Questions tagged [orbital-mechanics]
Orbital mechanics (also called astrodynamics) is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft on an orbital or escape trajectory. For the movements of celestial bodies, use [celestial-mechanics], not this.
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Using Orbital Rings to Achieve High Escape Velocity
Hoping an astrophysics-calculation-competent person could help confirm this scenario:
Say civilization has established an orbital ring around the Earth with an external launch track (using super-...
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Discrepancy between Keplerian Elements and real orbits? [closed]
I've written code for converting Cartesian State Vectors into Keplerian Orbit Elements (primarily from this answer). If we take a satellite 100km (X-axis) above the earth ($\mu = 398600km^3/s^2$) and ...
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Is it possible to change a satellite's eccentricity without changing semimajor axis (instantaneous maneuver paradigm)? What else needs to "give"?
I've been wondering whether it's possible to change a satellite's eccentricity without changing its semi-major axis. (I'm assuming instantaneous changes in velocity.) At first I thought that this ...
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What is the velocity of the ISS relative to the Earth's surface?
This was asked once before, but I believe there was no clear answer given and accepted.
The ISS has an orbital period of 92.9 minutes, or 5574 seconds. If it were in a completely equatorial orbit, ...
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Radial hyperbolic trajectories
Wikipedia informs me that
In astrodynamics and celestial mechanics a radial trajectory is a Kepler orbit with zero angular momentum. Two objects in a radial trajectory move directly towards or away ...
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What is the order of magnitude of perturbing forces in a lunar orbit in relation to the orbital altitude?
Although there are many sources that compare the magnitude of perturbing forces in an Earth orbit (see for example the answer to this question), I haven't been able to find the same information for ...
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How to calculate the ascending and descending node, as well as the true anomaly
I have the argument of perihelion, semi-major axis, eccentricity, inclination and mass. I have tried to look this up but get conflicting answers. Any help would be appreciated.
(Edit)
One physics ...
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How to determine Euler parameters?
I have two questions and I can't solve the second one. Here it goes:
Question 1
Consider a normalized system of units where µ = 1, Earth radius = 6378.165 km is the
length unity, and T = 806.81 s is ...
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Delta-v to hit the moon: is reaching Lunar L1 enough?
Lot of questions involve shooting things into the Sun. But there are no aliens on the Sun: they are on the Moon. I want to drop things on them, but since there's lot of them, I can just drop a ...
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How to apply primer vector theory to trajectory optimization under perturbed two-body problem?
I am currently reading the book Primer Vector Theory and Applications by John E. Prussing (https://doi.org/10.1017/CBO9780511778025) to learn primer vector theory. However, all the derivation and ...
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How long does one orbit around the Moon take in a typical parking orbit for a stage a lander is going to meet?
I have been pondering the relative advantages of placing a base near the Moon's equator, or at the poles. The poles have been defended as having a superior business case because of deposits of ...
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Integration of Varying Forces, Impulses in Simulators
I am a software dude working on a personal project for building a spacecraft simulation software. And I've been looking into numerical integration methods, and I am just confused on how to tackle the ...
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Will there be a controll mechanism to keep spacex starship in a controlled position during coasting and/or reentry?
Looking at the really interesting imagery from Starship Flight 3, it is obvious that Starship is rotating (tumbling-ish) during coasting, and also during the initial reentry phase. The plasma streaks ...
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How to implement SGP4 C++, satellite propagator?
I would like to ask about how to implement the SGP4 code in C++ by Vallado.
How can I implement the libraries that are available in https://celestrak.org/software/vallado-sw.php.
I think that are the ...
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What's the point of characteristic energy?
My understanding of orbital mechanics is that delta-v is the most useful notion of ability to change orbits in space, akin to energy being the most useful notion of the ability to do work. But if ...
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Does the dawn-dusk orbit maintain the inclination with respect to the ecliptic plane?
I'm trying to understand the mechanics of sun-synchronous orbits, specifically the dawn-dusk orbit.
If I understand correctly, the RAAN rotates around the plane of reference of the Earth, which is the ...
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Do any launches bypass LEO?
If sending a payload to GEO (geosynchronous orbit) or any other high orbit, you could start off launching to LEO (low Earth orbit), and then use a Hohmann transfer to raise the height of the orbit. I ...
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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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How to calculate a Hohmann transfer when the target is moving retrograde
Exactly as the title says. I have two objects, both in circular orbits, and with the target object in a higher, retrograde orbit. How do I modify the Hohmann transfer formulae to find the angular ...
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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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Orbit Determination from Position and Velocity
I'm working on a game, somewhat similar to KSP (no building rockets, just beautiful orbital acrobatics). It's in a "small" star system, radius of 6 AU, and it features celestial bodies ...
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At which direction do you apply thrust to perform an inclination change maneuver?
Assume that the vehicle is already at the orbital node. No combined plane changes are included.
At which direction is the thrust applied to do an inclination change maneuver?
So far, Google hasn't ...
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How did NASA Conclude that the General Theory of Relativity was not Needed for Earth-Moon Flight Path Computation?
This question is wholly seeking historical evidence and not about physics. It is a follow on from the Physics Stack Exchange question:
Could we send a rocket to the Moon without knowledge of general ...
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Why are orbits around a black hole not elliptic?
Most of the pictures of a black hole are like this:
Source: https://cdn.mos.cms.futurecdn.net/HsDtpFEHbDpae6wBuW5wQo-970-80.jpg.webp
Why are the orbits around it not elliptic? Is there any other ...
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Hawkeye 360 Triangular Formation Flying Design
I recently chanced upon the paper Making the Invisible Visible: Precision RF-Emitter Geolocation from Space by the HawkEye 360 Pathfinder Mission (32nd Annual AIAA/USU Conference on Small Satellites) ...
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Change in True Anomaly over time
From Wikipedia, the True anomaly is defined as the angle between the direction of periapsis and the position of the celestial body. I'm trying to find how the true anomaly changed over time for a ...
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Orbital Pathing Question [duplicate]
I have seen nearly all orbital 2D projections done like a sine wave. However, when I watch a launch from say, Cape Canaveral, it always "appears" that they are launching due east rather than ...
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What is the physical interpretation of the eigenvalues of the monodromy matrix and how are they associated with the invariant manifolds?
To define the monodromy matrix, assume that the period for one cycle of a halo orbit is denoted as $T$, the initial time as $t_0$, and the state-transition matrix is defined as $\phi$. Then, the ...
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Why does everyone say that it is better to launch a satellite into polar orbit from the pole than from the equator?
If the Earth were spherical, I would agree with this. But the Earth is not spherical. And at the equator, the radius of the Earth is 21 km greater than at the poles. By convention, the altitude of the ...
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Simplified WGS84 or EGM2008 model for rapid computations?
I am searching for a simplified model of EGM2008 that can be used for rapid, repetitive computations. It needs to be valid only up to GPS altitudes. I'm thinking such a model already exists but cannot ...
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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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Has propulsion utilizing solar sail / drag effects of solar panels achieved orbital rendezvous? If yes, is there any utility for clearing space junk?
It has been proposed to use solar panels as solar sails and drag control by alternately feathering panels during different phases of orbit. It is claimed this can alter light pressure and drag enough ...
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Would the Earth still precess if it were an ideal sphere?
I am trying (unsuccessfully) to acquire an intuitive understanding of planetary precession.
Is Earth’s precession Torque-free Precession due to its asymmetry as per https://en.wikipedia.org/wiki/...
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What Δv is needed to reach LEO from a space elevator?
In two recent questions about space elevators, the topic of reaching non-geostationary orbits came up, particularly the popular Low Earth Orbits.
This question is simply about how hard exactly it is ...
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Propulsion options for orbital transfers after release from space elevator
In a recent discussion of cost estimates of hypothetical space elevators it was mentioned that a space elevator is (obviously) well suited to bring payloads to a geosynchronous orbit while reaching ...
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To go from LEO to LLO describe a Bi-elliptic/Hohmann transfer burn sequence?
Being a newbie, I humbly submit the following question :
How to minimize the energy (in terms of delta-v burns) to transfer a mass of 1 metric ton (1000kg) from Very Low Earth Orbit (say 200km above ...
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Can electrodynamic tether propulsion use the solar magnetic field?
Electrodynamic tethers have been proposed for satellite propulsion in the magnetic fields of Earth and the Gas Giant planets.
Is it realistic to consider using the Sun's magnetic field for ...
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Is Mercury's orbit still considered potentially unstable (in the very long term)?
The subsection Mercury–Jupiter 1:1 perihelion-precession resonance in the Wikipedia article Stability of the Solar System links to the article Solar system could go haywire before the Sun dies in the ...
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What is the current state of the art in converting between mean and osculating orbital elements?
I want to implement algorithms to convert from mean to osculating elements, and vice versa.
I've been digging through Vallado's text (fourth edition), and under ...
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What can one do as an individual to help support the development of skyhooks?
In my recent research on the potential of a SkyHook, I've found a startling gap: it seems like no one is actively pursuing this technology. Many, including myself, believe that this could be the ...
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Orbits permanently in shadow
The James Webb telescope is parked in a halo orbit around SEL2, beyond the Earth's umbra, to avoid solar eclipse by Earth or Moon. Is there anything else which could shade JWST?
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Is this depiction of a Z-Bar docking approach accurate?
I am writing a document about orbital mechanics am trying to depict the different docking approaches in a simple way. Since I am using paint.net to draw the pictures, my drawings are not that great.
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How would one identify ionic thrust vs chemical thrust in an orbit transfer?
My nomenclature might be a bit off, I’m no expert but I’ve been reading to solve the question all the same. Say we detect an orbit transfer based off ephemeris records. We can get the 6 classic orbit ...
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What is the delta V required to access a polar lunar orbit?
The general reference figure (I use) for entering a low lunar orbit (polar included) is ~900 m/s, which is roughly what was set out in previous questions. However NASA released this white paper which ...
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Is there a way (working or in development) to track satellites in lunar orbit like we track objects in Earth Orbit?
I understand that Earth orbiting satellites are tracked using technologies such as radar, but due to the distance between the Earth and the Moon, they aren't really useful for Moon sats.
Is the ...
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sun pointing coordinate system design
I am trying to program slew maneuver procedure for a spacecraft. My goal is to define a target coordinate system that is aligned with sun vector so that the spacecraft can slew its attitude to always ...
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MATLAB Simple Elliptical Orbits with J2 perturbation and drag
For some reason I need to build a Elliptical Orbits satellite dynamic model by myself, in here I am using MATALB.
The model its fine before (I think the J2 effect part works well) I add drag effect on ...
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Can a meteor shower have a period of less than 1 year?
This question is inspired by the SE question Can a meteor shower have a interval greater than 1 year?
Most meteor showers repeat yearly (or natural multiples of 1 year). Can a meteor shower have a ...
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Are the Jupiter-Io Lagrange points stable?
Lagrange points are solutions to the three-body problem. Moving among Jupiter's Galilean moons seems likely to be at least a six-body problem, so there is no reason to assume the three-body solutions ...
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Could a “solar gravitational synchrotron ” use solar thermal rockets to "powerslide" spacecraft out of the solar system?
Could a “solar gravitational synchrotron ” use solar thermal steam rockets to launch spacecraft out of the solar system?
Solar thermal steam rockets https://en.wikipedia.org/wiki/Steam_rocket have ...
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