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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Is there a way (working or in development) to track satellites in lunar orbit like we track objects in Earth Orbit?

I understand that Earth orbiting satellites are tracked using technologies such as radar, but due to the distance between the Earth and the Moon, they aren't really useful for Moon sats. Is the ...
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Why put SunRISE in the graveyard? Why will it "fly slightly above geosynchronous orbit"?

The blots.nasa.gov article NASA’s SunRISE Mission Studying Solar Particle Storms Moves Toward Launch says that the upcoming SunRISE mission — short for the Sun Radio Interferometer Space Experiment — ...
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What factors would contribute to a spacecraft's ability to maintain a very low orbit (VLEO) or at least orbits with very low perigees?

I asked What does account for a high coffin corner of a plane? in Aviation SE. Now I wonder what factors would contribute to a spacecraft being able to maintain low circular orbits (e.g. within 200 km ...
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Design and optimization of a Sun-synchronous repeating ground track orbit constellation

I am currently researching about this topic and am very new to this. Have no clue how to go about designing a group of imaging satellites (constellation) that are sun synchronous with repeating ground ...
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Could a near earth asteroid perturb a satellite out of earth's orbit?

Given a satellite in GEO or a graveyard orbit, what characteristics of a passing NEO would be required to perturb said satellite out of Earth's influence and into a sun-bound or sun-centered highly ...
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GMAT Orbit Designer

I start to work with GMAT. I am looking into the API capabilites and I found several functions e.g. for the calculation of SSO Orbit Parameters, or Repeating Ground Tracks. So apart from this, is ...
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Impact Venus with Comet Leonard?

do we have the means to slightly alter Comet Leonard's trajectory so it impacts Venus instead of 'grazing' it in December 2021??
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Is there a neat formula for hyperbolic Kentucky windage?

When doing some back of a napkin calculations for a recent question Where would the Pascal B manhole cover be now?, I realised a quick way of solving these class of orbital mechanics question is to ...
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Where would the Pascal B manhole cover be now?

As part of the Operation Plumbbob series of nuclear tests, on August 27th, 1957, at 22:35 UT (15.35 Pacific Daylight Time), at the Nevada Test Range at 32°N 116°W, a 300 ton-yield atomic device was ...
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After inserting CAPSTONE into a "highly efficient ballistic lunar transfer trajectory" Lunar Photon; to what separate orbit for its safe disposal how?

NASA Ames's feature CAPSTONE’s CubeSat Prepares for Lunar Flight says CAPSTONE will use a hydrazine-fueled propulsion system during most of its three- to four- month journey to the Moon. This line of ...
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1answer
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GMAT: Finite Burns commands in If statements inside For loops

Does anyone know why GMAT won't execute finite burns when the BeginFiniteBurn command is placed inside an If statement which is inside a For loop? I'm sure the If condition is verified because there ...
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What is the "mass" of a Lagrange point?

Of the five Lagrange points, L4 and L5, as stable points, can be orbited by asteroids, satellites, and any other useful or interesting object. Assuming two-body motion however, calculating orbits with ...
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How do orbits around Jacobi ellipsoids behave?

The Earth is a Maclaurin spheroid (aka. oblate). This affects orbits, most notably $J_2$ rotating the node line for inclined orbits, enabling thins like Sun-synchronous orbits. But the Maclourin ...
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Can mascons have Lagrange-like points? In principle? At the Moon?

Background Lagrange points are a mathematical consequence of the The Circular Restricted Three Body Problem (CR3BP or CRTBP); two massive bodies orbiting around their center of mass and a third ...
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How to calculate velocity vector in perifocal coordinates [closed]

Well the formula for it is here: Though if r is the radius and f is the true anomaly (which I assume is radians), then what is r dot and f dot respectively?
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Energy to "nudge" a planet to a smaller orbit

Suppose we wanted to move a mass-$m$ planet to a much smaller new orbit around our mass-$M$ Sun. We'll assume the initial and final orbits are circles of radii $r_i,\,r_f$ with $r_f\ll r_i$, so GPE is ...
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ISS Live Views of Earth on Nasa's EHDC Camera appear to be retrograde orbit

If the Orbit of the ISS is Prograde and Synchronized with the same orbit as the Earth, would not the Live EHDC views motion appear Stationary?
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Can an orbit rotate around a non-orthogonal axis?

I'll attempt to draw a mental example, in case images are not kind (if they are kind, you can likely skip this first paragraph). Let us say that the Earth is at it's aphelion (arbitrary choice), and ...
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How would you convert keplerian orbital elments into cartesain vectors with quaternions?

Coverting the keplerian elements to cartesain vectors ( posistion and velocity) is relatievly simple by using rotation matrices show in the document here: https://downloads.rene-schwarz.com/download/...
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Earth to Mars (or reverse) Hohmann transfer orbits for the 21st Century

Is anybody aware of a nice graphic showing for the next 20-30 years or maybe the rest of the 21st century, the time periods for Earth to Mars launches? They occur about every two years, but I'm ...
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Flyby puzzler; starting from Earth, how many times can you use Jupiter flybys in one century?

Is there any limit to how many times you can increase velocity by repeated sling shot manoeuvres? and its answers have got me thinking, and that's always dangerous. Suppose you have a durable RTG-...
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Calculating the time of flight between two anomalies gives a negative result?

I want to calculate the time of flight (TOF) between two true anomalies on an orbit with known orbital elements. Based on this wikipedia article and the post Time of flight between two anomalies in a ...
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Does going to Mars take the same energy as making a rendezvous with something going to Mars?

I think I found a mathematical error in the 2015 movie The Martian1. Warning, there will be spoilers. The final plan they settle on to rescue Mark Watney is to have the Tiayang Shen rendezvous with ...
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what range of orbital inclinations will be needed to reach Mars from the Boca Chica launch site?

When SpaceX fly missions out of Boca Chica in South Texas to Mars what orbital inclination will the launch need to be to put the spacecraft on to best transfer orbit to Mars? And will this vary with ...
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How to calculate the velocity vector in the case of a hyperbolic orbit?

The problem I'm trying to get a formula to calculate the state vectors $\vec{r}$ and $\vec{v} = \dot{\vec{r}}$ on an orbit, given a true anomaly $\nu$. I'm following the process described here : https:...
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How to calculate the time to reach a given true anomaly? [closed]

I'm looking for a general formula or procedure calculate time to reach any given true anomaly.
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Are the initial conditions for the Apollo PFS objects' orbits known (or knowable) as well as they were for the ascent module?

This answer to Would we have spotted the ascent stage of Apollo 11's Eagle if it was still in orbit around the Moon? and discussion under it suggests that as a check of the orbital propagation ...
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How to generate TLEs based on a set of observation points (location, azimuth, elevation... no range)

I'm interested in generating a "corrected TLE1" based on observation data. I would have observed azimuth and elevation, site location, and time. All of those data fields are observed with ...
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1answer
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Finding the new true anomaly after performing a maneuver

Given a standard set of orbital elements (angular momentum, semi-major axis, eccentricity, inclination, longitude of the ascending node, argument of periapsis, and true anomaly), and a global time ...
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What is the shape of the envelope of all orbits with velocity of equal magnitude at their intersection?

Also known as: where can I go with my delta-v budget? For parabolic trajectories in uniform gravity, the answer is a parabola. Thats why I'm surprised that the same envelope for elliptical orbits ...
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Why does higher solar phase angle (SPA) allow for many more feasible FastKD (kinetic deflection) communications satellite “hijacking” missions?

Space.com's advert-laden Repurposed communications satellites could help save humanity from an asteroid impact ends with: The study results were presented at the Planetary Defence (sic) Conference ...
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References for constant low-thrust spiral up-coast-spiral down phasing maneuvers for circular and non-circular orbits?

I am trying to find papers that describe constant low-thrust spiral up-coast-spiral down phasing maneuvers for circular and non-circular orbits. The thrust is assumed to be fixed at $T_{const}$ when ...
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What are the energy requirements to reach Earth orbit and Mars orbit assuming no efficiency losses?

Suppose some magic propulsion method exists which directly converts electricity into kinetic energy. And its efficiency is 100%. And its weight is 0. What is a way to calculate the energy requirements ...
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1answer
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Puzzler; what can we learn about the distance and direction of Earth from this cool SpaceX-tweeted image of Earth and a vacuum nozzle?

The 18-June-2021 Spacex-tweeted below says: View from Falcon 9's second stage Merlin Vacuum engine There is information out there about the approximate exit diameter and length of the nozzle and ...
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What asteroids have the least delta-v to reach?

I think the question needs very little clarification - specific asteroids and/or their asteroid orbit type would answer it. My own interest is in what would best suit targeting for asteroid mining on ...
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1answer
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Rotation matrix / coordinate transformation of maneuver parameters from Prograde, Normal, Radial to Cartesian XYZ?

Say I have a state vector and Keplerian elements of an orbiting spacecraft: Position = [x, y, z] Velocity = [vx, vy, vz] Elements = [a, e, i, $\omega$, $\Omega$, $\nu$] And I have the maneuver I ...
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Is it possible for the exhaust plume of a rocket engine burning retrograde to accelerate an object into an even higher orbit?

A couple weeks back, a debris object was catalogued in a 210x540km orbit following the deorbit burn of the Falcon 9 second stage that launched CRS-22: Hmm... possible that CRS-22's stage 2 made ...
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1answer
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Do geodesics close on an ellipsoid?

I want to calculate the shortest distance between two points (Point A and Point B) on the ellipsoid surface. For this I need to use geodetic passing through these two points. Well, if I continue this ...
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Would knocking the moon off it’s tidal lock with Earth affect its orbit?

Lots of discussion about terraforming the moon involves smacking it with a comet such that it rotates with a 24 hour ish period. But I don’t know if this will affect its orbit in any way. Is it ...
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What orbits are Starlink satellites now deployed into? How low to do they go on their first perigee?

In my answer to Delta-V of Starlink Satellites I ballpark spherical-cow envelope-back estimated 190 m/s with 2 kg of krypton based on raising only from a 445 km circular orbit to a 550 km circular ...
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Textbook or scholarly discussion of equations used by the SDP4 part of SGP4 TLE propagators beyond Space Track Report #1?

(the famous) Space Tract Report #3 discussed at length in Dr. T.S. Kelso's Revisiting Spacetrack Report #3, AIAA 2006-6753 Describes the "deep space" corrections to the original SGP4 known ...
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1answer
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In a 3D space defined by semimajor axis, eccentricity and inclination, what would be the shape of the space where SDP4 works better than SGP4?

@BillGray's answer to Why can't custom-made TLEs for the DSCOVR launch booster in orbit around Earth work with SDP4? is quite interesting and informative; I fail to do it justice by summarizing it as ...
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Is the formula for nodal period of a near-Earth satellite given by Wikipedia correct?

Wikipedia has a formula for the nodal period of a near-Earth satellite, taking into account the oblateness of the Earth (J2), and neglecting other effects (https://en.wikipedia.org/wiki/Nodal_period)....
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Time to reach interstellar space

From my understanding, both voyager 1 and voyager 2 used a gravity assisted slingshot method to leave the solar system. Question(s): Since the planetary alignment used won't happen again for a while, ...
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How to find a vector's elevation angle with respect to a point on Earth?

tl;dr: Spacecraft's antenna should point to a ground station but there is a pointing error. I want to express the error as a vector rather than a simple angle that a dot product provides, so that I ...
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Source of Satellite and Debris Ephemerides for Analysis

I'm working on some code that will fuse ephemeris data, the raw telescope and radar data used for locating and tracking active satellites and space debris. Most of this data is owned by the Air Force ...
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How can we mine Near Earth Objects?

After skimming this Worldbuilding SE answer, I wonder if any companies or space agencies have plans in place to mine Near Earth Objects(NEOs) in the future.
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Just how much "dumb luck" was reaching the space age during the "Grand Tour" opportunity? Would we have been SOL 1050 or 2100 years before/after?

@OscarLanzi's answer to Why is the gas giant grand tour interval 175 years when the synodic period of Uranus and Neptune is 171 years? is an excellent answer describing a subtle situation; each pair ...
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Calculating body frame X vector's look direction in GEO (NED) frame from roll, pitch and yaw data, is this correct?

I have roll, pitch and yaw angle values for a LEO satellite. Satellite orbit frame and spacecraft body frame are defined as LVLH. The satellite position and velocity are given in ECI/GEI frame. I have ...
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How can I calculate the future position of a satellite orbiting a central body as a function of time using known orbital elements?

Given the position and velocity vectors at one point in an orbit, one can calculate the keplerian elements and thus graph the subsequent orbital path as a circle/ellipse/parabola/hyperbola depending ...

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