Questions tagged [orbital-mechanics]

Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. For the movements of celestial bodies, see [celestial-mechanics].

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Draper Semianalytical Satellite Theory (DSST) C/C++ version

Anyone knows where one could find the Draper Semianalytical Satellite Theory (DSST) semi-analytical propagator code in C/C++? I know Orekit includes the Java version inside its code. An in general if ...
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Satellite position using 2 station ranging

Two Station Ranging Given the position of 2 stations and the distance between both and the satellite (in km, say) and the fact that the orbit is geostationary and positioned at 45.1(degrees) west, ...
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Dimorphos natural orbit variability vs DART impact

As we know, DART spacecraft have impacted Dimorphos, a satellite of Didymos. The impact will change the orbital period. Depending on the properties of Dimorphos (mass, porosity, cohesion), the period ...
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What caused the jitter in the DART video as it approached Dimorphos?

If you look at the series of images DART took as it approached Dimorphos, the asteroid jumps around a bit as you approach. Does this mean small corrections were being made right up till near the end? ...
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what is 'f' (true anomaly) for in the orbital inclination change equation

I've been trying to make sense of the formula for an orbital inclination change for an elliptic orbit. This is for an orbit that is not altered in any way apart from its inclination. The equation from ...
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Optimal depth for underground flyby?

Planetary flybys are used to modify the orbital parameters of spacecraft. For maximum gain, a large deflection angle is often desired. But the deflection angle is limited by the closest approach, ...
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Can a meteor shower have a interval greater than 1 year?

Most meteor showers are yearly events. In the manga "SoSo no Frieren" the characters experience a meteor shower that happens only once every fifty years. The story does not take place on ...
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Would the Dzhanibekov effect be a problem for Von Braun Wheels?

If we look at Von Braun's Space Station, we can see that the axis is not completely symetrical. It is longer from one side: Von Braun Space Station 1956 - YouTube that looks a lot like this T-shaped ...
4 votes
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Optimal numerical method to solve BVP for optimal low thrust control

I need to solve a boundary value problem (BVP) for an optimal control in case of low thrust trajectories optimization. I want to include the J2 perturbations to the Edelbaum solution (multiple ...
2 votes
1 answer
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Is this a typo in the Python Skyfield API? "International Coordinate Reference Frame (ICRF)"?

In the Python Skyfield library there is a position object skyfield.positionlib.ICRF, in the documentation it states: An (x,y,z) position and velocity oriented to ...
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At what point on the Earth's surface does the +X axes of the J2000 coordinate system intersect?

From my newly and developing understanding of the J2000 coordinate system it is defined as the point at which the sun appears to cross the celestial equator from the Southern to the Northern ...
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How would I or who/what could help me find the trajectory of an "Extended Grand Tour" spacecraft, without having to take a long course on the subject?

(As forewarning, the most integral details of this question are bolded.) For context, I have been writing an alternate history involving the accelerated development of spaceflight technology for over ...
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Could we use Mars as as an asteroid mining base?

After getting a lot of helpful feedback I've arrived at a question: What if we setup base on Mars: I) Mine water, and split it for propellant. II) Load up light weight (expandable?) rockets with it....
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Calculating period/SMA delta and other parameters from Clohessy-Wiltshire

I'm working on the camera system for a game about relative motion. The orbital motion is completely described by Clohessy-Wiltshire. I would like to be able to calculate some things like eccentricity ...
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Did the Coriolis effect cause 'original spin'? [closed]

I just recently wondered if Coriolis effect (I'm strongly resistant to saying "Coriolis FORCE") is the origin of the spins that permeate our cosmos. For a rotating frame of reference needed ...
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How do we ensure an orbit of a satellite doesn’t interfere with existing ones?

How do we ensure a new orbit/route of a LEO satellite or even a swarm of LEO satellites doesn’t collide with currently existing ones when planning a mission? I’ve thought about running a simulation ...
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Why do the modified equinoctial elements use the semilatus rectum?

The classic orbit elements, $(a,e,i,\Omega,\omega,\nu)$, have annnoying singularities in their non-Keplerian perturbed dynamics at $i=0\pm \pi$ and $e=0$. So Arsenault, then Braucke & Cefola, then ...
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Revisit time estimation for a SAR constellation

I am studying satellite coverage analysis and I have read something about revisit time I did not understand. you can increase and increase the number of satellites to further improve the revisit time, ...
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What is the minimum transfer time for Earth/Mars cycler and still remain balllistic?

The classic Aldrin cycler doesn’t require onboard fuel when accounting for both earth and mars gravity assists. Which is fantastic. But it has a transfer time of roughly 5 months out to Mars. We ...
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What limits are put on mission profiles by maximum tolerated G-force?

NASA standards https://standards.nasa.gov/documents/viewdoc/3315785/3315785 includes this graph of maximum allowable G-force and duration: With some creative license, this curve could be extrapolated ...
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Is a geosynchronous (SSO-like) polar orbit around the Moon possible? [duplicate]

Imagine the equivalent of a sun-synchronous Earth orbit, just substituting the Moon for Earth and Earth for Sun. Such an orbit would have to have the following properties: It would be a polar or near-...
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Fuel economy on orbital launches

To achieve fuel economy during orbital launches (for a particular orbital altitude), do we select the first stage (its thrust), in such a way so as to achieve the desired altitude above the Karman ...
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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 ...
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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 ...
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Space-track SGP4 on MATLAB

I am new to orbital calculations and online resources, so I was hoping someone would be willing to help me get started. I have downloaded the space-track Astrodynamic standard library and I am ...
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1 answer
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What would the TLE data (Mean Motion, Eccentricity, Inclination, RAAN, Argument of Pericenter) of GEO and PO be like?

I am currently making a satellite tracker app for android. I want to test my orbit propagation algorithm and I want to make some made-up basic orbits, so I need to know how their TLE would be. I want ...
2 votes
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GPS SV velocity mismatch

When using classic Newton's second law we have $$ \vec{F} = m \vec{a} $$ $$ \vec{F} = G \frac{M m}{r^2}{e_{r}} $$ $$ \vec{a} = \left( \frac{d^2 r}{dr^2} - r \left( \frac{d \phi}{dt} \right)^2 ...
3 votes
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Patching two Lambert's problem solutions together

I am following this paper on the implementation of a genetic algorithm to find a good MGA trajectory. The way they approach the problem is by solving the Lambert problem for each planetary transfer. ...
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Visualizing halo orbits

I'd like to visualize JWST's orbit (or any halo orbit that resembles it) preferably in Python. Does anyone have any code or resource I could read? Thanks in advance!
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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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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....
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Why would binary asteroids created from YORP spin-up tend to have mutual orbits coplanar to their heliocentric orbit?

Vavilov, et al., "Evidence for widely-separated binary asteroids recorded by craters on Mars", Icarus 383 115045 (2022) says on page 8 that binary asteroids created through the Yarkovsky–O'...
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Are J2 and J4 cases of EGM2008 and other spherical harmonics models?

EGM84, EGM96, EGM2008... are Earth gravity models that contain coefficients "up to" a number of degrees. When using GMAT, STK, MATLAB Aerospace, this parameter is the "spherical ...
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Confusion regarding the series for true anomaly on Wikipedia

I hope this is the right place to ask. Please point me elsewhere if that is not it the case. I'm trying to calculate the position of Earth in its orbit given the day of the year. I found this ...
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Satellite’s Position and Path on 2D Map

When the ISS orbit the Earth, its path traced on a 2D Mercator Earth Map is similar to a sinusoidal wave. I am wondering is there any way to determine the trig function of the wave, knowing the ...
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1 answer
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If humans lived on the moon, could they send a mission with the same goals as Apollo to the Earth?

The humans on the moon have similar technology to the humans (us) on Earth.
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Plot ellipse using elements from TLE

I am trying to draw an ellipse as satellite orbit in three.js, It has an EllipseCurve class which takes these inputs and draws an ellipse around center. EllipseCurve( aX : Float, aY : Float, xRadius : ...
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Relationship between osculating eccentricity and Brouwer-Lyddane short eccentricity

I was under the impression that the mean elements are given by taking the average over an orbital period of the satellite, i.e.: $e_{mean}(t) = \int_{t}^{t+T(t)}e_{osc}(t')dt'[0.367in]$ where $T(t)$ ...
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Could a spacecraft theoretically fly a smooth, curved arc of a turn in space like an aircraft?

I understand there in no air is space which is what allows an aircraft to fly a curved flight path. This is strictly a theoretical question given today's technology. Here are the conditions: There ...
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Axis of an orbiting spaceship

When a spacecraft orbits around earth (assume a "long" spacecraft, so that it can have an axis along its length), does its axis PITCH so as to maintain itself (axis) tangential to the earth'...
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Gravitational field of the Moon and Earth

Is there any method to find a point or plane in space where the gravitational field of the Moon and Earth are the same? And if so, what happens to a spacecraft if it passes through that point or ...
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Satellite's EO sensor footprint on ground

I'm a student and I'm trying to compute the footprint of a generic EO sensor starting from sensor's characteristics and position and velocity vector of my satellite in ECEF coordinates. I followed ...
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Why is my C++ code for an orbit propagator wrong?

I tried making an orbit propagator C++ code. Its values seem to be propagating evenly but still I get a straight line orbit instead of an elliptical one. Why? ...
1 vote
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How to plot a satellite's orbit around Earth in MATLAB?

Given orbit height, mass and initial velocity how should I plot a satellite's orbit in MATLAB? I was hoping to use verlet integration (I need to implement a solver) possibly the velocity-verlet. I ...
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6 answers
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How could 99942 Apophis, in 2029, be captured and brought into a low Earth orbit?

I'm currently attempting to plan out a mission where, in 2029, during Apophis's close approach to Earth, a rocket is sent up to intercept Apophis and decelerate it, making it orbit the Earth. At it's ...
5 votes
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How to find the hyperbolic angle given the mean anomaly?

I'm modelling a hyperbolic gravity assist trajectory around Jupiter and trying to calculate the coordinates for each hour interval before/after passing periapsis. I've calculated $M_h = 0.0176$ is the ...
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How far is the solar system's center of mass from the sun? [duplicate]

We often say that the planets orbit the sun. But, in reality, they orbit the solar system's collective center of mass. How far is that point from the center of the sun?
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How does one calculate the look angle for non-geo satellites (i.e. LEO, HEO, etc.)

I'm trying to find a way to calculate look angles to not just GEO satellites, but LEO, MEO, and HEO sats. The only calculator I've found myself is here, which was referenced for a similar problem on ...
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Is there a python library to determine the position of a satellite at a given time from TLE data excluding the Satellite catalog number?

Or perhaps some simple code or formula that achieves this. I've used pyephem but it requires a Satellite catalog number.
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Why doesn't NASA fly its rockets on suborbital trajectories to the Moon?

After trying it out in Kerbal Space Program for a while, I was wondering why NASA doesn't fly on suborbital trajectories to the Moon. When I tested this idea in Kerbal Space Program I found out that ...

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