# Questions tagged [rotation]

Questions regarding an object or spacecraft rotating around an axis.

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### How do the roll-rings at the ISS work?

I get that on the ISS they need to keep the solar panels constantly rotating to keep them looking towards the sun. To transmit the electricity and data to and from the Solar panels truss structure ...
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### Eliptical orbit [closed]

If an object revolves around the earth in a perfectly circular path, where the center of the circular path is different from that of the earth, (which means the object is close to earth's surface at ...
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### How do orbits around Jacobi ellipsoids behave?

The Earth is a Maclaurin spheroid (aka. oblate). This affects orbits, most notably $J_2$ rotating the node line for inclined orbits, enabling thins like Sun-synchronous orbits. But the Maclourin ...
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### Can an orbit rotate around a non-orthogonal axis?

I'll attempt to draw a mental example, in case images are not kind (if they are kind, you can likely skip this first paragraph). Let us say that the Earth is at it's aphelion (arbitrary choice), and ...
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### How do astronauts turn in space?

A recent question back in Physics asks whether there is a way for an astronaut to rotate when in microgravity and without touching anything else, while still conserving angular momentum. One way to ...
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### How to calculate the speed of rotation of a given point on the Earth's WGS84 ellipsoid, about its axis?

Launches often happen near the equator in order to take advantage of Earth's rotation speed. This is why more launches are towards the East than towards the West. How can one calculate the speed of ...
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### What is the fastest that ParkinsonSat spun? Did it vary with solar activity?

Why would photon pressure be needed to keep ParkinsonSAT Spinning? explains that it was equipped with surfaces that resulted in a sunlight-induced torque which have ...succeeded in keeping the ...
128 views

### The rotation speed of the sun's equator in degrees per second [closed]

I'm just looking for a °/s speed of the suns equator. I'm coding a sun in unreal engine, so I'm looking for its equator speed. I've seen two incorrect posts using different speeds per day, and I'm too ...
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### Converting J2000 to ECEF?

Say I get the orbital elements for the ISS from JPL Horizons. Say that data is expressed in J2000, an inertial frame. I want to express it in ECEF. This is a simple rotation transform. All I need is ...
341 views

### How to find ECI coordinates for a circular orbit

Suppose a satellite is orbiting Earth in a circular orbit, of which I know the inclination $i$, the right ascension of the ascending node $\Omega$, the semi-major axis $a$ (or orbit radius given that ...
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### Practicalities of docking with a large spinning space station

We've all seen countless examples of spinning habitats in fiction. However there are certain practicalities with these space stations that I can't get my head around, namely around how you'd dock with ...
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### Using a fidget spinner to rotate in outer space

There is a question How do astronauts turn in space?, and related questions here and on physics.stackexchange, that detail how astronauts might maneuver by spinning their upper and lower body ...
164 views

### In what circumstance would it be useful for a satellite’s angular velocity to differ from its reference frame’s angular velocity?

Casually reading “orbital mechanics for engineering students” on rigid body attitude dynamics, i see the following passage: $$M_{net}=\dot{H}_{rel} + \Omega\times H$$ Keep in mind that, whereas \$\...
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### Changing the rotational rate of a natural body

Let's say that for the purpose of terraforming, we need to speed up the rotation of a planet (like Venus), a moon or an asteroid to near Earthian day. How would we go about doing this? Can this be ...
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### How can you make a vacuum proof rotatable seal?

Many systems have been discussed where you have a rotating spacecraft for artificial gravity purposes, with a portion of the spacecraft that doesn't rotate, perhaps the engine for instance. I've been ...
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### J2000 to current ECI transformation matrix

I want to find the transformation matrix that converts an ECI frame at some time 't' (lets say t = 1st January 2020) to J2000 ECI frame (that is ECI frame at noon of 1st January 2000). From what I ...
177 views

### Query on movement of space shuttle during lift off: Three examples

I have a small query here on the three different movements that I perceived after looking at videos during take off of Challenger (1986), Columbia (2003) and Atlantis (2010). Challenger (1986): ...
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### Which X-15 and SpaceShipOne flights took Coriolis forces into account on their flight path?

I wonder whether those X-15 and SpaceShipOne flights that reached space took into account the rotational Coriolis forces, so that they wouldn't reenter above a location where it would be too far from ...
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### How can I generate Chebyshev cofficients from SPICE for J2000 Inertial to Moon ME Frame?

I want to extract the Chebyshev coefficients in order to be able to calculate the time-varying transformation from the ICRF / J2000 Inertial frame to the Moon ME (moon mean earth) frame. I know I can ...
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### Would a Foucault pendulum work on the Moon and on the Galilean moons?

I wonder whether the Moon and the Jovian moons spin fast enough for a Foucault pendulum to swing on their poles. For instance, I think that it wouldn't swing on Mercury and Venus because these planets ...
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### Earth's rotation speed vs latitude [duplicate]

The above question may sound naive. Still I would be thankful to someone who helps me in understanding the concept. In the following link it is mentioned that earth's rotation speed with respect to ...
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### Why spacecraft 's trajectory is shown undulating curve on 2D image of earth? [duplicate]

As i am watching live-stream of Demo-2 mission,the trajectory of a capsule is shown curved(like sin wave). In other words, why their trajectory isn't along longitude so that in 2D, the path followed ...
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### At what altitude would I have to go in a lighter than air balloon to be above all wind and just have the earth rotate underneath me?

I know in the lower levels of the stratosphere we can still have 100 mph winds albeit low density winds. Could I possibly go high enough in a balloon or imaginary vertical craft that I would go above ...
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### How are satellites, rocket launches and other space programs affecting the earth’s rotation? How will it be affecting living beings?

Want to know the effects of the active satellite, rocket launches and space programs that affect earth rotation? how? And their effects on living beings due to effect in earth rotation?
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### How has the angular velocity of Earth changed over the past 100 years?

What is the total change in the Earth's Angular Velocity over the past 100 years? I have read other posts that discuss how much mass has been lifted out of Earth's Atmosphere. I'm trying to get an ...
206 views

### Is the retrograde (clockwise) rotation rate of Venus speeding up or slowing down?

In the update of the question "Would it be possible to "ride the wave" on Venus ?" there are links to articles in Science and in Science News that report that the atmosphere of Venus, hitting the ...
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### Does "Air Launch to Orbit" makes the best use of Earth's Rotation?

Usually, all artificial satellites are launched in the prograde direction, since this minimizes the amount of propellant required to reach orbit by taking advantage of the Earth's rotation. Further, ...
94 views

### Optimal shape for a spinning ship/station - downsides of spheres? (Radiation shielding)

What is the optimum shape for a spacecraft? So I've already read this link, and a few other similar ones, and the main issues I am already aware of... but yet it still seems like a large majority of ...
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### Do satellites in orbit undergo translational motion or rotational motion, when initially they are not given any additional spin?

Regarding the proposed duplicate: Thought the proposed duplicate has a similar titIe, I have read those answers and this question requires a different answer. We know satellites orbit around Earth, ...
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### How does water respond in 0g?

I'm imagining a small orb magnetically suspended inside a sphere of any paryicular size floating in 0g. What would happen if you rotated the orb at a high/varied velocity? And what if you change the ...
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### Would air circulate in a rotating station on its own?

I know air circulation was a tricky problem on the ISS . I think that in a rotating station the air would be moving with the station, but the air against the “floor” would be moving faster or have ...
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### Did the manned NASA capsules rotate during descent?

Watching the NS-11 launch, I noticed that during descent when the main chutes were deployed, the capsule rotated quite a bit, and would rotate back. Was this an issue as well during the Mercury/...
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### How to slow a spinning spacecraft externally?

I came accross the is question What are the consequences to breaking the ISS? and wander how would a spacecraft be made to stop spinning from the outside? Scenarios might include (but are not limited ...
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### Qualitative differences between gravity and a spinning habitat

I'm aware that living in a spinning habitat has a couple of noticeable differences from being on terra firma. For instance, running in the direction of the spin ought to make you feel heavier, while ...
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### Does a change in the rotational speed of something on its own axis (rpm) affect its orbit?

For example: if a satellite in orbit around earth had its prograde rotational speed increased from 60 rpm to 600 rpm, would its orbit be affected? Another example would be if earth’s rotational speed ...
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### How much does the rotation of the Earth affect re-entry and could we go against it?

I was thinking about how many things are affected by the Earth's rotation, and was wondering how much more difficult a retrograde re-entry would be (where the Earth's rotation direction is assumed ...
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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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### Rotating modules for ISS [duplicate]

Are there any offcial plans to introduce rotating modules for ISS? There are many theoretical considerations to do so, but is there more to it?
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### Could the Galilean moons tidally lock Jupiter?

From my understanding, given enough time, the gravity of the Moon is gradually increasing the time it takes for Earth to rotate around its axis, and that, as a result, in the distant future, Earth ...
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### How come we don’t put a huge windmill-like machine in space? [closed]

I am new to this sight, but since space being a vacuum there is little to no air resistance at all making a windmill spin forever. There is no wind in space however, if you spin it once, it should ...
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### How much will Bennu rotate faster and faster with mirrors facing the Sun on its left side?

Several answers to the question "Why paint only one-half of Bennu" describe the Yarkovsky effect as an important force acting on the asteroid 101955 Bennu. But what about the radiation pressure of ...
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### Would space ship/station rotation for artificial gravity cause the "axis" to also rotate?

Would space ship/station rotation for artificial gravity cause the "axis" to also rotate similar to that of a helicopter with out a tail rotor? Additionally would a second rotating section going in ...
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### Moment of Inertia of a planet

Radio Doppler measurements were taken with Viking and twenty years later with Mars Pathfinder, and in each case the axis of rotation of Mars was calculated. By combining this data the core size was ...
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### Why is the rotation rate of Venus so slow?

Venus has an extremely slow rotation rate, to the point that it actually rotates slower than it revolves around the sun. In other words, its day is longer than its year. With the exception of Mercury, ...
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### Could a satellite levitate above the magenetic fields of Earth?

Like the toy the base of the levitation could the Earth be the base and the space station the levitron? https://earthscience.stackexchange.com/questions/13854/where-on-earth-is-the-magnetic-field-...
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### How do constellations appear to stay constant despite Earth's spin and orbit? [closed]

Our Earth is spinning and also orbiting the Sun, so how do the constellations appear fixed and constant? Almost all galaxies and stars are said to be fixed relative to constellations.
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### Is centre of mass a factor in space without gravity?

Quick disclaimer; I'm not that well informed on many of the mechanics on space in general so sorry if this question is rather easy/basic. Is the center of mass in a object a factor in space when ...
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### Asteroid Catalog

Where can one find asteroids or comets that contain water ice suitable for a human mission. Perhaps there is comprehensive catalog of small bodies that can be searched for characteristics such as: ...