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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.

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How does the ISS Transit Finder website get the position of the ISS so accurately?

The recent Petapixel article How to Shoot the ISS Flying Across the Face of the Moon gives a lot of detailed, helpful advice for photographing transits of the ISS across the disk of the Moon. For ...
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Is SGP4 propagation necessarily more accurate near the epoch chosen for TLE generation?

This interesting answer includes a quote from Space-Track: From Space-Track.Org FAQ TLEs can contain future epochs. About 20 satellites are categorized as "multi-day objects" ...
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How to find Near Rectilinear Halo Orbits (NHROs)?

Looking all the good questions and answers in this site referent to CR3BP dynamics, periodic orbits, state transition matrices, etc. I wonder: what algorithm or steps do I have to follow to find the ...
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Calculating t(E)

The mean radius vector of an elliptic orbit is equivalent to the semi-major axis. If I sample the radius vector of an unperturbed elliptic orbit as a function of the eccentric anomaly with at a ...
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Software (besides Ltool) to simulate CR3BP (three body) problems?

Are there any other softwares for CR3BP besides Ltool? As I've learnt here Ltool is not generally available to the public. I would like to simulate three body orbits within the standard circular ...
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Why would ISRO's MOM-2 Mars orbiter mission's apoarion already be decided in such an early call for proposals?

ISRO's announcement Announcement of Opportunity (AO) for future Mars Orbiter Mission (MOM-2) says in part: It is now planned to have the next orbiter mission around Mars for a future launch ...
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What is optimum data interval algorithm for Orbit Determination?

I am trying to find Optimum data interval algorithm for orbit determination. Because in Leo, Geo orbit updates the measurement data can be different so that I want to implement an optimum data ...
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223 views

Using of the coordinate systems in orbit propagation

For the orbit propagation in ECI coordinate system, considering the effects of zonal harmonics and Sun/Moon perturbations the following procedure was formed: Convert the state vector to ECEF ...
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Elliptical orbits transformed to “equivalent” circular orbit

I'm trying to transform Mars' elliptical orbit into its circular "equivalent". I understand that if the semi-major axis is used as the radius, and the mean angular rate and period are kept the same, ...
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Earth geopotential effect on orbit propagation

I'm trying to take into account the Earth geopotential effect on the orbit. The only term I could consider, is J2. Are the terms (J2, etc.) change with time? I ...
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How can I calculate Mean anomaly from True longitude?

So, I have - TLE data - Reference frame: QMOD - Type: Osculating - Semimajor axis - Eccentricity - Asceding node - ...
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variables affect the trajectory in a stochastic way

What are the different variables affecting the trajectory of a rocket in a stochastic way for getting potential three-sigma trajectory?
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Low-thrust spiraling to escape, is the flight path angle (gamma) at C3=0 always 39 degrees?

@MarkAdler's comment led me to ask Why would a slow spiral from a C3 of zero take about 2.4 times as much ΔV as an impulsive maneuver? which resulted in this tidy and efficient @MarkAdler answer which ...
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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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Will asteroid 2015 YA have a collision with Venus in october 2018?

When you use the Small-Body Data Browser of JPL Solar System Dynamics and do the search for asteroid 2015 YA, and after that push the [ show orbit diagram ] button, you can see that on october 12, ...
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How to calculate the flight path angle, γ, from a state vector?

@Julio's excellent answer describes a flight path angle, and explains that it is the angle between the tangential direction (perpendicular to the radial vector to the central body) and the current ...
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Comparison of AOP change of the orbits

I'm comparing how the Argument of perigee (AOP) changes for 2 orbits (O1 and O2). The orbits ...
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Spiraling out from circular orbit to escape via low thrust, what is γ (gamma)?

@MarkAdler's comment led me to ask Why would a slow spiral from a C3 of zero take about 2.4 times as much ΔV as an impulsive maneuver? which resulted in this tidy and efficient @MarkAdler answer which ...
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Why would a slow spiral from a C3 of zero take about 2.4 times as much ΔV as an impulsive maneuver?

I just read a fascinating comment that I don't understand. In part it says ...the Oberth effect does not depend on the mass of the object. A slow spiral in to a low orbit from a C3 of zero will ...
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How could asteroid 2013 ND$_1$$_5$ become a moon of Venus with the aid of rocket engines?

Notice: Although this question is similar to this one, it is different because asteroid 2012 XE$_1$$_3$$_3$ has a transitional path between Venus's Lagrangian points L5 point and L3 point, whereas ...
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Low earth orbit propagation in GMAT

I'm propagating a Low Earth orbit using GMAT. I 'm trying to make the propagation realistic, considering the zonal harmonics, Sun, Moon, Jupiter, Venus perturbations, tidal forces and solar ...
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Could asteroid 2012 XE$_1$$_3$$_3$ become a moon of Venus with the aid of rocket engines?

2012 XE$_1$$_3$$_3$ is an asteroid, classified as near-Earth object of the Aten group that is a temporary co-orbital of Venus. It is following a transitional path between Venus's Lagrangian points L$...
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A software for orbit propagation, considering Moon, Sun and zonal harmonics

I have to propagate the orbit of a satellite in 1 year, complying with the Sun, Moon and zonal harmonics effects. Is there preferably a free software, which could be used? I was suggested to use ...
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Is a sun-blocking orbit possible?

Is it possible for an orbital "sun shade satellite" to have a geosynchronous equatorial orbit such that it is in an approximately straight line between the Sun and a fixed point on the Earth's ...
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How does the poliastro python package “Going to Mars with Python” example work? What's it really doing?

@astrojuanlu's answer mentions the existence of the Python package poliastro, and in the documentation there I found an example titled Going to Mars with Python using poliastro among others. Input ...
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Are patched conics (and by induction, KSP) “useless” for simulating ion propulsion?

My previous KSP question What can the KSP game actually teach about spaceflight and orbital mechanics, and what are its limitations? resulted in some really productive discussions and under-the-hood ...
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Maneuver to the optimal point of a given orbit

There is a spacecraft on an initial orbit. There is a target orbit. The Keplerian elements are given for the orbits. The problem is: when and what $\Delta V$ to apply to the SC to move it to the ...
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If a spacecraft is orbiting around the Moon, what direction would the nadir axis be?

Nadir for a craft orbiting the Earth would be radially in, is nadir always pointed towards the Earth or is it pointed towards the celestial body that the craft is orbiting?
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Outlier detection algorithm for orbit determination, how do different ones compare?

I have been reading about outlier detection algorithm for improving determinations based on realistic data. Outlier exclusion is an important tool in any analysis of realistic noisy data. There are ...
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2answers
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Is it possible to orbit a black-hole AT the event horizon? [closed]

https://en.wikipedia.org/wiki/Black_hole#Innermost_stable_circular_orbit_(ISCO) ISCO is apparently the current theoretical limit for orbiting black holes (as sourced by wikipedia). Original Question:...
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A spacecraft leaves Earth exactly with escape velocity V2 - what trajectory it will have in Solar System?

A textbook solution: if a spacecraft leaves the isolated Earth with escape velocity V2 (=11.2 km/s at Earth's surface) it will have parabolic escape trajectory. But Earth is in orbit around Sun. The ...
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1answer
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Drag-only and gravity-only satellite orbit propagation, need help understanding the results

I'm trying to propagate the orbit of an Earth satellite. I've tried my calculation with gravity only (no drag), and also with drag only (no gravity). The gravity-only calculations work fine and ...
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Space train concept picking up/releasing cargo

The space train concept involves a ship moving between 2 bodies such as earth/mars with a constant speed and without slowing down. As it flies by each body it orbits around it and continues to the ...
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Difficulty trying to use the SPK file ast343de430.bsp

I'm looking for a NAIF SPK file (these typically end in .bsp) for a bunch of asteroids in the J2000 reference frame. I found ...
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Do Kepler's laws of planetary motion apply also to satellites of the Earth?

Do Kepler's laws of planetary motion apply also to satellites in orbit around the Earth? I would assume yes, but I'm not sure why...?
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Going from LEO to lunar using only low-thrust ion propulsion - can it be done?

@SF.'s question What are the parameters of the new Iodine electrical rocket engine developed by RSC Energia? links to the short RT article 'Ten times cheaper': Russian space company testing iodine ...
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How precisely do we know mass of the ISS?

Everyone knows that in space, every gram counts. Knowing how much mass an orbital object has is necessary for precise motion calculations. So how precisely do we know the mass of ISS? I'm sure we can ...
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Does the “17” really mean anything with respect to GNSS orbits being rational factions of a sidereal day?

This answer suggests that the orbital periods of the four large GNSSS contstellations are linked to the sidereal rotation period of the earth by rational numbers with 17 or 34 as the denominator in ...
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computing radial, along track, cross track components (differences) from two ECEF coordinates and velocities [closed]

I need to compute radial, along track, cross track components (differences) for two points in the orbital planes. I found the unit vectors of radial, along track, cross track but couldn't sure how ...
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thrusters, force torque, distribution matrix , orbit maneuver

I have a few questions about computing torques and forces. I use the same configuration as in the thesis titled An Attitude Control Sysytem Design Based on the Turksat-1b Geostationary Satellite. ...
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How to calculate the orbital distance between 2 satellites given the TLEs

I have 2 LEO satellites with the same orbital plane with same inclination & longitude of the ascending node. I have the TLEs for each satellite. How do I calculate the orbital distance between the ...
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How would a laser “shoot down” space junk?

This question links to an article describing a ground-based laser designed for shooting down orbiting space debris: "The scientists intend to use the massive soon-to-be-built telescope at the Altay ...
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I've almost learned to spell Chebyshev, why has JPL switched to Hermite interpolation for DE438?

According to @ChrisR's thorough answer One caveat however is that the interpolation in DE438 is a Hermite interpolation, and no longer a Chebychev interpolation, so you may need to update your code....
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What are the problems that need to be taken in consideration when trying to find planetary position by using jpl ephemerides?

I'm currently trying to determine the position of the sun and the moon from jpl ephemeris DE200 which is referred to the dynamical equator and equinox of 2000 and uses tdb time. I am using the j2000 ...
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How to calculate the delta-v necessary for a suborbital “transfer” of ice from Mars' pole to equator?

I have a big chunk of water ice that needs to go from (say) one of Mars's poles to its equator. Neglecting the atmosphere, how would you calculate the delta-v necessary for this trajectory, and what ...
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What is the angle between two orbits in the equatorial plane?

My orbit is in the equatorial plane. When i apply thrust in the y or x axis, it rotates around the focus or planet - see red and blue orbit in the image below. I know the the semi-major-axis and ...
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Apollo 11 mission report shows velocity well below escape velocity thousands of km on the way to the Moon

This is from the Apollo 11 mission report. It says the vehicle was going at 7.6 km/s when the CSM separated from the third stage. It was not in orbit at this point, it was thousands of KM from earth. ...
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Detecting propulsive maneuvers in a table of state vectors

The question Unravelling Cassini's “ball of yarn” orbit around Saturn, tabulation of propulsive maneuvers? asks for a source for documentation of orbital maneuvers of the Cassini spacecraft. Suppose ...
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How can I calculate the $\Delta V$

I'm learning about Astrodynamics, and I would like to ask how can I calculate the $\Delta V$ for an interplanetary mission. I used a website for the porkchop plots (http://sdg.aero.upm.es/index.php/...
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How many kinds of closed or periodic orbits are there in the circular restricted three-body problem?

Question: How many kinds of closed or periodic orbits are there in the circular restricted three-body problem? Has anyone made an attempt to enumerate and classify/categorize them? Notes: If there is ...