Skip to main content

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.

Filter by
Sorted by
Tagged with
3 votes
0 answers
59 views

Testing astrodynamics software

As I’ve been developing my own solutions (and implementing existing ones) to problems in astrodynamics to solve textbook questions and to build applications, I’m becoming increasingly interested in ...
gaharaz's user avatar
  • 101
0 votes
0 answers
15 views

Issue in orbit propagator with wmm2020 output

I am trying to build an orbit propagator with input of latitude and longitude in wmm2020 to plot the magnitude of the geomagnetic field. The orbit seems good but the field plot is completely wrong. ...
Felipe JulianoDev's user avatar
5 votes
1 answer
106 views

Where does this formula for the argument of periapsis come from?

I was looking at Poliastro/Hapsira python code determining orbital elements from the position and velocity vector. On this line, argp or $\omega$ is determined as (...
TheWanderer's user avatar
5 votes
1 answer
293 views

After a spacecraft departing from the ISS has performed its deorbit burn, what is the altitude at the perigee of its elliptical orbit typically?

I am attempting to quantify how aggressively returning spacecraft reenter the atmosphere. There is likely a trade-off between aerobraking more gradually and splashing down accurately. I'm hoping that ...
phil1008's user avatar
  • 5,634
4 votes
1 answer
491 views

Does earth's revolving around sun affect polar orbit ground track?

As the earth revolves around the sun, does the ground track of a polar orbit change? I realize the oblateness of the earth causes precession of the nodes, I want to know if there's another effect. As ...
Bruce Ediger's user avatar
3 votes
0 answers
45 views

Why my calculations for the eccentric anomalies at the start and end of an interplanetery transfer seem to be off?

For a game, to determine an interplanetary transfer I have implemented the method from here. Using the data for their example problem, I get the result with the lowest $\Delta v$ which appears ...
TheWanderer's user avatar
6 votes
2 answers
2k views

Using Mars' inner moon Phobos as a brake

In case of a StarShip (but it could be any other lander), it would arrive a Mars with minimal fuel remaining and it would need to slowdown for reentry, how can it be slowed down for free? Maybe using ...
estinamir's user avatar
  • 349
4 votes
3 answers
304 views

How exactly would nuclear thermal or nuclear electric propulsion enable short duration human missions to Mars?

Today (May 1, 2024) NASA Administrator Bill Nelson testified before the House Science, Space, and Technology Committee that nuclear thermal propulsion would enable us to go faster to Mars. He said: ...
phil1008's user avatar
  • 5,634
5 votes
2 answers
153 views

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-...
C. Burns's user avatar
  • 111
4 votes
1 answer
190 views

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 ...
NeutronStar's user avatar
  • 1,049
1 vote
0 answers
48 views

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 ...
Djembo's user avatar
  • 11
2 votes
1 answer
90 views

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 ...
Starfish Prime's user avatar
2 votes
0 answers
96 views

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 ...
Starkie's user avatar
  • 31
2 votes
0 answers
35 views

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 ...
Alexandre Augusto's user avatar
1 vote
0 answers
37 views

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 ...
Liu's user avatar
  • 61
2 votes
2 answers
187 views

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 ...
Roger Wallberg's user avatar
2 votes
2 answers
114 views

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 ...
Ken Ibarra's user avatar
2 votes
1 answer
108 views

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 ...
popeye's user avatar
  • 23
1 vote
1 answer
101 views

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 ...
Hayler's user avatar
  • 11
3 votes
1 answer
224 views

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 ...
w94n9's user avatar
  • 33
1 vote
0 answers
81 views

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) ...
Shawn Lim's user avatar
  • 185
8 votes
2 answers
1k views

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 ...
Anonymous's user avatar
1 vote
1 answer
195 views

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 ...
Shawn Lim's user avatar
  • 185
0 votes
0 answers
76 views

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 ...
Skittles's user avatar
  • 101
12 votes
5 answers
6k views

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 ...
N.Li's user avatar
  • 123
11 votes
3 answers
5k views

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 ...
Roman's user avatar
  • 113
8 votes
1 answer
494 views

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 ...
leftaroundabout's user avatar
5 votes
2 answers
477 views

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 ...
Peter - Reinstate Monica's user avatar
2 votes
0 answers
64 views

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 ...
Woody's user avatar
  • 22.1k
4 votes
1 answer
165 views

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 ...
Danny's user avatar
  • 215
8 votes
3 answers
1k views

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 ...
Dino 's user avatar
  • 81
1 vote
1 answer
149 views

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. ...
The Rocket fan's user avatar
4 votes
1 answer
159 views

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 ...
Barry Jenakuns's user avatar
2 votes
2 answers
1k views

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?
Josh Berryman's user avatar
4 votes
1 answer
177 views

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 ...
Dylan's user avatar
  • 321
1 vote
1 answer
120 views

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 ...
Achilles chan's user avatar
4 votes
1 answer
224 views

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/...
Woody's user avatar
  • 22.1k
15 votes
1 answer
3k views

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 ...
Woody's user avatar
  • 22.1k
6 votes
1 answer
196 views

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 ...
c roald's user avatar
  • 161
4 votes
1 answer
108 views

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 ...
C. Burns's user avatar
  • 111
3 votes
1 answer
639 views

Vis-Viva equation applied to Earth

We know that the Vis-Viva equation is given by: $v=\sqrt{G M\left(\frac{2}{r}-\frac{1}{a}\right)}$ If I plug-in the values for Earth (the mass is obviously that of the Sun): $G=6.6743 \times 10^{-11} \...
Vincent ISOZ's user avatar
1 vote
1 answer
109 views

Equivalent Vis-Viva equation but for acceleration

I know that thanks to the Vis-Viva equation, knowing the elliptic parameter of a celestial orbiting object we can get its speed on any point of the orbit. But what about the acceleration? Is there an ...
Vincent ISOZ's user avatar
0 votes
0 answers
108 views

I want to write a program to calculate optimal trajectories, where can I find info on the maths

I want to write a program to calculate the optimal way for a spacecraft with a given engine to reach some body astronomical body with the minimum fuel burn (possibly adding in constraints on time, ...
Pioneer_11's user avatar
1 vote
0 answers
117 views

Objects move clockwise instead of counter-clockwise

I'm trying to write an orbital simulation with patched conics. For my sources I'm using https://orbital-mechanics.space/ and Fundamentals of Astrodynamics (Second Edition). Both sources suggest to use ...
Dzejkop's user avatar
  • 63
11 votes
1 answer
373 views

Using today's technology, is interstellar navigation possible?

I was watching this video essay discussion about space elevators, and on a bit of a tangent, the physicist talks about difficulties with interstellar missions, specifically comments about navigation ...
Dragongeek's user avatar
  • 19.1k
3 votes
3 answers
191 views

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 ...
hater's user avatar
  • 31
2 votes
0 answers
50 views

NASA’s NIAC has awarded phase III funding for Diffractive Solar Sails. Demonstration mission in the works?

Diffractive lightsails use small gratings embedded in thin films to produce diffraction (which causes light to spread out when it passes through a narrow opening). Diffractive light sails are a ...
Woody's user avatar
  • 22.1k
5 votes
2 answers
984 views

Object slowest at periapsis - despite correct position calculation

I'm coding up a simulation of celestial bodies using patched conics. At the moment I'm stuck with calculating the velocity of the object in the perifocal frame. For the position I'm simply using the ...
Dzejkop's user avatar
  • 63
0 votes
0 answers
56 views

Eclipse/sunlight detection for LEO satellites

I am trying to use poliastro to obtain the positions of the propagated spacecraft and the lighting conditions at each position. The documentation in poliastro page shows an example of the shadow ...
Spiros Makris's user avatar
11 votes
5 answers
1k views

In circle orbit, give a delta V to a satellite, how to find final orbit altitude?

I think this is a very very simple question for me, but unfortunately I cant solve it... A satellite is orbiting in a circular path at an altitude of 600 kilometers. If the satellite is capable of ...
Achilles chan's user avatar

1
2 3 4 5
37