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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GMAT - Locating S/C to S/C contact, instead of S/C to Groundstation

GMAT implements two "event locators" that find eclipse times and line of sight intervals. However, this only lets you analyse data between a ground station and a spacecraft. Is there a way ...
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Orbital mechanics from Daniel Suarez's book “Delta-V”

In the book Delta-V, a climactic scene involves a high-acceleration return from the orbit of Ryugu to Earth. The book makes a big deal about the delta-v needed for the trajectory (hence the name) so I ...
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How to calculate the very special orbit of 2020 SO

From a NASA JPL page: Earth May Have Captured a 1960s-Era Rocket Booster Source (Sorry, I got an error when I tried to include an animated gif.) 2020 SO was captured by Earth's gravity on Nov. 8, ...
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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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How do I obtain geocentric position vectors at three successive times before I use Gibbs' method?

I would like to try out Gibbs' method of preliminary orbit determination, which requires that from observations of a space object at the three successive times $t_1$, $t_2$ and $t_3$ ($t_1 < t_2 &...
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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 ...
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Tutorial for orbits from TLE data

I've been looking for a new hobby, and have been reading some about satellite tracking. I was wondering if there was a good tutorial that walks through how to use TLE data. So far I have found ...
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GMAT targeting - why targeting RMAG and DEC works while RadApo and INC doesn't?

The GMAT examples demonstrate targeting using this method for targeting a specific Apoapsis increase maneuver: Vary the prograde speed Apply Maneuver Propagate to the Apoapsis Achieve "the ...
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What is/was legacy TLE ephemeris type 2? (TLE, line 1, column 63)

Wikipedia's Two-Line Element Set entry for line 1, column 63 (1.12) says: Ephemeris type (internal use only - always zero in distributed TLE data)13 13Celestrak Frequently Asked Questions: Two-Line ...
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Using the Clohessy-Wiltshire equation, what would be the expression for ' r '?

I'm looking for an expression for r. The difficulty I'm facing is simplifying the C-W equation
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How do space agencies choose arrival dates to planets (i.e. Mercury) from a gravity assist (i.e. Venus)?

Assuming I was looking for arrival opportunities from 2020 to 2030, how can I calculate the possible arrival dates to Mercury given a departure date from a gravity assist from Venus?
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When B is directly below A, as shown, what's B’s velocity (in vector notation) relative to A?

Spacecraft A and B are in coplanar circular orbits around the Earth. The orbital radii are as shown in the figure. (Not looking to use C-W equation. Just the equation describing relative velocity ...
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Can we just throw a satellite in to mars orbit with a very high spin?

I am thinking about this scenario of throwing a satellite to Mars orbit with a high spin, Can we just throw that? one hypothesis can be that high-frequency spinning generates apparent gravity so it ...
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When sending astronauts to the ISS, how does each spacecraft sense the other?

When spacecraft with astronauts tries to dock with the ISS, are there special sensors in each used to track the other? Does one usually do the detection, tracking and orientation in order to "...
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Can a moon orbit its planet faster than its planet rotates?

Can a moon orbit its planet faster than its planet rotates? Can a moon orbit its planet more than once per the planet's day? It seems possible but I'm not sure. Are there any known examples of this ...
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What are the shortest orbital periods used for their repeat ground track properties?

The most well-known repeat ground track orbits are geostationary and geosynchronous orbits, having orbital periods in a 1:1 ratio with the revolution of the Earth. Faster repeat ground track orbits ...
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Under what conditions can a non-resonant satellite stay hidden from an observer on the ground?

From the perspective of someone on the ground, a satellite is usually not above the horizon all the time. But can a satellite have such an orbit that it is never above the horizon? Such orbits clearly ...
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Are LVLH and RSW coordinate systems the same thing?

I've been reading into satellite relative motion, and I noticed that the literature split on using LVLH (local vertical local horizontal) and RIC/RSW (radial intrack crosstrack) coordinate frames. ...
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Is it possible to predict if an orbiting satellite will pass over a given point on Earth after n periods?

I'm learning basic astrodynamics, and I have a question that I cannot find on the Internet (maybe I'm not looking hard enough). My question is, is there a way to predict how many periods would a ...
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Changes in Orbital Parameters Due to Drag

Other than STK, are there any commercially software packages available to model changes in orbital parameters due to increases/decreases in satellite drag. I am trying to figure out if aerodynamic ...
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What is $\theta_{GMT}$?

What is $\theta_{GMT}$?, and how do you convert this into time and angle? I found this article, but I don't think it's exactly what I'm looking for. http://www.cs4fn.org/mobile/owntimezone.php
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How the B-Plane parameters are generally determined

Reading from this document, I am trying to simulate the New Horizons probe trajectory in GMAT and I am puzzled with how the authors of the original paper (by legendary mission designer Robert W. ...
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Calculate distance to Sun

At Cornell University's Ask an Astronomer I was reading How can I find the distance to the Sun on any given day? (Advanced) and it mentioned you can find the distance to the Sun on any day of any year ...
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Analysing a phasing maneuver using GMAT- how do I reliably quantify their “phase difference”

I am trying to recreate a phasing problem that was solved on paper the previous semester, and verify my solutions using GMAT. Two identical satellites are released on a 550km sun-synchronous orbit by ...
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Gravitational force of asteroid Bennu

How can the gravitational force of Bennu (being so weak) hold the spacecraft in orbit?
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Calculating specific dates of reaching apses given orbital elements?

Given a specific date and heliocentric orbital elements ($a, e, i, \Omega, \omega$, mean anomaly) of a spacecraft in a heliocentric orbit, how can we calculate when it will reach perihelion and how ...
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Thrust value for space mission from Earth's orbit to Venus' orbit

If I had to take a spacecraft from Earth's orbit (400km above earth) to an orbit around Venus (6151km X 50,000km elliptical orbit), how much thrust will I need. Delta V is 5km/s using hohmann transfer?...
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What is the highest number of impulses required for an optimal orbital transfer?

Given two arbitrary orbits around a point mass, there exists some optimal transfer between them in terms of delta-v. What's the highest number of impulses such a transfer could require? (That is, I'm ...
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Why is the gas giant grand tour interval 175 years when the synodic period of Uranus and Neptune is 171 years?

The "Grand Tour" path Voyager 2 took, flying past Jupiter-Saturn-Uranus-Neptune, repeats every 175 years. As the original paper by Gary Flandro puts it: Earth – Jupiter – Saturn – Uranus – ...
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Are ECI and ECEF both frames and/or coordinate systems? Is there a difference?

I don't know really know the difference between a frame and a coordinate system. I'd proposed ECEF and ECI tags, do we need them? Frames seems to be the standard in meta but there is concern so any ...
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Satellite tracking telescope integrated program in Matlab

How can I get a comprehensive, integrated MATLAB program to set up and capture SGP4 output for telescope mounting? I am currently receiving state vectors from the SGP4 program, which include the ...
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Magnetometer in space

See, i recently buy a magnetometer to experiment with arduino, i want start building a litle fly computer for a cubesat (this cubesat have an ion engine, so, have thrust). I start reading the Azimuth ...
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Land a cubesat on the moon with ion engine

Say I have a 3U cubesat with a BIT-3 ion thruster, an iodine tank and landing legs. Can it land on the Moon with just an ion thruster?
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Calculating Orbital Velocity without Semi-Major-Axis

When playing Kerbal Space Program, I realized that there is a difference between surface speed and orbital speed; this difference is quite variable, although the Kerbin's surface speed is only 175 m/s....
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How to determine the delta V required in order for the satellite at pt. A to hit the earth at pt. B?

I'm confused about how would I go about obtaining delta-v in this case. I'm aware of orbital transfers such as bi-elliptical but that is not the answer to this. Kindly help
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What would be the influence of nearby planets on a Dyson sphere or Dyson swarm?

Considering orbital mechanics, I would like to ask what would be the effect of nearby planets such as the Earth or Jupiter on a Dyson sphere. A Dyson sphere is not realistic because of the tremendous ...
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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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How can we express velocity of the Apollo mission relative to a moon-centered reference frame instead of an inertial reference frame?

I am really interested in the Apollo mission and I was wondering how fast did the astronaut pass by relative to the moon. I wanted to compare it with the speed of the car. I have been able to ...
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Travel time from lunar orbit (EML2) to Jupiter using skyhook only?

I am doing background research for a science fiction story, and hoping someone can help with this navigational question. Voyager 2 reached Jupiter from Earth in about 2 years. However (if I understand ...
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How much delta-v have I used here? What's the “official” equation for delta-v from parametric thrust?

I took a break from Stack Exchange, jumped in my spacecar and flew the following squiggle: $$a_x = \cos(10 \ t)$$ $$a_y = \sin(5 \ t)$$ $$a_z = \cos(2 \ t)$$ starting at ...
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Why is “delta-v + $\sqrt{{v_E}^2 + C_3}$ where ${v_E}^2 = $11.19 km/s” the correct way to calculate total propulsive delta-v? Please show all work

There is one answer to What spacecraft has had the greatest total propulsive delta-v? and I can not understand how its numbers have been calculated. Response to comments does not seem forthcoming so I'...
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Tools for high-thrust trajectory optimization

I've tried using some of the freely available tools for making pork chop plots to explore the potential of transfers between planets. But as far as I can tell, these really are not designed for and do ...
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Does mass of orbiting body affect the orbital speed? [duplicate]

Does mass of orbiting body affect the orbital speed? Suppose if Moon is at same distance from Earth as International Space Station. Would Moon's orbital velocity change? Also secondary question, ...
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Do I have enough info to find the true anomaly of an orbit?

For a personal coding project, I'm trying to model orbits of satellites around the Earth. I take in some values from a user and use them to determine the shape of the orbit. I want to model the ...
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What is the closest polar lunar orbit that can be sustained? What are the limiting factors on closest approach?

I'm wondering how close a lunar orbit can get at periapsis to the south pole. I want an orbit that is sustainable for at least ~20 orbits. I'm working on a small sat concept for studying the lunar ...
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What does a low thrust apoapsis raising look like?

Say you are in a simple circular orbit, $r = 1$ and want to raise your apoapsis to some higher altitude, say an orbit $r_P = 1, r_A = 2$ A high thrust spacecraft would to this in one impulse, at $\...
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How to create a satellite intersection/conjunction in GMAT?

Starting to learn GMAT. I've been able to get my satellite to move around in space pretty well with various targets and maneuvers in the mission sequence. Now I would like to have my satellite target ...
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Soyuz/spacecraft deceleration speed for reentry

I recently saw a program by Prof. Brian Cox (Human Universe Ep.1) where he mentioned that just by using two equations - f=ma and the universal law of gravitation, you could calculate how much a ...
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Range of travel time between particular planets using the Interplanetary Transport Network/Interplanetary Superhighway?

I understand the Interplanetary Transport Network allows for travel at low speeds between different planets in the solar system using very little energy. Is there flexibility in how long it would take ...
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Phasing maneuvers; methods to travel between satellites with very similar circular orbits

If you imagine two satellites orbiting earth, each in a circular orbit in the same plane and at the same altitude, but varying in their angular position, the simplest way in my mind to travel from a ...

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