# 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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### How to determine the distance between where Earth and Mars are two specific dates?

How would I find the solar-system-relative distance between where Earth would be on 2106/8/16 and where Mars would be on 2106/10/16, or any combination of dates. Image source-Bing Is there software ...
1answer
192 views

### 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 ...
1answer
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### Calculating trajectories of payload fairings

How can I calculate the trajectory of a payload fairing assuming that I have several data points of height or speed of rocket? I'd like to know which topics are necessary to study this.
0answers
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### Does the shape of Cruithne's orbit change within one period?

The question Why not explore Cruithne? includes the GIF below. I've extracted two frames and extracted the red pixels of Cruithne's orbit where ...
1answer
80 views

### Why do orbits in the Iridium constellation have an inclination of 86.4°?

Wikipedia's Iridium_satellite constellation; In-orbit spares says that Iridium satellites have an inclination of 86.4°: Significant orbital inclination changes are normally very fuel-intensive, but ...
1answer
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### Atmospheric reentry drag and friction

What is the difference of air drag in ground level with let say moderate speeds like fast cars 200km/h to 400km/h with high speed vehicle reentry at high altitude where the air is so rarified. Making ...
1answer
52 views

### Would a space rocket launching from Ceres in a path to Jupiter be faster relatively to the sun than one launching from Earth?

Suppose you have a space rocket which when launching from Earth its speed relatively to Earth it's 11 km/s. For what I've read in another topic in Space SE, the orbital velocity of the planet where a ...
2answers
99 views

### 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 "...
0answers
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### How to estimate which astronaut ends up furthest from the ISS after one orbit?

Three astronauts; Goofus, Gallant and Zippy the Pinhead play a game. All three take their cold gas thruster-powered jet packs and quickly move 100 meters away from the ISS. For some reason after ...
0answers
42 views

### How to calculate delta v for orbit change around body; not necessarily Earth?

Let me express my joy at having found this great place of Stack Exchange. My question concerns the calculation of delta v requirements when already in orbit around a body and lowering or raising ...
1answer
79 views

### What's the method behind this TDRS triplet inclination “madness”?

Previous "method to the maddness" questions: 1, 2. The image below is from Why does TDRS 1's inclination evolve so much differently than that of all the others starting in 1995? and I've used it a ...
0answers
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### How much harder would space exploration be if the Earth rotated like Uranus does?

Let's say the Earth got knocked a bit silly in the distant past and somehow space-loving life evolved on this planet. They roll around on an Earth with an axial tilt of 98°. How much harder is it for ...
3answers
309 views

### 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 ...
2answers
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### How does the dynamics of the Jupiter and Saturn system make them be well suited for low-energy transfer?

Many papers mention that the compact and complex dynamics of the Jupiter and Saturn systems makes them ideal low energy transfer. My question is how? How does the dynamics of the Jupiter and Saturn ...
0answers
63 views

### Calculate velocity vector of hyperbolic trajectory

I am writing a little 2d space program and I need to calculate a velocity vector for my program. I already have my elliptical orbits working well but once the eccentricity of the orbit goes over 1 the ...
0answers
56 views

### moon's true anomaly at date of new moon

I've seen on this site: https://eclipse.gsfc.nasa.gov/SEhelp/moonorbit.html a table that gives the true anomaly of the moon at the time of new moon. The difference between the true anomaly at one new ...
1answer
191 views

### What will happen to a spacecraft if it cancels its galactic velocity?

A spacecraft in a circular LEO orbits at ~7.7km/s. If it performs a retrograde burn and cancels this velocity (within the Earth reference frame) it will start falling towards the Earth center along a ...
0answers
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### How can I plot satellite's trajectory from three different TLEs to detect any deviation on path with time?

I have obtained TLE information of a satellite from space-track.org for three different times. I am trying to study any deviation of the satellite trajectory from its usual path. Here I am comparing ...
1answer
84 views

### Do Lagrange points still exist if there is significant radiation pressure on the third body from the first?

From this answer: To obtain the distance to L1, find the smallest value of $r$ such that $$\frac{M_2}{r_1^2} + \frac{M_1}{R^2} - \frac{r_1(M_1+M_2)}{R^3} - \frac{M_1}{(R-r_1)^2} = 0.$$ To ...
0answers
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### Defining overshoot and undershoot boundary of entry corridor

I have been reading up on the mathematic of atmospheric entry. I have found different methods to theoretically calculate the corridor width but I don't understand how to define the overshoot and ...
0answers
68 views

### Getting the Velocity Vector in an Elliptical Orbit

I have a 2-D two body set up. I am using the vis-viva equation to get the velocity scalar of my elliptical orbit. I have the Semi-Major Axis, the radius, the eccentricity vector. I am sure I can ...
1answer
138 views

### How can you determine the nature of an object from its flight path angle, velocity, and radius alone?

Assuming that a defense system is capable of determining an object's flight path angle ($\gamma$), velocity (v), and radius (r), how could one differentiate between an ICBM, a satellite, or a solar ...
0answers
72 views

### How long does the SYLDA fairing stay in orbit after deploying?

For dual-manifest missions, Ariane 5 often uses the Système de Lancement Double or SYLDA system to encapsulate the lower of two stacked satellites. It can be seen in the following image encapsulating ...
1answer
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### Help with Vector format N-body state transition matrix

[Update] This is for an on-board autonomous navigation system (3-dimensions, interplanetary) using a Kalman Filter. There is no target trajectory. I have the position and velocity measurement models ...
1answer
50 views

### How to find instantaneous mass of a central body that results in a given osculating orbit?

This question was underspecified, so I'm going to try again. Osculating orbital elements are Keplerian elements of a hypothetical orbit around a specified center which would be tangent to a specified ...
3answers
112 views

### How do two-line element sets handle rev numbers > 99,999?

In a two-line element set (TLE), five characters in line 2 -- columns 64-68 -- are for the rev number. (https://en.wikipedia.org/wiki/Two-line_element_set) But some satellites have been around the ...
1answer
115 views

### Can L3 have halo orbits?

I've recently said you see one co-linear libration point, you seen 'em all. That's what I always say and while halo and other orbits associated with Sun-Earth L1 and L2 work similarly, L3 is 2 AU ...
5answers
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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 ...
0answers
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### How do you calculate shift in argument of periapsis for a not instantaneous burn assuming you're starting in circular orbit?

Most times we assume that burns are instantaneous, in this case if you burn (without a radial component) at the periapsis or apoapsis there is no shift in argument. Let's say the engine is weak and ...
0answers
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### How are rocket launches scheduled?

With all the satellites and other objects already in space; how exactly are launches scheduled and coordinated? Is there some kind of clearinghouse? How do the mega constellations affect the ...
1answer
85 views

### Analytical treatment of relative positions between satellites?

I have been searching the internet for estimation of relative position between two satellites. However, all sources seem to be pointing to methods used for proximity operations, where the math ...
0answers
82 views

### How can I plot a satellite TLE from its orbital parameters using python and skyfield?

I have a function that uses TLEs (Two-line elements) from Celestrak to plot the visibility of a satellite in Python. Is there a method with skyfield or poliastro to plot a TLE from given orbital ...
7answers
12k views

### Could we wait for Mars to come to us?

This may be a stupid question but I didn't find much information online about it. The concept is simple, could we launch a vehicle into space from Earth, stop right on Mars trajectory and wait for the ...
2answers
189 views

### 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 ...
1answer
234 views

### Would it be possible to grab on to a satellite, and use it to keep yourself in orbit in an emergency situation?

You are orbiting Earth when your spacecraft falls apart and you are left flying through space. Will your spacesuit keep you alive long enough to be rescued? Or will your orbit lower to quickly and you ...
1answer
287 views

### Can we go anywhere in space with only THREE reaction wheels and ONE chemical thruster?

I had a discussion the other day with some of my peers and they were very keen on the fact the it is possible to change your orbit as desired using a single thruster and a three reaction wheels. The ...
0answers
40 views

### How to calculate the amount of lunar regolith needed to reduce solar radiation in an area on earth by 0.2% or 0.5%

I am working on a climate change that doubles as a lunar infrastructure project. I am wondering if anyone could direct me to resources or help me answer the question of how much regolith scattered ...
2answers
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### How do stable equilibrium points work in GEO? If all geosynchronous spacecraft suddenly lost stationkeeping, would most “fall into” one or the other?

The (currently unanswered) question Quantitatively, how deep are the stable equilibrium points in GEO? How much delta-v to move from one to the other? (also see comments at Delta-v to move from GEO to ...
1answer
342 views

### Why is FORTRAN recommended for astrodynamics rather than MATLAB?

I understand that FORTRAN might be faster in terms of computation time, but I don't understand why it is always recommended by people in the field. Everyone tends to avoid MATLAB for astrodynamics; is ...
1answer
483 views

### Mars and back, staying only a few days

This article states that once you arrive at Mars you'll only have a couple of weeks before you'd have to begin a fresh Hohmann transfer back to Earth, otherwise you'll have to hang out on Mars for ...
2answers
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### What is the reason for secondary oscillations in apogee and perigee plots for objects 41332 and 41333?

This answer provides quite interesting plots of apogee and perigee for objects 41332 and 41333. The primary (sine wave -like) oscillations are probably due to perturbations caused by potential ...
1answer
553 views

### Can dust be in orbit around a spacecraft which orbits the Earth or Moon?

In the title above, Can dust be in orbit around a spacecraft which orbits the Earth or Moon? let's define "in orbit" to mean gravitationally bound to the spacecraft long enough to go around it a few ...
2answers
151 views

### Satellite of a satellite of a satellite

How long can the chain of satellites of satellites be? The Lunar Reconnaissance Orbiter is a satellite of the moon, which is a satellite of Earth, which is a satellite of the sun, which orbits ...
1answer
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### Confusion with direction (vector) of minimum velocity required to reach an orbit and escape velocity

In order to achieve a stable orbit around Earth, a spacecraft has to travel at velocity not smaller than approximately 7.8 km/s. If my understanding is correct, this figure refers to component of ...
2answers
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### Two-body problem VS Three-body problem Applications

The two-body problem deals with two bodies under certain assumptions while the restricted three-body problem deals with three bodies where one has a negligible mass (i.e. spacecraft or comet) I was ...
1answer
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### Trajectory Optimization To The Moon (Case Study: Chandrayaan-2)

People always ask this million dollar question of " What is the best path/trajectory to take to reach a certain orbit or point in space". Chandrayaan-2 had a pretty neat transfer to the moon, it took ...
1answer
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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-...
0answers
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### Major topic headings for lunar CubeSat mission design planning?

I am working on a project to design a complete mission for a lunar CubeSat. Assuming that the launch segment is already covered and I need to focus on the spacecraft design. I wanted to know what ...
1answer
80 views

### How satellite orbital vacancies are determined?

Before a new satellite is launched, its desired orbital altitude, inclination is determined. Now with thousands of satellites already in orbit at different altitudes, how do we know if our desired ...
0answers
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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 ...