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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7
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2answers
928 views

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" because ...
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2answers
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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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0answers
187 views

How do astronauts get to the ISS?

It's about orbital mechanics. I've been looking for a school assignment at how did SpaceX Crew-2 get to the ISS and how do astronauts nowadays get to the ISS. I have been introduced to the Hohmann ...
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6answers
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Can a satellite work like a radiometer?

Like a Crookes Radiometer, could a satellite have a stiff vain to maneuver? With a white side to let light pass and the black side capture light radiation be enough provide radiation pressure to keep ...
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1answer
161 views

Does Lightsail-2 take significant advantage of the Oberth effect?

The cubesat Lightsail-2 has been deployed and has communicated with ground stations. See The Planetary Society's LightSail 2 Healthy as Mission Team Continues Spacecraft Checkouts In the near future,...
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1answer
203 views

How do I calculate the characteristic energy for a rocket to near rectilinear halo orbit where the Deep Space Gateway is going to orbit the Moon?

How do I calculate the characteristic energy for a rocket to near rectilinear halo orbit (NRHO) where the LOP-G or the Deep Space Gateway is going to be orbiting the Moon? Or if someone already has a ...
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3answers
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How to calculate Orbital Inclination knowing the launch azimuth and launch latitude?

A new spaceport is proposed for Camden County, Georgia (USA). The latitude is 30.56N and the only available launch azimuth is 123 degrees. What is the resulting LEO without mid-course maneuvers? Can ...
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1answer
604 views

Does the “17” really mean anything with respect to GNSS orbits being rational factions of a sidereal day?

This answer to Why are orbital periods different for different GNSS positioning system constellations? suggests that the orbital periods of the four large GNSSS constellations are linked to the ...
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1answer
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Is the Gateway's halo orbit bound to Earth? Would the Gateway remain in Earth orbit of the Moon disappeared?

Discussion below this answer involves my feeling that calling halo orbits in very asymmetric systems (e.g. Sun-Earth or Earth-Moon) as orbits around the primary, in 1:1 resonance with the secondary. ...
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1answer
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Station-keeping delta-v per year for an Earth-Moon vanilla halo orbit?

This answer reminds us that an Earth-Moon L1 or L2 vanilla1 halo orbit remaining always visible to some patch on the Moon's surface requires station-keeping. Queqiao uses such an orbit having ...
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2answers
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Transform ECI to ECEF

I need to transform ECI to ECEF coordinate. Here, I need the formula in math and algorithm. I have looking for the formula in the internet, but I can find one. I have x, y, z cartesian coord in ECI. ...
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2answers
456 views

How accurate can a satellite's orbit be?

How precise can an artificial satellite be when it comes to following the exact orbit in relation to Earth or hitting the same point above Earth in orbit? Which orbit would be the most stable for this?...
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1answer
81 views

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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1answer
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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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1answer
2k views

Online Porkchop Plotter

Is there an online tool available to calculate porkchop plots at arbitrary resolutions? Real world only please -- I am aware of the tools available to do this for, say, KSP.
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4answers
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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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1answer
78 views

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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1answer
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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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3answers
171 views

Inclination maneuvers for GEO satellites

I was wondering about the orbital location to perform inclination nulling maneuvers for GEO satellites. I know from basic astrodynamics that the best place to perform inclination correction is at ...
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3answers
172 views

Is there a formula for converting a rocket's performance for one orbit to another? E.g. SSO performance to GSO?

If a rocket can take 1,000 kg to SSO at 500 km, is that enough information to determine what its capacity to, say, GTO or GSO would be? If so, how would one calculate it?
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1answer
73 views

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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4answers
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Was the Apollo spacecraft always gravitationally bound to the Earth-Moon system?

When the Apollo spacecraft was en route to the Moon, was it an escape trajectory from the Earth-Moon system? If not for the burn(s) to enter lunar orbit, would it have continued in an independent ...
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1answer
73 views

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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4answers
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What uses would the Aldrin-Cycler have?

An Aldrin-Cycler is a vessel on an orbit on which it passes both Earth and Mars every few years without expending much fuel. At first glance this seems like a great thing for a permanent ...
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0answers
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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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1answer
144 views

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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1answer
182 views

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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0answers
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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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2answers
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Given an arrival date, is there a way to calculate the declination and right ascension of the arrival asymptote into Mars?

I am designing an Earth-Mars transfer. The launch window is 03-Jul-2026 (departure from Earth) & 22-Jun-2028 (Mars arrival). The declination and right ascension for the departure asymptote from ...
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0answers
27 views

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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0answers
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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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1answer
153 views

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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0answers
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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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1answer
85 views

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 ...
2
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1answer
104 views

Does a spaceship traveling to Mars from Earth via orbital skyhook still have to wait for a transfer window? [closed]

In order for it to make the three months travel time does it still have to wait for a transfer window or can it go at any time of the year?
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0answers
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Alfonso Gonzalezs Orbital mechanics simulation

I basically copied all the code on Orbital Mechanics Series of Alfonso Gonzalez (because I really don't have any experience with coding, but would like to in the future) on Youtube (for a school ...
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2answers
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Tiangong-1 reentry impact place probabilities

Following all the news concerning Tiangong-1, I have seen the following plot made by the Aerospace Corporation where Blue area: null probability of impact Yellow area: high probability of impact ...
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2answers
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Does it even make sense to talk about Mercury's triangular libration points (L4, L5)?

The recent question How much radiation shielding would be required for a habitat at Mercury–Sun L5? got me thinking. There are a large number of disadvantages and challenges to building or putting a ...
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2answers
270 views

First interplanetary launch from California! How far from Earth will InSight be when it separates from the Centaur 2nd stage?

The Phys.org article Bound for Mars—countdown to first interplanetary launch from California says: In the early morning hours of May 5, millions of Californians will have an opportunity to witness a ...
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3answers
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energy needed to accelerate in space

I was thinking about possibility of cargo transport between, say, earth and mars when a “pusher” accelerates propulsion-less cargo vessel, which is catched and decelerated at the other end of ...
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7answers
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Can you tack against the sun using a solar sail?

Solar sails are a great, inexpensive way to move out from the sun, if you’re not in a hurry. Ocean going ships are able to tack against the wind, and to move up wind. Could a solar sail gain inbound (...
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1answer
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How to model payload deployment in General Mission Analysis Tool

I just started reading the manuals and doing the tutorials for GMAT. I'd like to use it to model deploying multiple satellites from a launch vehicle and see their resulting orbits. Searching the ...
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5answers
12k views

Why does the ISS track appear to be sinusoidal?

Okay, time for a stupid question, but it keeps me up at night trying to figure it out. The ISS 'route' appears on paper as such: I am imagining it has to do with a combination of its orbit and the ...
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3answers
1k views

Is there an intuitive reason for why the shape of the orbit at perigee is the mirror image of that at the apogee?

Is there an intuitive reason for why the shape of the orbit at perigee is the mirror image of that at the apogee? It seems strange to me, because the situation is so different at the perigee compared ...
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1answer
78 views

What is the acceleration in an orbit decaying due to air resistance relative to one not decaying?

This answer to Is there an upper limit for the internal size of space stations? has this paragraph: Finally, if you are stuck ["stranded" in the middle of a room in a space station filled ...
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2answers
2k views

Can a satellite orbit the ISS?

Is stable orbit of a small satellite around the ISS theoretically possible with minimal station keeping?
4
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1answer
66 views

Difference between rotated frame and rotating frame

Suppose we have a spacecraft orbiting around Earth and we neglect all effects of Earth's $z$-axis motion, i.e., no wobble, precession, or nutation. For simplicity, we only assume a rotation rate $\...
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0answers
73 views

How many burns does it take to reboost the ISS?

When the International Space Station is given a reboost, how many burns are performed? Is it a Hohmann transfer orbit, with one perigee burn and one apogee burn? Or is it one burn at apogee just to ...
3
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1answer
70 views

Launch Elements

I already know about the six Keplerian Elements that are fundamental to a planet's orbit around the Sun, and for a few weeks now, I thought I'd got it down. Then, I wanted to have some fun, and test ...
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0answers
38 views

Translate/shift ECEF coordinates given certain distance

I have some orbits in ECEF coordinates overlapped at the origin, and I would like to "move" some of them given a certain distance from the original orbit similar to the following picture: ...

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