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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1answer
2k views

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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401 views

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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115 views

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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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: ...
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1answer
243 views

Can you operate a satellite in the disposal “graveyard” region

The NASA safety standards allocate the region between 2,500km to 18,833km altitude for the disposal of LEO satellites. Most satellites, as far as I understand, will either operate in LEO (so well ...
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414 views

Propagation of pressure waves in Low Earth orbit

So in a Wikipedia article about space debris i read that---- At higher altitudes, where air drag is less significant, orbital decay takes longer. Slight atmospheric drag, lunar perturbations, ...
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1answer
295 views

How to determine the optimal orbit for a LEO satellite

Our goal is to determine the best orbit that will allow a ground station (so this is a fixed point on earth) to communicate a maximum number of times par day with a LEO satellite. So the question is :...
5
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319 views

Hovering Carbonite! Why do these satellite videos of Earth appear to be made from a geostationary location?

The BBC News article UK satellite makes HD colour movies of Earth has led me to a series of YouTube videos as well recorded by the Carbonite-2 spacecraft built by Surrey Satellite Technology to be ...
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To what extent is the orbital Time Period of ISS affected by soyuz thrusters?

Numerically, to what extent is the orbital time period of ISS affected during the time when it boosts back higher to gain the lost altitude, using Soyuz thrusters/engines?
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Which LEO satellite lost over 30 km of altitude in the geomagnetic storm of 13-14 March 1989?

This answer includes the following information: During the great geomagnetic storm of 13-14 March 1989, tracking of thousands of space objects was lost and it took North American Defense Command (...
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Why doesn't the ISS use ion engines to maintain altitude?

So the ISS uses small thrusters on the Soyuz (usually) to perform occasional reboost burns to raise its orbit. This goes through, from what I can tell, around 3,500 kilos of fuel per year. Would it ...
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1answer
180 views

How does DigitalGlobe plan to re-image a specific area “as frequently as every 20 to 30 minutes”?

The Spaceflight Now article DigitalGlobe books two launches with SpaceX for Earth-imaging fleet goes beyond describing the two launches to talk about DigitalGlobe's future plans. Fitted with imaging ...
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Was SpaceX's launch of Formosat-5 more vertical than normal for any particular reason?

Reading both the abstract and the plain language summary of the recent paper published in the journal Space Weather Gigantic Circular Shock Acoustic Waves in the Ionosphere Triggered by the Launch of ...
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1answer
264 views

How large would be the seasonal variation of eclipse duration for a spacecraft in LEO?

The question How long will a 500 km altitude satellite spend in Earth - shade per orbit has several answers, and there is some discussion of constraints related to maximum eclipse, due to some issues ...
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557 views

How fast is the onset of periodic eclipse for a spacecraft in LEO?

A spacecraft in low inclination LEO will undergo regular eclipsing of the Sun and this is a big issue for power management. How fast is the light-to-dark transition, say 90% to 10% sunlight intensity ...
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379 views

What are the legal implications for a child being born in space?

So, in this case, I asked back in the chat about the side-effects of childbirth AND what legal implications that would have for a person born outside of a celestial body; a "spacer", if you will. So,...
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163 views

How can I plot a precessing orbital plane of an artificial satellite on a polar plot from a TLE in Python?

How can I plot the orbital plane of an artificial satellite on a polar plot from a TLE in Python? Very new to all of this. As I understand it I need to extract TLE's from Space-track.org. Then use ...
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1answer
202 views

How can you calculate the minimal cone angle between two satellites to prevent interference?

I have a model of 2 ground stations (G1 and G2) and 2 LEO satellites (S1 and S2). G1 and G2 are located close to each other. S1 transmits data to G1 and S2 transmits to G2 with almost the same ...
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1answer
179 views

Could a sounding rocket or a space gun payload at apogee be put into orbit with a rocket impulse from there?

Consider a sounding rocket that launches its payload to several hundreds of kilometers of altitude, straight up. Imagine that this payload at apogee then points itself accurately and has a propulsion ...
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299 views

What planning tools and techniques are used to avoid collisions in space during launches?

What tools and techniques are used to calculate as well as to ensure a collision free trajectory when space junk as well as real live useful satellites are so numerous? While the chances of hitting a ...
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3answers
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How did the Roadster get high enough to take a whole-Earth picture?

According to telemetry as seen in videos of the event, the car was ejected from the Stage 2 rocket at 114km above Earth. Anything less than 160km will immediately enter a rapidly decaying orbit and ...
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971 views

How to determine an algorithm for Low Earth Orbit propagation, considering perturbation from the moon, sun, etc?

I'm trying to determine an algorithm for orbit propagation for a satellite on LEO, with high accuracy in a six month time ...
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1answer
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Telecommunication CubeSats

Does anyone know of any company that is using CubeSats for telecommunication services or is this a new idea not yet implemented into the commercial arena?
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PSLV-C39/IRNSS-1H TLE accuracy

The TLEs accuracy for PSLV-C39/IRNSS-1H seems low when compared to that of the other LEO satellites (ISS, HST, Tiangong, Sfera 2, ...). Look, for example, at the following graph that shows the radius ...
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732 views

What's the unshielded radiation dose in mSv in Low Earth Orbit?

Say we have a guy orbiting Earth in LEO with no spacesuit (I know, I know), what would be the millisieverts he would be receiving?
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534 views

What is the Fischer 1960 Mercury Ellipsoid, and why is it called that?

Don't be distracted by the 1960 Mercury shown below. Reading about Irene Fischer (also here, and mentioned in this answer) and seeing the Fischer 1960 Mercury Ellipsoid turn up in tables of ellipsoid ...
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How is the altitude of a satellite defined, given that the Earth is not spherical?

The altitude of a satellite is the distance between the Earth's surface and the satellite, but the Earth itself is not spherical. At the equator the Earth's radius is 21 km more than at the poles, and ...
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1answer
101 views

If a cube or micro satellite could collect 1-2 cm space debris in Earth orbit could they be deorbited while raising the sats orbit?

A lot of space debris on LEO are small 1 to 2 cm pieces. Removing these threats is a concern to anyone using LEO. Can a cube/micro satellite use collected small debris and propel them to both ...
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2answers
390 views

Temperatures in “near” space compared to LEO

I've been reading about High Altitude Balloons (HAB) lately, and it seems that they take much greater pains to fight cold temperatures than cubesats do. Loads of insulation, especially on batteries, ...
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What caused this bright light from the ground at night seen from the ISS?

The music video on the NASA Johnson YouTube channel The Sound (& Visions) of Silence shows images and video of Earth taken from the ISS by astronauts Sergey Ryazanskiy, Paolo Nespoli, and ...
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Determine orbit type from TLE

I was wondering if, and how, one can tell from the values in a TLE whether an orbit is LEO, MEO, HEO, or GEO. I'd like to do this in code eventually, so any formulas or threshold values would be much ...
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How can the delta-V be calculated depending on the launch altitude above sea level?

If we assume that we have a given launcher that is able to produce a $\Delta v$ of 10km/s at sea level takeoff, and is able to reach an LEO of 200km above sea level, what LEO altitude would that ...
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209 views

How do you compare a simulation with a fitted orbit?

I am very confused with regards the simulation and fitting of satellite orbits. For example, how does one compare the results of a numerically integrated force model with an orbit that has been ...
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2answers
749 views

What are the advantages and disadvantages of assembling a space station in LEO before sending it to its intended Lunar orbit?

Government space agencies and some of the largest space companies are talking about building a space station somewhere in cis-Lunar space, the so called "Gateway". As far as I've heard, the (still ...
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1answer
534 views

Was the Space Shuttle the most efficient orbital launcher, based on the launch/LEO mass ratio?

It seems that the mass of the Space Shuttle at launch was around 2,000 tons, and it could deliver a total payload of around 122 tons to LEO. This would give it a launch/LEO mass ratio of around 16.4. ...
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1answer
315 views

Trying to understand the two “holes” in this alt/az plot of the ISS

I'm plotting the position of satellites in the sky using Skyfield. If I project the .altaz() data on to a rectangle (in a similar fashion to the way ground track ...
2
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1answer
242 views

How can satellites serve a large number of devices on earth?

Say we have a LEO satellite. There are 5000 low power devices on earth (They are in the close vicinity, can be served by same satellite) which needs to be communicated with the satellite. Now my ...
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2answers
235 views

Questions about the Dynamic Solid Tide

I found the following plot in the book Satellite Orbits; Models, Methods, Applications by Oliver Montenbruck and Eberhard Gill, Springer, 2000. The figure and description can also be found in google ...
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3answers
670 views

What is the typical relative impact velocity of orbital debris in low Earth orbit?

We all know that space is about going really fast. We also know that what matters in a collision isn't really absolute speed, but relative velocity. (Two cars with matched speeds on a highway touching ...
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0answers
429 views

How can a paint fleck make a window bullseye?

This answer repeats the fact that something as small as a few micrometers in diameter can make a visible bullseye in a window in orbit. I heard it with respect to the space shuttle, and now they have ...
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4answers
10k views

Why would a box full of 1cm balls released into LEO be so scary to an engineer supporting the ISS? - (Updated)

update March 2018: I just saw this in Buzzfeed (Google sent me there, I don't normally read it): Rich People Will Soon Be Able To Buy Fake Meteor Showers On Demand. It seems this might happen in 2018. ...
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Artificial Shooting Stars - how could this possibly work (economically/technologically)?

update March 2018: I just saw this in Buzzfeed (Google sent me there, I don't normally read it): Rich People Will Soon Be Able To Buy Fake Meteor Showers On Demand @Antzi mentioned below the question ...
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1answer
237 views

Is there a significant difference between launching a polar orbit mission south from New Zealand versus launching it north?

The Channel News Asia article New Zealand launches into space race with 3D-printed rocket says: Ships and planes need re-routing every time a rocket is launched, which limits opportunities in ...
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1answer
262 views

Is the recently discovered VLF-induced radiation barrier in any way important or useful?

There are several popular news articles that refer to this video, who's notes point to the NASA news item NASA's Van Allen Probes Spot Man-Made Barrier Shrouding Earth which points to the ...
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How will several thousand Low Earth Orbit satellites affect the night sky?

SpaceX has unveiled its plans to launch a bunch of satellites into the Low Earth Orbit, and according to Wikipedia, the number is either 4500 or 7500 (not sure, could be the sum of both). The ...
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1answer
449 views

How do those little dish antennas sticking out of the HST track their target independent of telescope pointing?

Almost all the photos I see of the HST show the two small dish antennas at the ends of the two long, opposing booms with the "top" one pointed straight ahead at 12-o'clock, and the "bottom" one at 3-o'...
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258 views

What are the disturbing torques on the ISS?

What are the orders of magnitude of disturbing torques on the ISS itself, preferably split into the following categories, but any numbers (with source) will be useful: Gravity gradient Magnetic Solar ...
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0answers
418 views

If a sun-synchronous orbit passes over the poles twice a year, how can it have a constant (e.g. 98°) inclination?

I am sooooo confused. The answer to Are sun synchronous orbits possible for any place on Earth? ends with In short, yes, sun-synchronous orbits are possible for any location on Earth. and mentions ...
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2answers
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What precisely is downrange distance - how is it defined mathematically?

Wikipedia: Downrange is the horizontal distance traveled by a spacecraft, or the spacecraft's horizontal distance from the launch site. Spacecraft don't travel horizontally. I don't even know how ...
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1answer
247 views

Could a cubesat in a 500km SSO orbit effectively monitor earth?

If you were looking for, say, a 1m per pixel quality, what focal length/sensor size would you need? Would there be any off the shelf/commercial solutions?

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