Questions tagged [artificial-satellite]

Questions about objects in orbit which are human made, such as communications and GPS satellites, orbital observatories and space stations, and other man-made object in permanent or semi-permanent orbits around the Earth, other celestial objects, aside from the Sun, or even other satellites. Not to be confused with non-orbited man-made objects in space, that are usually referred to as "probes", or simply "spacecraft".

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Starlink CONSTELLATION cycle time? Not the orbit time for a specific sat but the time to be over the same spot twice

STARLINK constellation, how many hours for the constellation to cycle? IOWs if a sat is overhead this instant how long till that same sat is over this same spot. The time for the constellation to ...
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6 votes
1 answer
100 views

What size are the typical keep-inside boxes of geostationary telco satellites?

Geo sats need station-keeping and the size of their keep-inside box is a design parameter. A smaller box implies more manoeuvres to stay inside the box. All depending on the various orbit ...
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1 vote
1 answer
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Is it possible to determine the classical orbital elements for an Elliptic Repeating SSO?

As in the title, it is possible to have a repeatable Sun-synchronous orbit but with an elliptic eccentricity? If yes, which equations I have to consider to determine its classical orbital elements?
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Feasibility of Brilliant Pebbles Missile Defense [closed]

The Smart Rocks, later Brilliant Pebbles, concept for ballistic missile defense proposed thousands of orbiting self-guided rockets to detect and intercept ICBMs. It was said to be impractical. But I ...
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2 votes
1 answer
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Plot ellipse using elements from TLE

I am trying to draw an ellipse as satellite orbit in three.js, It has an EllipseCurve class which takes these inputs and draws an ellipse around center. EllipseCurve( aX : Float, aY : Float, xRadius : ...
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4 votes
1 answer
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Where do I find ECEF coordinates of a satellite?

I am taking a university course named 'satellite navigation' as a part of my master degree in aerospace engineering. For the exam we are required to elaborate the coordinates of a LEO satellite (it ...
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1 vote
2 answers
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Determine Yaw, Pitch, Roll from two vectors

I need to find the roll, pitch an yaw rotation to point a satellite to a precise point on Earth. I know the satellite position and velocity in ECEF coordinates, the position of the site on Earth (also ...
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1 answer
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Sourced RSO catalogs and CDMs

I often go to space-track.org and download the latest space catalog on Resident Space Objects (RSO) and also like to look at the Conjunction Data Messages to check out the probabilities. what other ...
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8 votes
3 answers
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How often do active satellites have to change course to avoid other active satellites?

I'm only aware of the ESA and SpaceX incident in 2019. Does this happen more regularly especially now with more active Starlink satellites and other constellations? More importantly, are there efforts ...
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Satellite's EO sensor footprint on ground

I'm a student and I'm trying to compute the footprint of a generic EO sensor starting from sensor's characteristics and position and velocity vector of my satellite in ECEF coordinates. I followed ...
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2 answers
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Can a human base jump to earth from a satellite? [duplicate]

Only Felix Baumgartner managed to parachute from a helium balloon in the stratosphere is about as close as it gets. But is it technically possible to do so from an orbiting satellite? Advantages is ...
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How does one calculate the look angle for non-geo satellites (i.e. LEO, HEO, etc.)

I'm trying to find a way to calculate look angles to not just GEO satellites, but LEO, MEO, and HEO sats. The only calculator I've found myself is here, which was referenced for a similar problem on ...
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1 answer
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How many lives have space agencies saved? [closed]

Either the agencies themselves, lives saved by a satelitte launched by them, or how many people would have died if not for space services. How many lives have space agencies saved?
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How could Webb's lifetime be extended? [duplicate]

This article says why the lifetime of the Webb telescope is limited by the fuel it carries. Why NASA’s James Webb Space Telescope Will Never Live As Long As Hubble In short, Webb must stay near the ...
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1 vote
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Is there a python library to determine the position of a satellite at a given time from TLE data excluding the Satellite catalog number?

Or perhaps some simple code or formula that achieves this. I've used pyephem but it requires a Satellite catalog number.
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7 votes
5 answers
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What is the maximum distance between two satellites orbiting at 400 km that would still allow them to communicate with each other using radio waves?

All satellites have the same inclination. At an altitude of 400 km, the circumference of their orbit is $2\pi \cdot (6371+400) = 42\ 543$ km. If, for example, you have only 2 satellites separated by ...
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2 votes
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How does one generate a formula(s) for an artificial satellite's location at time t given a set of known locations at discrete times?

Given a set of spatio-temporal points in space {(Lat_1, Lon_1, Alt_1, Time_1), ... (Lat_n, Lon_n, Alt_n, Time_n)}, I need a function (i.e. a formula) that takes these points (or subset of points) as ...
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Where to find the network topology of Iridium-Next?

This is my first post on Space Exploration. I'll preface this by saying that I just started learning how satellite communications work from a technical perspective. Until a few days ago I had never ...
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6 votes
1 answer
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Satellites - predominant apparent motion?

Recently, while foolin’ around with Stellarium, and checking out its simulation capabilities, I recorded some satellite activity. Sped up ~30x, here are about 12 minutes of simulated sky on March 31, ...
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Are the TLE of a satellite computed with the ECI or ECEF?

I want to compute the distance of a certain satellite, given the TLE, to a ground station in the earth. I have the latitude, longitude and altitude of the ground station. But I don't know if the TLEs ...
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how I can find the radius vector and the velocity vector satellite in elliptic orbits? [closed]

In order to evaluate the following expression at each point in an elliptical orbit, I first need the state vector $\mathbf{r}, \mathbf{v}$. $$ \omega_j=\frac{1}{r^2||\textbf{v} \times \textbf{r}||} \ \...
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5 votes
2 answers
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How can I find the true anomaly of satellites in elliptic orbits?

I want to find the true anomaly of satellites in elliptic orbits. How can I do that with following information about elliptic orbit: Altitude, km 543.8832 Period, sec 6114 Eccentricity 0.0727 Semi-...
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2 votes
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What is the difference between SBAS and PPP used in GNSS accuracy corrections?

I've found that Satellite Based Augmentation System uses reference stations to compute a model for correction and send them via a master station to a geosynchronous satellite, then to GPS receiver. I ...
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1 vote
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satellite ground track in skyfield

I'm trying to get the geographic location (longitude & latitude of a satellite) converted from the position in space for example: position = (7033.45648791, 178.93192295, 0.00290722) Km. longitude ...
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satellite orbit propagation from initial position and velocity [duplicate]

I'm trying to get the satellite orbit at a certain time given the initial position and velocity (SGP4) say I have a TLE file that is taken in epoch:(2022-01-05 11:25:15.578) and I need to get the ...
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2 answers
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what is the difference between inertial pointing and nadir pointing?

I want to know, what is the difference between inertial pointing and nadir pointing for a satellite?
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4 votes
1 answer
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Kinetic equations

The kinetic equation of rotational motion of a satellite using Newton’s law can be expressed as follows: $$ \frac{\partial H_b}{\partial t}+\omega_b\times H_b=T_d \qquad(1) $$ In the above relation ...
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How to calculate Azimuth/Elevation of a satellite?

I have a ground stations' lat/lon as well as a satellite's lat/long. I want to calculate the azimuth/elevation of the satellite relatively to the ground station. Currently, I am using these formulas (...
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17 votes
2 answers
3k views

Why is this Planet Labs video wobbly?

Planet Labs recently tweeted ( https://twitter.com/planet/status/1481790983155044352 ) a video showing a Falcon 9 first stage landed on a pad. Strangely, the image looks like it was taken by a camera ...
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9 votes
2 answers
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When and why did three-axis stabilization become prominent in geostationary satellites?

Since the very first Sycom 1, geostationary satellites from 1960s to 1980s are cylindrical with solar cells covering the body of the satellite. Such examples include: GOES 1 to 7 AsiaSat 1 and its ...
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5 votes
1 answer
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Is there any website where we can view live orbit of all satellites to scale?

As the question says, Is there any website or app which has a graphical view of all satellites which are currently in orbit with sizes to scale. An option to view in fast forward is appreciated.
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4 votes
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Which countries have military satellites in orbit?

Which countries have active military satellite(s) in orbit? And which countries had military satellite(s) in orbit but don't have them anymore (inactive or de-orbited)? Wikipedia says: As of December ...
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1 vote
1 answer
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Very slow blinking object — high orbit satellite or some balloon? Any idea?

Could anyone help me to explain? This evening I played with a Gen 3 night vision binocular. I spotted a very slow blinking light 5 hours after sunset. I made a 5 minute video, I but can't attach that ...
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2 votes
0 answers
55 views

General range of maximum RPMs used in reaction wheels in spacecraft?

I was wondering what would be the general range of RPMs used in Reaction Wheels (RW) on a satellite, and I have several closely related questions on this topic: It would definitely depend on the max ...
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7 votes
1 answer
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What is different between Hill frame and LVLH frame in satellite?

What is different between Hill frame and local-vertical, local-horizontal (LVLH) frame in satellite? I add one figure to show this two frame. reference of figure: Weiss, Avishai, Uroš V. Kalabić, ...
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2 votes
1 answer
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Training ML models in space

It's not really space exploration unless space crews need to train new machine learning (ML) models for some new problems they face during their journey but I read this: https://www.technologyreview....
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0 votes
1 answer
194 views

Nuclear or Solar power for satellites?

For satellites do they use solar or nuclear for the main power source? I do know that they have both but I do not know which is primary. for an example: Galileo, does it use solar or nuclear?
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28 votes
3 answers
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Can Voyager 1 reach the Andromeda Galaxy?

Right now, as of 2021, Voyager 1 has left the Solar System. If it has reached such a great distance, is it possible for it to reach the Andromeda Galaxy? Also, will we be able to still be in contact ...
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2 votes
1 answer
85 views

Solid metal fuel for nano satellite thrusters

A South African company is developing a solid metal fuel thruster that was initially researched by NASA but was not further developed, an electric reaction could be used to vaporise solid metal fuel, ...
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4 votes
0 answers
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What are the specifications for electrical connectors that can be used for repeated mating in space?

We’re working on an interface between satellites that when docked has to transmit power and data. The interface needs to have a port for transmitting power and data. Majority of the connectors ...
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4 votes
1 answer
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How to read stuffin.space data?

In a comment to this question, @PcMan suggested my stuffin.space for satellite data. Now I am not quite sure of how to interpret the data, take for example the following screenshot: Why is the ...
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Arc length between two satellites [duplicate]

When considering two satellites in the same circular orbit, is it correct to say: The arc length between the satellites is...? Is there a more appropriate term when talking about the curved distance ...
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-5 votes
1 answer
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International space station(ISS) viewed from planet earth

Is it possible to view International space station (ISS) using sophisticated Telescopes from planet earth?
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7 votes
1 answer
610 views

List of circular satellite orbits for testing inverse square law of gravity

For a high school activity I am looking for a list of (maybe 10 or so) circular satellite orbit data including radius $r$ or diameter of the orbit and orbital period $T$. Then I want to calculate from ...
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5 votes
2 answers
683 views

Distance between two satellites

What is the appropriate term for arc length between satellites moving in the same circular orbit?
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3 votes
2 answers
218 views

Number of satellites needed for global 4-fold coverage as a function of altitude?

I want to estimate how many satellites (and how many number of planes) are needed for achieving a 4-fold global coverage on earth (global coverage with at least 4 satellites in view in each location). ...
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3 votes
0 answers
94 views

How to calculate the phase angle between satellite and sun with the use of skyfield

With the discussion that took place on answer(s) to How to calculate cone angle between two satellites given their look angles? I would like to ask if my proposal solving that question works like ...
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3 votes
2 answers
257 views

Why haven't we seen more origami in spacecraft?

I remember watching a few videos awhile back talking about origami designs in spacecraft: Origami in Space: BYU-designed solar arrays inspired by origami Engineering with Origami I've only done a ...
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5 votes
2 answers
870 views

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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2 votes
1 answer
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How to calculate the height above the horizon of a geostationary satellite on a given latitude?

Wikipedia's Geostationary orbit; Communications says: Geostationary communication satellites are useful because they are visible from a large area of the earth's surface, extending 81° away in both ...
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