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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47
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2answers
10k views

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 ...
46
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1answer
30k views

How often does ISS require re-boosting to higher orbit?

I know that ISS, being in low Earth orbit, requires regular boosts. But I can't seem to find information on how often does this happen. Is it done during each resupply mission, only during some of ...
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5answers
12k views

Is photography from a satellite good enough to make out a person on the ground?

When I first saw Google Maps satellite view many years ago, I remember being greatly impressed (and somewhat surprised) with the image quality, considering the photographs came from up there in space. ...
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3answers
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Do any (LEO) satellites move east-to-west?

Earth's rotation provides considerable horizontal thrust to all launched satellites, nearly 1700km/hour near the Equator. That means considerable fuel savings and generally lower costs, and so most ...
32
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1answer
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Why does the ISS rotate exactly once per orbit?

Looking at the HDEV experiment, one can see that the orientation of the ISS is always the same with respect to the Earth. This means that the ISS must rotate exactly once per orbit (like the Moon ...
31
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2answers
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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 (...
30
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4answers
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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. ...
30
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5answers
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Do any launches bypass LEO?

If sending a payload to GEO (geosynchronous orbit) or any other high orbit, you could start off launching to LEO (low Earth orbit), and then use a Hohmann transfer to raise the height of the orbit. I ...
30
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3answers
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What is the total mass sent into orbit over all history?

I would like to find a good estimate of the sum total amount of payload that humans have put into space, that is, over all years, all space programs, and all types of payload that reached orbit. ...
29
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1answer
772 views

Reason for space debris clustering in LEO

A paper (Active Debris Removal: EDDE) contained this diagram of orbital debris. This is the angle seen by the spacecraft horizontally and altitude vertically. What are the reasons for the lines and ...
29
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1answer
2k views

How is the Hubble main mirror protected from debris?

The Hubble Space Telescope recently hit 25 years in space. It orbits at ~550 km altitude (limited by the altitude the shuttle could reach to service it) and has sustained minor/trivial exterior ...
28
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4answers
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Why not travel to Mars in 2 months?

Just to clarify... I've made some research and generally know what the case is, didn't mean to make the question sound stupid... :) I know there is a thing called Hohmann transfer orbit, named after ...
28
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4answers
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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 ...
24
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1answer
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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 ...
24
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1answer
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SpaceX's 4,425 satellite constellation - what's the method to the madness?

The BBC article SpaceX aims to launch internet from space discusses the SpaceX proposal for a dense array of over 4,000 LEO satellites for global internet coverage, and links to SpaceX non-...
23
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2answers
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Could the shuttle's SRB alone reach orbit?

If one equipped the SRB like the ones used with the Shuttles with minimal attitude control systems and launched it as a standalone rocket with no payload - what speed would it reach? Would it be ...
23
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5answers
49k views

Is it possible to reach space using home-made rocket?

The first stage would be a high altitude balloon, which could reach 30km. Then start a rocket-candy from that high. Without cargo, is it possible to reach the edge of space (Kármán line - 100km), or ...
22
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1answer
908 views

What is the South Atlantic Anomaly, and what can I do to protect satellites from it?

I've heard of something called the South Atlantic Anomaly (SAA), which seems to have a lot of Low Earth Orbit Satellite Operators quite worried. What is it, and how can I protect my spacecraft against ...
21
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2answers
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How are EVA's in LEO affected by being at the night side of Earth?

Orbital periods in LEO are quite short, about 92 minutes for the ISS. So every other almost 46 minutes it is in Earth's shadow. Not only is it then out of direct sunlight, I suppose that the night ...
20
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1answer
1k views

What are the end-of-life options for large classified satellites?

The Delta IV Heavy recently launched NORL-65 to a low Earth orbit. Some of these missions will be in the range of 390 km altitude with circular orbits. Plus, the Delta IV Heavy is a big rocket, with ...
18
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5answers
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Why won't JWST deploy in LEO where it is potentially serviceable?

The James Webb Space Telescope will deploy (unfold mechanically) while on the way to L2. Couldn't it do so in LEO, where it is potentially serviceable? Starliner CST-100 and Dragon are planned to soon ...
18
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3answers
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Space debris half life

In case there will be zero space launches starting at some point in time. How long will it take for the space debris mass in LEO to be halved?
18
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What's salvageable from a dead satellite?

DARPA has proposed orbital maintenance and salvage robots. I had gathered a list of links that was lost when DARPA rearranged their website. But I was able to find this page: Phoenix Makes Strides in ...
18
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1answer
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How often does the ISS orbit align with the day/night terminator?

In the following image (coming from SAT-Flare) you can see the orbit of the ISS (in red) and the day/night terminator (in blue). The terminator separates night from day along the surface of the Earth. ...
18
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2answers
605 views

Early high-inclination crewed flights

I noticed to my surprise today that the very early Soviet flights were to a very high inclination - all the Vostok flights were between 64.9° and 65°, and the Voskhod flights were at 64.7° and 64.8°. ...
17
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2answers
666 views

What caused the ISS's sudden loss of altitude in January 2015?

This image from Heavens Above that @PearsonArtPhoto links to in this answer shows the orbital altitude of the International Space Station: In general, the ISS altitude decreases gradually with time ...
17
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1answer
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What was the distant bright light in the SpaceX webcast of Orbcomm OG2 deployment?

As I was watching the SpaceX launch today on YouTube, I have noticed a bright distant light as the satellites were being deployed. What was that light? Also, after each deployment there was something ...
16
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2answers
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How does a spacecraft such as Soyuz detect when it's on collision course with an object?

Today Roscosmos reported (in Russian, here's a machine translation into English) that the Soyuz vehicle on its way to the ISS avoided collision with a piece of Japanese rocket body, allegedly launched ...
16
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5answers
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What would the Δv cost of bringing the space shuttle external tank to orbit be?

There was an independent proposal that the space shuttle external tank could have been lifted all the way to orbit, and then used as a structural material in space stations. In terms of propellant ...
16
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1answer
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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 ...
16
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1answer
340 views

Criticality in space junk

What density of satellites in LEO is permissible before a single collision has a reasonable chance of triggering the catastrophic destruction of everything in orbit? How many orders of magnitude are ...
16
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2answers
949 views

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 ...
15
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Minimum Orbit Altitude

What is the minimum altitude required for a Cubesat*-like object to orbit around the Earth? Could you initiate an orbit inside the Earth's atmosphere? *A CubeSat is a 10 cm (1 liter) cube with a mass ...
14
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2answers
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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 ...
14
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2answers
368 views

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 ...
14
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2answers
1k views

How bad is Kessler Syndrome?

From what I gather, the general consensus seems to be that if a satellite collision took place in LEO, then it would probably start a chain reaction, creating a debris cloud that could stop mankind's ...
14
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1answer
582 views

What would have been the absolute maximum LEO payload of a two-stage Saturn V?

I read about the Skylab 1 mission in which SA-513 was used to lob the Skylab OWS into orbit. One source (http://forum.nasaspaceflight.com/index.php?topic=12519.20) gave some payload masses: Total ...
13
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5answers
19k views

Why is the life span of a LEO satellite less than that of a GEO satellite?

The average life span of a LEO satellite is approximately 5 years, but the average life span for a GEO satellite is approximately 8 years. Why is this?
13
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4answers
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Why are rocket mass on the launch pad and payload mass to LEO not strongly correlated?

What explains the relation between how much a launcher weights on the launch pad, and how much mass it can lift to orbit? I had expected that more payload requires more fuel to be launched and that a ...
13
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2answers
960 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 ...
13
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1answer
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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 ...
13
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1answer
2k views

Why are LEO satellites not aerodynamically shaped?

In Do atmospheric tides have any impact on orbiting satellites or rocket launches? we learned that the atmosphere does impact satellites in Low Earth Orbit (LEO), and that "most satellites have ...
13
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3answers
853 views

Does it snow in LEO?

How does water spray behave in Low Earth Orbit (LEO), from the side exposed to the Sun to the side in Earth's shadow? Could it be used as means of augmenting atmospheric drag and deorbiting defunct ...
13
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3answers
21k views

How much Energy is required to put 1 kg in LEO?

I was wondering, what is the minimum amount of energy required to put 1 kg of payload into LEO?
12
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2answers
2k views

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 ...
12
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2answers
3k views

How feasible would it be to move the ISS to the surface of the Moon to recycle its components in future?

I see it as an awful waste of energy in not only creating the International Space Station (ISS) components, but also in getting them into space to only decommission the station by letting it fall back ...
12
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2answers
3k views

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 ...
12
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2answers
5k views

Calculating Which Satellite Passes are Visible

Using the Python library pyephem I am calculating passes for the ISS based on TLE data and my lat/long, but how can I tell which of the many passes it returns per day are visible? I understand that ...
12
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1answer
1k views

How is rocket engine cutoff controlled?

In a typical, modern satellite launch, what triggers the cutoff of the orbital insertion stage's rocket engines? I can think of three basic possibilities: Compute how much fuel you need for the ...
12
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1answer
1k views

Civilian requirements/restrictions for sending satellite into LEO

What requirements and restrictions are there for a civilian organisation sending a satellite into LEO? (Apart from cost. I'm talking about any laws, agreements between nations etc) This is in ...

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