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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Could photons orbit a black hole if fired at the correct angle? [migrated]

My experience with Kerbal Space Program gives me the impression that it's impossible to transfer from a stable orbit of one body to the stable orbit of another without deceleration. But is this true ...
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How can I edit the STK report output?

I have been dealing for a while on a report which is generated by STK. It contains basically time, azimuth, elevation and range data. Besides those data I need to also generate the theta and phi ...
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I want to go to the moon and then comeback to Earth [closed]

I want to design a mission for which I want to select some samples from the moon, I am new to Orbital mechanics so I need some guidance related to the Mission orbit access plan. How my spacecraft will ...
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Where can one find the accelerations due to high-order terms of the geopotential model?

The expression for the orbital perturbation due to J2 ($\mathbf{a_{J2}} = [a_r \ a_s \ a_w]^T$) as well as its derived effect on the argument of perigee and the right ascension of the ascending node ...
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How can I calculate the weight a aero-spacecraft occupant experiences during sub-orbital but non-ballistic trajectories?

Once in orbit, astronauts experience "weightlessness" relative to their capsule or space station because they are moving at the same orbital velocity as the surrounding spacecraft. I have ...
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In which direction does the x axis of the ECI at 1.1.2000 at 12:00 (J2000) go and where is the 0 deg meridian?

I am currently getting a bit lost in reference frames and coordinate systems. From my point of view, I am currently in the ICRS frame. I know that the ECI from my point is only moving but not rotating,...
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How much delta-v does it take to go from one arbitrary orbit to another?

This is, in theory, very basic rocket science. I can't seem to find a solution on here though, so I'm asking in the hopes you'll enlighten me and my amateurish ways. I've got a set of Keplerian ...
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Create a sensor in STK [closed]

how do I create a Sensor object which has a Rectangular 100x100 deg field of view? Note, this is the actual field of view; Rectangular Sensors are defined in STK by vertical and horizontal half-angles....
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ISS nodal precession

I was confused by JPL Horizons data showing time variations in the ISS longitude of ascending node, until I realized maybe the orbital plane itself rotates around earth... A quick web search then ...
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Reasonable argument of periapsis?

My intuition for orbital parameters is still poor, so I'm wondering if someone can tell if my argument of periapsis seems reasonable. I'm simulating a launch from Kennedy (28.1 deg latitude, -80.6 deg ...
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Orbit design guidelines for rendezvous with ISS?

Are there guidelines for orbit design if you're launching a payload for delivery to the ISS? Altitude, maybe phase angle constraints? Orbital approach maneuvers, maybe? I've figured out how to control ...
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Why does it take so long for ISS garbage to fall out of orbit?

The ISS recently jettison some garbage and expects it to take 2-4 years to de-orbit and burn up. From Gizmodo's ISS Ditches 2.9-Ton Pallet of Batteries, Creating Its Most Massive Piece of Space Trash: ...
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Why (the heck) did Tianwan-1 insert into a low inclination orbit then execute a plane change from 11.8 to 86.9 degrees?

eoPortal's Tianwen-1 (China's first Mars Exploration Mission) shows the following graphic, caption and link. It's often discussed that orbital plane changes are like certain table wines in that they ...
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Oberth Effect in Solar Sails: Where does the extra energy comes from?

Suppose, the reflectors of Solar Sails are opened for same amount of time at both periapsis and apoapsis. How does Oberth effect work in this case? Will Delta-V be same and hence change in Kinetic ...
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What does a 6-month GTO to GEO transfer look like in practice?

Based on How much time does it take to circularize a GTO orbit using ion propulsion? and the launch and entry into service dates, it takes about 6 months of continuous ion propulsion to transfer a GTO ...
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Satellites below perigee on Stuff in Space website

A friend of mine noticed that many satellites on Stuff in Space website can reach an altitude lower than their declared perigee, as you can see in the following screenshot: We observed these ...
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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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Can we determine the position of an artificial satellite using Kepler's parameters?

I have read that an orbit is defined by Kepler's parameters, so is it possible to determine an exact position of an artificial satellite using those parameters? Forgive me if this is a redundant ...
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This ISS trash deployment looks more like 2 feet than 2 inches per second, was it too fast or are these articles incorrect?

Digital Trends' Watch a NASA astronaut jettison part of the ISS into space which was linked in says: Writing in Air & Space last year about the process of jettisoning objects, veteran NASA ...
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Which orbital elements are normally targeted at launch?

Say you launch a rocket for rendezvous with the ISS. You'll want to set the target orbital inclination and longitude of ascending node. These will ensure the rocket is in the plane of the ISS. You'll ...
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Determining the launch period for Hohmann transfer

How do you determine the day of a specific launch? I know there are launch windows but they only refer to the time at which a spacecraft must be launched. For a LEO it is apparently 365 days, but what ...
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Why can Amazônia-1 observe the Amazon “every day or two” while Landsat takes 16 days between observations? Is “orbital magic” at play here?

The news item in Science Brazil’s first homemade satellite will put an extra eye on dwindling Amazon forests says: Right now, Brazil’s Amazon monitoring program relies on flyovers from the U.S. ...
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Precision in the space navigation [duplicate]

I am curious about the precision NASA and other agencies have in the space navigation. Are they always accurate to the meter in position they aim for; in mission like the recent rover landing on the ...
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Coordinate systems for state vectors

I am currently working on a project from this book. In appendix D, they provide a few projects that can be coded as a review of all the material in the book. I finished the first project, Site/Track ...
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Lowest possible lunar orbit and has any spacecraft achieved it?

Because the Moon has no atmosphere a spacecraft can theoretically cruise at a very low orbit. What is the lowest possible lunar orbit and which spacecraft achieved it? Was it the Lunar Module of ...
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How to find ECI coordinates for a circular orbit

Suppose a satellite is orbiting Earth in a circular orbit, of which I know the inclination $i$, the right ascension of the ascending node $\Omega$, the semi-major axis $a$ (or orbit radius given that ...
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Hill approximation of the CRTBP (Circular Restricted Three-Body Problem) derivation

Dear fellow space enthusiasts, Let us first consider the classical CRTBP equations of motion by defining the position vector of the spacecraft \begin{equation} \boldsymbol{r}=[x,y,z]^{T}, \end{...
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Understanding the paper “Determination of Satellite Orbital Elements by Means of On-Board GPS Receiver and Its Verification” by Yoshiwo Okamoto et. al

I have been assigned with implementing the algorithm proposed in the paper "Determination of Satellite Orbital Elements by Means of On-Board GPS Receiver and Its Verification" by Yoshiwo ...
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Setting up orbit propagation in Orekit

Please forgive my ignorance, I'm new to orbital dynamics. I am using Orekit [https://www.orekit.org/] for orbital propagation in order to determine rise and set times for a MEO satellite, and am ...
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How is satellite's footprint/coverage calculated?

I was using Orbitron - Satellite Tracking software the other day and I saw that clicking on any of the satellites, you will see their footprint (they are usually not-ideal circles, usually ellipses), ...
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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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Why is the re-entry velocity of Orion almost the same as the escape velocity?

I have read that the predicted re-entry speed on the Artemis I mission for the Orion spacecraft into the Earth's atmosphere is about 24,500 mph or 10.9 km/s. Why is it almost the same as Earth's ...
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Largest single burn spacecraft delta-v in deep space?

This 700 m/s maneuver that was avoided got me thinking and then CNN's NASA mission will zoom by asteroid before returning sample to Earth said: "Leaving Bennu's vicinity in May puts us in the '...
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Why would a launch request for a gravitational assist at Mars specify a DLA (Declination of Launch Asymptote) of 30 to 32 degrees?

The recent intriguing question Why is NASA proposing an EMEJ (MEGA) trajectory for Europa Clipper instead of EEJ? quotes "A launch service request... recently put out for Europa Clipper to do a ...
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How to know in which quadrant is the RAAN?

Having found the right ascension of the node, for example, $$ \begin{align*} \boldsymbol{\Omega} &= cos^{-1}\frac{N_X}{N} \\ &= \underline{15.60^\circ} \end{align*} $$ How do we know in ...
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How would an n-body numerical orbit simulator use hierarchy in its Jacobian?

This question is about techniques to calculate orbits. The Github post On the dynamical stability of Principia's modified Jool system (cited in this answer) says: Principia computes the trajectory of ...
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Minimum delta V required to return a piece of metallic asteroid 16 Psyche to Earth?

Suppose somebody sent a rover to Psyche 16 and found massive concentrated deposits of platinum-group metals near the surface, and turned it into a 10 ton sphere of platinum/iridium/osmium/gold alloy ...
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rocket trajectory simulation in inertial frame, with drag

I created a rocket trajectory simulator and optimizer using the following equations of motion for a non-rotating frame of reference $$\dot{v} = \frac{T \cos \varepsilon - D}{m} - g \sin \gamma$$ $$v \...
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What is the purpose of eccentric, parabolic and hyperbolic anomaly?

I am currently reading David Vallado's 'Fundamental of Astrodynamics and Applications' and I have this doubt on the 2nd chapter named 'Kepler's Equation and Kepler's Problems'. Although I understand ...
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Are Jool's moons' orbits stable?

The fictitious Kerbol system includes ...five planets: Moho, Eve, Kerbin, Duna and Jool; and two dwarf planets: Dres and Eeloo; orbit around it. Kerbol contains 99.97 % of the mass in the Kerbol ...
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Why does it cost more to get to L4/5 than C3=0?

I was looking at Delta-V budgets and noticed that it costs 4.1 km/s to get from LEO to L4/5, but just 3.2 km/s for LEO to geocentric C3 = 0 (escape velocity). I find that counter-intuitive. Why does ...
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Does apsidal precession rate have any dependence on the argument of periapsis? Perhaps higher order?

Writing this comment got me thinking, which invariably leads to confusion in my case. @DavidHammen's answer to show that for Juno's near 90° polar orbit the major precession is apsidal; periapsis is ...
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How big is an orbit of “X by Y miles”?

While reading the NASA overview of Apollo 11, says: Apollo 11 launched from Cape Kennedy on July 16, 1969, carrying Commander Neil Armstrong, Command Module Pilot Michael Collins and Lunar Module ...
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“NASA's Europa Clipper has been liberated from the Space Launch System” How would the “physics” of a Starship-based mission differ from SLS?

The Hill's NASA's Europa Clipper has been liberated from the Space Launch System is quite an illuminating read about the politics of space launch. However, I noticed that it also says: Both the ...
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Can a satellite orbit the ISS?

Is stable orbit of a small satellite around the ISS theoratically possible with minimal station keeping?
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How can you calculate a course based on constant acceleration burn and deceleration burn?

In the TV series The Expanse, a sci-fi space-engine called the "Epstein Fusion Drive" is a thruster capable of performing constant acceleration (up to and beyond "20g" (about $200 ...
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Satellites Orbital Parameters

I want to access satellites' orbital parameters like inclination, right ascension of ascending node and argument of perigee. Unfortunately, I haven't been able to find this information. Is there a ...
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Bucket loop between Earth and Moon?

Please don't bite my head off. If this is so stupid that it deserves to be squashed, I'm quite happy to delete the question. I mainly would like to know whether anyone's ever suggested this (I ...
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Why is the Orbital Velocity after SECO of Crew Dragon with 27K km/h lower than of ISS?

Crew Dragon after SECO: Orbital Vfelocity at 27,000km/h at 200km altitude (roughly 9-10min after liftoff). ISS Orbital Velocity at ca. 28,000 km/h at 400km altitude.iss_altitude,iss speed However from ...
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I want to simulate the antenna pointing error when tracking LEO satellites

I am trying to simulate the antenna pointing error of our antenna when tracking LEO satellites using TLE data. I am using the Skyfield library in python. First I loaded the TLE data from the Celestrak ...

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