# 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.

287 questions
Filter by
Sorted by
Tagged with
1answer
16 views

### 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 $w_r$ ...
1answer
37 views

### 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 ...
0answers
16 views

### 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)
0answers
28 views

### 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 ...
2answers
89 views

### 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 ?
4answers
184 views

### 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 ...
2answers
1k views

### 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 ...
2answers
100 views

### 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?
1answer
37 views

### 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 ...
1answer
72 views

### 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 ...
0answers
64 views

### 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 ...
0answers
21 views

### 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 ...
0answers
33 views

### 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 ...
1answer
83 views

### 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 ...
3answers
73 views

### 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 ...
1answer
73 views

### 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 ...
1answer
57 views

1answer
312 views

### 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 ...
8answers
6k views

### 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 ...
1answer
89 views

### 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 ...
1answer
4k views

### 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 ...
1answer
26 views

### 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 ...
3answers
105 views

### 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 ...
2answers
61 views

### 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 ...
1answer
66 views

### 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\...
1answer
61 views

### 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 ...
1answer
157 views

### 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 ...
0answers
35 views

### 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 ...
1answer
32 views

### 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.
3answers
150 views

### 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 ...
1answer
43 views

### 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?
1answer
103 views

### 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 ...
1answer
46 views

### 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. ...