# 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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### How would an n-body numerical orbit simulator use hierarchy in its Jacobian?

This question is about techniques to calculate orbits. The Github post On the dynamical stability of Principia's modified Jool system (cited in this answer) says: Principia computes the trajectory of ...
173 views

### Are Jool's moons' orbits stable?

The fictitious Kerbol system includes ...five planets: Moho, Eve, Kerbin, Duna and Jool; and two dwarf planets: Dres and Eeloo; orbit around it. Kerbol contains 99.97 % of the mass in the Kerbol ...
43 views

### rocket trajectory simulation in inertial frame, with drag

I created a rocket trajectory simulator and optimizer using the following equations of motion for a non-rotating frame of reference $$\dot{v} = \frac{T \cos \varepsilon - D}{m} - g \sin \gamma$$ v \...
97 views

### Source of Gregorek's popular drag equation in ESTES TR-11?

In the early 1970s, Gerald Gregorek wrote a technical note on drag for ESTES (maker of model rockets and parts from what I gather). The note is still very popular in the model rocket community, and it ...
40 views

### I want to simulate the antenna pointing error when tracking LEO satellites

I am trying to simulate the antenna pointing error of our antenna when tracking LEO satellites using TLE data. I am using the Skyfield library in python. First I loaded the TLE data from the Celestrak ...
107 views

### Why shouldn't we illustrate spacecraft trajectories on top of static pseudo-potential surfaces?

Three-body spacecraft orbits1 are regularly discussed here and from time to time someone will include a pseudo-potential plot from Wikipedia in their explanation. The discussion often goes south when ...
55 views

### CesiumJS: Hayabusa 2 location w.r.t Earth

Given these coordinates w.r.t Sun: Hayabusa: x = 86014493 y = 112689997 z = 54295960 Earth: x = 82241037 y = 112748971 z = 48876281 How do I calculate Hayabusa coordinates w.r.t Earth center? I ...
93 views

### Modelling a circularizing burn at Apogee

I am relatively new to rocket physics and am looking into modelling burns. Is there a good place to start modelling an orbital burn? I know about the rocket equation but perhaps that is not what is ...
82 views

### My vector math seems to be off in this 2D simulation of a solar system

I intend to simulate gravitational acceleration on a 2D plane (simplified, no gravitational constant). My code is interpreted without any error in the console, but instead of having the two circles ...
42 views

### Why does Gravity Simulator's rendering of TESS' orbit look like a pretzel? How can I unpretzefy it?

Below is a screen shot from the amazing Gravity Simulator driven by our own @HappyKoala. If you haven't seen it recently go check it out now, then come back in 30 minutes and read the rest of my ...
172 views

### Cis-L2 Libration Point Halo Orbit

Queqiao became the first satellite to orbit the Cis-L2 libration point (far side of the moon). Link: https://en.wikipedia.org/wiki/Chang%27e_4 Does anyone have any insight on how to model this orbit ...
2k views

### Is this plot of deep space trajectories correct? Did most launch retrograde from Earth? Why do some change direction between planets?

This answer contains some nice plots of deep space spacecraft trajectories. Noticing that Voyage 2's heliocentric velocity dropped substantially just before 1990 I wanted to see why. Wikipedia's ...
370 views

### Why not simulate certain regions of the atmosphere of Venus?

Many people would like to know if any form of life could survive anywhere in the atmosphere of Venus. Researchers have simulated conditions on Mars and found that after a month some cyanobacteria ...
369 views

### Simulating launch velocity of falcon 9

Help! I finished my numerical simulation of falcon 9 launch in google sheets, where I calculate all the value changes with time. But, when I looked at real launch to compare the values, I got really ...
1k views

### Is this C# code to obtain the coordinates of the planets correct?

This should be a comment to an 2012rcampion's answer to this question: Determining orbital position at a future point in time I'm using the linked data of that answer, under "Computing Position ...
179 views

### Why we do not refuel and assemble in orbit?

Using simple math or playing Kerbal SP inevitably leads to re-using first stages and refueling in orbit for missions far away. It seems, it is always the most economical and simple approach to refuel ...
1k views

### Is there a mathematical formula to calculate drag force without empirical testing?

Typically people put the interested rocket prototype in a wind tunnel to find out the drag force and use the drag force equation to calculate the drag coefficient of the rocket model. I am wondering ...
3k views

### The Martian: Does it really take a supercomputer to calculate spaceflight maneuvers?

My preemptive apologies for asking a question about a movie, and the spoilers within said question, but considering the widespread support for its scientific plausibility, I'm hoping you'll let it ...
193 views

### How much of the Shuttle was physically realized in the simulator?

How much of the Shuttle physically existed in the simulator? Was it just the flight deck? Or were the mid-deck, lower equipment bay, and/or payload bay also included?
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### Was it possible to simulate another atmosphere during Shuttle training?

This answer points out that the Space Shuttle's cabin atmosphere was designed to be equivalent to sea level air, in terms of both total pressure and oxygen partial pressure. However, could any of the ...
97 views

### What happened during this shuttle simulation malfunction involving a failure of a shuttle arm joint while moving the JEF?

This author (cough) begins to relate the details of a particular training incident during simulations for STS-127. However, they very sadly have not finished the tale. Does anybody (cough cough) know ...
256 views

### How does one test Ground Segment communications with, and “downlink” data from a spacecraft that's still on the ground?

NASA News item Ground Segment Testing a Success for NASAās James Webb Space Telescope says: Testing teams have successfully completed a critical milestone focused on demonstrating that NASAās James ...
232 views

### Accuracy of converting from TLE/Orbital Elements to Cartesian if used for other propagator?

Say that I wanted to propagate a real-life satellite based on an initial position in space. However, the only source of data I can get is from a tracking website like CelesTrak or Space-Track, where ...
711 views

### How to implement SGP4 C++, satellite propagator?

I would like to ask about how to implement the SGP4 code in C++ by Vallado. How can I implement the libraries that are available in https://celestrak.com/software/vallado-sw.php. I think that are the ...
2k views

### Does Kerbal Space Program have a software migration path to Lagrange points, halo orbits, and other 3-body goodies?

At about 05:37 in Scott Manley video Kerbal Space Program 2 - What We Know About The Sequel So Iām cautiously optimistic and I really obviously want this to be ...
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### Rocket Engine - Actuator in Loop Simulations

For Actuator-In-Loop simulations, why are the rocket engine nozzles along with the thrust vector control assembly (including the actuators) kept inverted on a platform like in the attached image or as ...
141 views

### Are planet orbits available to download in some vectorial format file?

I would like to work with solar system planet orbits in a Geographic Information Software like QGIS, so: Are available to download the orbits of solar system planets in some vector format? EDIT: ...
179 views

### Has NASA ever included a ground controller or astronaut becoming insane/irrational/belligerent in a training simulation?

NASA training simulations have included a wide variety of problems thrown at the pilots and ground controllers -- not only the typical technical failures, but also some unusual outside-world stuff ...
862 views

### Getting state vectors from JPL Horizons ephemerides

I'm simulating the Sun-Earth-Moon system by numerical integration of equation of motion. I've confused a little bit in JPL Horizons ephemerides. Could anyone explain (if possible, on pictures), how ...
87 views

### Direct conversion of Keplerian orbital elements to Equatorial coordinate system

In the context of a computer simulation of satellites that orbit earth, I am looking for a (accurate) method for converting Keplerian orbital elements directly to Equatorial coordinate system. The ...
144 views

### Optimal point in LEO to perform interplanetary injection burn

I wrote a simulation program in Python to calculate Earth <-> Mars trajectories. Now I would like to test it agains well known trajectories. I used NASA Ames Research Center Trajectory Browser ...
141 views

I have a need to train a model on various trajectory data of flying objects (for clustering purpose). I found trajectory data of air planes online. But since trajectory data for missiles, satellites ...
112 views

### Implementation of NASA Breakup model Area to Mass distribution

In the research "NASA's new breakup model of evolve 4.0" the implementation for the area to mass distribution of fragments produced by collisions and explosions is provided. The distribution ...
120 views

### Possible idea for a simulation in orbital mechanics using data from the JPL [closed]

I have to write a research essay and have decided to write it on orbital mechanics where I would use data from the JPL to perform an experiment (simulation). I was thinking of using the location data ...
103 views

### ECSS Simulation Modelling Portability

Is there anyone who applied "ECSS-E-ST-40-07C Space engineering ā Simulation modelling platform standard" to their simulation? I wonder is the standard really applicable or applied by someone. Some ...
1k views

### What's is this very CGI looking clip in this NASA video of the Alpha Magnetic Spectrometer installation?

This is the NASA video AMS Time Lapse Installation a time-lapse of the Alpha Magnetic Spectrometer (AMS) installation at the International Space Station. At about ...
91 views

### How significant is orbit propagator choice/error when considering a year-long satellite coverage simulation, and which is the most appropriate?

I'm currently considering a project to simulate the (Earth-seeing) coverage of 1 or more satellites over the course of a year. The point would be to compare how different orbits result in different ...
537 views

### What orbital mechanics toolkits available today are suitable for a real-time simulator?

I'm a software engineer and I've always loved Orbiter (also here). However I feel that it's growing a bit antiquated, and it would be nice to have a more modern, open source, or otherwise hackable ...
204 views

### What space simulators are the most accurate at simulating real world physics?

We've all at least heard of KSP, a popular space flight simulator. its not the best but can teach someone the basics at rocket science, delta V, burntime, basic orbital maneuvers, retrograde, prograde,...
9k views

### Can Kerbal Space Program act as a suitable simulator with the right mods?

The game is great alone, but if we install a mod called Real Solar System and another called Realism Overhaul, the force of gravity, engine power atmospheric heights and everything happens to real ...
124 views

### Controlling suicide burn landing location in a python simulation?

I recently asked a question in stackoverflow about Simulation of suicide burn in openai-gym's LunarLander. Sadly most of my assumptions about suicide burn implementaion were wrong but the answer given ...
454 views

### Why is FORTRAN recommended for astrodynamics rather than MATLAB?

I understand that FORTRAN might be faster in terms of computation time, but I don't understand why it is always recommended by people in the field. Everyone tends to avoid MATLAB for astrodynamics; is ...
248 views

### Was a real Space Shuttle ever used as a really big simulator?

@OrganicMarble's answer to How much of the Shuttle was physically realized in the simulator? makes me wonder if Shuttle crew ever sat or stood or otherwise experienced being in an actual Space Shuttle ...
204 views

### Is “Space Shuttle” written as a proper noun in the spaceflight industry?

Writing the question Was a real Space Shuttle ever used as a really big simulator? (and several others) I capitalize Space Shuttle because as far as I know, that's the actual name of NASA's spacecraft,...
14k views

### Why is my Earth simulation slower than the reality?

It took me a long time to create a simulation of the Earth like that. I wanted to show the real spinning speed of the Earth. Here's my video: From this NASA live ...
650 views

### How were Apollo spacesuits cooled during simulations/rehearsals on Earth?

The answer and comments to How have space suits dissipated the heat removed from astronauts? explain that the Apollo space suits used the sublimation of ice into the vacuum of space to constantly ...
132 views

### Recalculate Orbital Elements after a ĪV

I would like to write a program able to simulate a keplerian orbite given an initial position and velocity (r0, v0) and able to manage accelerations in different directions. To simulate the orbit, I ...
241 views

### Apollo 15 State Vector recreation

I am trying to get the state vectors for Apollo 15 before, during, and after critical manoevers [sp]. IE TLI, LOI1, LOI2, lunar launch, preocking, postdocking, and TEI. I am a totally newbie at all ...