# 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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### What is the acceleration in an orbit decaying due to air resistance relative to one not decaying?

This answer to Is there an upper limit for the internal size of space stations? has this paragraph: Finally, if you are stuck ["stranded" in the middle of a room in a space station filled ...
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### What does 'a nudge' mean in the context of rocketry?

The following paragraph is from a wired.com article: When I visited this past fall, SpinLaunch employees were still unpacking from the move. As we walked among giant sheets of steel, Yaney explained ...
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### How much is really known about those liquid metal droplets orbiting the Earth? (e.g. sizes, composition, orbits…) Are any actually tracked?

The question Orbit Guardians - bs, right? mentions a company proposing a smallsat that will capture then give a roughly 200 m/s retrograde "kick" to liquid metal NaK alloy droplets in LEO ...
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### How much would it cost to launch a 0.5U Satellite?

I have seen the figures for 1U, 3U and 12U Satellites such as those provided here, but I have been unable to find pricing for the launch of a single 0.5U or 0.25U satellite. I have seen many academic ...
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### How problematic is debris for Starship storage/depots?

So with the recent announcement that Starship has been selected as NASA's HLS (which is pretty radical), it's raised a question in me that been around for a while. For HLS; a Starship storage(depot) ...
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### Is it possible to determine whether a spacecraft is in the thermosphere or in the exosphere?

The Earth's thermopause is varying greatly between 500 km (310 mi) and 1000 km (620 mi) altitude. If a craft orbits inbetween these altitudes, or reaches them at some point of their orbit, is there ...
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### Is Starship planned to fly directly to the ISS without first stage? Is it even possible?

I'm having difficulty understanding how/if Starship and/or Super Heavy could be used to deliver crew to LEO. Is it expected to deliver astronauts to the ISS Crew-Dragon-style, but without the 2nd ...
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### Where can one find the accelerations due to high-order terms of the geopotential model?

The expression for the orbital perturbation due to J2 ($\mathbf{a_{J2}} = [a_r \ a_s \ a_w]^T$) as well as its derived effect on the argument of perigee and the right ascension of the ascending node ...
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### What is the fastest that ParkinsonSat spun? Did it vary with solar activity?

Why would photon pressure be needed to keep ParkinsonSAT Spinning? explains that it was equipped with surfaces that resulted in a sunlight-induced torque which have ...succeeded in keeping the ...
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### Biggest orbital inclination change done in Earth's orbit

Generally orbital inclination change is said to be (fuel) expensive. What is the biggest orbital inclination change (in degrees) done in Earth's orbit for an orbiting object? Can this be broken down ...
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### Future trends in Earth Observation and Communications from VLEO; are there any?

Question: In order to better understand the wider market need and uses for Very Low Earth Orbit (VLEO)-enabling technologies, I'd like to ask about future trends in Earth observation imagery and ...
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### Calculating angular deviation from LEO magnetic field

The situation I need to calculate pointing errors for a satellite that points along Earth's magnetic field. The satellite's position and orientation are given to me w.r.t ECI J2000. The orientation is ...
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### Determining the launch period for Hohmann transfer

How do you determine the day of a specific launch? I know there are launch windows but they only refer to the time at which a spacecraft must be launched. For a LEO it is apparently 365 days, but what ...
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### Why 53º orbits for Starlink?

In the UCS satellite dataset, I see a very modest number of non-Starlink LEO satellites around 53º (see graph below). Conversely, Starlink satellites are regularly deployed around that inclination. ...
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### How much does smallsat launch to LEO cost?

In early 2021, SpaceX, Rocket Lab, and Virgin Orbit list prices as follows: ...
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### How to calculate sheath area

Suppose we have a cubesat in LEO, if the metallic surface of the satellite is at a positive potential it will attract electrons from the ionosphere plasma, the current collected will be I = J * A, ...
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### Bronze material compatibility for mechanism exposed to LEO

I'm looking at using a worm gear for a latching mechanism on a spacecraft that's destined for a LEO trajectory. The mechanism is on the outside of the spacecraft, but the worm gear itself would be in ...
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### How big would a QR code have to be on my roof for a satellite to be able to scan it given today's allowable resolution?

Say, using the Planet Labs satellites Thank you
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### Do we have an effective way to dispose of space debris at LEO?

There are a lot of articles and news that companies have plans on how to get rid of space debris. But I never found a single proven and reliable method. Perhaps I was looking in the wrong place? Or ...
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### I want to simulate the antenna pointing error when tracking LEO satellites

I am trying to simulate the antenna pointing error of our antenna when tracking LEO satellites using TLE data. I am using the Skyfield library in python. First I loaded the TLE data from the Celestrak ...
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### What is the extent of on-orbit refueling experience at the ISS? Which fuels? which spacecraft?

In a discussion associated with this answer a comment includes the following: The ISS is the only spacecraft in the world that has experience with regular on-orbit refueling. What is the extent of ...
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### Small satellite launcher to LEO dedicated launch vehicle [duplicate]

well today i was thinking, why nobody do something like the SS-520 but comercial? a small rocket entry dedicated to launch a cubesat, that probably go to have a lot of adventages and probably is realy ...
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### Conceptual reusable orbital launch engine prototype for nanosatellites [closed]

I have realised that the process in which we go to space is highly inefficient and we should create a hypersonic spaceplane which take offs and goes to low earth orbit to release nanosatelite and ...
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### Payload capacity of a rocket

Why does a rocket have far more payload capacity when placing an object in LEO compared to when it's placing the object in farther orbits, like on the Moon? If a rocket has sufficient thrust to take ...
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### Has a totally eclipsed Sun been photographed from low Earth orbit?

I'm hoping to get a sense of how much of the corona can be seen during an eclipse of the sun from outside of Earth's atmosphere. Have any photographs been taken in the visible part of the spectrum, ...
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### IMLEO orbit height

Initial Mass in Low Earth Orbit is a well defined cost metric for space missions [1]. However, this is somewhat subjective since it depends on the orbit height. My guess is that there is a ...
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### What is the name of the area on Earth which can be observed from a satellite?

The following image shows Earth and the trajectory of the ISS. A green line indicates which part of the earth can be observed from the ISS simultaneously. What is the name of this line or this area?
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### How did three 1.2 meter spheres and a Xe+ plasma contactor keep the Shuttle “grounded”? What did they look like?

Statement of relevance This answer to Highest DC voltage ever intentionally produced in space? mentions particle beam experiments done from the Space Shuttle while it flew through Earth's atmosphere ...
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### Problems with spaceflight high voltage

What problem exists if the surface of the satellite is at a high positive potential in LEO? What is the maximum voltage it could withstand? is there any document about it?
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### Is an electric fuel tug from LEO to moon orbit economically feasible?

Does it make economical sense to use an electricaly powered fuel tug to supply a moon landing program with fuel? I am imagining an architecture of launching a 25t payload of mostly fuel into LEO which ...
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### How many (presumably friendly) lasers are being shot at us from space? (pew! pew!)

A comment below @A.Rumlin's answer to Is there any spacecraft that is ping-able? links to a Facebook page (in Russian) which shows an astrophotographer's photograph of stars plus a big green flare ...
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### Does the Newton-Rhapson solution to Kepler's equation diverge?

I have the following simple solution to the Kepler's equation which uses newton-rhapson iterative technique. I have read various papers about the initial guess and divergence near an eccentricty of 1, ...
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### Why use a Mars orbital Earth return vehicle for sample return?

NASA's plan is to use two separate missions to bring home the drill core samples that the Perseverance rover will take. The samples will in plan be picked up by a landed mission and launched to Mars ...
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### Error in Propagating equatorial orbit using GMAT

I propagated an orbit with semi-major axis of 7000km and the rest of the keplerian orbital elements 0 on GMAT. Since the orbit is circular and in the Equatorial plane, it should not change over time. ...
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### Why can't I just use dot product angles to get satellite vision of a point on Earth?

Right now I'm using MATLAB and can easily get the ECEF coordinates of the satellite and the point on the Earth. Since ECEF is cartesian, why can't I just rearrange:  r_{es}\cdot r_{ps} = \|r_{es}\| ...
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### Solar wind density in LEO

Does anyone know where I can find real (not approximate) solar wind data in LEO? I am particularly interested in the density and current of electrons
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### Are spacecraft put into Earth orbit frequently equipped with small thrusters to separate their orbits from their co-orbiting rocket bodies?

Brandon Rhodes' retweet says I’ve recently followed @TSKelso as a fun way to keep up with the surprising volume of rocket launches these days, and the new http://celestrak.com viewer shown here is ...
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### Most efficient (computationally) orbit propagation for simplified J2 effects

I am looking into modeling large scale constellation (hundreds of satellites) and there coverage over earth given a defined conical FOV. The simplified process is a user defines: Constellation (...
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### Is the use of whipple shields on satellites common?

How common is the use of whipple shields or of any micro-meteor and debris shields in general for satellites in low earth orbit , I couldn't find any relevant statistics on the internet, a rough ...
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### Was the ISS closer to Baja California or California when this ISS press event started? When exactly did it start?

The NASA video Expedition 63 Inflight with New York Times, Fox News, and USA Today - July 7, 2020 begins with NASA astronaut and Expedition 63 commander Christopher Cassidy discussing with an ...
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### Why will it take a couple of weeks to complete CRYOSAT 2's orbit raising of a few hundred meters?

The BBC's Esa and Nasa line up satellites to measure Antarctic sea-ice says: Authorisation was given on Tuesday for Europe's Cryosat-2 spacecraft to raise its orbit by just under one kilometre. This ...
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### Why are ICESAT-2 and CRYOSAT 2 both at inclinations of almost exactly 92 degrees?

The BBC's Esa and Nasa line up satellites to measure Antarctic sea-ice says: Authorisation was given on Tuesday for Europe's Cryosat-2 spacecraft to raise its orbit by just under one kilometre. This ...
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### HDEV Goodbye Video- similar projects planned?

I just found that nice "Goodbye HDEV" video on the Columbus-Eye-Projekt-Webpage. (http://columbuseye.rub.de/) Seems like the HDEV-housing is already burned during re-entry. Does anyone know ...
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### What does a typical delta-v budget look like for a LEO satellite?

In terms of launch, initial orbit correction, stationkeeping, deorbiting, etc. for a typical 100-200 kg LEO satellite? Is there any source online with specifications for non-private Earth-orbiting ...
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### Is SLS capable of launching the core stage into LEO?

After watching the Hazegrayart video If Rockets were Transparent I realized that I didn't really have a clear idea what the Space Launch System (SLS) is capable of doing. Question: Is SLS capable of ...
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### position of an emitter on ground from space

Could anyone throw some light on what is the minimum number of satellites that I require to find the location of a RF emitter on earth from a LEO orbit satellite constellation having a single receiver ...
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### What speed variation would there be in a realistic LEO orbit at a nominal height of 200 km?

So in a previous question, How much variation in orbit altitude is caused by gravitational variation, in LEO? we established that an LEO orbit of ~200 km would actually change altitude by up to +/-20 ...
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### How much variation in orbit altitude is caused by gravitational variation, in LEO?

Imagine a hypothetical spacecraft in LEO, at 200km. Ignore air resistance for a moment. It's actual height will vary, due to both gravitational anomalies and the shape of the Earth. Do we know ...