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# Questions tagged [simulation]

representation of environment or process in a more accessible form using virtual or physical imitation or analogues, often for the purpose of training or testing, includes both real-world (physical) and numerical techniques.

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### GMAT edit object fields in Mission Sequence

I am trying to change the ISP of an Impulsive Burn during the Mission Sequence. But why so ever, GMAT does not allow me to do so? I looked at the source code as well, and I do not see any indicators (...
• 121
9 votes
0 answers
173 views

### Looking for information on this Apollo era CGI animation

In the NASA documentary The Computer and Manned Space Flight, early CGI animations of lunar landing, rendezvous, earthrise etc. are shown. The narration says that these simulations were made prior to ...
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1 vote
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### Any ideas?: Calculating wet-mass and burn altitude for a Mars landing, using a Python simulation

In this post, I will explain the problem, provide some detailed context, and finally explain what I am searching for (what my question is basically). First of all, this should be quite a fun but ...
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3 votes
1 answer
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### What are some best practices for coding a satellite orbit propagator and ground track plotter?

I've seen interesting projects like this and I've been doing a decent amount of orbit propagation (numerically integrating state vectors, accounting for perturbations, etc.) in python and animating ...
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2 votes
2 answers
143 views

### Integration of Varying Forces, Impulses in Simulators

I am a software dude working on a personal project for building a spacecraft simulation software. And I've been looking into numerical integration methods, and I am just confused on how to tackle the ...
3 votes
1 answer
410 views

### Orbit Determination from Position and Velocity

I'm working on a game, somewhat similar to KSP (no building rockets, just beautiful orbital acrobatics). It's in a "small" star system, radius of 6 AU, and it features celestial bodies ...
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1 vote
0 answers
57 views

### Simulation satellite channel in Matlab

Where can I find values for delays and pdp to simulate the satellite-ground channel? PS 3GPP TS 36.116 document contains multi-path delay profiles used for the performance measurements in a multipath ...
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1 vote
0 answers
122 views

### Objects move clockwise instead of counter-clockwise

I'm trying to write an orbital simulation with patched conics. For my sources I'm using https://orbital-mechanics.space/ and Fundamentals of Astrodynamics (Second Edition). Both sources suggest to use ...
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5 votes
2 answers
992 views

### Object slowest at periapsis - despite correct position calculation

I'm coding up a simulation of celestial bodies using patched conics. At the moment I'm stuck with calculating the velocity of the object in the perifocal frame. For the position I'm simply using the ...
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5 votes
2 answers
738 views

### What does a "handover" really mean in satellite communications?

I am working on simulating a satellite constellation and I keep coming across the term "handover". My general understanding is that a handover is when a ground station switches its connected ...
1 vote
0 answers
83 views

### How to maintain minimum distance between satellites for duration of their orbits

I am working on a simulation in python that involves propagating hundreds of satellites over time. For simplicity, let's assume I have satellites at only a single inclination separated into multiple ...
2 votes
1 answer
323 views

### Converting Keplerian Orbital Elements into 2D State Vectors in Unity C#

I have done an extensive amount of research into this topic, but am really struggling to implement the math necessary to pull this off correctly. Just for some context: I'm trying to create a semi-...
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3 votes
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111 views

### Difference Result of Numerical Satellite Propagator

Currently, I am trying to build a numerical propagator platform for satellite that accommodates for all kinds of perturbation. So, for validation purpose, I compare the result of my own program and ...
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0 votes
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149 views

### How to Model the Aerodynamics of Landing a Falcon 9

I'm currently working on a landing simulation for the Falcon 9. One of my primary tasks is to model both the environment and the rocket. In a previous rough simulation, aerodynamics were mostly ...
1 vote
1 answer
157 views

### How to get contact locator events in GMAT using Python

I am trying to write a python script for GMAT to detect contacts between a satellite and a ground station. I have declared the contact locator as such: ...
2 votes
0 answers
112 views

### Beginner to simulating communications systems of space missions. I have GMAT, MATLAB and NASA's SPICE library. Where would I start?

I recently managed to load SPICE kernels into GMAT to simulate the trajectories of real missions, and got its MATLAB interface working (still trying to understand how to use the two software together)....
3 votes
0 answers
97 views

### Developing a ROS-based Space Cleaning Robot

I am currently developing a space debris cleaning robot based on ROS (Robot Operating System) and I am facing challenges in finding suitable simulation software to create a realistic physical ...
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2 votes
2 answers
399 views

### Difference in using flat earth or round earth model for equation of motion

according to the book of Mr. Peter H. Zipfel (Modeling and simulation of aerospace vehicles) for high speed or/and long flight applictions kinematic simulations should be done by round rotating earth ...
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1 vote
1 answer
200 views

### Circularization of an orbit on gmat

I'm using Gmat to turn to zero the eccentricity of an orbit around Mars with an electric thruster. I modeled the initial orbit, introduced the engine, the tank and the solar arrays and created the ...
3 votes
1 answer
441 views

### Calculating and Drawing the orbit of a body in a 2D gravity simulation in python

I'm making a space exploration game and its in a 2d plane so no z axis, and I'm using Newton's law of universal gravity, I would really like to calculate anddraw the predicted trajectory of a body, ...
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12 votes
4 answers
4k views

### Have any bits of a space mission ever collided with a planet or large moon (not Earth) that was not a target of the mission?

For example, a mission to Mars for which some bit of hardware ended up entering Venus's atmosphere. Has this ever happened, or at least are there projections that it may happen?
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12 votes
1 answer
2k views

### If Earth had a second moon, where would it be positioned? [closed]

Could Earth theoretically have another moon, beside the existing one, that would have a stable orbit? If it is possible, could Newtonian physics describe where it would be (i.e its position relative ...
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5 votes
2 answers
1k views

### Developing intuition about altitude and velocity in multi stage rockets

I just started learning some basics of rocketry and am struggling to understand the outcomes of a simulator I’m programming. All other things being equal, when I attempt to simulate the altitude over ...
3 votes
1 answer
416 views

### GN&C free / open source softwares suggestions

I am looking for a GN&C software free (and open source if possible) capable to compute the attitude and control including hardware profiles, example: RWs (reaction wheels) profiles I know 42 does ...
3 votes
0 answers
139 views

### Temperature distribution of air around a rocket

I am doing some simulations in ANSYS Fluent of a rocket traveling at speed of 100 m/s at an altitude of 12000 m where the surroundings temperature is 216.7 K. The image above is the temperature ...
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4 votes
1 answer
2k views

### Python orbit simulation using TLE-tools and poliastro

I have a source of satellite TLE data - similar to space-track.org. For testing purposes I would like to create a simulation that doesnt rely on the real source of data. I was able to download a json ...
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1 vote
1 answer
318 views

### What is the difference between a Trans-Mars Injection and a Mars Transfer Orbit?

So I'm using this transfer orbit calculator and when simulating a transfer from LEO to Mars, in the delta-v breakdown, appear two different values: TMI (Trans-Mars Injection), at around 3000 m/s, and ...
3 votes
1 answer
273 views

### Different/better ways to calculate the shadow region passage of the satellite and the effect of orbital elements, other than shadow cone technique?

The NASA Technical Publication Method for the calculation of spacecraft umbra and penumbra shadow terminator points; TP-3547 describes the following: A method for calculating orbital shadow ...
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2 votes
0 answers
282 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 ...
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5 votes
2 answers
298 views

### Difficulties with higher order Runge-Kutta implementations

I've been trying to implement a higher order Runge-Kutta numerical integrator in MATLAB for a bit now with ambitions of n-body trajectory fun. Unfortunately, I have not had success in reaping the ...
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1 vote
0 answers
65 views

### How does a fusible wire deployment mechanism work?

Situation Me and my student team are considering to use fusible wires in our CanSat to control the parachute and payload deployment. In detail, a mechanism using a fusible wire should release a loaded ...
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4 votes
1 answer
232 views

### Software to estimate radiation dose for an orbit

I am searching for a software/method, possibly open-source or free, to estimate the radiation dose for an orbit around earth.
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5 votes
0 answers
456 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) ...
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1 vote
1 answer
1k 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 ...
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3 votes
1 answer
464 views

### Is there an API for accessing old TLEs of non-historic objects?

There are various APIs online for accessing TLEs for a satellite object from CelesTrak. However, the APIs retrieved are usually the most recent ones generated. There are also a lesser number of APIs ...
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5 votes
1 answer
128 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 ...
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10 votes
1 answer
714 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 ...
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6 votes
2 answers
359 views

### Interpolation method in pitchover maneuver: what type?

Consider the space shuttle or the Saturn V. Launch would begin with an open-loop pitch schedule obtained from simulation with the day’s winds. The pitch schedule would be specified as a lookup table ...
2 votes
0 answers
250 views

### Drag and lift coefficient tables/plots for Saturn V/Space Shuttle/Other

I'm looking for drag and lift coefficient data to plug into my launch simulation. I could assume constant coefficients, but I'd like to structure my model to accept lookup tables, so I'm looking for ...
6 votes
1 answer
246 views

### Is space shuttle simulator in a museum somewhere?

Really curious if the space shuttle launch simulators are in a museum somewhere for visitors to see and learn more about? Also curious if maybe there is a technical book on those simulators?
4 votes
0 answers
141 views

### Space Shuttle: What are the filters in the attitude error calculation?

Here's a schematic from the space shuttle training manuals showing how the "attitude" error signal used to drive the thrust vector controllers was determined. "Attitude" in quote ...
0 votes
0 answers
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### Space Shuttle: How were I-Load launch programs calculated?

The space shuttle launch program was based on a target attitude profile calculated for the mission and the latest winds. The attitude profile would include roll, pitch, and yaw as functions of time ...
0 votes
0 answers
67 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 ...
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4 votes
1 answer
272 views

### Space shuttle PEG ascent burns

I'm reading a public document on the powered explicit guidance algorithm used in the space shuttle. The document suggests that PEG ascent maneuvers always involved at least three phases: Constant ...
5 votes
0 answers
162 views

### Aerospike calculator software doesn't seem to altitude-compensate - am I misunderstanding aerospikes?

I'm using mvernacc's Aerospike Nozzle Design GUI, which is supposed to be able to design and predict the performance of aerospike rocket engines. The workings of the software are apparently based on ...
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0 votes
1 answer
259 views

### SpaceX launch simulation software?

Say you're a SpaceX launch engineer. You have a mission design meeting where you'll talk about different mission scenarios. The meeting is in a few hours. Would you run a quick simulation in KSP to ...
1 vote
0 answers
101 views

### Soyuz TMA Neptune IDS Button Lights Behavior On Click

I made a simple virtual Soyuz TMA Neptune IDS using simple coding (a work in process). The purpose of it is solely for the buttons location familiarization of the control panels. The buttons react on ...
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4 votes
1 answer
105 views

### Space shuttle state propagation

Space shuttle training manuals say the GNC system obtains state information from the IMU platform at a low rate (0.25-0.5Hz) and that state propagation algorithms estimate the vehicle's state vector ...
1 vote
0 answers
97 views

### Most realistic 2021 rendering of the milky way galaxy [closed]

Images of our own galaxy are either the "edge-on" inside view or artist renditions. However, we have mapped out 2% of the stars. Most stars are red dwarfs, so the more luminous stars will be ...
1 vote
1 answer
283 views

### What is Direct Simulation Monte Carlo and why is it a good method for simulating spacecraft drag in VLEO?

Reducing spacecraft drag in Very Low Earth Orbit through shape optimisation J. A. Walsh and L. Berthoud (2017) show simulations calculating drag coefficients for different "nose cone" shapes ...
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