Questions tagged [satellites]

Satellite is a generic descriptor for any body that orbits a much larger body. The term commonly refers to objects orbiting planets, like artificial satellites and moons, but it can sometimes also refer to planets, small stars, satellite galaxies, and other objects.

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Transport theorem in spacecraft control: tracking a reference angular velocity

I am reading the book named "Analytical mechanics aerospaces systems" by Schaub and Junkins. In section 7.2, the task is to control the spacecraft to track a specified angular velocity $w_r$ ...
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Energy conservation and calculating second cosmic velocity

I am curious about such a thing. While calculating second cosmic speed we consider this equation: $$E = \frac{mv^2}{2} - G\frac{M_E m}{r_E}$$ which we say must be $0$, when the satellite escapes from ...
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How are satellites tracked using Doppler Shift?

I need to understand how Doppler Shift is used to track satellites in LEO, (research papers also appreciated)
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Doubt regarding elliptical orbits and eccentricity relation with masses

I was working with Roche's Limit , You can visit the wikipedia page on Roche's Limit and Hill's Sphere (not important here). A query raised in my mind about the elliptical orbit in which the moon is ...
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Is Acceleration of Earth Constant in its Orbit around the Sun?

According to this link , we can say that the Earth's acceleration is constant as the path is circular. But how ?
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Satellite around a black hole

Let's say there's some satellite revolving around the Earth. Its orbital velocity would be $$v=\sqrt{\frac{GM}{r}}.$$ Evidently, this is independent of the distribution of the mass of the earth, and ...
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Why can't the Chinese rocket Long March 5B keep revolving around the Earth without re-entering?

The out-of-control part of the Chinese rocket Long March 5B is expected to re-enter the atmosphere of the earth and crash on the earth in a few hours. (Today is May 8th, 2021) At the moment, it is ...
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Can electricity be transferred via satellites?

Internet data is transferred through satellites. Mobile Networks are based on wireless transfer. Why can't electricity be transferred wirelessly?
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Damage from the Sun on a Raspberry Pi Camera Sensor with a Fisheye Lens

I'm working on a CubeSat mission which uses two Raspberry Pi V2 cameras (without special filters) as sensors. I am trying to estimate if they could suffer thermal damage if they were to have the Sun ...
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Could you use a balloon to show the drag from the gas/atmosphere of something orbitting near the ISS?

If a balloon were floating next to the International Space Station (ISS), how big, light, and/or dense would it need to be such that the gas/atmosphere at that distance from the earth's surface would ...
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Experimental Test for the cyclic $G_{earth}$ prediction of a Cosmological Model

Can anyone suggest a way to measure or rule out a tiny cyclic variation in the earth’s gravitational constant $G_{earth}$, predicted by an alternative cosmological model? It’s an annual cyclic ...
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Earth's surface area covered by a communication satellite

If there is a communication satellite, whose height has been given above the earth. How do I find out the earth's surface area covered by the satellite. What is/are the concept(s) behind the same? Any ...
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When does a satellite 'meet' the same place of a rotating earth? [closed]

I'm stuck with a problem on GPS: What I tried is to calculate first turnaround time of the satellite. Secondly I calculated the angular speed of both trajectories. The conditions that need to be ...
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What is the orbital angular velocity of a satellite?

Angular velocity ω is by definition the runned angle $dθ$ per time $dt$ elapsed: $ω=dθ/dt$. If the time elapsed in a specific point on the earth's surface is $dt$, the dilated time elapsed on ...
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Can I use the formula for the centrifugal force to solve this gravitation related exercise problem?

I have a problem in which I need to find the kinetic energy to put in orbit a satellite already at a height $h$. So far I have worked out that $F_g = F_c$ (gravitational force = centrifugal force) so ...
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What is the speed of a satellite?

Linear velocity $v$ is by definition the runned space $ds$ per time $dt$ elapsed: $v=ds/dt$. If the time elapsed in a specific point on the earth's surface is $t$, the dilated time elapsed on ...
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Application of the principle of conservation of angular momentum and the principle of conservation of energy [closed]

I came across this question and was left confused. A satellite is launched in a direction parallel to the surface of the earth with a velocity of $36900 \; \mathrm{\frac{km}{hr}}$ from an altitude of $...
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Total work done on a satellite

I have a question about the concept of work in relation to conservative and non-conservative forces. Is Total work done $=$ change in kinetic energy or change in total energy $?$ This question arose ...
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Calculate orbital speed of object around earth (SpaceX data)

I am just reading SpaceX rocket data satisfies elementary Hohmann transfer formula, a paper of how to use SpaceX telemetry data in educational physics. In particular the paper contains the following ...
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Can a satellite have one axis horizontal to its host, and spin about that axis?

Apologies if I'm not getting the terminology quite right with this question. Some natural satellites (e.g., most planets) have orbital position and axial tilt disconnected; that is, they're rotating ...
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Equation to define the change in orbital radius given a situation where angular momentum is conserved but energy is lost

I am considering the motion of two satellites around a Protostar. I need an equation to define the change in orbital radius given a situation where angular momentum is conserved but energy is lost. <...
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How is the synthetic aperture of a radar done?

In the case of SAR (synthetic aperture radar), the Doppler effect is used to simulate an antenna (syntetic) whose resolution is better. What I would like to know is how this is done in detail, what ...
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What additional velocity must be imparted to an orbiting satellite so that it leaves the earth's gravitational pull?

Consider this problem from my physics workbook: A spaceship is launched into a circular orbit close to the earth's surface. What additional velocity must now be imparted to the spaceship to overcome ...
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What happens with trash that is left after a satellite expires?

I was reading an article that Japan is experimenting with wooden chassis for satellites so that they can keep the trash minimal. I was wondering if it was possible to design the satellites in a way ...
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Are planets without large moons getting weaker magnetic fields?

Recently I read a study according to which in order for a terrestrial planet to have a magnetic field, a sufficiently large satellite is needed, since the satellite's gravitational influence melts the ...
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Does a non-rotating satellite always show the same side towards the main body?

If an initially non-rotating (zero angular momentum) satellite starts moving around a main body, such as the earth, will then the satellite continue to have zero rotation or will it show the same ...
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Is Sergei Krikalev living slightly in the future, or is his body just younger than it otherwise would have been? [closed]

Due to cosmonaut Sergei Krikalev's time on board space station Mir in Earth orbit, the combined effects of velocity and gravity have caused him to experience an accumulated 20 milliseconds of time ...
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How does a satellite maintain circular orbit?

Given a crewed satellite placed at a distance $r$ from the center of the Earth, with an initial velocity perpendicular to its position vector, the magnitude of the initial velocity that would allow it ...
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Radial perturbation to a satellite moving in a circular orbit

A satellite is in a circular orbit of radius $R$ around the earth. I am expected to calculate the period of small radial oscillations of the satellite if it is slightly disturbed from its circular ...
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How to determine the degrees of freedom and generalised coordinates in this satellite exercise?

(image below) We have a satellite on an elliptical orbit. m1=m2=m in this case. The problem is only 2 dimensional in the x-y-plane. One should determine the degrees of freedom and choose suitable ...
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Can a radially launched projectile orbit a planet?

Imagine a spherical planet with no atmosphere. A ball is launched radially with a velocity $v$, maintaining $\frac{v_e}{\sqrt2}<v<v_e $ and there is no other objects in the universe (Ideal two ...
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Atmospheric depolarization rate in case of a Earth-Space channel

I am trying to write a quantum simulator using netsquid, but i ran in the problem that there aren't really any resources, on how to calculate the depolarization chance of a quantum bit in the ...
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Why does atmospheric drag speed up satellites?

I've read that old satellites slowly lose altitude when encountering the very thin atmosphere, and strangely enough they speed up. My theory is that the work done by the drag force is insignificant in ...
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Dot product between relative velocity and relative position in orbital mechanics

Reading Curtis' book Orbital Mechanics I found this relation that confused me. $$ \underline{r}\cdot\underline{\dot{r}}=r\dot{r} $$ What happens, say, for a circular orbit where $\underline{r}$ and $\...
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How to calculate the gravitational force of a black hole outside event horizon at a given distance $r$? [duplicate]

Let $g_{bh}$ $[kg·\frac{m}{s^2}]$ be the force caused by the gravity of a black hole. How do we calculate the force $g_{bh}(r)$ outside event horizon $R_{Sch} = \frac{2GM}{c^2}$ onto a satellite with ...
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Why is Microgravity called “Microgravity”?

I find the term "microgravity" to be misleading, how was it coined? NASA provide this definition: Microgravity is the condition in which people or objects appear to be weightless. The ...
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Elliptical Orbits

Two astronauts are in the same circular orbit of radius R around the Earth, 180 deg apart. Astronaut A has two cheese sandwiches, while Astronaut B has none. How can A throw a cheese sandwich to B? In ...
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Why is the period of a geostationary satellite not exactly 1440 minutes?

When reading about Astra satellites on Wikipedia (https://en.wikipedia.org/wiki/Astra_1KR), I saw that the period of the Astra 1KR satellite, positioned at 19.2° E, is 1,436.1 minutes (source: NORAD ...
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Understanding the spatial resolution of a imaging sensor, should it evenly divide the overall image resolution?

I am reviewing the Landsat 1 satellite, specifically its Multispectral Scanner (MSS) imaging system. The system had the following specifications ...
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My question is about satellite motion and gravitation

Our teacher told us today: Suppose a satellite is moving around the earth in a circular orbit of radius $r$. Suddenly an external agent stops its motion so that its kinetic energy becomes zero but ...
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Radius of Circular orbit of a Satellite around Earth always constant (if Space was a perfect vacuum) WHY?

The way I see it: Assuming space is a perfect vacuum, a satellite should stay in circular orbit with CONSTANT RADIUS around earth forever but I think the radius should gradually decrease for the ...
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Confusion on Gravitation/Orbital Mechanics

In polar coordinates, we can write: $$\frac{d^2\vec{r}}{dt^2}=\frac{-GM}{r^2}\hat{r}=(2\dot{r}\dot{\theta}+r\ddot{\theta})\hat{\theta}+(\ddot{r}-r\dot{\theta}^2)\hat{r}$$ $$\frac{-GM}{r^2}=\ddot{r}-r\...
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Are fireballs in the wrong direction?

So I was just reading about satellites burning up in the atmosphere. The book pointed out that it wasn't the gravitational velocity (towards the earth) that caused objects to burn up (which makes ...
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Why aren't orbits transferred at the perigee?

In example 10.6 titled "Satellite Orbit Transfer 1" of Kleppner and Kolenkow the author says The most energy-efficient way to put a satellite into circular orbit is to launch it into an ...
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Is the delta-V value from Low Earth Orbit (LEO) to Low Mars Orbit (LMO) equal to the delta-V value from LMO to LEO at same altitudes?

Radius of Earth = 6378km Radius of Mars = 3397km Sun-Earth distance = 149597600km (1 AU) Sun-Mars distance = 227986742km (1.524 AU) LEO = LMO = 500km NOTE: Assuming Earth and Mars revolve the Sun in ...
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Satellite path dependence on velocity

How does a satellite planetary path depend on its speed and other factors. I want to know more about parabolic, elliptic and hyperbolic paths of satellite.
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Why is a projectile trajectory parabolic while that of a satellite elliptic?

I understand that the parabolic trajectory is an approximation of a more elliptical trajectory, since acceleration due to gravity is taken to be a constant for a projectile. However I'm intrigued to ...
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Satellite return ro Earth

When satellite is return from space orbit to earth how they lower the potential energy? Do satellite need to fire engines as they launch? How we apply energy conservation laws?
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Why does a satellite moving around earth in circular motion its speed is constant?

I do know the satellite's tangential velocity is always perpendicular to gravity, therefore its speed must remain unchanged, however, I have some confusion. If I separate both the tangential velocity ...
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Planetary motion considering natural satellite

Using Kepler's laws of gravitation we can determine the time period of a planet revolving around the sun. However, this excludes the gravitational effect due to satelite(s) orbiting around the planet. ...

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