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Questions tagged [artificial-satellite]

Questions about objects in orbit which are human made, such as communications and GPS satellites, orbital observatories and space stations, and other man-made object in permanent or semi-permanent orbits around the Earth, other celestial objects, aside from the Sun, or even other satellites. Not to be confused with non-orbited man-made objects in space, that are usually referred to as "probes", or simply "spacecraft".

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“Deep space” corrections in SGP4; how does it account for the Sun's and Moon's gravity?

The Simplified Perturbations model SGP4 is used to calculate Earth satellite state vectors (position and velocity) using standard ephemeris data encoded as TLEs (Two Line Elements). According to ...
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What would be the (most difficult) challenge to make a “10,000 year satellite”?

Update: Bezos' recent Tweeted update on the 10,000 year clock. Also see The Verge's Construction begins on Jeff Bezos’ $42 million 10,000-year clock The discussions associated with the question Can ...
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Is it possible to track an object as small as the Tesla Roadster around the Solar System

I have heard that we will soon lose track of the Tesla Roadster launched with the Falcon Heavy test launch. Yet, we know where Voyager is out beyond the Solar System and we followed other satellites ...
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What is the math behind Magnetorquers?

I'm trying to better understand the mathematics behind how torque rods work. I know that even if you have 3 axis of magnetic torquers, in effect there is only 2 axis of control, and I'm trying to ...
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The Orbital Mass Accelerator Engine Theory

Can 2 satellites equal in weight traveling on the same orbital path in the opposite directions intersect and propel each other to gain altitude in orbit? Can orbital perturbation be negated during ...
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Are there terms for Earth orbits with rational number multiples of 1 sidereal day?

An Earth orbit with a period of 1 sidereal day (and zero inclination) is a geosynchronous orbit, orbits slightly above and below that are supersynchronous and subsynchronous orbits, and a Molniya ...
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Why do malfunctioning satellites come back to Earth?

In school, I learned that if a satellite moves at a speed $\sqrt{gR}$ (the square root of the product of the acceleration due to gravity and radius of the Earth), then it will remain in Earth's orbit. ...
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WHY did Rosetta have to go into hibernation for 2.5 years?

It seems the Rosetta spacecraft was put (put itself) into hibernation 08-June-2011. It spun itself up to stabilize its attitude, then shut down navigation, attitude control, communication systems as ...
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Is this the longest that a spacecraft “went to sleep” and then woke up on schedule?

For various reasons, spacecraft are sometimes "put to sleep" for periods of time on long voyages. Many systems are shut down, and radio communications suspended. Tracking of spacecraft at very large ...
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What artificial satellite has the farthest orbit around the Earth?

What is the furthest Earth orbiting satellite? What is its speed and purpose?
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In “spacecraft talk” is nadir just a fancy word for “down”?

Assume the approximation that the Earth is spherically symmetric — without higher order gravitational multipoles, and other effects that might be related to gravity from other bodies or the ...
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Does Humanity Star have non-reflective triangular panels? If so, what are their characteristics?

Rocket Lab has successfully launched a rocket from New Zealand and placed several objects in orbit, see here for example. One payload is New Zealand's first satellite the Humanity Star, a reflective ...
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How does GPS receiver synchronize time with GPS satellites?

GPS satellites transmit time values regularly, but if we put in consideration the time delay between the satellite and the receiver, the time value received wouldn't be accurate insofar as I know GPS ...
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Why didn't NASA use the shuttle to make a profit?

My understanding is the shuttle was designed as cost-effective workhorse, a space-van to ferry cargo up to the ISS, conduct zero-G experiments and put satellites into orbit. So why didn't NASA take ...
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What is the accuracy / uncertainty of Two Line Elements (TLEs)?

I use TLE sets supplied on this website to find the future position of satellites (well usually just the ISS) using the SGP4 propagation method implemented in C++. My question is: What is the ...
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What's the largest aperture telescope sent beyond the Earth-Moon system?

The question and answer about telescopes sent to different planets got me wondering. There are so many solar system bodies that have been photographed by deep space spacecraft, planets, dwarf planet(s?...
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Can an artificial satellite stay in orbit forever?

If an artificial satellite is in orbit around the Earth, it collides with dust and gas and loses a very small amount of kinetic energy to these collisions, and eventually will spiral down towards ...
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Can a satellite work like a radiometer?

Like a Crookes Radiometer, could a satellite have a stiff vain to maneuver? With a white side to let light pass and the black side capture light radiation be enough provide radiation pressure to keep ...
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How can I plot a satellite's orbit in 3D from a TLE using Python and Skyfield?

I have obtained a Two Line Element (TLE) of a satellite in Earth orbit from Celestrak at https://www.celestrak.com/NORAD/elements/ and I would like to use it to calculate an orbit. How can I ...
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Are large halo orbits around L₁'s and L₂'s preferred over small orbits for reasons other than geometry?

There have been many examples of the placement of satellites in orbits around Lagrange points, most have been sun-earth and earth-moon $L_1$ and $L_2$ due to their proximity to earth. In each case ...
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Does a satellite naturally turn in phase with its orbit, always facing Earth?

Assume you want a satellite to constantly point its radio dish towards Earth while orbiting it, or its solar panels towards the Sun if it is instead orbiting it. Is any of the following true about ...
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Which artificial satellites in lunar orbit are currently active?

Most of artificial satellites of the Moon has depleted their batteries, lost communication, been deorbited or impacted the surface after orbital decay. The list doesn't exactly make it clear which ...
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What satellites did the Shuttle retrieve from orbit?

Hobbes wrote: The Shuttle was designed for things NASA rarely or never used: [...] The ability to retrieve satellites from orbit was used a few times, but not as often as envisioned. I wasn't ...
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Will Glonass, Galileo, or BeiDou-2 satellites provide better cis-lunar navigation than GPS?

My question is: Has there been any effort to improve or optimize the radiation patterns on the subsequent satellite navigation constellations (e.g. Glonass, Galileo, BeiDou-2) to facilitate trans-GEO ...
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How does NASA get information from space probes?

So I have briefly gone over answers to how things are stored as from this answer: https://space.stackexchange.com/a/2273/1247 but how is the information sent back? I'm thinking of probes like the ...
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How could tiny Hagoromo have been seen visually from earth confirming its lunar orbit?

I saw the following sentence in The Space Review, and became intrigued: Japan’s Hagoromo lunar orbiter, deployed in 1990, reached orbit but ceased transmitting enroute. If it ceasted transmitting ...
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Temperature of photovoltaic cells vs efficiency - is it ever actively controlled?

The efficiency of photovoltaic cells is surprisingly strong function of junction temperature. Hotter usually means lower efficiency. If one searches for example for images and sites tagged with "...
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How will GOES-R simultaneously point some instruments down at Earth and others sunward?

GOES-R is scheduled to launch soon and put in geostationary orbit over North America for high bandwidth continuous monitoring of Earth, with only 120 minutes per year interruptions caused by ...
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Is there any way to find and track Pioneer 10, 11, and Voyager 1, 2?

The space probes Pioneer 10, Pioneer 11, Voyager 1, and Voyager 2 are the first man-made devices to have escaped from our solar system. The main problem they face is the lack of power source in them. ...
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Why are the GPS constellation satellites in such a high orbit?

Most satellites are in Low Earth Orbit. Some other satellites are in Geostationary Orbit because their function requires it. The GPS (and other GNSS, e.g. GLONASS) satellites are in a much higher ...
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Is the Pi really fit for outer space?

Recently, there has been growing interest in using Raspberry Pis in CubeSats. NASA is even in on the trend. But, considering that outer space is pretty harsh on electronics (i.e. radiation and cosmic ...
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Who/What is the international authority to assign/refuse orbit to a satellite/space-craft?

This book writes to say In 1981 the USSR requested and was allocated seven satellite slots in 24-hr orbit for Earth observations, calling the system Prognoz Whom was the request made to? Who ...
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Are any geosynchronous satellites visible with the naked eye?

It is very easy to spot LEO satellites during dusk or dawn. I am wondering if satellites further out in a geosynchronous orbit are also visible. Of course, if even possible, these would appear more ...
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Suppose Zuma wasn't “lost” — what would it take to detect it?

Being a secret government launch, there has been speculation maybe the Zuma satellite wasn't lost, and claims to the contrary are a ruse to throw off parties who'd like to track it. There is possible ...
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Can you make out the shape of the ISS with the unaided eye as it passes overhead?

Someone claimed to me that they could see the actual shape of the ISS as it passed overhead without use of any optical device. I would think this isn't possible since it is only about 100 meters wide ...
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It's been over two weeks now, will the real Humanity Star please stand up?

edit: This must be some kind of record! (cf. ISRO's PSLV-C37 with 104 satellites - after 56 hours only six TLEs, which factor is greatest challenge? This time its only six total!) At the end of ...
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What actually happened here with a satellite, the ISS and the moon?

I can't follow exactly what happened from this string of tweets - I'm not really twitter-literate. It seems like there was a predicted conjunction of the ISS with the moon, and an actual video of what ...
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ISRO's PSLV-C37 with 104 satellites - after 56 hours only six TLEs, which factor is greatest challenge?

It's been 24 hours 56 hours since ISRO's PSLV-C37 launched from Satish Dhawan Space Centre (SRI) at 09:28 local time (03:58 UTC). I see satcat numbers and object names for 105 total objects; ...
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Are these really deep space amateur radio satellites?

In this answer there is a link to an amateur radio website listing what looks like satellites of interest to that community. The list is long (over 400 lines) and has a designator character in the ...
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Was the NOAA-N Prime satellite really dropped on the floor?

Recently, Donald.McLean posted this image in The Pod Bay, the site chat room: It's a rather disturbing image once you think about it for more than about half a second. Did it really happen? What ...
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Calculate Satellite Coordinates From TLE Data

I know it is not that hard for those familiar with the equations for it, but I am having trouble with the math. In order to fully understand the orbit elements of TLEs I read this which I found very ...
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Is it possible to see animals from space?

Will satellite imagery be able to see the backs of big animals such as lions, tigers, elephants, horses or zebras from space when they venture out in the open? I've not been able to find satellite ...
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What is the smallest operational artificial satellite?

Miniaturisation has many advantages, and in recent times, nanosatellites, picosatellites, and femosatellite concepts have emerged. The Wikipedia article on miniaturised satellite has some pointers. ...
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What risk management options are available for Mars orbiters and rovers to mitigate threat of impacting with Siding Spring cometary debris?

I was reading this article on New Scientist titled Fiercest meteor shower on record to hit Mars via comet. Long story short, the Oort cloud comet C/2013 A1 Siding Spring is predicted to near-miss Mars ...
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What is a “Double Iridium Flare” and how close can the two satellites be?

I just saw the term "Double Iridium Flare" and I'm wondering how close two Iridium satellites might actually be (in distance (km) and angle). I found this video as an example. ...
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How much power loss does the LLCD suffer in transit?

Space.com writes to say (freeform improved quote): The LLCD (Lunar Laser Communication Demonstration) space terminal is designed to beam data from the moon at a rate six times faster than the best ...
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Could a spy satellite image another satellite?

Is it possible for one satellite to image another at high resolution? Would this information be useful from an intelligence perspective?
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What are these air-vent-like structures on this satellite?

I struck out with my previous question so I'll try again. What are these large circular 4-vane structures on the sides of NOAA-19 - the satellite that "fell down"? They remind me of adjustable air ...
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Why did early satellites (e.g. China's Fanhui Shi Weixing) re-enter the atmosphere narrow end (nose)-first?

I was surprised to find out from @JohnnyRobinson's new answer that China's series of Fanhui Shi Weixing spacecraft (FSW) used impregnated oak heat shields. I found this in astronautix: The capsule ...
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Need help getting the true ICRF coordinates of SOHO using Horizons

In this answer I calculated the approximate angular separation between Mercury and the Sun as seen by the SOHO satellite using Skyfield's method of ...