Questions tagged [gravity]

Questions regarding the attractive force present between two masses. If about research in artificial gravity (i.e. manmade substitutes for gravity), please use the artificial-gravity tag.

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5
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1answer
202 views

How would humans with appropriate equipment travel the surface of Saturn's moon Titan on foot?

Taking into account the physical characteristics of Titan (e.g. surface gravity, atmospheric pressure), what would be the most efficient method of motion for an astronaut to travel the surface of ...
4
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1answer
3k views

How can a rocket approaching the Karman Line then return to earth faster than 53 m/s terminal velocity?

In the book, How to Make a Spaceship: A Band of Renegades, an Epic Race and the Birth of Private Spaceflight the opening chapter details the June 2004 attempt to take SpaceShipOne to the Karman Line. ...
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2answers
825 views

Would a self-winding watch work in space without gravity?

Could a watch that winds itself with a pendulum work in space with no gravity? Could a pendulum or the self winding part be modified to work off the movements of the wrist in a microgravity ...
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1answer
95 views

Tesseral Part of the Geopotential

I am working on the design of a constellation for academic purposes. I try to describe a phenomenon that appears in the simulations by means of analytic expression and I can't really find a good ...
3
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1answer
121 views

Does a gravity model exist for satellites in LEO?

I'm wondering if there's a C-based (or similar language) program that will output the gravitational strength given input geodetic LEO coordinates (which I can convert to ECI etc. if needed). Ideally ...
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3answers
5k views

Could a human jump off Mimas without return?

A similar question has already been asked on dwarf planet Ceres: Could a Human reach escape velocity by jumping from the surface of Ceres (a dwarf planet)? Ceres has 2.9% of Earth's gravity. Saturn's ...
18
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2answers
3k views

Are there any videos of onboard the Apollo Lunar Module while landed on the Moon?

These would be very worthy videos since there is air in the Lunar Module and they don't wear the heavy spacesuits, so one could see how they behave on the Moon in a breathable atmosphere and without ...
4
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1answer
235 views

At what point when travelling faster and faster around the earth are you not gonna be falling back again (7km/s? 8km/s?)

My dad and I thought about a problem we had when discussing Earth's gravitational field. This wasnt the original question but I still would like to know the answer. So essentially my question is: ...
4
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2answers
430 views

Comparing gravity wells: Earth from the Moon vs Surface of Mars

Hypothetically if a manufacturer was considering building a factory on the Moon or on Mars, which location has the smaller gravity well to escape? Assuming final destination of the goods produced is ...
0
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1answer
179 views

What could possibly happen if an object accelerates 9.81 m/s^2 upwards if it started from the ground ? [closed]

Will the acceleration of the object and the acceleration due to gravity cancel each other and that object remains at the same space coordinate?
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1answer
112 views

How large would a alien spaceship have to be to affect the earths gravitational orbit? [duplicate]

Would a large enough ship generate enough gravity to affect earths course?
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0answers
38 views

why dark matter causes gravity as its property is different than ordinary matter? [closed]

For temperature, pressure, vacuum, electomegnetisum etc. there is only one physical phenomena responsible(it can not be created by other means). Is it true? If so, why dark matter causes gravity as ...
3
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1answer
149 views

Relation between GOCE gravity model and Earth shape

There are a couple of viral videos claiming that "NASA shows that Earth is shaped like potato". The source of such videos is 3D visualization of data collected by GOCE satellite (full animation, video ...
4
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1answer
691 views

JGM-3 vs EGM2008 coefficients

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here ...
2
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1answer
371 views

Can an air conditioner be made to work with 0 gravity?

In another question: How does the freon compressor work at 0 gravity? This seems overly complicated to get some cold air in space. Can an A/C compressor (we use in our house) be made to have gravity ...
3
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1answer
209 views

Calculating the Earth Geopotential effect

I'm calculating the acceleration due to the harmonics in ECEF frame. Gravity potential in spherical harmonics is shown here (I just removed "$1+$", as considering only harmonics effect). $U_{har}=\...
8
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3answers
1k views

Impact of tidal forces to a liquid in a half-full tank

The german Wikipedia article about tidal forces contains a sentence which mentions, that tidal forces have an impact to an half-full fuel tank: Wo keine mechanisch feste Verbindung besteht, können ...
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0answers
63 views

Is there a maximum gravity limit for conventional rockets? [duplicate]

The "tyranny" of the Tsiolkovsky rocket equation means that more and more fuel is needed to reach higher delta-vs, and that the amount of fuel needed grows in greater than linear way. Does this mean ...
2
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2answers
486 views

Earth geopotential effect on orbit propagation

I'm trying to take into account the Earth geopotential effect on the orbit. The only term I could consider, is J2. Are the terms (J2, etc.) change with time? I ...
3
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1answer
68 views

Can we build a gravitational Radio by modulating the speed of Nuclear Reactions? [closed]

The idea is, if we can modulate the rate at which nuclear reactions take place (Fusion/Fission), can we create and modulate gravitational ripples in space time, more or less in the same was as we do ...
15
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2answers
5k views

How does a space probe maintain its trajectory while passing through the extreme gravitational field of the gas giants of our solar system?

Space probes like Voyager 1, 2, New Horizons, etc, traveled beyond those gas giants, how did they cope up with their extreme gravity? How was the trajectory of these probes unhindered by the immense ...
5
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1answer
547 views

How can I verify my reconstructed gravity field of Ceres from spherical harmonics?

Based on @DavidHammen's very helpful answer I've made progress reconstructing the gravity field of Ceres from the Dawn radiometric data. The question there contains further information, but suffice it ...
2
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1answer
284 views

Ceres gravity from spherical harmonics from Dawn, how to get the coefficients, definitions and potential?

update: I think I've found what I'm looking for. The file JGDWN_CER18C_SHA.TAB has what looks like spherical harmonics up to order 18, except I don't know the ...
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0answers
100 views

Space model transfer to moon displacement [closed]

I'm having a problem with the insertion from a LEO orbit into a moon orbit/ moon flyby in my gravity simulator. I use the calculations listed below. I think it is due to the fact that the moon pulls ...
15
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2answers
5k views

Is Mars' gravity strong enough to hold a human-breathable atmosphere?

If we ever try to make Mars outdoors habitable, won't the air just keep flying off into the outer space because of low gravity?
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1answer
100 views

Gravitational forces affecting acceleration on a space ship with artificial gravity [closed]

I and my brother are having an argument on gravity on a space ship. For this argument lets say, you are in a void. There are no outside gravity forces, ie planets or solar systems in the near region. ...
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1answer
149 views

What orbit is this?

Can this orbit exist around the Earth and the Moon if the weight and speed of the satellite is ideal? I have added a picture below with the orbit drawn.
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2answers
238 views

Gravity mapping of grail mission

This I asked has answers about how gravity is mapped of earth using orbit data of the satellites as measured by ranging. Using ranging one can fit the model parameters to fit the orbit as it passes ...
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2answers
132 views

Gravity Model measurement technique

Geopotential model are used whenever propgation has to be done of the orbit. Geopotential model models the potential of earth via spherical harmonics. These models are generally published by NASA as ...
5
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1answer
559 views

What living organisms adapt to 0 gravity?

Other than humans are there any other organisms with a brain that learn how to maneuver or act normal in 0 gravity? I saw a video of cats and pigeons at 0 gravity freak out but in time could they ...
2
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1answer
251 views

How quickly is the force of gravity exerted? Is a finite “speed of gravity” used in orbit calculations?

So I was reading a post of "What would happen if the sun disappeared". An excerpt: After eight minutes, the Earth would not only lose the sun's light and heat, but also its gravitational influence. ...
5
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2answers
365 views

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 ...
3
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1answer
195 views

Is there a way to reproduce Earth-like gravity on a spacecraft close to a more massive body such as the sun?

My gut impression is that an orbit would negate the feeling of gravity, and that if gravity were to be felt, it would indicate the orbit is decaying; an orbit, in effect, is the speed (or is it ...
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2answers
2k views

Why are centrifuges not used on the space station? [duplicate]

The low tech county fair ride in the picture below is a centrifuge. How difficult would it be to send modified one like this picture to space? It could spin on non bearing engine indefinably to ...
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0answers
46 views

How massive can a planet become before it is impossible to escape from using chemical rocket propulsion? [duplicate]

Assuming a vaguely Earth like world but with higher gravity, at what point is it no longer possible to launch a human being from the surface into orbit? Or anything into orbit?
2
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2answers
422 views

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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0answers
114 views

Are there clusters of small asteroids in the Kuiper or asteroid belt which could threaten the Earth?

I watched an episode of Curious Droid talking about the types of impacts of asteroids the size of Near Earth Objects. Are there clusters of small asteroids which are gravitationally bound together (or ...
2
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1answer
613 views

How to dock space-craft to the ISS?

ISS is orbiting the earth at a speed of 7.66 km/s. It's a really very high speed. So how does a spacecraft that is trying to dock achieve it? Do both spacecraft move at the same speed and in same ...
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0answers
57 views

Seismic effects resulting from tidal action on Ganymede and Europa

What kind of seismic activity is going to be generated by the tidal forces exerted on these two moon's ice sheets by Jupiter? Would it be a great enough differential in the ice sheets to preclude ...
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1answer
50 views

Asteroid belt to earth orbit [closed]

Given a constant 1g acceleration with a reaction-less drive how long would it take to achieve zero-zero in earth orbit from the asteroid belt?
16
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3answers
3k views

Can we destroy an asteroid by spinning it?

In a YouTube video Colonizing the Solar System, part 2: the Outer Solar System, Isaac Arthur who is a YouTuber and also a physicist says something like "you don't spin an asteroid for artificial ...
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3answers
4k views

Is is possible to generate centrifugal gravity by doing donuts?

With the correct rocket setup would it be possible to thrust around in a circle, like you would do donuts in a car, to generate centrifugal gravity?
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0answers
154 views

Satellite altitude variances in orbit

I understand that all satellites must have burn corrections to keep their orbits where they are needed. However my question is specifically about what those changes are in magnitude from the desired ...
4
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1answer
269 views

Earth gravity lens focus

Reading this question and then this report in a comment by @called2voyage At some point they talk about possibility to send (using antimatter as propellant) a space mission to solar gravity lens ...
16
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2answers
536 views

How large could Hyperion be and stay porous?

Here is a question originating on the Worldbuilding stack. Hyperion is porous, with a density of 0.55 g/cc; a little more than half that of water. from https://www.space.com/20770-hyperion-moon.html ...
4
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2answers
482 views

Estimate of effectiveness of gravity turn compared to vertical flight

How much higher is a rocket following a gravity turn going to be able to reach compared to a rocket following a vertical flight ? I understand that it depends on which type of rocket and which type ...
1
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1answer
304 views

What objects travel at the speed of light? [closed]

What elements travel at the speed of light. I was under the impression it was light and gravity but apparently electromagnetic waves (radio waves) travel that fast as well. And is element the right ...
4
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1answer
693 views

How does hypergravity affect the human body?

What would happen to humans if we set foot on Kepler-442b, where the surface gravity is predicted to be about 30% percent stronger than that of earth? If humans colonized the planet, would it then ...
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0answers
1k views

For the mathematical relationship between J2 (km^5/s^2) and dimensionless J2 - which one is derived from the other?

The term $J_2$ seen in discussions of nodal precession of orbits (e.g. sun-synchronous) appears to come in two flavors. For example, in the Wikipedia article Geopotential model it has a value of $1....
17
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1answer
454 views

Is GR required to send a probe to Mercury?

I understand that Newton's Law of Gravitation is still used today to calculate the paths of probes, since it is such an accurate theory. However, the Law of Gravitation does not accurately describe ...