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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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
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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 ...
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GN&C and more examples for 42 NASA tool

Anyone knows where to find some further examples about 42 applications and examples, mainly relative to GN&C and small satellite Earth missions ( also constellations in case...)? In the repo ...
3 votes
1 answer
326 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
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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
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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
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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
119 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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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 ...
5 votes
2 answers
189 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 ...
1 vote
0 answers
59 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 ...
4 votes
1 answer
82 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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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) ...
1 vote
1 answer
366 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
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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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1 answer
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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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8 votes
1 answer
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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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5 votes
2 answers
244 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 ...
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2 votes
0 answers
169 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 ...
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6 votes
2 answers
223 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?
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4 votes
0 answers
131 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 ...
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0 votes
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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 ...
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0 votes
0 answers
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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
165 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 ...
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5 votes
0 answers
117 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 ...
0 votes
1 answer
148 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 ...
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1 vote
0 answers
67 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 ...
4 votes
1 answer
94 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 ...
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1 vote
0 answers
78 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
208 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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2 votes
1 answer
108 views

Space shuttle position and velocity calculations from IMUs?

How were the space shuttle's rate gyro and accelerometer outputs converted into reliable position and velocity vectors before being fed into GNC software? Is there a document detailing those ...
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2 votes
1 answer
143 views

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 ...
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3 votes
1 answer
147 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 \...
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4 votes
2 answers
863 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 ...
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3 votes
0 answers
202 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 ...
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8 votes
3 answers
539 views

Why shouldn't we illustrate spacecraft trajectories on top of static zero velocity 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 ...
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3 votes
2 answers
379 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 ...
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0 votes
1 answer
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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 ...
2 votes
0 answers
64 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 ...
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2 votes
0 answers
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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 ...
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10 votes
1 answer
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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 ...
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6 votes
1 answer
573 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 ...
2 votes
1 answer
430 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 ...
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6 votes
3 answers
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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 ...
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9 votes
1 answer
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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 NASA’s James Webb Space Telescope says: Testing teams have successfully completed a critical milestone focused on demonstrating that NASA’s James ...
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5 votes
2 answers
237 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 ...
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3 votes
0 answers
127 views

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 ...
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16 votes
0 answers
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Has NASA ever included a ground controller or astronaut becoming insane/irrational/uncooperative 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 ...
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7 votes
2 answers
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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 ...
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4 votes
1 answer
946 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 ...