# What is Orbital dynamics: Definition and 30 Discussions

Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and law of universal gravitation. Orbital mechanics is a core discipline within space-mission design and control.
Celestial mechanics treats more broadly the orbital dynamics of systems under the influence of gravity, including both spacecraft and natural astronomical bodies such as star systems, planets, moons, and comets. Orbital mechanics focuses on spacecraft trajectories, including orbital maneuvers, orbital plane changes, and interplanetary transfers, and is used by mission planners to predict the results of propulsive maneuvers.
General relativity is a more exact theory than Newton's laws for calculating orbits, and is sometimes necessary for greater accuracy or in high-gravity situations (e.g. orbits near the Sun).

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1. ### I Plotting the orbits of the planets from Ephemeris data

I would like to plot the position of planets around the Sun for different dates and describe their orbits. I got the Ephemeris data for each planet from the JPL Horizons System, I got: Date__(UT)__HR:MN R.A.___(ICRF)___DEC Ang-diam ObsSub-LON ObsSub-LAT ObsEcLon ObsEcLat however...
2. ### A satellite in orbit in a system with one planet and two moons

1) Considering the forces on one of the moons, I have: ##\frac{GMm}{(10R)^2}+\frac{Gm^2}{(20R)^2}=m\frac{v^2}{10R}\Leftrightarrow v=\sqrt{\frac{G}{10R}(M+\frac{m}{4})}.## 2) Considering the initial situation in which the satellite is at rest on the surface of the planet...
3. ### I About the relation between number of sidereal and solar days

Hi all, I've a doubt about the following formula for the number of sidereal vs solar days for a generic planet orbit (e.g. the Earth's orbit around the Sun): $$N_{sid} = N_{sol} + 1$$ Section 1.5 of the book "Foundation of Astrophysics" - B. Ryden shows how to calculate the above equation...
4. ### B How long it takes the Earth to fall halfway to the Sun--ellipse method

There's a classic physics problem that is: If Earth is orbiting the Sun at 1 au from and is suddenly stopped. How long does it take to fall into the Sun (neglecting the size of the Sun/Earth)? I know that a clever way to solve this problem is by using degenerate ellipses and an object...
5. ### Orbital dynamics math review for a computer simulation

The program begins by prompting the user to input the initial angle and speed. Once these values have been input, the program calculates the initial velocity components for the asteroid in two dimensions. printf("Input an initial angle from 10 to 80 degrees\n"); scanf("%f", &theta)...
6. ### A Calculating Orbital Trajectories for Spaceflight Simulators

Hi! Basically I am developing a spaceflight simulator specifically for the space shuttle. Coding the Shuttles Systems etc. is not actually the hardest part, as I had thought before. The real problem is the physics engine :confused: The main problem I have is, that with all the Equations for...
7. ### On the convergence of the three body disturbing function

For the three-body-disturbing function expanded in multipolar orders with respect to the ratio of the semi major axes, the function converges for small ratios, how to check the convergence for a certain set of parameters? I'm using the work of the Laskar in his paper "Explicit expansion of the...
8. ### Extract anomalies from two-line element set (TLE) on ISS

Homework Statement I am faced to a problem of interpretation illustrated on figure below : I must precise that I talk about **mean anomaly**. Homework Equations for the 2 questions, I am asked to find : 1) at which anomaly is the ISS at the two lines epoch ? 2) at wchich anomaly is the...
9. ### B Feasibility of a L1 Gravity Swing Cold Launch?

At an L1 LaGrangian point between two bodies, one could - materials science notwithstanding - pit two of Newton's Laws (LM3,UG) against each other to provide thruster-free stationkeeping. Would it be feasible to use that to launch free from the system ? either spit out like a watermelon seed...

26. ### Need assistance with orbital dynamics questions

Hello, I am currently writing a novel and there are quite a few situations that I would like to create that involve orbital dynamics. I would like to be as realistic as possible. I am seeking a knowledgeable person that can ballpark these problems. I do not think that it would take to much of...
27. ### Gaining Understanding Orbital Dynamics & N-Body Simulation

Hello. I have a project in school in which I will be attempting to gain an increased understanding of orbital dynamics and the maths related to it and using this information to create a n-body simulation. I have a like 3-4 months to finish it and I'm currently in high school so I am only...
28. ### An odd question on orbital dynamics

Is there any kind of celestial event that could occur that could completely lock the Earth's rotation such that it is constantly facing the sun, in the same way the moon is tidally locked to the earth? What would it take? Could it be caused by the passage or entrance of a new gravitational...
29. ### Astrophysics: orbital dynamics - duration of a transit of Venus

Edit: perhaps this might belong in one of the Physics help forums? Oops. Mods, please move if so! Homework Statement Show that a transit of Venus across the Sun’s disk lasts at most about 8 hours. The synodic period of Venus is 584 days and its orbital radius is 0.723 A.U. The Sun’s angular...
30. ### How can I find the shape of an orbit under an inverse cube law of force?

Homework Statement I've found the a general form of equation for the explicit integration of the shape, r(\theta), of a one-body-problem (a particle rotating about a set point, O) for arbitrary \mathbf{f} = -f(r)\hat{\mathbf{r}}, and used it to find r(\theta) for an inverse square law f(r) = \mu...