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Questions tagged [low-earth-orbit]

Questions regarding Low Earth Orbit or LEO, which refers to orbits at an altitude between approximately 160 kilometers / 99 miles and 2,000 kilometers / 1,200 miles.

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History of multiple-payload launches?

Another question asks why Spirit and Opportunity weren't launched together. My gut response was that multiple-payload launches were less common then than they are today, but I don't actually know if ...
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How fast do optical surfaces get dirty or damaged in space?

These answers: (1, 2) to Do things get dirty in space? mention the Hubble Space Telescope but if I understand correctly refer to the outside of the telescope rather than its optical surfaces. Answers ...
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Calculating orbital parameters for given requirements

I'm trying to determine what's the best way to calculate the required orbit for a LEO remote sensing satellite. I understand there exists the trade-off between sensor coverage and sensor accuracy, but ...
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How could we transfer large amounts of energy sourced in space to Earth?

At the rate we are using energy, it is inevitable that we will need to source energy from outside of Earth, eg from space. I was wondering how one would transfer this energy from that energy collector ...
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What fractions of the time did Skylab spend in Earth-oriented versus Sun-oriented attitudes?

The Introduction section of NASA Technical Memo TM-X-64628 Angular momentum desaturation for Skylab using gravity gradient torques begins: The Skylab Apollo Telescope Mount (ATM) experiments ...
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What if GOCE rolled 90°?

Reading this question: Is GOCE a satellite or aircraft? I wondered what would happen if GOCE rolled 90° in either direction, so that it's solar panels become parallel to Earth's horizon, and then ...
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Temperature of a satellite orbiting in low Earth orbit

I am working on a project for science fair that involves a deployable component that will not be heated on a CubeSat. I am trying to find data for the skin temperature of a satellite (or the ISS) over ...
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660 views

Can the Right Ascension and Argument of Perigee of a spacecraft's orbit keep varying by themselves with time?

I came across the orbital data for a low Earth orbit spacecraft and one thing which I am not able to understand is why does its Right Ascension of ascending node and Argument of Perigee keep changing ...
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How was Skylab's orbit inclination chosen?

As referenced in this question, there were a number of early spaceflight missions at higher inclination than may be expected (given limited payload capability, higher inclination further limits ...
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829 views

Where did Heinlein say “Once you get to Earth orbit, you're halfway to anywhere in the Solar System”?

I know what it means. I've seen delta-V charts. But I don't know if Robert Heinlein wrote this down, or simply said it off-the-cuff to somebody. Variations include: "Reach low orbit, and your ...
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Would a Hohmann transfer within LEO be useful?

Hohmann transfer is often used between a lower LEO orbit and MEO, GTO, GEO or beyond. But if the target is a high altitude within LEO, how would a direct ascent compare to ascent to a lower orbit ...
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What is OneWeb's constellation's “progressive pitch” and how does it avoid interference with Ku-band satellites in GEO everywhere on Earth?

The Wikipedia article section OneWeb satellite constellation; Design characteristics tells us: The satellites will operate in the Ku band, communicating in the microwave range of frequencies in the ...
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How do orbital spacecraft calculate reentry?

For a given spacecraft, in a given LEO orbit, assuming you have all the required data, how do you choose the needed burnout speed and timing (or position in orbit), in order to reach a certain point ...
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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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Where was the space station this morning?

Did the space station fly over North Carolina this morning (January 22, 2019) about 6:30am I live in Roxbro NC 27574. I spotted an unusual object in the sky about 140-150 degrees, toward the South ...
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Could a spacecraft produce lift using sublimating material?

Following this question, could a spacecraft approaching upper atmosphere from very low circular Earth orbit, produce lift to soar propulsively, bleeding speed at constant apoapsis, by sublimating ...
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Does launching to interplanetary space from LEO require the least delta-v?

Based on this chart from wikipedia, (I do not know if I am reading it correctly) This all assumes LEO-Eq LEO to C3/0=3.22 LEO to GEO to C3/0=3.9+1.3=5.2 LEO to EML-1 to C3/0=3.77+0.14=3.91 LEO to ...
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How long could a spacecraft be attached to ISS?

I've recently noticed how the "Design life, when docked to Space Station" parameter, varies across some of the modern spacecraft that are capable of docking to ISS these days: H-II Transfer Vehicle - ...
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1answer
162 views

Where can I find the TLE of ExseedSat 1, India's first ever private LEO satellite?

On 3rd December 2018, a private Indian company Exseed Space launched it's first ever satellite into space called ExseedSat 1. But I couldn't find the TLE for this satellite. I looked it up on n2yo ...
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88 views

Atmospheric re-entry speed

What would be the difference in atmospheric re-entry speeds from LEO and GEO, assuming a Hohmman transfer orbit from GEO to re-entry? If I am getting the transfer orbit concept correct?
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1answer
442 views

Calculating the radial, in-track and cross-track distances

I'm computing the relative distances between satellites. The following picture shows the distances, which are considered as risky. What do Radial, In-track and Cross-track mean and why are they ...
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Cubesat mass density (kg/U) statistics?

The stuff of which COTS cubesats are made (aluminum, silicon, G10/FR-4, battery) has a density in the ballpark of 2 to 3 (g/cm^3) while vacuum is roughly 0. I'd always figured that cubesats built from ...
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Satellites that take advantage of, or require constant availability of sunlight on the spacecraft itself, available in Sun-synchronous orbits?

ditto: "Are there satellites that take advantage of, or require constant availability of sunlight on the spacecraft itself, available in Sun-synchronous orbits?" This question is an offshoot of this ...
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What are the causes of these episodes of faster than average altitude loss by the ISS?

@Cristiano's question No reboosts for the ISS shows the plot below. I don't have the original source. I've added some annotations including four arrows to indicate what looks like short periods (a day ...
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2answers
181 views

How much fuel to maintain VLEO for communication satelites?

A recent answer about communication satellites in VLEO (≤350 km) estimates a useful orbital life of about month without fuel. I.e. Once the vehicle is out of fuel to maintain orbit, THEN it has ...
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How low is VLEO? (FCC's newest approval for SpaceX)

Engaget's SpaceX gets FCC approval to deploy thousands more internet satellites says SpaceX's plan to build a global, high-speed wireless internet network using satellites has taken another step ...
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153 views

How is a satellite constellation launched?

If want 10 satellites chasing each other around the earth (evenly spaced) all one the same plane, these satellites would be evenly distributed around the globe after launch by slightly raise or lower ...
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Why are there no LEO satellites in the earth's equatorial plane?

From my elementary school understanding of Satellite orbits, I know that GEO satellites are placed in equatorial plane, MEO satellites are placed in an smaller degree inclined plane while LEO ...
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Was Roadster (Starman) seen in Earth orbit, before the long burn to deep space?

Discussion in comments below this answer tend to conclude that 1st stages come back to Earth and so (essentially) all those tumbling rocket body objects in Heavens Above are 2nd stages, though I ...
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Spacecraft-fixed coordinate system

I am working with data from a polar-orbiting satellite (inclination 97 degrees) with limited attitude information. I am trying to define a coordinate system which is fixed with respect to the ...
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How much is LEO worth?

I've seen valuations of the space industry at ~$350bn annually. How much of this is coming from LEO vs MEO/GEO?
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Did the Soviet Union put an unmanned satellite in “very low orbit”above the Kármán line which used aerodynamic attitude control?

This interesting, archived page https://www.webcitation.org/618QHms8h?url=http://www.fai.org/astronautics/100km.asp which I found in this answer, says: Later in the same decade (or very early in ...
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What is the speed of ISS relative to ground surface?

Is it 7660 m/s or (7660-460)m/s? If it is the former then the ISS orbits about the Earth at 8120 m/s. I think it should be (7660-460)m/s relative to ground based on this orbital period formula, $$T=...
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How to calculate azimuth and elevation angles from satellite point of view of a ground station?

How to find azimuth and elevation from satellite of a ground station when yaw, pitch, roll, lat, long position of satellite and lat, long position on ground are given? ...
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Parameters and restrictions of a Single-satellite and Single Ground Station system [closed]

I am designing a ground station system to retrieve data from a single satellite sending at a given bandwidth in LEO, and I am confused of which parameters I have to take into account when designing a ...
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Attitude of the upcoming “Orbital Reflector”; will it result in good visibility?

There's a new (passive solar) orbital reflector, called the Orbital Reflector. While Mayak (Маяк) was a crowdfunded project at Moscow State Mechanical Engineering University and the Humanity Star ...
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Are there satellites in LEO that can be seen by naked eyes in the daytime?

Are there any satellites in LEO that we can see with naked eyes in the daytime, or any special situations where they might become visible during the day? If there is, how high, and at what ...
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Does a LEO mission to study the marine debris exist or is at least planned?

Would a mission to LEO to study and record the amount of marine debris be of use or is someone already doing it?
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Lighting an area of the Earth Surface from LEO

What does the math look like to calculate the size of an object in LEO that when angeled off the sun, would illuminate a part of the Earth's surface? For example, if I wanted to 'lightup' a square ...
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174 views

Hyperspectral Imaging from Low Earth Orbit

We're going to be putting a CubeSat into orbit next year and want to use a hyperspectral imaging device onboard. My questions relates to the maths needed to calculate the imaging lens needed to ...
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191 views

Split cost of bringing 1 kg to LEO

Historically seen, space logistics prices decrease, as shown here, from $20K/kg to expected 1.7K/kg thanks to reusable rockets. But, how does the cost split look like and vary in detail? i.e. "fuel - ...
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Have spacecraft ever dipped below the Karman line and then safely continued spaceflight?

The item in Science Alert's A Harvard Astrophysicist Says Outer Space Is Actually Closer Than We Think (see also Science; Outer space may have just gotten a bit closer) talks about the recent Acta ...
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How rare is it in the 21st century to use five stages to get to LEO, especially for a low-mass payload?

@BobJacobsen's comment about the MX Missile (and protests) in the 1980's got me clicking in Wikipedia, which led me to the Minotaur IV launches, the most recent of which seems to be ORS-5 or "...
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What are these bright streaks in MODIS Earth images? Why are they shaped this way?

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua (EOS PM-1) satellite generates images of most of the Earth each day, though there are small gaps near the equator where the ...
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thrusters, force torque, distribution matrix , orbit maneuver

I have a few questions about computing torques and forces. I use the same configuration as in the thesis titled An Attitude Control Sysytem Design Based on the Turksat-1b Geostationary Satellite. ...
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1answer
426 views

How to calculate the orbital distance between 2 satellites given the TLEs

I have 2 LEO satellites with the same orbital plane with same inclination & longitude of the ascending node. I have the TLEs for each satellite. How do I calculate the orbital distance between the ...
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1answer
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How do I determine the ground-track period of a LEO satellite?

I was analyzing a LEO satellite with polar orbit for work purposes. I am relatively new to the field of Satellite orbits. I know that TLE can give information about the current & future orbits ...
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Can ISS astronauts see the lava from the Kilauea volcano at night?

The google news said "Lava from the Kilauea volcano can be seen from space" but it just links to the YouTube video of the same name. The screen shot of the video below shows a small ESA credit at the ...
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Multiple problems with horizontal launch and cryo storage for Stratolaunch?

The Stratolaunch system claims to be a way to revolutionize launching into LEO. The many problems associate with stress loads for horizontal assembly and the need to carry a rocket to launch altitude ...
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1answer
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How much fuel is necessary to cause delta-v?

For a project, I need to calculate how much thrust and how much fuel I need for getting into LEO. What I know: Delta-V necessary ($\approx 9.4$ km/s) Dry (empty spacecraft mass) What I don't know: ...