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Questions tagged [orbit]

Questions regarding the mechanics or attributes of objects falling 'around' other objects, thereby orbiting them.

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ECI to LVLH transformation

I am working on a transformation of ECI coordinates to LVLH (Local Vertical Local Horizontal) coordinates in order to calculate satellite maneuvers. Does anybody know how should I approach the problem?...
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2answers
950 views

Have any humans orbited the Earth in anything other than a prograde orbit?

As per the title, have any humans been launched into an orbit around the Earth which is anything other than prograde? E.g. retrograde or polar.
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3answers
4k views

Why use a retrograde orbit?

I've been looking around and saw on What is the highest inclination orbit ever attained from a Cape Canaveral launch? a question about launching into retrograde orbit. Of course, due to range safety ...
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1answer
61 views

Trouble deriving rectangular components of acceleration of satellite in orbit around Earth with J2 consideration

I am trying to derive the rectangular components of acceleration for a satellite in orbit, with Earth oblateness in consideration, in order to use the RK4 method to find the updated position and ...
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3answers
225 views

How much of a rocket's energy is used to achieve altitude vs horizontal velocity?

Given how it is significantly easier to achieve suborbital spaceflight, I was wondering about how a rocket spends its energy budget. If you magically could launch a rocket from 0 km/s but from an ...
3
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1answer
131 views

Have there been any spacecraft with an ecliptic Earth orbit?

Have any spacecraft (manned or unmanned) orbited the Earth in the same plane as the Sun? (Please read the question carefully. It is not an orbit centered around the Sun, nor an equatorial orbit.)
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1answer
828 views

How to calculate density of unknown planet?

Having approached an unknown planet, a spaceship went in a low circular orbit. Would astronauts be able to determine the average density of the planets using only a watch
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1answer
67 views

Argument of Perigee for a circular orbit

For a perfectly circular orbit (e=0), how is the argument of perigee defined?? Thanks.
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2answers
66 views

Where can I find examples of orbital state vectors?

I'm currently trying to write a program that can calculate orbital trajectories. The goal is to take any orbital state vector (position, velocity) and convert it into Keplerian orbital elements, or ...
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1answer
90 views

How would 2 spacecraft be launched to be in sync in opposite directions?

How would 1 spacecraft be launched to have a prograde orbit and the another be launched retrograde to have a mirrored orbital path around the sun or otherwise? Would the 2 spacecraft launch together ...
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0answers
57 views

What is the physics behind a rocket landing on a celestial body with an atmosphere?

I would like to know the different physics concept I would need to land a rocket being in orbit. I know the timing is important to leave it, how can one find this out ? Then how to compute the ...
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1answer
76 views

Is it possible to establish a synchronous lunar orbit without using Lagrange points? [closed]

I find this interesting, and so far haven't found anything in an internet search.
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0answers
63 views

Calculate Date of Spring Equinox, possibly using JPL's Horizons website?

I'm familiar with orbit ephemerides and the ways to use those to plot orbits and positions. However, in all the charts I find, I can't seem to find a way to determine when an equinox on another planet ...
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1answer
119 views

Astrophysics on “The Martian”

In the movie the martian what was the purpose of the hermes crew in blasting a part of the ship? Was that explosion on the front or back of the ship? After the explosion what happened to the speed ...
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90 views

Suggestion for software which allows orbit data generation under different conditions (such as J2, ATM drag etc)

I am an amateur astrophysics enthusiast trying to generate orbit data. What I want to achieve: I want to be able to generate orbits while only considering effects of (J2, J3, atm drag, solar ...
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1answer
68 views

How to calculate angle in elliptic orbit?

I would like calculate angle in elliptic orbit ZCP at any time, where: Z (position of periapsis), C (center of ellipse), P (current position of planet). I find topic, where is picture (in accepted ...
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0answers
117 views

Speed needed for the ship to escape Mars, on The Martian movie

Based on the two speeds and altitudes that are presented in the movie: "The Martian" which are respectively 741 m / s and 1350m, 850 m / s and 1843 m I would like to prove with calculations whether or ...
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28 views

Orbit class or library or functions [closed]

I am (like a hundred other people, like a thousand other people) trying to make a space flight simulator. I'm not a student. (That said, I found Orbit – space flight sim. It’s excellent.* You ...
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3answers
163 views

Are sun-synchronous orbits always North to South?

So someone told me that weather satellites orbit from north to south generally because that helps them to obtain a sun-synchronous orbit (his explanation for why this was true was too complicated for ...
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1answer
172 views

Are we changing Earth's rotation?

Can rockets launching change Earth's rotation, and can going into orbit do the same?
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1answer
67 views

Ellipse area section from foci

I am wondering how to calculate the area between the 2 red dots towards the bottom and in turn calculate the time elapsed between the right red dot and the green dot at apogee. I figure if I can find ...
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1answer
77 views

True Anomaly of Circular Orbit

How would you calculate the true anomaly of a circular orbit (e=0)? I'm trying to design an orbit for a mission on STK and so I'm not sure what the eccentric anomaly (in order to calculate true ...
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0answers
52 views

Compute heliocentric ecliptic coordinates from Kepler's laws

I'm writing a program to compute the heliocentric ecliptic position of planets and asteroids. I want to output rectangular coordinates oriented according to the ecliptic: positive X in the direction ...
2
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1answer
78 views

Moon Polar Days And Night

Moon's rotation axis from the orbit plane of earth is about 1.54° tilted. Just like earth because of tilt, do polar regions experience 6 months day and 6 months night? If so, aren't these places ...
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1answer
81 views

How does lightsail 2 plan to raise its apogee

Lightsail 2 is supposed to be a demonstration flight for solar sail technology. They plan to demonstrate that they can raise the apogee of their satellite using only light pressure on their sail. But ...
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1answer
140 views

Is it possible to capture geostationary satellites with DSLR?

DSLR is to be mounted on a tripod and pointed at sky with a zoom lens. Would a sufficiently long duration of exposure reveal these non-moving satellites as bright "stars" amongst the streaks caused ...
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0answers
42 views

How to get true anomaly using subsatellite point (latitude)?

I am working on an application which is using an orbit propagator. I have a satellite which sets its latitude using this orbit propagator. I want to change the latitude of the satellite by a new value,...
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1answer
90 views

Distribution of satellites by inclination

What is the distribution of Earth orbiting satellites by inclination? In other words, what inclinations are more or less popular? I work with Earth observation myself, where many satellites are Sun-...
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0answers
83 views

Computing the local orbital frame vector directions and angles of gyroscope direction in the satellite

In the context of the study of a cubesat (little satellite), I am asked to define the local orbital frame and compute the local orbital frame vector directions as a function of time (...
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2answers
140 views

How to get experiments to space?

How would a person get an experiment done in space? What is the chain of command on something like that? I would like to drop some inflated balloons from space to reenter the atmosphere to see which ...
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1answer
66 views

How low does OSIRIS REx's record-setting orbiting around Bennu go?

This OSIRISREx tweet says: It's official! I'm in orbit around #asteroid Bennu -- now the smallest body ever orbited by a spacecraft. My snug path around the asteroid also sets a new record for the ...
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1answer
164 views

What is typical lifetime of GTO rocket stages before reentry?

Most of geostationary satellites are launched at geostationary transfer orbit (GTO) first by rocket's upper stage. Than satellites separate and circularize the orbit by own propulsion. The upper ...
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2answers
3k views

How far have astronauts been in space?

I just listened to a podcast where it was said that astronauts have only been at most 400 miles from Earth (except for the moon of course in the '60s/'70s). Is this true? I know that the ISS orbits ...
5
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1answer
109 views

At what altitude do the effects of atmospheric drag completely disappear?

The spate of K-questions got me thinking: At what point does atmospheric drag disappear1 with the pressure from sunlight, solar wind, or other forces becoming overwhelmingly dominant? I'm guessing it'...
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1answer
209 views

Deviation of semi-major axis

If I calculate the semi-major axis of Molniya-1T with $a = \sqrt[3]{\dfrac{GM}{n^2}}$ with $n=3.18683728\text{ }d^{-1}$, I get another apoapsis ($a=19505.7$ km) as noted at Heavens Above: apogee ...
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1answer
77 views

Which orbit around Earth has the least perturbation?

Which orbit around Earth would have the least amount of perturbation from the moon, Sun etc.? Does an orbit exist where in either direction of travel that the perturbation would be the same? The ...
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4answers
460 views

What could a High Earth Orbit be used for in practice?

I was perusing wikipedia and saw this awesome infographic: Original location of infograhpic: Wikipedia Then it hit me, in all the time I've been browsing space articles and such... I've never ...
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2answers
73 views

How close will the cubesats be when numerous of them are launched simultaneously?

Checking the onboard video of PSLV C43 gives a feel like the CubeSats are released in very proximity. Does this mean that these CubeSats will be orbiting in such very close proximity through out ...
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2answers
196 views

What are the advantages of a Molniya orbit over a tundra orbit?

As I understand them, Molniya orbits and tundra orbits are very similar: they are both intended to provide satellite coverage over large latitudes and provide a large apogee dwell time over the large ...
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1answer
136 views

What is the darkest orbit around Earth?

What orbits around Earth has the least and most sun light exposure? I wondered: When taking pictures either of Earth or otherwise with various telescopes in orbit, does it help to be in Earth's ...
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5answers
670 views

Is it possible to navigate space travel with no computer?

From launch to land could a person travel in space with only mechanical devices like a sextant? With enough experience what would be the minimum devices needed? Which vehicle currently would be easier ...
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1answer
112 views

What orbits are popular?

So the two I can think of are the ISS orbit and GEO. Are there any other orbits that consistently have 10+ launches a year? For this question, when I say matching orbit, I mean eccentricity, ...
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1answer
177 views

Why was Dawn placed into an orbit that would only be stable for “decades”

Last year NASA put Dawn into an orbit around Ceres that Ars Technica said "would remain stable for decades" so as to not contaminate Ceres. Decades are pretty small on the cosmic scale though. Why ...
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2answers
2k views

Question on giant satellite orbit

So here's a strange question that came up in a class tonight. It is axiomatic that satellites in the same orbit travel at the same speed. But is there some size of satellite whose mass is so great ...
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0answers
38 views

What would astronauts see if they were in an Earth Moon L1 Lissajous orbit?

Would they be moving fast enough that the change of their position relative to the Earth and the Moon would be perceptible? Or would that change be too slow to notice moment by moment? I take it as ...
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0answers
58 views

What forces and motion would astronauts experience in a spacecraft in Earth-Moon L1 & L2 Lissajous orbit?

What is the maximum velocity they would experience? Would they be aware of the movement based on the positions of the Earth, Moon, or stars, or would it be too slow to notice? Would they feel any G ...
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1answer
275 views

What did Karman's original “Karman line” calculations look like?

Looking for the atmospheric parameters (density for example) and vehicle parameters (CL for example) as well as formulae that were used in the original calculation. Primary sources strongly preferred,...
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2answers
799 views

How would the International Space Station be maintained unmanned?

Russia's lunch to the ISS failed and the crew may have to leave it unmanned. How would the ISS run without a crew? Could some one else take it over or squat in it? https://www.npr.org/2018/10/11/...
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1answer
295 views

Why are 22N and 440N liquid engines quite common?

One can often spot that liquid apogee engines are 440 N and attitude control systems are 22 N. Is there a reason why the thrusts are proportional? If the engines are scaled for reducing development ...
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1answer
420 views

How can I calculate the orbital elements from two position vectors and a time difference?

I have two position vectors for my satellite, and I know that the satellite reaches these two positions 15 minutes apart. I know I can find the inclination using linear algebra and my position ...