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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Why does Earth not appear to be at the focus of TESS' elliptical orbit in this video?

An excellent review of all of the considerations and work that has gone into designing TESS' orbit can be read in the ArXiv preprint A High Earth, Lunar Resonant Orbit for Lower Cost Space Science ...
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Does the shape of Cruithne's orbit change within one period?

The question Why not explore Cruithne? includes the GIF below. I've extracted two frames and extracted the red pixels of Cruithne's orbit where ...
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Why do orbits in the Iridium constellation have an inclination of 86.4°?

Wikipedia's Iridium_satellite constellation; In-orbit spares says that Iridium satellites have an inclination of 86.4°: Significant orbital inclination changes are normally very fuel-intensive, but ...
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Atmospheric reentry drag and friction

What is the difference of air drag in ground level with let say moderate speeds like fast cars 200km/h to 400km/h with high speed vehicle reentry at high altitude where the air is so rarified. Making ...
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Would a space rocket launching from Ceres in a path to Jupiter be faster relatively to the sun than one launching from Earth?

Suppose you have a space rocket which when launching from Earth its speed relatively to Earth it's 11 km/s. For what I've read in another topic in Space SE, the orbital velocity of the planet where a ...
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How to find the point of interest using the two line elements [closed]

Good evening everyone, We know that the point of interest of any elliptical orbitiis located at the perigee... If I have the 6 orbital elements how to calculate the location on the earth surface (...
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How do two-line element sets handle rev numbers > 99,999?

In a two-line element set (TLE), five characters in line 2 -- columns 64-68 -- are for the rev number. (https://en.wikipedia.org/wiki/Two-line_element_set) But some satellites have been around the ...
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Why does TDRS 1's inclination evolve so much differently than that of all the others starting in 1995?

The plot below is from the question Why do the geosynchronous TDRS satellites have this distribution of inclinations?, and the explanation says Inclination and mean motion (rev/day) for TDRS ...
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How does accelerating a spacecraft at the apogee affect its orbit?

I was reading an article about the Oberth effect. It describes the orbital maneuver. The article said that the spacecraft performs a burn at perigee and gets into higher orbit. So the question is "...
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How does the dynamics of the Jupiter and Saturn system make them be well suited for low-energy transfer?

Many papers mention that the compact and complex dynamics of the Jupiter and Saturn systems makes them ideal low energy transfer. My question is how? How does the dynamics of the Jupiter and Saturn ...
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How to estimate which astronaut ends up furthest from the ISS after one orbit?

Three astronauts; Goofus, Gallant and Zippy the Pinhead play a game. All three take their cold gas thruster-powered jet packs and quickly move 100 meters away from the ISS. For some reason after ...
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How to calculate delta v for orbit change around body; not necessarily Earth?

Let me express my joy at having found this great place of Stack Exchange. My question concerns the calculation of delta v requirements when already in orbit around a body and lowering or raising ...
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Analytical treatment of relative positions between satellites?

I have been searching the internet for estimation of relative position between two satellites. However, all sources seem to be pointing to methods used for proximity operations, where the math ...
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How to solve this exercise in orbital mechanics; the moon stops in its orbit, what happens next?

As an exercise in orbital mechanics, suppose the moon were to suddenly stop orbiting Earth, and instead at time $t=0$ begin moving in the same direction as Earth so that their relative velocity were ...
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What's the method behind this TDRS triplet inclination “madness”?

Previous "method to the maddness" questions: 1, 2. The image below is from Why does TDRS 1's inclination evolve so much differently than that of all the others starting in 1995? and I've used it a ...
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What would the perihelion of Ulysses's orbit have been without a trajectory adjustment after its Jupiter swingby?

I'm wondering what the perihelion of the orbit of Ulysses spacecraft would have been had a trajectory adjustment after its Jupiter swingby not taken place? On Wikipedia it says "The size and shape of ...
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Why is the ribbon of decommissioned geosynchronous satellites skewed?

I was looking at this 3D map of satellites orbiting earth and noticed something interesting. Around the green ring of active geosynchronous satellites, there is a ribbon of what I assume are obsolete ...
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Teleporting an object into geosynchronous orbit

Assuming that a method was found to teleport objects, and at huge range, if an object was teleported from the surface to a location at the correct height (Wikipedia says about 42,164 km from the earth'...
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How much harder would space exploration be if the Earth rotated like Uranus does?

Let's say the Earth got knocked a bit silly in the distant past and somehow space-loving life evolved on this planet. They roll around on an Earth with an axial tilt of 98°. How much harder is it for ...
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Can we go anywhere in space with only THREE reaction wheels and ONE chemical thruster?

I had a discussion the other day with some of my peers and they were very keen on the fact the it is possible to change your orbit as desired using a single thruster and a three reaction wheels. The ...
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Calculate velocity vector of hyperbolic trajectory

I am writing a little 2d space program and I need to calculate a velocity vector for my program. I already have my elliptical orbits working well but once the eccentricity of the orbit goes over 1 the ...
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moon's true anomaly at date of new moon

I've seen on this site: https://eclipse.gsfc.nasa.gov/SEhelp/moonorbit.html a table that gives the true anomaly of the moon at the time of new moon. The difference between the true anomaly at one new ...
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What will happen to a spacecraft if it cancels its galactic velocity?

A spacecraft in a circular LEO orbits at ~7.7km/s. If it performs a retrograde burn and cancels this velocity (within the Earth reference frame) it will start falling towards the Earth center along a ...
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Solar system galactic velocity vector relative to ecliptic plane

The Solar system moves through the Milky Way galaxy with velocity of 230 km/s. The ecliptic plane is located ~60 degrees with relation to the galaxy plane, according to this source. The page also ...
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How can I plot satellite's trajectory from three different TLEs to detect any deviation on path with time?

I have obtained TLE information of a satellite from space-track.org for three different times. I am trying to study any deviation of the satellite trajectory from its usual path. Here I am comparing ...
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How frequently do asteroids collide with each other?

Space is empty ... lots of empty. Apparently so empty that the risk of collision between a spacecraft of our times, and an asteroid in the asteroid belt is said to be infinitesimal. Running a search ...
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Why does the ISS track appear to be sinusoidal?

Okay, time for a stupid question, but it keeps me up at night trying to figure it out. The ISS 'route' appears on paper as such: I am imagining it has to do with a combination of its orbit and the ...
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Can a satellite utilize gravity gradient stabilization, solar power, electrodynamic tethering and dynamic quadrupole momentum at once?

Have any analysis been done using 2 or more devises above to function as a satellite where 1 alone would not to maintain orbit without propellants? Will this system or one with a different ...
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2D Orbital Path from State Vectors

Given a planet of mass $M$ at the origin, and the state vectors $\textbf{r}$ (in meters) and $\textbf{v}$ (in $m/s$) at time $t = 0$ for a satellite, what are are the equations for: Distance $d(t)$ ...
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Defining overshoot and undershoot boundary of entry corridor

I have been reading up on the mathematic of atmospheric entry. I have found different methods to theoretically calculate the corridor width but I don't understand how to define the overshoot and ...
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Do Lagrange points still exist if there is significant radiation pressure on the third body from the first?

From this answer: To obtain the distance to L1, find the smallest value of $r$ such that $$\frac{M_2}{r_1^2} + \frac{M_1}{R^2} - \frac{r_1(M_1+M_2)}{R^3} - \frac{M_1}{(R-r_1)^2} = 0.$$ To ...
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How far would the Mars L1 Lagrangian Point be from Mars?

I am a sci-fi writer, and I've heard about the concept of putting some type of magnetic deflector near the Sun-Mars L1 point to deflect charged particles from the Sun to reduce radiation effects on ...
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Balancing a mirror

A possible way of heating up Mars is to use mirrors to direct more sunlight towards the planet. I am not asking about the feasibility or cost of such a gigantic project, but I have a question ...
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How can you determine the nature of an object from its flight path angle, velocity, and radius alone?

Assuming that a defense system is capable of determining an object's flight path angle ($\gamma$), velocity (v), and radius (r), how could one differentiate between an ICBM, a satellite, or a solar ...
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Getting the Velocity Vector in an Elliptical Orbit

I have a 2-D two body set up. I am using the vis-viva equation to get the velocity scalar of my elliptical orbit. I have the Semi-Major Axis, the radius, the eccentricity vector. I am sure I can ...
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What would be different about satellite orbits if Earth were prolate? Would we have Sun-synchronous and Molniya orbits?

It's hard to imagine how it could happen naturally since on geological timescales the Earth would either be spherical if it didn't rotate, or oblate if it did, but from an orbital mechanical ...
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Help with Vector format N-body state transition matrix

[Update] This is for an on-board autonomous navigation system (3-dimensions, interplanetary) using a Kalman Filter. There is no target trajectory. I have the position and velocity measurement models ...
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How long does the SYLDA fairing stay in orbit after deploying?

For dual-manifest missions, Ariane 5 often uses the Système de Lancement Double or SYLDA system to encapsulate the lower of two stacked satellites. It can be seen in the following image encapsulating ...
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How to find instantaneous mass of a central body that results in a given osculating orbit?

This question was underspecified, so I'm going to try again. Osculating orbital elements are Keplerian elements of a hypothetical orbit around a specified center which would be tangent to a specified ...
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Can L3 have halo orbits?

I've recently said you see one co-linear libration point, you seen 'em all. That's what I always say and while halo and other orbits associated with Sun-Earth L1 and L2 work similarly, L3 is 2 AU ...
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Why does launching east result in an orbital inclination equal to the latitude of the launch site?

As mentioned briefly in this answer and this Everyday Astronaut video: And just as a reference, if you launched straight east out of Kennedy Space Center, you'd be on a 28.6° inclination which you ...
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How often does ISS require re-boosting to higher orbit?

I know that ISS, being in low Earth orbit, requires regular boosts. But I can't seem to find information on how often does this happen. Is it done during each resupply mission, only during some of ...
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How can I plot a satellite TLE from its orbital parameters using python and skyfield?

I have a function that uses TLEs (Two-line elements) from Celestrak to plot the visibility of a satellite in Python. Is there a method with skyfield or poliastro to plot a TLE from given orbital ...
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How do you calculate shift in argument of periapsis for a not instantaneous burn assuming you're starting in circular orbit?

Most times we assume that burns are instantaneous, in this case if you burn (without a radial component) at the periapsis or apoapsis there is no shift in argument. Let's say the engine is weak and ...
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When (roughly) will North Korea's Kwangmyongsong-4 satellite re-enter?

North Korea recently launched Kwangmyongsong-4 but it wasn't entirely successful and is tumbling out of control. I read on a Wired article that “This thing is probably a failed attempt to get higher ...
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How are rocket launches scheduled?

With all the satellites and other objects already in space; how exactly are launches scheduled and coordinated? Is there some kind of clearinghouse? How do the mega constellations affect the ...
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Could we wait for Mars to come to us?

This may be a stupid question but I didn't find much information online about it. The concept is simple, could we launch a vehicle into space from Earth, stop right on Mars trajectory and wait for the ...
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How do stable equilibrium points work in GEO? If all geosynchronous spacecraft suddenly lost stationkeeping, would most “fall into” one or the other?

The (currently unanswered) question Quantitatively, how deep are the stable equilibrium points in GEO? How much delta-v to move from one to the other? (also see comments at Delta-v to move from GEO to ...
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What's the reasonable “window” in days for a Mars-Earth Hohmann transfer?

As any popular science reader knows, when traveling between Earth and Mars, there's a Hohmann transfer opportunity about every two years (I believe it's every 26 months, specifically). What I've ...
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Would it be possible to grab on to a satellite, and use it to keep yourself in orbit in an emergency situation?

You are orbiting Earth when your spacecraft falls apart and you are left flying through space. Will your spacesuit keep you alive long enough to be rescued? Or will your orbit lower to quickly and you ...

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