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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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 many hours long is Earth's longest possible sub-orbital flight?

This comment below How long will last the Blue Origin New Shepard space flight? says (in part): The words "suborbital spaceflight" as the first words on Blue Origin's webpage for the New Shepard ...
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How exactly did Jupiter change Ulysses orbital plane from nearly ecliptic to polar?

Ulysses spacecraft trajectory is truly amazing. Utilizing gravity assist from Jupiter it was sent into polar orbit around the Sun. I can understand gravity assist concept, I can also (intuitively) ...
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Preliminary Orbit Determination Packages

I have been looking for free orbit determination packages that take in 3 sets of RA,DEC and time, along with observation position and spits out a preliminary orbit estimate. Even if it is a Matlab/...
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When was Newton “not good enough” for spaceflight; first use and first absolute requirement for relativistic corrections?

Concepts in Special Relativity (1905) and of General relativity (first developed between 1907 and 1915) substantially predated spaceflight; they were well known and had been tested well before objects ...
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Space and Newton laws

I've read some articles which explain that we can't totally rely on Newtonian gravity concepts for understanding the motion of objects in space. My question is how the use of relativity helps us to ...
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Given r/a, what are the limits on the direction that an orbiting body could be moving (e.g. solid angle vs r/a)?

An orbiting object at distance $r$ and semimajor axis $a$ will move at $\sqrt{2 - \displaystyle \frac{r}{a}}$ times the speed of a circular orbit at $r$, no matter what the eccentricity or which ...
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What would be the best course of orbital maneuvers for soft landing an asteroid near the lunar south pole? [duplicate]

Wouldn't it be nice for a colony near the south pole of our Moon to have a nickel-iron asteroid on the surface nearby ! Thousands near-Earth asteroids (NEAs) have been discovered with a diameter up to ...
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Question about orbital mechanics and trajectories for a space infrastructure project/climate adaption idea

I’m working on an alternate approach to the concept of using a solar shield to shade the earth from the Sun (to help with climate change adaptation). It would use streams of lunar soil from multiple ...
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When is it okay or at least helpful to use energy arguments in orbital mechanics?

When faced with energy-based questions about spaceflight we often comment something like orbits are about momentum, not energy and use delta-v math in answers. But in this answer to How big a nuke ...
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Are the estimated chances of Bennu hitting Earth in the next 200 years still about “1 in 1410” now that OSIRIS REx has scanned it?

This 2016 answer to Does Bennu pose a risk to Earth? And how can OSIRIS-REx's mission save us? says: Does Bennu pose a risk to Earth?: recent calculations produced a cumulative probability of 1 in ...
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Geocentric latitude and longitude of sub-satellite point

I was trying to derive the expressions for the geocentric latitude and longitude of the sub-satellite point using Keplerian elements. The final equations connecting the combination of the Keplerian ...
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Will it be possible for the crewed Orion spacecraft to fly over the lunar south pole to land the VIPER rover there?

Artemis 2, the planned crewed mission of the Orion spacecraft, will be launched in the fourth quarter of 2022 and will then be the first crewed spacecraft to the Moon in 50 years ! VIPER is a lunar ...
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Why don't spacecraft get left behind once in deep space?

On earth, I know that if I throw a tennis ball straight up while in a car, it comes straight back down thanks to Newton's first law. The ball, the air in the car, and myself are all moving at a speed, ...
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Is it possible for a moon to have a higher surface gravity than the planet it is attached to?

Is it possible that a moon has a higher surface gravity than its planet? I guess it would mean that the moon has a higher mass, but then it would be the planet gravitating around the moon and the ...
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How can Earth-Centered Inertial (ECI) coordinates be properly called “inertial” if the Earth's orbit is always accelerating towards the Sun?

I've just realized (again) that I don't understand anything, something that often happens to me after reading a @DavidHammen answer. How can Earth-Centered Inertial (ECI) coordinates be inertial if ...
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What (the heck) are “space-fixed coordinates” as described in Apollo mission trajectory analyses?

@Ludo's answer to If I wanted to reconstruct an entire Apollo mission's crewed spacecraft trajectories, what are the key sources of historical data I'd look for? shows the table and its source shown ...
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How did the Corona (Key Hole) satellites film canisters deorbit?

The Corona Photographic Surveillance satellites transferred photos back to Earth by releasing a canister with the film, which would deorbit, re-enter, release a parachute and then a plane would ...
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Definition of a trans-Earth injection

Should every "propulsion maneuver used to set a spacecraft on a trajectory which will intersect the Earth's Sphere of influence" be called a trans-Earth injection? Regardless where the spacecraft ...
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Commercial 3DoF/6DoF trajectory simulation and optimization tool for launch vehicle

Is there any 3DoF/6DoF trajectory simulation and optimization tool for launch vehicles like POST available commercially? If there whether it's how reliable when it comes to using for real-time ...
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Statites - Are they possible in anything but theory?

In this question someone mentioned the idea of a Statite, a satellite which is stationary above a planet without being in orbit, usually in an orientation which is not possible with an orbit. It seems ...
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Could a framework of mirrors static in space above the Lunar south pole illuminate a moonbase there continuously?

When near the south pole of our Moon a permanent human community is established to search for and produce water in the permanently shadowed regions there, it would be nice to have some light from ...
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What is known about the trajectory of J002E3 (Saturn V IV-B stage of Apollo 12)?

This answer taught me about J002E3, an object detected in Earth orbit in 2002 that is assumed to be the Saturn V IV-B stage from Apollo 12. It's trajectory through space is fascinating: (source) ...
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Does trajectory of an object orbiting a planet depend on the object's mass? (With hypothetical Apollo example)

For example (hypothetically), if an Apollo crew of one of the lunar missions went on EVA just after Trans Earth Injection burn and carefully released a small bolt, or a plastic package from their food,...
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Would ISS raise up with the help of the self-powered ion thrusters?

The solar arrays provide about 100 kW of power, so we can put the two HiPEP thusters providing 1 N (1000 mN) power combined, with the specific impulse as high as 6000–9000. Such an acceleration force ...
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Most fuel-efficient deorbit from geostationary

Say a spacecraft in geostationary orbit needs to be deorbited (not very common, but bear with me). How does one decide when and how long should the retrograde burns be, in order to have started with ...
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Would it be possible to Boost ISS to L1 or Lunar Orbit?

NASA and Russia plan to retire the ISS before 2030, and to launch a new lunar outpost to lunar orbit. This output could then be a gateway to future mission to Mars or the outer solar system. My ...
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Why does this formula for the required delta v of a semi major axis alteration not work or am I I misinterpreting it?

My spaceflight mechanics lecture script has this formula, without derivation or reference. But I think it does not work. For example let us assume we find ourself in a circular 250km orbit around ...
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How to calculate 𝛥𝑣 that required to change orbit with same radius but different inclination?

How could I calculate the total 𝛥𝑣 required to change the inclination of a Geostationary orbit to another circular orbit with an inclination of 30° and the same radius? (The sidereal day is used for ...
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What information can I get if an elliptical orbit intersecting a circular orbit of radius 𝑟 and velocity of ellipse is equal to velocity of circular?

How can I approach solving the question below? Consider an elliptical orbit intersecting a circular orbit of radius $r$ as shown below. If $v_{ellipse} = v_{circular} = v $, find: True anomaly ($\...
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Free Return Transfer Problem

I'm trying to understand how a free-transfer return works. It makes sense to me conceptually, but putting numbers to it it is unclear. I'm not sure how to obtain information about the transfer ...
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Good example of early and simple orbital mechanics?

I am doing a talk on Katherine Johnson at my school extremely soon and I was wondering if you could give a relatively quick example of a simplified calculation in any kind of orbital mechanics ...
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Velocity of a rocket needed to get to Mars

At 2:16 in this video, Don Pettit says he used the Rocket Equation to determine the velocity of the rocket needed to travel to Mars, which was 16 km/s. I am not sure as how he did it though, and was ...
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Could a solar sail composed of smart glass stay near the L1 point of Venus?

From answers to this question i've learned that the Lagrangian L$_1$ point of Venus is not stable, despite the almost circular orbit of the planet and the fact that it has no moon. Nevertheless would ...
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Circular to elliptical orbit delta V requirements

this might be a dumb question, but i've been recently trying to calculate the delta V to deorbit a satellite, and I've run into a problem. Assuming a 400km circular starting orbit(and disregarding ...
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How does a Spacecraft change its orbit?

I am a high school student. I saw the latest Indian spacecraft "CHANDRYAANN 2", which was in orbit around the Earth for 14 days..... I am so curious to know how a spacecraft changes its orbit. I ...
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How to find the optimal launch trajectory for a rocket launched from a planet with an atmosphere?

I originally asked this question on maths stack exchange As the title states I am trying to find the optimal launch trajectory for a rocket launched from a planet with an atmosphere (Earth) in order ...
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Inclination maneuvers for GEO satellites

I was wondering about the orbital location to perform inclination nulling maneuvers for GEO satellites. I know from basic astrodynamics that the best place to perform inclination correction is at ...
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Better launching location to Neptune

I'm a big fan of space movies, especially when they're based on actual science and/or near-future. So of course I went to see Ad Astra (IMDB). In a nutshell, Brad Pitt's character flies into an orbit ...
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How does the “eccentricity-inclination vector separation” technique work for colocated GEO satellites?

This answer to How are co-located satellites positioned relative to each other? links to the paywalled paper Separation of Geostationary Satellites with Eccentricity and Inclination Vector with the ...
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Orbital mechanics: Jump from ISS, where will I meet again?

This is a hypothetical question, and I hope it is on-topic here. If an astronaut would stand on the surface of the ISS, and they will make a jump directed perfectly towards the earth, what will their ...
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Finding Equations for all of the Orbitals of the planets - IB Math IA

I am doing an IA for an IB math course and my topic is "have/will all the planets ever come within a certain degree of each other?" I am starting out by nullifying certain aspects that would make ...
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Interplanetary Taxi Orbit

I would like to know the feasibility of an interplanetary "bus" or "taxi" which moves between, say, Earth-Mars or Earth-Venus without entering the orbit of either. The idea is that the taxi is large--...
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Lightsail-2: Increased Orbit from Sunlight or Lowering Periapsis?

Has Lightsail-2 really increased the total energy of its orbit by utilising energy from sunlight, or has it simply exchanged energy by lowering its periapsis in order to raise its apoapsis? And if so, ...
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How to deteremine the angle between Sun and 2 probes?

I have the orbital position and velocity and the orbital parameter of 2 spacecraft at LEO, how to define the angle between Sun - Probe 2 - Probe 1 in ECI frame (If you imagine at a point sun then ...
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Issue with SGP4 modelling from scratch in MATLAB

I am trying to develop the code from this source , this research paper and from this too as same as bibliography of that aforementioned source. So, here as you can see at page 14, they have defined ...
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Orbital vocabulary confusion! How can the tangential velocity of an elliptical Kepler orbit not be tangent to the orbit?

I'm now officially confused about the usage of "tangential" when breaking down orbital velocity components. It started with edits and comments on this answer to Orbital speed is (vector) sum of ...
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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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How to calculate the radii of high orbits above the parallels of 45 and 80 degrees?

The new theories in the field demonstrate the possibility of non-Keplerian orbits. https://www.pourlascience.fr/sd/spatial/de-nouvelles-orbites-geostationnaires-10636.php I am interested in ...
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Did Juno just do a plane change? If so, by how much?

There are several reports in the news that the Juno spacecraft executed a very long propulsive maneuver so that it wouldn't pass through Jupiter's shadow. Apparently it would be in dark so long that ...

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