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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.

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Diagram of Hayabusa 2 in “Hill Coordinate System”; what is that exactly? How to convert it to inertial?

These JAXA's Hayabusa-2's two Tweets: 1 2 show a diagram of the spacecraft's motion relative to Ruygu in what they call a Hill Coordinate System, This is a diagram of the trajectory during solar ...
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How much does the tidal effect affect satellites in a retrograde orbit?

How much more unstable are satellites in retrograde then a pro-grade orbit? Does the stability of a retrograde orbit increase with altitude? This answer said this orbit is unstable and made me think,...
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How would propagation differ between a GEO and a Retrograde GEO?

A Binary Equatorial Synchronous Retrograde Orbit is an orbit that would travel in the opposite direction of GEO and would pass over the same point on Earth twice per day at the same altitude of GEO. ...
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Software for Orbital Mechanics simulation and analysis

I am trying to create a Lunar Flyby mission for small nanosatellites and I want to plot an orbit for it. The problem is that no website has proper information as to what variables, problems and ...
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Game for teaching basics of orbital mechanics

I am looking for a game that would be suitable for teaching basic orbital mechanics concepts to primary school students (grades 6-8). Contrary to most of the questions here asking about spaceflight ...
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How well the orbits of Jupiter Trojans to be visited by Lucy may be predicted?

The orbits of the large planets are very well known and their position may be precisely predicted for the planning of complex swing by maneuvers of interplanetary space probes. There are exact ...
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How to correctly make a fake, counter-propagating TLE?

In this answer I have said: Do not make FAKE TLEs! I would now like to make a fake TLE. Specifically I'd like to generate a counter-propagating "twin" of an orbit by flipping inclination by 180° ...
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How presise could 2 satellites “thread the needle” in orbit?

I have a question about using a magnetic field to propel 2 satellites off each other while traveling in opposite directions on the same orbital plain to intersect either 2:1 or 1:1 on each orbit ...
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How fast are trips to the Moon for unmanned spacecraft typically?

The period of an orbit around the Earth is given by: $$T = 2 \pi \sqrt{a^3/GM}$$ For Earth GM is about 3.986E+14 m^3/s^2. Put in $a$ = ((6378+400)*1000) for the ISS in LEO (as a test) and you get ...
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Launch Vehicle LM2D

As it is well known, the circularization of orbits needs at least 3 stages. How could the Chinese launch vehicle LM2D circularizes its orbit with only 2 stages?
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Could Galileo GNSS satellites 5 and 6 join the constellation if their orbit was raised, or is even more delta-v needed?

The Gallileo GNSS satellites numbers 5 and 6 have been used to make a record-breaking precision measurement of gravitational time dilation as a bi-product of them being in the wrong orbit. See (just ...
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Would the orbits intersect during 7 days?

I'm calculating the probability of collision of the satellites. I'm trying to filter the set of orbits to minimize the calculations. Which conditions may definitely say that the given 2 orbits ...
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What could a High Earth Orbit be used for in practice?

I was perusing wikipedia and saw this awesome infographic: Original location of infograhpic: Wikipedia Then it hit me, in all the time I've been browsing space articles and such... I've never ...
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Calculating the radial, in-track and cross-track distances

I'm computing the relative distances between satellites. The following picture shows the distances, which are considered as risky. What do Radial, In-track and Cross-track mean and why are they ...
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The dreaded apocalyptic asteroid approaches Earth but lands safely on the Moon at zero relative velocity

An asteroid approaches and the Moon 'catches' it in the same way that a sports player catches a ball - that is to say by matching the velocity of the hand to that of the ball. Could a lucky slingshot ...
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How do you find lunar flyby using Apollo 13 mission report data?

Link to mission report: https://www.hq.nasa.gov/alsj/a13/A13_MissionReport.pdf So Im trying to do analysis on the mission phases of Apollo 13 but my part is to only focus on the flyby part. My ...
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Proper handling of terminal guidance of finite burn closed-loop execution for rendezvous conditions?

I'm writing some software which uses Optimal Control Theory / Calculus of Variations / Pontrayagin's Minimum Principle / Primer Vector Theory to do closed-loop execution of finite burns (in KSP). ...
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How does a Mars lander reach a chosen landing site?

I see lots of questions how landing sites are chosen, but none so far how these landing sites are reached. It already looks like magic how the target planet can be reached at all, but when are ...
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Could solar sails be used in station keeping?

Could solar sails work in place of solar vanes for passive stabilization in station keeping a satellite fixed in the Lagrange 2 point on a parallel orbit with the Moon? Related: What is the ...
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What is the darkest orbit around Earth?

What orbits around Earth has the least and most sun light exposure? I wondered: When taking pictures either of Earth or otherwise with various telescopes in orbit, does it help to be in Earth's ...
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General expression describing the trajectory of a bullet in orbit - fired in an arbitrary direction (version 2)

This replaces a previous similar question that I could have formulated better. I'm in orbit and I fire a bullet in an arbitrary direction. I could shoot (1) Along the direction of the orbit ...
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What do terms of NASA's event list of SOHO mission mean?

In the SOHO mission Event List SOHO Event List there are a few terms I am hoping to understand. I assume MCC1 X-1 Burn refers to a mid-course correction. What does the number 1 and X-1 mean? For ...
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Could a ball of water stay in orbit?

Could a water bubble (spherical occlusion of water in air or vacuum) similar to the one in the picture below remain in Earth orbit without evaporating, dispersing, or disintegrating? Assume the orbit ...
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Accuracy of ECI (J2000) to ECEF (WGS84) for a LEO satellite only accounting for Earth Rotation

I am working on developing a simple J2 orbit propagator for a project I am working on and am at the stages of converting from ECI to ECEF. Looking at this reference document in section 2.4, what ...
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Bombing the Moon: how much debris would there be in stable orbit?

If someone had actually nuked the Moon (e.g. here or Bombing Moon and Mars: What would it look like? ), what's the probability of some debris reaching a stable orbit around the Moon? This would not ...
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Software for orbital sketches

I am looking for recommendations on software that can create orbit sketches such as the image below. Adding an informative sketch to an article can help readers better understand the idea. I am ...
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How do I calculate the Characteristic Energy for a rocket to Near Rectilinear Halo Orbit where the Deep Space Gateway is gonna orbit moon?

How do I calculate the Characteristic Energy for a rocket to Near Rectilinear Halo Orbit (NRHO) where the LOP-G or the Deep Space Gateway is going to be orbiting the moon? Or if someone already has a ...
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Would a self-winding watch work in space without gravity?

Could a watch that winds itself with a pendulum work in space with no gravity? Could a pendulum or the self winding part be modified to work off the movements of the wrist in a microgravity ...
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Calculations Apollo astronauts were trained to do by hand if loss of guidance computer and/or data & coms link to Earth?

This answer to the question is it possible to navigate space travel with no computer? currently contains the line Yes, as long as you don't care where you end up but I am not so sure this is true. ...
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Why might NASA need to “practice moving a spaceship in different orbits in deep space”?

The NASA.gov feature Q&A: NASA’s New Spaceship says Q: NASA’s really building a spaceship?! A: That’s right! NASA is working with its partners to design and develop a small spaceship ...
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Is there a flight simulator showing the gravity well of the Earth and Moon? [duplicate]

I tried the Kerbal Space program and could not get it working on my CPU. Is there a chart or program that is light weight that I can run simulations on?
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Why does ExoMars have more landing ellipse flexibility in 2020 than in 2018?

The BBC's ExoMars: Where to send Europe's robot rover? discusses the decision-making faced by the ExoMars Site Selection Working Group. The working group will spend Thursday and Friday discussing ...
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Ideal shape for a long, skinny reaction mass for LEO to cis-lunar and beyond? (a “space rail gun”)

@Ingolifs' answer got me procrastinating thinking further. What you're asking about is a mass driver space station in low earth orbit that a payload or ship launched from earth can dock with, and ...
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How is a satellite constellation launched?

If want 10 satellites chasing each other around the earth (evenly spaced) all one the same plane, these satellites would be evenly distributed around the globe after launch by slightly raise or lower ...
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Tesseral Part of the Geopotential

I am working on the design of a constellation for academic purposes. I try to describe a phenomenon that appears in the simulations by means of analytic expression and I can't really find a good ...
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Where is Lucy going? (asteroid mission)

On Halloween (31-Oct-2018) NASA Goddard announced that Lucy has a green light: NASA’s Mission to Jupiter’s Trojans Given the Green Light for Development All I have are these links which are now ...
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Why are there no LEO satellites in the earth's equatorial plane?

From my elementary school understanding of Satellite orbits, I know that GEO satellites are placed in equatorial plane, MEO satellites are placed in an smaller degree inclined plane while LEO ...
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What was the speed (avg, min, or max) of ARTEMIS-P1 spacecraft as it orbited L1 and L2

If not specifically ARTEMIS-P1, then what is the average speed (or mins and maxs) of a spacecraft orbiting EM L1 and L2 in halo and Lissajous orbits? Are there varied orbital periods for those points?...
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RIP Kepler, how shall we call your orbit? Does this cyclic flip-flop process have a name?

So long, and thanks for all the Fish Planets The captions in the NASA Ames Research Center video What Will Happen to NASA’s Kepler Spacecraft? read as follows: NASA’s Kepler space telescope found ...
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What's the difference between zenith and radial?

When it comes to orbital mechanics, are zenith and radial the same? Or to put it another way, are nadir and anti-radial the same?
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Geometry of full global coverage with 4 supersynchronous satellites, 3 or 16 control stations

in order to provide a truly global coverage of the Earth from space, including the polar regions, a minimum of just 4 satellites is required. Placed in precise 63.4 degree supersynchronous orbits, one ...
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Measuring the effect of Earth tides

In order to calculate the acceleration due to the geopotential, I've already implemented the EGM-2008 TideFree model, getting the coefficients from the link. Is the Earth tides effect already ...
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How to make satellite ground track on map?

I want to make satellite ground track using matlab. I already had a position of satellite(ECI) by solving Kepler equation. And I know convert ECI to ECEF using rotation determinant. Then I convert ...
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Could a satellite in LEO “pump” or change mass distribution to gain forward momentum?

Similar to pumping your feet on a child's swing can a satellite run up and down a pole to produce a forward momentum? Red dots is the satellite's position running up and down the pole on an ...
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What is the source of Scott Manley's plot of Messenger's end of mission perihermion loss?

In the video Why Does it take BepiColombo 7 Years To Get To Mercury? Scott Manley nicely explains some of the basic orbital mechanical aspects of the mission and compares it to the Messenger mission. ...
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The sorting of perturbational effects by the power

I have developed an orbital propagation tool, which considers the effects of Sun, Moon, Earth harmonics, SRP, drag, relativistic correction. First question Considering the LEO orbit, I would sort ...
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Spacecraft-fixed coordinate system

I am working with data from a polar-orbiting satellite (inclination 97 degrees) with limited attitude information. I am trying to define a coordinate system which is fixed with respect to the ...
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How would a Jupiter flyby have helped to get to the Sun? Why was it later ruled out?

The quote below surprised me. What were the orbital mechanical details of using a Jupiter flyby to get a probe from Earth so close to the Sun? Was a "U-turn" possible; single flyby of Jupiter into a ...
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Would adding a long pole to the International Space Station keep it from tumbling via gravity gradient stabilization?

What things can be done mechanically to make the ISS more stable in a dormant state without a crew? I have listed a couple of links that may work, but I am open for constructive criticism and new ...
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What will happen to Parker Solar Probe in the long term?

Will the probe be intentionally crashed anywhere? Or is keeping space decontaminated not an issue here since temperature and radiation will sterilize anything in that kind of orbit?