Questions tagged [orbit]

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

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3
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1answer
91 views

Why does the eccentricity vector equation always equal -1?

This is the eccentricity vector equation, $$e=\frac{1}{\mu}[(v^2-{\mu \over r})r-(r \cdot v)v]$$ $$e=|e|$$ Now this equation is written differently from many different sources but they essentially ...
2
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0answers
96 views

Orbiting clock visible with the naked eye

Does anyone remember from the 1980s or possibly early '90s in the UK news a (serious) story about contructing a huge orbiting clock so that people would be able to look up at the sky to read the time ...
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0answers
26 views

Tools for testing look angle generator?

I'm looking for a software test tool with a specific capability: Given the lat/long/altitude of a point on the ground and the az/el/range from that spot to a point in space, generate a TLE for a ...
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0answers
53 views

Poincaré map of orbital trajectories

A Poincaré map, by definition, is supposed to be a reduction of a phase diagram on a codimensional plane cutting normal to the original trajectory. In this form, one should plot points from the phase ...
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5answers
3k views

How could a satellite follow earth around the sun while staying outside of earth's orbit?

I'm wondering if its possible for a satellite to follow earth around the sun while staying outside of its orbit. I wondering for the sake of space based solar infrastructure or just something ...
3
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2answers
204 views

Why was the Energia’s payload capacity to lunar orbit greater than its payload capacity to geosynchronous orbit?

The Energia rocket, developed in the 1970s and 1980s to launch the Soviet Buran space shuttle, had the second-highest payload capacity (100 tonnes to LEO) of any rocket ever flown (and the highest-...
3
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1answer
116 views

Tiny orbital body detection

What technology would be required to detect a coconut-sized sphere in Earth orbit, at the average altitude of communications satellites?
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0answers
22 views

Special Case Constellation Analysis Approach: Walker Constellation with Circular (e = 0) orbit in LEO

I am familiar with the general approach to propagate orbits using orbital parameters, and how to account for basic J2 perturbations. I am looking to perform some analysis on large walker ...
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1answer
48 views

PIR application as a sun sensor

Is there any history or merit to using a PIR (Pyroelectric ("Passive") InfraRed Sensor) as a sun sensor for determining the attitude or position of a Satellite?
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0answers
100 views

Recalculate Orbital Elements after a ΔV

I would like to write a program able to simulate a keplerian orbite given an initial position and velocity (r0, v0) and able to manage accelerations in different directions. To simulate the orbit, I ...
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2answers
127 views

How many stages needed for a launch ? How to plan a launch

I am looking on how to find out how many stages are needed to reach a certain orbit. I come across equations to compute the height reach by a stage of a certain time. On the other hand I don't find ...
5
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1answer
724 views

How precise must a satellite's orbit be?

I was thinking about the question on solid upper-stages and my feeling that a liquid upper-stage would allow a more precise orbit. But... how precise does an orbit actually have to be? I guess I mean ...
5
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1answer
96 views

Reference to understand the notation of orbital charts

To address various orbital evolutions of spacecrafts, some particular orbital charts are taken into account. For example, the following is used to depict how a chaser reaches a target: The only thing ...
4
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1answer
76 views

How would off-apsis burn effect the angle and position of new apoapsis

Let's say you have an elliptical orbit, if you burn prograde at the periapsis, you extend the apoapsis by some factor(according to vis-viva equation). But if you burn prograde on somewhere during the ...
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1answer
104 views

On the dynamics of two connected objects located at different circular orbits

I'm just thinking about the qualitative and quantitative implications of a hypothetical orbital problem, but what I ended up does not make sense as it should. In particular, assume that two objects ...
28
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6answers
9k views

Do simulator games use a realistic trajectory to get into orbit?

In videogames (such as KSP or Spaceflight simulator) people put rockets in orbit with the following procedure: Turn on the engines and move vertically for a bit. Start a roll program to turn the ...
3
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4answers
169 views

Could we build a sunlight regulator to orbit the sun and help with global warming? [duplicate]

like less sunlight around the poles would be good. if we put it in orbit close to the sun we may not need it to be that large. we can keep it in good position with RF cavity thrusters and mini ...
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0answers
20 views

Where will BioSentinel be relative to Earth while running experiments?

The Space.com article In 2020, NASA Will Send Living Things to Deep Space for First Time Since Apollo describes (among other things) the BioSentinel spacecraft, and links to a NASA BioSentinel fact ...
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52 views

ECI to LVLH transformation [duplicate]

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
1k 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 ...
4
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1answer
64 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 ...
6
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3answers
259 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
137 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
831 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
2
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1answer
118 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
104 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 ...
2
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1answer
95 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
65 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 ...
2
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1answer
77 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
64 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
135 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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0answers
97 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 ...
3
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1answer
74 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
122 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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0answers
30 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 ...
6
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3answers
212 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 ...
4
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1answer
179 views

Are we changing Earth's rotation?

Can rockets launching change Earth's rotation, and can going into orbit do the same?
3
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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 ...
2
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1answer
105 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 ...
2
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0answers
66 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
92 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 ...
1
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1answer
108 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 ...
2
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1answer
159 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
50 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,...
4
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1answer
109 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
99 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
144 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 ...
1
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1answer
70 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 ...
5
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1answer
185 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 ...