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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The strange orbit of Ofeq 11 - how does it (actually) do this?

I assume the retrograde orbit ($\theta_{inc}=142°$) is a side-effect of geography - ocean overfly access only lies West of the secured launch site - this article in Spaceflight 101 makes several ...
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Delta-v penalty for stopping in a distant Earth orbit versus using atmospheric reentry for braking and returning to Earth from Mars?

Comments below this answer to What precautions are planned to prevent an accident or anomaly from releasing Martians into Earth's environment? say: Seems to me like a high earth orbit lab might be a ...
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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 ...
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Why are all space initiatives designed to get to space overnight when in Nature all extreme feats are achieved in a gradual process

Is the current design paradigm of space engineers still too anti-naturalistic? Why not design Space Cruisers first large & slow but steady into outer orbit, over months rather than in a day? I ...
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1answer
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How could one determine the acceleration of a satellite given its ephemeris data, taking into account the earth's oblateness?

I am looking to determine the acceleration vector of a satellite orbiting the earth at a certain point in time given its ephemeris data for that same point in time. I am taking into account the ...
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Is there a basic 2 or 3 body space simulator

I would like an educational tool to allow a child to 'drag and drop' or 'add' a planet to a workspace, adjust the x, y and z velocities as well as the size and mass. OF the numerous simulators I have ...
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Compute eccentricity and angular momentum vectors of a binary

I having some trouble finding the direction vectors (in 3D) of the eccentricity and angular momentum of a binary. The issue is that the binary has only been described in Keplerian orbital elements and ...
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Optimum delta-v burn to change periapsis or apoapsis at an arbitrary point on an elliptical orbit?

This question is explicitly not about doing burns at the apoapsis or periapsis in order to raise/lower the other apsis. Of course those are going to be the most efficient maneuvers, and the burns ...
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Will the new “TLE format” be orbitally-mechanically better than traditional TLEs?

Celetrak's A New Way to Obtain GP Data (aka TLEs) by Dr. T.S. Kelso 2020 May 27 explains the arrival a new infoblob format that in several ways is "better" than the ancient TLE, and contains ...
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Where will the DSCOVR mission Falcon 9 2nd stage rocket body end up?

This answer to Why would a mission to Sun-Earth L1 have an instantaneous launch window? suggests that this was quite a delta-v-intensive launch. It left the F9 2nd stage in a very high 17 day orbit ...
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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 ...
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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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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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What is the cheapest possible way to land a crew of 2 on the moon?

During the Apollo moon missions, a single very large rocket sent both the Apollo CSM and the LM to the moon in a single shot and it took only around 3 days to get there. However, after the Apollo ...
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How to get semi-major axis from TLE?

This should be fairly straightforward, but, how do I get the semi-major axis (a) from at TLE. For example if I have the TLE: ...
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Keplerian to cartesian elements issue

I am trying to convert between keplerian orbital elements to cartesian position and velocity but something is going wrong. The issue is that I (as a check) compute some keplerian orbital elements with ...
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1answer
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How do I calculate re-entry velocity when decaying from a circular orbit?

I am trying to find the velocity of an object during re-entry so that I can calculate the peak heat flux but I'm a bit stuck. I know how to find the velocity of the original, circular orbit (300km) ...
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1answer
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Calculating synodic periods at a given point in the orbit

Calculating the regular synodic period of two orbiting bodies is pretty straight forward, but what if I wanted to know when they would meet in a specific position? For example if they share a periapse....
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1answer
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Could someone explain this formula for da/dt?

The paper Ballistic Coefficient Estimation for Reentry Prediction of Rocket Bodies in Eccentric Orbits Based on TLE Data gives the formula (3) to calculate the time derivative of the semi-major axis ...
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3answers
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What's the planetary exploration word for “impact parameter” (distance of closest approach if gravity were “turned off”)?

In particle scattering there's a term called "impact parameter", which is the minimum distance a particle would pass a second particle at rest, if the attractive or repulsive force were ignored or "...
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What is the relationship between the periapsis altitude and the change in velocity in a gravity assist?

In a gravity assist maneuver if I were to decrease the distance from the rocket to the periapsis of the planet it is orbiting (I believe this is called the periapsis altitude but I may be wrong) it ...
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2answers
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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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1answer
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What are the units for the orbital period equation?

I'm trying to find the time taken for a Hohmann transfer orbit. I've tried using all three of these equations, but when compared against known periods they all evaluate to the same wrong answer, 100 ...
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1answer
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Get dates when a satellite has performed maneuver from historical TLE data (python)?

I have been recently acquainted with orbital mechanics and am trying to do some analysis on the subject. Since I don't have subject matter expertise, I am at a crossroads with trying to decide that ...
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Nature of Hayabusa-2's “Home Position” relative to Ryugu? Is it Ruygu's L1?

This tweet "from Hayabusa-2" via JAXA shows the diagram below, which seems to suggest that the Hayabusa-2 spacecraft tends to remain between the asteroid Ryugu and the Sun. Does Hayabusa-2 have to ...
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2answers
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Stable and Unstable point for GEO satellite

For GEO satellite, 24h period, it has four equilibrium points (two stable point and two unstable point). At the equilibrium point, the transverse acceleration is zero, so semimajor axis changes slowly....
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How is it possible to connect trajectories at a Poincare section using the “bisection” method?

When constructing a heteroclinic connection (a connection between two different periodic orbits at two different libration points), the stable and unstable manifolds of two different libration points ...
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1answer
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Difference between true anomaly and mean anomaly

What is the difference between true anomaly and mean anomaly in orbital mechanics? I want to understand the physical meaning of mean anomaly, for example true anomaly is the angular position of a ...
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Escaping moons conflict with what I understand of gravity

I have known that the Earth's Moon, let's call it Luna (tip of the hat to The Expanse), has been slowly but surely increasing it's distance from the Earth by a small measure each year. This week I ...
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Is the Flyby Anomaly still a thing?

The Flyby Anomaly is a name given to an unexplained, unexpected difference between the best theoretical calculation of a change in several different spacecraft's velocities due to flyby (Gravity ...
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2answers
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Why is L2 Langrangian point stable?

I was reading about Langrangian points between Sun and Earth. I understood that $L_1$ Langrangian point was stable as the gravitational pull by Sun on the satellite towards itself was equal to the ...
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Effects On ISS Orbital Mechanics Resulting From Added Mass Of Dragon Capsule Visit

Does the ISS require any type of orbital mechanics management once the Dragon capsule was confirmed with a positive airlock seal, and the mass of the spacecraft, 2 additional astronauts, and supplies ...
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1answer
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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 ...
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1answer
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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 ...
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0answers
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Hohmann transfer Earth-Mars: 1060 m/s or 2944 m/s?

This diagram has been discussed quite a lot, but my issues is with the Delta v requirement for a Hohmann transfer to Mars. The diagram states that the Delta v for change from Earth intercept to Mars ...
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2answers
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Orbital Rendezvous vs Hohmann Transfer

Let's assume that a spaceship (capsule) is about to dock to the ISS the distance between spaceship (capsule) and ISS is 20 meters the relative velocity between the spaceship (capsule) and ISS is ...
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Calculate Satellite ground track

I'm trying to find equations to calculate satellite position based on orbit parameters and given time. What I currently have is a mess that is basically giving me bunch of garbage. What is latitude ...
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Would the Yarkovsky effect ever be faster than a solar sail from a 1 AU orbit to the Sun?

Previously I'd mistakenly asked Would the Poynting–Robertson effect ever be faster than a solar sail from a 1 AU orbit to the Sun? when I'd meant to ask about the Yarkovsky effect which can be much ...
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1answer
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What happens to orbit after a radial burn?

We know from Hohmann-Transfer or bi elliptic transfer maneuvers that a burn in the tangential direction of an orbit changes the radius of the orbit. But what happens to an object in orbit, when there ...
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Do you need 0 km/s velocity to crash into the sun?

I was reading a popular thread about the delta-v required to escape the solar system compared to the delta-v required to crash into the sun. I get it: the earth itself already has a high speed (29.7km/...
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1answer
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How are orbit insertion changes in altitude and RAAN designed?

Assuming that desired inclination is achieved during the launch, how are the target altitude and RAAN usually achieved in satellite missions, if the launch could only place the satellite on a ...
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13answers
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What are the choices today for orbital mechanics simulation software?

I used to be familiar with the various choices out there for orbital mechanics simulation software. Alas, those days are gone. What are the choices today, preferably sorted by platform? This ...
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0answers
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Is there a calculator or set of formulas for estimating aerobraking on Mars?

I am looking for a calculator or formulas that can be used to calculate the aerobraking on Mars mission. I have found some data on previous Mars flights where aerobraking was used and all my current ...
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How model 3-stage rocket to LEO in STK

I'm trying to design a three-stage rocket ascent flight trajectory to LEO using AGI's Software SKT but I'm in trouble. Could anyone help me with designing it?
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Interplanetary space mission debris orbits

I was wondering if anyone knew about a database of orbits for debris from previous interplanetary space missions. I am referring to debris or expired missions by NASA, ESA, JAXA, etc. I know there are ...
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3answers
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How is foot-pounds of energy defined?

Tom Lodgson's classic textbook Orbital Mechanics: Theory and Applications frequently measures energy in foot-pounds, which I'd always thought to measure torque. The book doesn't define it. Is it the ...
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What exactly is a solar gravity well manouver and in what cases would it be helpful?

In this answer to the gedankenexperiment question With current state of technology if we wanted how long would it take for newly launched probe to overtake Voyagers? I've seen the term "solar gravity ...
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What does the term “libration point gateway” mean?

In the Circular Restricted Three Body Problem, natural paths exist between periodic orbits or the libration points that have negligible cost. These are commonly known as free transfers between ...
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1answer
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Does Kerbal Space Program have a software migration path to Lagrange points, halo orbits, and other 3-body goodies?

At about 05:37 in Scott Manley video Kerbal Space Program 2 - What We Know About The Sequel So I’m cautiously optimistic and I really obviously want this to be ...
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2answers
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How far apart are ISS launch windows?

Being on an eccentric orbit, I imagine the launch windows are instantaneous (which they are) and different for each launch site whether it be Baikonur, Cape, Tanegashima, or the ESA launch site. How ...

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