Questions tagged [low-earth-orbit]

Questions regarding Low Earth Orbit or LEO, which refers to orbits at an altitude between approximately 160 kilometers / 100 miles and 2,000 kilometers / 1,200 miles.

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Draper Semianalytical Satellite Theory (DSST) C/C++ version

Anyone knows where one could find the Draper Semianalytical Satellite Theory (DSST) semi-analytical propagator code in C/C++? I know Orekit includes the Java version inside its code. An in general if ...
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How to check LTAN online?

I have written a routine to compute LTAN from TLE/Kepler parameters; however, I am not sure whether my implementation is correct. Is there a website or an online resource where I can check LTAN values ...
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Optimal numerical method to solve BVP for optimal low thrust control

I need to solve a boundary value problem (BVP) for an optimal control in case of low thrust trajectories optimization. I want to include the J2 perturbations to the Edelbaum solution (multiple ...
1 vote
1 answer
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What are the product terms shown here representing an orbit?

I can compute Kepler parameters from a given TLE using Skyfield. I am checking the satellite information from this website and the orbit is represented as $$ 546 \times 548 \text{ km} \times 53.1 \...
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Could a third stage be added to Starship?

SpaceX has predicted that Starship will be able to lift up to 150 tons to LEO. Could some of the payload that it will carry have a third stage? If so could that save another flight of Starship since ...
1 vote
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Could it be more cost-effective to refuel with on the lunar south pole produced methalox instead of refueling methalox in LEO, on the way to Mars?

In the article Prominent volcanic source of volatiles in the south polar region of the Moon it is calculated that 8 x 109 kg $CO_2$ has been vented billions of years ago by pyroclastic events in the ...
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2 answers
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Revisit time estimation for a SAR constellation

I am studying satellite coverage analysis and I have read something about revisit time I did not understand. you can increase and increase the number of satellites to further improve the revisit time, ...
1 vote
2 answers
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What does LMO mean?

I know that LEO means low Earth orbit. I thought that LMO would mean low Mars orbit, but my friend said it means low Mercury orbit. Does LMO mean low Mars orbit, low Mercury orbit, none of those or ...
2 votes
2 answers
269 views

Weaponizing the Starlink constellation

Starlink aims at having tens of thousands of satellites in orbit in a few years. At any given point in time there will be a large number of satellites close by any inhabited places, including the ...
6 votes
1 answer
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Would satellites going into a rendez-vous show a difference in potential leading to an arc between the structures?

I'm researching into satellite rendez-vous. I know (NASA-HDBK-4006A) that in space (more precisely LEO) there is a plasma made up with electrons and atomic ions and a 'plasma potential'. I also learnt ...
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Significance of measure of dispersion in Orbit determination output

I am trying to understand the significance of specifying dispersion measure of 3 sigma or ½ sigma along with Orbit determination output. I am assuming a Space Craft in LEO sun-synchronous orbit of ...
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How long can the SpaceX Starlink satellites survive before they deorbit?

Like most Low Earth Orbits (LEOs), the satellites will probably eventually have their orbits decay and burn up in the Earth's atmosphere. How long, on average, would this take. I am assuming that ...
4 votes
1 answer
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Draper Labs' Control Moment Gyroscope Spacesuit

Back in 2013/2014 Draper Laboratory announced that they were designing and testing a "spacesuit jetpack" that employed control moment gyroscopes (CMG) to allow astronauts to preform EVAs ...
5 votes
2 answers
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Is there any orbital launcher capable of removing the second stage from orbit after inserting the payload satellite into LEO?

The Space Shuttle was able to place a satellite into orbit and to return to Earth. Is there any second stage that may deliver the payload satellite into LEO and do a deorbit burn after that using its ...
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Repeat ground track with 1 day repetition

I'm struggling with a doubt regarding repeating ground tracks (RGT). I've a satellite in a LEO circular orbit with a predefined non-polar inclination (64°) and I want to determine the needed semi-...
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2 votes
1 answer
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How much energy would be required to launch a 10km x 10km x 10km cube into LEO?

I know this is a bit of a ridiculous scenario, I am just looking for a very conservative estimate as to how much force would be required to get something orders of magnitude bigger and more awkard ...
6 votes
1 answer
387 views

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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Using belt drive in LEO spacecraft?

I am designing a concept for a LEO spacecraft and need to transmit mechanical power (0.5Nm @200rpm rotation) over a distance (1-2ft). Chains or belts would be a natural choice for terrestrial ...
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How much will global warming increase the density of debris in LEO? What are predictions currently saying?

After about 08:00 in Scott Manley's hot off the press new release SpaceX Loses 40 Satellites To Solar Storm linked below he drifts away from the solar activity-...
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How much force is required to expedite reentry of space debris?

I'm trying to understand how much a small reduction in orbital velocity can affect the orbital decay rate of space debris. I understand that there are multiple factors to consider, such as debris in ...
4 votes
1 answer
200 views

What is the average solar irradiation in low earth orbit?

I am trying to figure out how much power I can expect for a CubeSat in Low Earth Orbit. Is there some dataset or constant that describes the average rate of solar irradiation (per unit of area) in LEO?...
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What fraction of the Kapton thickness on the ISS' solar panels was likely eroded throughout their lifetime? Predictions? Measurements?

Background @Tristan's answer to How are the silicon PV cells constructed in the ISS's solar panels? Are they as flexible as they appear here? informs us that Kapton is part of the "blanket" ...
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ISS propagation becomes much more accurate with reduced drag. Any ideas why?

I have currently been testing my implementation of a numerical propagator with the ISS. Without going into much details, the propagator considers Earth gravity (with the GGM03S model including zonal, ...
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Which Low-Earth Orbits Spend the Least Time With Access to Sunlight?

Regarding the (maybe completely absurd) possibility of powering a satellite via a ground-based laser, and perhaps (theoretically) also using that same laser to destroy any incoming projectiles or ...
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Are there any Earth orbits where the duration of eclipse increases with semi-major axis with all other parameters fixed?

This answer to Is there a low Earth orbit with a 24-hour day night cycle? suggests that: In fact, it's a rule of thumb that the higher you go the less time you spend in Earth's shadow: the shadow not ...
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1 answer
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Is there a low Earth orbit with a 24-hour day night cycle?

Are there any possible low-Earth orbits that use precession to match Earth's day/night cycle? So like SSO, but specifically aimed to achieve a 24hr day/night in LEO. If so, what would its parameters ...
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51 votes
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Shouldn't space junk fall back to Earth on its own? How long will take for a ~1 cm piece of junk in LEO to fall back to Earth on its own for example?

I'm a noob in this subject and know little about space exploration, but I wonder about this every time I read the news: Wouldn't drag make all space junk fall back to Earth after some time? I'm ...
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Has Buzz Aldrin’s Line-of-Sight rendezvous method ever been used?

Has Buzz Aldrin’s Line-of-Sight rendezvous method ever been used? Buzz Aldrin’s 1963 doctoral thesis describes a line-of-sight (LOS) rendezvous technique which is independent of computer and radar ...
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6 votes
1 answer
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When the ISS is de-orbited, what is the likely mass of the largest impact fragment?

Some parts of the ISS will be more fragmentation-proof than others. Engine bells and pressure vessels, for instance. Has NASA done a formal assessment of component survivability to determine what big ...
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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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Distance between two satellites

What is the appropriate term for arc length between satellites moving in the same circular orbit?
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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). ...
4 votes
2 answers
385 views

Optimal inclination for a long term LEO station serving as an intermediate stop to and from the Moon

Consider we want to build a long term LEO station which serves as an intermediate stop for flights to the Moon and back (possibly with aerobrake). Refueling, docking, crew transfers etc. Several ...
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3 votes
0 answers
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Design and optimization of a Sun-synchronous repeating ground track orbit constellation

I am currently researching about this topic and am very new to this. Have no clue how to go about designing a group of imaging satellites (constellation) that are sun synchronous with repeating ground ...
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5 votes
1 answer
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Is there a standard 'low orbit' for other solar system bodies?

Is there a standard or convention for what 'counts' as a low orbit for other solar system bodies? I'm currently writing code for computing arbitrary Hohmann/ patched conics transfers, and I am looking ...
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1 vote
1 answer
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What are these squiggly lines in Jonathan McDowell's tweets about Yunhai-1?

Anton Petrov's new video Another Satellite Collided in Space, But Everyone Missed It Until Now (below) is fun to watch, and links to Jonathan McDowell's tweet string which begins Space-Track catalog ...
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7 votes
2 answers
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How big will a space billboard have to be to be visible?

So recently there's been the news story about how SpaceX is launching a billboard to space (space billboards are an approximately bi-annual occurrence). This "billboard" is a cubesat that ...
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1 answer
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Why was the Rossi X-ray Timing Explorer decommissioned in 2012? Why wasn't it deployed another ~100 km higher where drag would have been a lot less?

The Rossi X-ray Timing Explorer (1995-074A) was an incredibly prolific space telescope between 1996 and when it was decommissioned/deactivated on January 5, 2012. It reentered the atmosphere soon ...
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What is final positioning of rideshare satellites (like transporter-2 mission) and how do they get there?

Looking at deployment of transporter-2 mission I did not see any information about the final position of these satellites (relative to the second stage or to each other) and how do they get there (...
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Measuring and analyzing the tumble of space debris

How well or accurately can we measure the tumble of space debris? I know that we can make ground-based measurements based on light curve data acquired by telescopes. Can tumble be measured from radar ...
2 votes
1 answer
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Cubesat surface material

In wikipedia I read that the structure of the cubesat are made of aluminum alloys of 7075, 6061, 5005, and 5052. Is this the surface layer of the satellite or it is necessary to cover it with kapton ...
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Do space industry companies want their defunct satellites back?

Space junk debate aside, many large satellite companies (and governments too) are responsible for a large number of both operational and defunct sats that are still in orbit. When other companies or ...
6 votes
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How was the high rate of degradation of Hubble's main mirror initially predicted? Why did it turn out to be lower? Were cosmic rays really a concern?

This answer to How long was the HST initially supposed to work? in Astronomy SE quotes Assessment of Options for Extending the Life of the Hubble Space Telescope: Final Report as follows: Hubble was ...
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Can a LEO based satellite constellation revive the analog radio or TV era?

Many analog terrestrial radio and tv transmitters have been replaced by digital ones like DTT and DRM technologies. Analog radio signals include FM, MW and even SW. Although the quality of reception ...
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What orbits are Starlink satellites now deployed into? How low to do they go on their first perigee?

In my answer to Delta-V of Starlink Satellites I ballpark spherical-cow envelope-back estimated 190 m/s with 2 kg of krypton based on raising only from a 445 km circular orbit to a 550 km circular ...
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How is Prospero doing now? Was it really heard in 2004 and have there been recent attempts to contact it?

Screenshot from the excellent historical review in Curious Droid video Black Arrow : The Lipstick Rocket - A Very British Space Program with a photo of Prospero or at least a representation thereof. ...
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In situ Fuel in LEO / MEO

I have been thinking on controlled de-orbiting of Satellites. You can carry a supply of conventional chemical fuel, and use it to apply a delta-V that would de-orbit them. There are also methods of ...
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How to find a vector's elevation angle with respect to a point on Earth?

tl;dr: Spacecraft's antenna should point to a ground station but there is a pointing error. I want to express the error as a vector rather than a simple angle that a dot product provides, so that I ...
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10 votes
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Which satellite constellations are already operational in LEO (Low Earth Orbit)?

I am researching information on active and operational constellations in LEO (Low Earth Orbit) but from what I can see, many missions are still only planned (e.g. OneWeb, Amazon) and the only one ...
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Calculating body frame X vector's look direction in GEO (NED) frame from roll, pitch and yaw data, is this correct?

I have roll, pitch and yaw angle values for a LEO satellite. Satellite orbit frame and spacecraft body frame are defined as LVLH. The satellite position and velocity are given in ECI/GEI frame. I have ...
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