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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3-Body Simulation and Accuracy of Lambert Interplanetary Solver

I've found that using a Lambert solver together with the equations of the patched conic approximation for an interplanetary flight from Earth to Mars is quite inaccurate, when taking Earth's ...
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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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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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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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What is the smallest body that has sufficient gravity for another body to orbit it?

In the question Will Rosetta have to adjust its orbit around Chury due to the comet's coma and tails? and related answers it is implied that the Rosetta spacecraft will actually orbit 67P/...
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How was Juno's arrival set up to be on the evening of July 4th?

Presumable it is largely a coincidence that Juno arrives at the perfect moment for American pride in NASA's achievements, but not entirely. The video below of the trajectory, released in July 2011 ...
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If a rocket launched due East from a high latitude, what happens to its path?

Let's say a rocket launches from Iceland at 65oN headed for LEO, but instead of using an inclination that works from that latitude, it heads due East. It attains orbital altitude and acceleration, and ...
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How long will a 500 km altitude satellite spend in Earth - shade per orbit

I used to know how to do this, but for the life of me I can't remember the source of the equations. This is clearly a question of geometry rather that any specific space science however I still feel ...
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Why do malfunctioning satellites come back to Earth?

In school, I learned that if a satellite moves at a speed $\sqrt{gR}$ (the square root of the product of the acceleration due to gravity and radius of the Earth), then it will remain in Earth's orbit. ...
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Aborting a de-orbit maneuver

I was contemplating on how a de-orbit may be abandoned post completion of the orbit burn, say, from LEO. A situation in which this might be necessary would be detecting a breach in the heat shield ...
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Clohessy-Wiltshire/Hill's Equations - F=ma?

I have been researching the genesis of the Clohessy-Wiltshire (C-W, or Hill's) equations. These equations are used to describe relative motions between the "chaser" and "target" ...
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What would happen if I throw a grenade in space?

What would happen if I throw a grenade in space? Would it explode? Or will it just keep floating forever?
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Many moons in same orbit

Is it possible to have a stable orbit comprised of many moons(>2) that keep themselves roughly equal distance apart? Sort of like Epimetheus and Janus around Saturn but comprised of many moons. The ...
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Is it theoretically possible to dispose of the larger pieces of space junk into the Sun?

Space junk is a real threat to working satellites in the Earth's orbit. Is it theoretically possible to make this space junk escape from the Earth's gravity (by giving them some kinetic energy to ...
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What is the effect of gravity slingshots around Earth on Earth's rotation and orbit time, and is this effect worth considering?

Several space probes have used gravitational slingshots around Earth as part of their mission plan to get to other places in our solar system. Some examples I could find quickly are Galileo, Messenger ...
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How much variation in orbit altitude is caused by gravitational variation, in LEO?

Imagine a hypothetical spacecraft in LEO, at 200km. Ignore air resistance for a moment. It's actual height will vary, due to both gravitational anomalies and the shape of the Earth. Do we know ...
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Orbit stability

This is my first question. I am a space enthusiast but I don't have a formal understanding of celestial mechanics, so I would like to ask how stable against perturbation an orbit is, given the ...
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Reasons for using a bi-elliptic transfer for Soyuz-ISS rendezvous

According to the ESA movie Soyuz rendezvous and docking explained, Soyuz uses a bi-elliptic transfer to move from the phasing orbit to the ISS orbit. Why is this more complex transfer used instead of ...
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Geosynchronous orbits around other Solar System objects

Earth's geostationary orbit has many human-made satellites which have helped vastly with communications and research. Aside from this artificial collection, are there any other objects orbiting a ...
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Falcon 9 maximum point-to-point landing range

Has anyone here ever done enough back-of-the-envelope math to come up with a rough estimate of the maximum landing range of the F9 first stage? I'm talking unladen-swallow-quality math here -- trying ...
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Why are orbit raising maneuvers for Mangalyaan done in the early hours?

I was reading this news article, and it was mentioned that orbit raising is done in early hours. In all the five orbit raising operations, they are raising them only during night. What could be the ...
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What happens to JWST after it runs out of propellant?

JWST will be orbiting L2 which is unstable equilibrium thus will require propellant for station keeping. JWST will carry propellant for 5-10 years. What will happen once it runs out of propellant? ...
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Why was Kepler's orbit chosen to continue to drift away from Earth?

The Kepler telescope was launched from Earth on March 7 2009 and placed in an independent orbit around the Sun, with a semimajor axis of 1.0132 AU, period of 372.53 days, and an eccentricity of 0.036 ...
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How does SGP4 work?

For calculating orbital state vectors of satellites, SGP4 (simplified perturbations model) is often used in conjunction with two-line element sets to calculate future positions of orbiting objects. ...
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How (the heck) can 2014 MU69's orbit be know well enough for a close flyby by New Horizons?

The object 2014 MU69 is much smaller and dimmer than Pluto. Even as New Horizons approaches, it will be much harder for its 8.2 inch aperture, cooled CCD long range imager LORRI to get a fix on it ...
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What are the practical limitations of gravitational assists?

Is there any specific, practical reason why we couldn't have a probe swing by Saturn, Uranus, Jupiter multiple times, over and over, before getting hurled into interstellar space at insane speed, ...
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Launching east from a mountain on the equator at midnight during a new moon; ranking of each contribution?

This answer is intriguing and I'm curious if it's correct, and especially which effects are most important. If you want to avoid gravity assists, the most fuel-efficient way out of the Solar System ...
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How is the minimal $\Delta v$ transfer between non-coplanar orbits calculated?

If the orbits are co-planar (lie in the same plane), the required minimal $\Delta v$ is calculated by the well-known Hohmann transfers. But what is the case if they aren't co-planar? How many orbital ...
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Thrust and rotation strategy to circularize a standard GTO orbit using ion propulsion?

The previous question How much time does it take to circularize a GTO orbit using ion propulsion? has a good, quantitative answer based on a known delta-v. But I'm wondering how would you actually ...
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What are the requirements for $ɣ$ shape flyby?

Understanding Kepler's laws, a body with speed exceeding escape speed of a major body will move in a hyperbolic trajectory, entry and exit vector, a "less than ellipsis" curve. You don't get closed (...
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How does the ISS Transit Finder website get the position of the ISS so accurately?

The recent Petapixel article How to Shoot the ISS Flying Across the Face of the Moon gives a lot of detailed, helpful advice for photographing transits of the ISS across the disk of the Moon. For ...
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Oberth Effect for non-tangential acceleration

Due to the Oberth Effect, it is most efficient to accelerate a spacecraft along its orbit at or as close-as-possible-to periapsis, and decelerate within close proximity to apoapsis. But all ...
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To what extent could a single Triton flyby slow down a direct Hohmann transfer to Neptune for NOI?

I can't seem to find any good sources online for this, all I get are documents on how Nice model was used to compute Neptune's gravity capture of Triton via a binary dissociation, possibly because of ...
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How to calculate apoapsis of sub-orbital trajectory?

I have made a RK4 simulator for launching a cannonball from a tower. Which has the state variables: Position vector r Velocity vector v Mass of planet M To simplify it, working in only 2 dimensions (...
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At which point would two GSO/GEO satellites with similar orbital elements be closest to each other?

While I was answering another question on How closely spaced are satellites at GEO I came to realize I can't really word it with much conviction how two close proximity satellites in GEO/GSO orbits ...
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What force is bringing Cassini down into Saturn's atmosphere in another 145 days; drag, or…?

Headlines suggest (as do their articles) that as a gravitational result of Cassini's final flyby of Titan, it's fate is sealed and it's orbit is destined to take it into Saturn's atmosphere on ...
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Why has the Earth's motion carried it out of view of Pioneer 11's antenna?

According to The Pioneer Missions, my emphasis, The Pioneer 11 Mission ended on 30 September 1995, when the last transmission from the spacecraft was received. There have been no communications ...
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Why is a near rectilinear halo orbit proposed for LOP-G (formerly known as Deep Space Gateway?)

Why is a near rectilinear halo orbit a good place for a Lunar Orbital Platform-Gateway (formerly known as Deep Space Gateway)? Are there specific logistical and orbital-mechanical advantages over ...
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Why do the LRO's orbital elements appear to constantly oscillate - except recently?

I plotted some of the orbital elements of the Lunar Reconnaissance Orbiter from JPL's Horizons database, and I see that there are constant oscillations. The period of the semi-major axis and ...
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How might one approach using AI (convolutional neural network) to predict collisions in orbit?

CNN's Tomorrow's Hero profile Meet Amber Yang. She's trying to prevent a space debris catastrophe describes an investigation into the use of a convolutional neural network (CNN) to predict possible ...
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Navigating in space with only cameras

I'd like to figure out how to determine where something is in space (solar system) based only solely on measurements that can be preformed on location visually/with a camera. Let's say I'm floating in ...
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Does the “17” really mean anything with respect to GNSS orbits being rational factions of a sidereal day?

This answer suggests that the orbital periods of the four large GNSSS contstellations are linked to the sidereal rotation period of the earth by rational numbers with 17 or 34 as the denominator in ...
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What is the smallest body in which a sling shot maneuver can be performed?

This question asks about the smallest sling shot maneuver performed. What was the smallest intentional, acknowledged slingshot maneuver? I'm asking how small of an object be to perform a sling shot ...
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What's the eccentricity of an orbit (trajectory) falling straight down towards the center?

Discussion below this answer has got me thinking. A circular orbit has eccentricity of $\epsilon = 0$, ellipses $ 0 < \epsilon < 1$ (between but not including 0 and 1), and parabolic and ...
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Can one put a large nickel-iron asteroid into an elliptical solar orbit that results in a soft(ish) earth landing?

My daughter and I are debating whether it is technically feasible to bring a nickel iron asteroid to the surface or the earth non-destructively. I felt it was impossible. Her thought was that with a ...
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What is “propulsive passivation” and why will the SpaceX STP-2 mission do it?

The Teslarati article SpaceX’s Falcon Heavy flies a complex mission for the Air Force in launch video discusses the upcoming third Falcon Heavy mission STP-2 and quotes the caption on the linked ...
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How would a laser “shoot down” space junk?

This question links to an article describing a ground-based laser designed for shooting down orbiting space debris: "The scientists intend to use the massive soon-to-be-built telescope at the Altay ...
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How long would a Falcon Heavy last in orbit around Mars before degrading?

Elon Musk made another characteristic splash recently with his plan to launch a Falcon Heavy into orbit around Mars, with the bonus payload of his personal Tesla Roadster inside. Of course, it's an ...
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Is there a simple relation between delta-v and travel time?

For example, if it takes a delta-v of 4 km/s to fly from LEO to Mars in 8 months, according to one mission plan, would it take half the time, 4 months, if the delta-v was doubled to 8 km/s? Is there ...
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Why are lunar orbits unstable?

I've seen a few times now that objects in orbit around the moon tend to crash into it in relatively short time frames. The orbits tend to become more elliptical until they intersect the surface, is ...

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