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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. For the movements of celestial bodies, see [celestial-mechanics].

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Mass production rate vs mass consumption rate in solid rockets

Do the two terms mean the same? mass production rate, mass flow rate and mass consumption rate in a solid propellant rockets.
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When burns are made during inefficient parts of the orbit, where does the lost energy go?

Any Kerbal Space Program player will know that burns prograde and retrograde to the velocity vector are most efficient closest to the body being orbited, while burns normal and anti-normal are most ...
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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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GMAT: Finite Burns commands in If statements inside For loops

Does anyone know why GMAT won't execute finite burns when the BeginFiniteBurn command is placed inside an If statement which is inside a For loop? I'm sure the If condition is verified because there ...
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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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Why will the SunRISE mission "fly slightly above geosynchronous orbit"?

The blots.nasa.gov article NASA’s SunRISE Mission Studying Solar Particle Storms Moves Toward Launch says that the upcoming SunRISE mission — short for the Sun Radio Interferometer Space Experiment — ...
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GMAT Orbit Designer

I start to work with GMAT. I am looking into the API capabilites and I found several functions e.g. for the calculation of SSO Orbit Parameters, or Repeating Ground Tracks. So apart from this, is ...
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What factors would contribute to a spacecraft's ability to maintain a very low orbit (VLEO) or at least orbits with very low perigees?

I asked What does account for a high coffin corner of a plane? in Aviation SE. Now I wonder what factors would contribute to a spacecraft being able to maintain low circular orbits (e.g. within 200 km ...
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Why do GPS (but not GLONASS or Beidou) satellites have increasing eccentricity over time?

When comparing GPS, Beidou, Galileo, GLONASS, and potentially other GNSS, we can see that the eccentricities of GPS spacecraft are increasing with time (i.e. apogees increasing and perigees decreasing)...
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Given an arrival date, is there a way to calculate the declination and right ascension of the arrival asymptote into Mars?

I am designing an Earth-Mars transfer. The launch window is 03-Jul-2026 (departure from Earth) & 22-Jun-2028 (Mars arrival). The declination and right ascension for the departure asymptote from ...
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Why was InSight planned to launch from Vandenberg?

Why does the InSight Mars lander mission intend to launch from Vandenberg, which does not allow for prograde launches? Will it launch into polar or retrograde orbit? Why? It will do an interplanetary ...
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First interplanetary launch from California! How far from Earth will InSight be when it separates from the Centaur 2nd stage?

The Phys.org article Bound for Mars—countdown to first interplanetary launch from California says: In the early morning hours of May 5, millions of Californians will have an opportunity to witness a ...
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Impact Venus with Comet Leonard?

do we have the means to slightly alter Comet Leonard's trajectory so it impacts Venus instead of 'grazing' it in December 2021??
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Design and optimization of a Sun-synchronous repeating ground track orbit constellation

I am currently researching about this topic and am very new to this. Have no clue how to go about designing a group of imaging satellites (constellation) that are sun synchronous with repeating ground ...
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Could a near earth asteroid perturb a satellite out of earth's orbit?

Given a satellite in GEO or a graveyard orbit, what characteristics of a passing NEO would be required to perturb said satellite out of Earth's influence and into a sun-bound or sun-centered highly ...
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Did Rosetta improve on models of non-gravitational effects on comet 67P's orbit?

Question: Since the presence of the Rosetta spacecraft near comet 67P allowed for a detailed mass measurement, extremely precise position and velocity determinations, and physcal measurement and ...
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Would the Yarkovsky effect ever be faster than a solar sail from a 1 AU orbit to the Sun?

Previously I'd mistakenly asked Would the Poynting–Robertson effect ever be faster than a solar sail from a 1 AU orbit to the Sun? when I'd meant to ask about the Yarkovsky effect which can be much ...
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How can gravity gradient forces be calculated?

I'm working on a theoretical problem that I came up with; Given the extremely low atmosphere in low Earth orbit (300-500 km), would an arrow that had orbital velocity keep flying 'true' due to the ...
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Why shouldn't we illustrate spacecraft trajectories on top of static pseudo-potential surfaces?

Three-body spacecraft orbits1 are regularly discussed here and from time to time someone will include a pseudo-potential plot from Wikipedia in their explanation. The discussion often goes south when ...
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Does Kepler's Method for Determining Time of flight between two True Anomalies break down with eccentricities approaching 1?

Pretty simple question here. I'm calculating time of flight between two true anomalies by converting those true anomalies to mean anomalies and using the following equation: $\Delta t = t_2-t_1 = \...
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Is there a neat formula for hyperbolic Kentucky windage?

When doing some back of a napkin calculations for a recent question Where would the Pascal B manhole cover be now?, I realised a quick way of solving these class of orbital mechanics question is to ...
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How to calculate velocity vector in perifocal coordinates [closed]

Well the formula for it is here: Though if r is the radius and f is the true anomaly (which I assume is radians), then what is r dot and f dot respectively?
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What are the limitations to using this "trick" to quantitatively relate altitude changes (via their speed) with applied forces that cause them?

In this comment I used a "trick" to double check a calculation in the post above it. Using the vis-viva equation I first determined that if the ISS lost 10 meters of altitude in 86400 ...
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What is the "mass" of a Lagrange point?

Of the five Lagrange points, L4 and L5, as stable points, can be orbited by asteroids, satellites, and any other useful or interesting object. Assuming two-body motion however, calculating orbits with ...
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How significant is orbit propagator choice/error when considering a year-long satellite coverage simulation, and which is the most appropriate?

I'm currently considering a project to simulate the (Earth-seeing) coverage of 1 or more satellites over the course of a year. The point would be to compare how different orbits result in different ...
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Where would the Pascal B manhole cover be now?

As part of the Operation Plumbbob series of nuclear tests, on August 27th, 1957, at 22:35 UT (15.35 Pacific Daylight Time), at the Nevada Test Range at 32°N 116°W, a 300 ton-yield atomic device was ...
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How can I calculate the future position of a satellite orbiting a central body as a function of time using known orbital elements?

Given the position and velocity vectors at one point in an orbit, one can calculate the keplerian elements and thus graph the subsequent orbital path as a circle/ellipse/parabola/hyperbola depending ...
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After inserting CAPSTONE into a "highly efficient ballistic lunar transfer trajectory" Lunar Photon; to what separate orbit for its safe disposal how?

NASA Ames's feature CAPSTONE’s CubeSat Prepares for Lunar Flight says CAPSTONE will use a hydrazine-fueled propulsion system during most of its three- to four- month journey to the Moon. This line of ...
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How many times will the Photon fire its Curie in order to "reach the right spot" to deploy CAPSTONE towards the Moon?

note: it's been a year and a half and Capstone is scheduled to be launched soon, so perhaps there is more information available now? The Verge's How small launcher Rocket Lab plans to pull off its ...
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How does the Parker Solar Probe have such a wide launch window?

The Parker Solar Probe is set to launch on August 11th 2018. It will perform 7 orbit-lowering gravity assists around Venus for ~6 years before reaching its final operational orbit. It has been well ...
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Are some Halo Orbits actually Stable? (stable orbits about unstable Lagrange points)

UPDATE: I found another reference! While I always enjoy a good video starring Jimmy and Linda Carter, this one has Dennis Wingo describing ISEE-3's original Halo orbit. He describes Sun-Earth $L_1$ as ...
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How to calculate the local maximum solar radiation on Mars from day to day throughout a full martian year?

I would like to know where on Mars the least lowest daily temperatures depending on the time of year will be. At first glance one might think, as I did, that it has to be along its equator, but ...
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How do orbits around Jacobi ellipsoids behave?

The Earth is a Maclaurin spheroid (aka. oblate). This affects orbits, most notably $J_2$ rotating the node line for inclined orbits, enabling thins like Sun-synchronous orbits. But the Maclourin ...
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Could you stably orbit around a square (cubic) body? Would the orbit destabilize automatically if not corrected by input?

Given that the cubic body is of homogeneous mass (say Iron) and we want to start with the best possible orbit and input nothing afterwards, could something orbit this cubic body stably?
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Can mascons have Lagrange-like points? In principle? At the Moon?

Background Lagrange points are a mathematical consequence of the The Circular Restricted Three Body Problem (CR3BP or CRTBP); two massive bodies orbiting around their center of mass and a third ...
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What was the first practical use of a satellite constellation?

If I loosely define "constellation" here as a group of earth satellites where different ones are visible at different times, and you need all or most of them to get round-the-clock coverage, some ...
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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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Using a sling whirled around above the head, could someone on the moon throw a stone into orbit?

Similar to this question except not about using a machine: What payloads and launch speeds could a sling launcher get using modern materials on the Moon? How fast could a stone be thrown using a sling ...
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Energy to "nudge" a planet to a smaller orbit

Suppose we wanted to move a mass-$m$ planet to a much smaller new orbit around our mass-$M$ Sun. We'll assume the initial and final orbits are circles of radii $r_i,\,r_f$ with $r_f\ll r_i$, so GPE is ...
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ISS Live Views of Earth on Nasa's EHDC Camera appear to be retrograde orbit

If the Orbit of the ISS is Prograde and Synchronized with the same orbit as the Earth, would not the Live EHDC views motion appear Stationary?
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Do all dangerous asteroids first pass through keyholes?

Scitech Daily's MIT Engineers Devise the Best Way to Deflect an Incoming Planet-Killer Asteroid Now MIT researchers have devised a framework for deciding which type of mission would be most ...
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Can an orbit rotate around a non-orthogonal axis?

I'll attempt to draw a mental example, in case images are not kind (if they are kind, you can likely skip this first paragraph). Let us say that the Earth is at it's aphelion (arbitrary choice), and ...
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Juno's original orbit around Jupiter - is this apsidal precession? If so, need expression

Below is a plot of Juno's originally planned orbit around Jupiter, extracted from JPL Horizons. It's shown in J2000 ecliptic coordinates, centered on the Jupiter barycenter. It turns out the orbit is ...
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How would you convert keplerian orbital elments into cartesain vectors with quaternions?

Coverting the keplerian elements to cartesain vectors ( posistion and velocity) is relatievly simple by using rotation matrices show in the document here: https://downloads.rene-schwarz.com/download/...
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How many active or inactive artificial satellites are in Mars orbit?

I just read in the BBC news that four nations have placed satellites in Mars orbit. How many active or inactive artificial satellites are there in orbit around Mars (2014)?
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Is it possible to throw a baseball so hard it circles the earth above your head?

Assuming the earth had no atmosphere, and you could throw a baseball as fast as you wanted to, and you were standing on the surface of the earth, is it possible to throw the baseball so fast that it ...
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2nd stage speed - with respect to what? (SpaceX webcast of Orbcomm OG2 deployment)

As a follow-up question to this answer by @TildalWave, exactly what frame is used to calculate the "speed" in the inset display of speed and altitude in the SpaceX broadcast of the Falcon 9 launch and ...
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Earth to Mars (or reverse) Hohmann transfer orbits for the 21st Century

Is anybody aware of a nice graphic showing for the next 20-30 years or maybe the rest of the 21st century, the time periods for Earth to Mars launches? They occur about every two years, but I'm ...
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Flyby puzzler; starting from Earth, how many times can you use Jupiter flybys in one century?

Is there any limit to how many times you can increase velocity by repeated sling shot manoeuvres? and its answers have got me thinking, and that's always dangerous. Suppose you have a durable RTG-...
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How to calculate the velocity vector in the case of a hyperbolic orbit?

The problem I'm trying to get a formula to calculate the state vectors $\vec{r}$ and $\vec{v} = \dot{\vec{r}}$ on an orbit, given a true anomaly $\nu$. I'm following the process described here : https:...

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