# 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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### Is it possible to change to different orbit inclinations with a simple push?

Supposedly launching to different orbital inclinations is quite difficult, with launchers trying to launch from different launch sites to using mid air launches to avoid geographic restraints. If a ...
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### What's considered the boundary for “earth orbit?” [closed]

According to this CNET article, The last time a human broke free from Earth's orbit was the Apollo 17 mission in 1972. I thought that the moon orbited the Earth, and that visits to it were still ...
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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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### How much goes Phobos in the direction of Mars with a constant force in that direction? [duplicate]

Edit: Although this question may look similar to this one, here I am asking about a constant force in the direction of Mars, and no one of the answers there have answered this question. Because ...
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### Can a ship go straight into geosynchronous orbit of Mars?

What is the easiest orbit or most most fuel efficient orbit to achieve around Mars? How difficult is it to go from one type of orbit to another? I want to see if it is more fuel efficient and less ...
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### What is the distance of the Sun-Jupiter L4 and L5 points relative to Jupiter?

What is the distance between Jupiter and the L4 and L5 points of the Sun-Jupiter system? I need it to attempt to calculate the $\Delta v$ needed to reach Jupiter from there.
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### What types of engines are able to go from Earth orbit to Martian orbit? [closed]

What engine is the most efficient in fuel and/or time to go from Earth orbit to Mars orbit and back again that are not capable of launching from the ground?
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### How does the orbit of the Voyager and New Horizons probes manage to get into interstellar space?

I understand that every probe launched has been launched into an orbit. The further you want to go into the solar system, the faster it needs to be moving. And everything orbits the sun until it finds ...
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### Will a spacecraft accelerate in a gravitational field via the use of a powered rotating mass?

I believe that a powered rotating mass on board a spacecraft should result in the spacecraft being propelled in a continuous increasing velocity towards the source of the gravitational field. To help ...
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### Which point in an orbiting body most closely follows its Keplerian trajectory?

Keplerian orbits can describe the motion of a negligible mass around a massive fixed central body, but they can also describe the motion of two bodies around their center of motion... with some ...
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### How to match orbital speeds of 2 or more satellites in different orbits?

Satellite ME is orbit around the Moon and Earth. Satellites E is around Earth. I understand the low orbit satellites orbit at higher speeds. Can Sat ME match the speed of any of Satellites E at any ...
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### What force would it take to launch a 100kg projectile into orbit from a big cannon?

What force would it take to launch a 100kg projectile into orbit from a big cannon? And what would be the optimum angle of the barrel of the cannon? I'm working on an animation and it's going to ...
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### Relative speeds

How can astronauts conduct EVAs without the ISS falling away and leaving them behind? Similarly; a spaceship returning to the Earth from the Moon, should it not undershoot the earth given Earth's ...
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### What are the forces in an elliptical orbit, broken down into x and y factors?

I know that, if I wanted to map the circular orbit of an object by an iteration of time, I know that I can use the relationship between centripetal force and gravitational force...this is how we can ...
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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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### If we make a “Ring around the earth” in orbit - a wire ring in orbit - could we use it generate electricity?

I envision a conductive wire that is extruded out of a satellite as it completes it orbit, and then goes past it's start point a bit before stopping the extrusion. Then the satellite is sent to grab ...
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### TLE data conversion to osculating orbit elements [closed]

I got the latest TLE from www.celestrak.com for a satellite. How could I convert it to osculating elements? Please, share some links/references.
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### Is there a table of the gravitational pull of a spacecraft? [duplicate]

I would like to put a spin on What is the maximum mass of a satellite that can be placed in GEO? Gravity is a function of the mass of both (all) bodies, and their relative separation. Wikipedia lists ...
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### How to determine the delta V required in order for the satellite at pt. A to hit the earth at pt. B?

I'm confused about how would I go about obtaining delta-v in this case. I'm aware of orbital transfers such as bi-elliptical but that is not the answer to this. Kindly help
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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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### Coupling satellites already in orbit reduce drag and debris?

How would 2 or more satellites be joined to reduce atmospheric drag? Could a 3rd satellite tow and join 2 or more satellites that are in similar orbits to prevent Kessler syndrome? At the very least ...
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### Apollo 11 space mission Lunar Orbit Insertion

I'm doing a basic analysis of the trip to the Moon. I've estimated the speed as follows: ...
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### How to find instantaneous positions of a central body of specified mass that results in an osculating orbit?

If I understand correctly, osculating orbital elements such as those posted in JPL's Horizons represent the mathematical osculating (tangential or "kissing") Keplerian orbit about a specified location ...
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### What orbit is this?

Can this orbit exist around the Earth and the Moon if the weight and speed of the satellite is ideal? I have added a picture below with the orbit drawn.
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### How to interpret and use characteristic energy C3 in this case?

In this answer I've interpreted the x axis of the plot in the question (also shown below) labeled as $C_3$ (characteristic energy) to be the "excess $v^2$ above escape velocity from Earth", and so I'd ...
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### Equation for orbital period around oblate bodies, based on J2?

In this answer I point out that the period of items (ring particles, moons, spacecraft, etc.) around an oblate body will not scale exactly as $a^{3/2}$ because the closer you are to the planet, the ...
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### Why is “delta-v + $\sqrt{{v_E}^2 + C_3}$ where ${v_E}^2 =$11.19 km/s” the correct way to calculate total propulsive delta-v? Please show all work

There is one answer to What spacecraft has had the greatest total propulsive delta-v? and I can not understand how its numbers have been calculated. Response to comments does not seem forthcoming so I'...
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### Delta-v difference between Mars and Moon

Considering a simple Hohmann transfer, does it take less Delta-v and propellant to go to Mars than to the Moon
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### Does the elliptical orbit have many periapsis points?

If I have the position and velocity vectors of a satellite in an elliptical orbit for one point in time, then I can know its position in its orbit at any other time, and with that I can calculate the ...
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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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### LVLH to ECI Conversion

I'd like to transform LVLH coordinates to ECI coordinates. I've been looking at academic papers and other answers on here and other websites and have only seen the transformation in the other ...
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### Does the arrow in this STEREO trajectory animation point heliocentric prograde, or towards the Sun?

This answer links to this NASA page. The first video shows the two STEREO spacecraft use two and three passes by the Moon to leave Earth orbit and enter into an orbit around the sun. Below is a GIF ...
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### What's delta V and propellant required to go from LEO to HEO?

I know others have touched on this, but I'm looking for the LEO to HEO case specifically. Here are the parameters I have: LEO 454 km circular orbit at 61 degree inclination; HEO 1100 x 9000 km at 64 ...
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### Is specific orbital energy a constant? How does this affect the semi-major axis?

I'm working on a simulation with 2 bodies - one a star and the other an orbiting planet. I calculated the orbital energy from the first part of \${v^{2} \over {2}}-{\mu \over {r}}=-{\frac {\mu }{2a}}...
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### When B is directly below A, as shown, what's Bās velocity (in vector notation) relative to A?

Spacecraft A and B are in coplanar circular orbits around the Earth. The orbital radii are as shown in the figure. (Not looking to use C-W equation. Just the equation describing relative velocity ...
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### Possible idea for a simulation in orbital mechanics using data from the JPL [closed]

I have to write a research essay and have decided to write it on orbital mechanics where I would use data from the JPL to perform an experiment (simulation). I was thinking of using the location data ...
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### Given initial true anomaly and arc length of space flight, figure out new true anomaly

In a hyperbolic orbit/trajectory, if you know the distance traveled, and the initial true anomaly in the orbit, how do you figure out the new true anomaly? You know the mass, eccentricity, axis values ...
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### Would the PoyntingāRobertson effect ever be faster than a solar sail from a 1 AU orbit to the Sun?

In this answer to Do you need 0 km/s velocity to crash into the sun? I mention solar sails for retrograde thrust and the PoyntingāRobertson as two ways an object could ever-so-slowly spiral into the ...
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### How many flavors do dawn-dusk Sun-synchronous orbits come in?

In a series of comments below For a given 48 hour observing period, what fraction of the celestial sphere is available to CHEOPS? there's been a discussion of that spacecraft's dawn-dusk Sun-...
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### What is the planned orbital configuration of Astrocast's planned IoT constellation?

The Space Daily article Astrocast signs contract with GomSpace Sweden to deliver propulsion systems says in part GomSpace Sweden - a subsidiary of GomSpace Group AB, has received an order from ...
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### how much does plasma proplusion cost as compare to conventional fuel in spacecraft? [closed]

I want to know how much does plasma propulsion cost as compare to other fuels in space crafts in the orbit
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### How deep a crater could an impactor spacecraft cause on Mars?

What would the best way be to crash an impactor into Mars with greatest topological effect? And how deep a crater could it excavate? Mars missions to date have been designed to approach the planet at ...
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### Optimal time and coordinates of intersection of a spacecraft with an object on orbit

Spacecraft and an object are rotating on orbit. The spacecraft is controlled via the velocity vector change, may change its velocity to intersect another object. Needed to find the time and ...
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### How does the distance in orbit relate to azimuth?

I'm calculating the azimuth and elevation in a ground point to see some satellites, but if for example the error in orbit for a satellite grows 1 km how is that distance (error) represented in radians ...
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### Using the Clohessy-Wiltshire equation, what would be the expression for ' r '?

I'm looking for an expression for r. The difficulty I'm facing is simplifying the C-W equation
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### Is a 2:1 “figure-eight” Lissajous orbit possible in the Circular Restricted Three Body Problem?

Was Queqiao in a halo or Lissajous orbit? Why do sources disagree? says Proper halo orbits have the same period for their in-plane oscillations and out of plane oscillations, so they are closed ...
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### Lagrange Coefficients for Hyperbolic Orbits

Here is the expressions for f,g and f dot for elliptic orbits. I would like to find similar expressions for hyperbolic orbit case.
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### Roughly express how much of our Moon's apparent libration amplitude seen from the Geocenter is due to different effects?

My understanding is that when tidal locking of a body first happens it transitions from a state where the average rotation period is faster than the orbital period to a state where they are the same ...
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### Why can't custom-made TLEs for the DSCOVR launch booster in orbit around Earth work with SDP4?

This fascinating answer to Why has no TLE been published for the DSCOVR satellite and the Falcon 9 R/B? presents links to custom-made TLEs for the Falcon 9 rocket body that put DSCOVR into orbit, and ...