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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Was there a spacecraft that was clearly the first to be put in a polar orbit?

Was there a first spacecraft put in a polar orbit? It might not be clear if it's too hard to say what high inclination orbit is or is not polar, for example if 91 satellites were launched in 0, 1, 2.....
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What are the orbits of all Starlink satellites launched?

Latest batch of SpaceX Starlink satellites went into elliptical orbit. Using all available data (launch times, release times, applications by SpaceX etc), what are the orbits of all current 300 ...
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Why do orbits in the Iridium constellation have an inclination of 86.4°?

Wikipedia's Iridium_satellite constellation; In-orbit spares says that Iridium satellites have an inclination of 86.4°: Significant orbital inclination changes are normally very fuel-intensive, but ...
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Fastest time to Sun Earth L2 (or L1)?

Of all the past, present or planned probes to SE-L2 (or L1*) which has or will take the shortest amount of time to arrive from leaving low earth orbit, or from passing that location if the probe doesn'...
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What does “MSR” represent in the context of this predicted satellite conjunction?

In a series of four tweets starting with this one (found in 2 satellites will narrowly avoid colliding at 32,800 mph over Pittsburgh on Wednesday) 1/ We are monitoring a close approach event ...
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How did two satellites end up in almost the same orbit except moving in opposite directions?

In a series of four tweets starting with this one (found in 2 satellites will narrowly avoid colliding at 32,800 mph over Pittsburgh on Wednesday) 1/ We are monitoring a close approach event ...
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Fast Methods for analyzing large scale Walker constellations

I have been doing some research and with the growing scale of large number of small sats and I am trying to see if there has been work done to study the coverage capability for these constellations. ...
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What was the first unplanned “over-the-air” software update of a spacecraft?

From time-to-time spacecraft have had to be rebooted, in one case Voyager 2 mutinied and had to be reprogrammed and in another Opportunity had it's memory "hacked". As far as I know, deep space ...
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Would a vantablack coating on the starlink satellites cause overheating problems? [duplicate]

I'm an amateur astronomer and have recently being hearing space x catching alot of flack for the amount of reflection the satellites would cause. While I believe that program is more important than my ...
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How exactly does atomic oxygen cause problems for spacecraft in VLEO?

In very low Earth orbit there are (at least) two problems; aerodynamic drag, and atomic oxygen (O rather than O2). Drag can be compensated with a low thrust from an ion engine. Question: But what ...
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Issue with SGP4 modelling from scratch in MATLAB

I am trying to develop the code from this source , this research paper and from this too as same as bibliography of that aforementioned source. So, here as you can see at page 14, they have defined ...
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What are the calculations for gas transport to the Moon with a pipeline?

This paper, acquired from this question about tethers on the Moon, describes LADDER, a mission to deploy a Lunar Space Elevator (LSE). The space tether, made of Zylon fiber, would be 264,000 km long,...
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Point Ahead Angle Calculation between LEO-GEO Satellite (ISL Scenario)

So, I have got two reference TLE from 2 different Satellite in LEO-GEO, which are as follows: (1st TLE for LEO, 2nd TLE for GEO) ...
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Why have JWST in a Sun-Earth L2 halo orbit?

What is the main reason JWST will be in a halo orbit around the Sun-Earth L2 LaGrange point? There have been questions on this site that ask Why won't JWST deploy in LEO where it is potentially ...
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How can I calculate if a satellite is currently in sunlight or eclipse using pyEphem or Skyfield (preferred)?

I'd like to add this to some existing python scripts to model cubesat battery life and payload temperature but the math escapes me.
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What is Buzz Aldrin's T.O.R. plan? How does it work?

Buzz Aldrin is recently quoted in Ars Technical's Buzz Aldrin is looking forward, not back—and he has a plan to bring NASA along: “This T.O.R. plan may be the most important thing I’ve ever done in ...
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Can Astronauts really see firework displays from space?

ISS Expedition 59/60 astronaut Nick Hague tweeted: Sporting our red, white, and blue on @Space_Station!🇺🇸 Planning a “cookout” tonight. Beef patties, corn, blueberry cobbler, and lemonade are all ...
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How is the proper LEO picked, and, since they are all fairly close, isn't there a lot of debris there?

Some orbits have a clear reason why they are exactly where they are: geostationary orbits and Kepler points, for example. Yet the vast majority of stuff in space is in the LEO range. And my ...
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How can I calculate the azimuth from an earth station to a satellite

I have computed the ecef coordinates of both the user location on the ground, the satellite's ecef coordinates, as well as other inputs such as altitude, lat, long of both satellite and earth station....
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Would it be possible to de-orbit a small object by throwing it with human strength? [duplicate]

If an astronaut went on a spacewalk (say from the ISS), tethered him/herself to a relatively massive object in orbit around the earth (say the ISS), and threw a small object in the direction opposite ...
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IRIS Transceiver for LEO Missions?

My professor really wants to know if the IRIS transceiver, which flew on MarCo, will be used in LEO. In fact so much that he doesn't accept "no" for an answer. I have searched for an example but found ...
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What is the longest manned re-entry from Low Earth Orbit ever recorded?

What is the record for the longest amount of time that a manned spacecraft has taken to re-enter from low Earth orbit (LEO)? I would prefer the duration between the beginning of the re-entry burn ...
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How frequent do TLEs of LEO satellites change?

I was doing some MATLAB simulations on LEO satellites using TLEs obtained from n2yo websites and I observed that n2yo was displaying a different TLE for the same satellite after a few days. I don't ...
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Is the Starlink array really visible from Earth?

I was browsing YouTube when I came across this video, recorded from a sky gazer who apparently spotted the Starlink satellites. In my lifetime, I haven't seen many satellites in the night skies (maybe ...
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Getting from LEO to a station in geostationary orbit and docking with it using a Hohmann transfer?

How long would it take for a spacecraft with a mass of 30,000 kg, to go from LEO to reach and match the speed of a space station in geostationary orbit so it could dock with the station, using a ...
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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 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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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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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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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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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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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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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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