elevation angle as ...
  • 11
2 votes
1 answer
378 views

Trying to run NASA GMAT on Ubuntu 20.04, I get the error "no main manifest attribute, in gmat.jar"

I downloaded GMAT from https://software.nasa.gov/software/GSC-17177-1 Then I extracted using ...
4 votes
0 answers
47 views

How to get GMAT to treat planets as solid objects (that satellites can't pass through)?

I'm running a bunch of trajectories and want some way of stopping calculation on those that intersect the Earth at the time they intersect the Earth. Is there some way to get GMAT to treat Earth (and ...
2 votes
0 answers
283 views

GMAT Orbit Designer

I start to work with GMAT. I am looking into the API capabilites and I found several functions e.g. for the calculation of SSO Orbit Parameters, or Repeating Ground Tracks. So apart from this, is ...
  • 91
1 vote
1 answer
113 views

GMAT: Finite Burns commands in If statements inside For loops

Does anyone know why GMAT won't execute finite burns when the BeginFiniteBurn command is placed inside an If statement which is inside a For loop? I'm sure the If condition is verified because there ...
5 votes
1 answer
100 views

Are the initial conditions for the Apollo PFS objects' orbits known (or knowable) as well as they were for the ascent module?

This answer to Would we have spotted the ascent stage of Apollo 11's Eagle if it was still in orbit around the Moon? and discussion under it suggests that as a check of the orbital propagation ...
  • 147k
8 votes
1 answer
239 views

Using GMAT to simulate phasing orbits with finite burns

I'm working on a project which requires me to use GMAT but I'm new to the program (and to asking questions on this website). I'm supposed to send a spacecraft from a known GTO to the Moon. A direct ...
  • 101
4 votes
1 answer
190 views

Why does targeting in the VNB frame lead to a different maneuver magnitude than targeting in an inertial frame?

In GMAT, I set up a targeter (this script) to compute an impulsive maneuver in an inertial frame. The differential correcter finds a maneuver of 3.1161 km/s . If I change the impulsive maneuver to be ...
  • 5,985
1 vote
1 answer
98 views

How to model payload deployment in General Mission Analysis Tool

I just started reading the manuals and doing the tutorials for GMAT. I'd like to use it to model deploying multiple satellites from a launch vehicle and see their resulting orbits. Searching the ...
  • 45
2 votes
1 answer
101 views

Difference between distance from Mars (Rmag) and B-plane R coordinate

I am running some GMAT simulations on Mars 2020 trajectory to Mars, following the ephemerides published by JPL. I create a target sequence and target the planet using the b-plane coordinates B and T. ...
0 votes
0 answers
46 views

GMAT compilation does not generate gui

I am compiling GMAT 2020a on opensuse linux from source code downloaded from sourceforge. I have gotten the compilation completed. Ran ok, except the /bin ...
  • 2,242
1 vote
2 answers
187 views

GMAT code -- Change animation speed

I find the animations initiated by the run command are so fast that visually I cannot follow them in any detail. I have been unable to find any setting in the program to slow them down. Likewise I ...
  • 2,242
2 votes
0 answers
105 views

GMAT: LEO to GEO with Electrical Thruster simulation?

I would like to get a simulation from LEO to GEO with an electrical Kick-Stage. GMAT seems to be able to do it. Is there any Script/Scenario already written? The aim is to perform a parametric study ...
  • 21
0 votes
1 answer
74 views

Save data in array on General Mission Tool

I have problems for using NASA's General Mission Analysis tool (GMAT). I am trying to save a data in report file (SMA or Semi Major Axis) into a new array. This SMA has 25 lines. I have tried this ...
2 votes
1 answer
233 views

GMAT: How to do a Hohmann transfer from a larger orbit to a smaller orbit

I've figured out how to do a Hohmann transfer to a larger orbit but can't seem to figure out how to do one back to a smaller orbit (e.g. GEO to random smaller orbit). Any advice would be amazing, ...