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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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2answers
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Supports in 3d printing

Do astronauts print 3D in space with supports? They are needed only because of gravity, which - on a space station - obviously is not a problem.
6
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0answers
184 views
+200

What was Sutton talking about? How to “obtain small accelerations by taking advantage of difference in gravity as a function of altitude”?

Sutton and Biblarz's Rocket Propulsion elements says in Chapter 1, section 1.2 (editions 7, 8, 9, possibly earlier as well) that: Totally different methods of producing thrust are used in ...
23
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4answers
8k views

If human space travel is limited by the G force vulnerability, is there a way to counter G forces?

I read somewhere that prolonged G forces (even 2 Gs) are not tolerated by human physiology and that this ultimately limits our ability to sustain space travel. Are there any tactics to reduce G force ...
2
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2answers
155 views

Would a mouse trap snap faster or slower in space than on Earth?

Would a spring loaded mechanism outside a spacecraft activate a lever faster or slower in space with no atmosphere and gravity than on Earth? Basically this is in reference to mechanical instruments ...
8
votes
1answer
178 views

How far will the debris cloud from Hayabusa-2's touch-and-go sample recovery travel around Ryugu? Will any have escaped to heliocentric orbit?

HAYABUSA2 MOMENT OF TOUCHDOWN This animation, extracted from a longer video, shows the moment of Hayabusa2's 21 February 2019 touchdown on asteroid Ryugu. JAXA Source: Planetary Society's Watch ...
2
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1answer
104 views

Time to fall into the Sun from Mars orbit

If a body starts to fall freely from Mars orbit towards the Sun, then how can we calculate the time to touch the Sun' surface? I have tried the third equation of motion that says R=(1/2 dg)*dt^2. ...
2
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0answers
60 views

Will people living in Mars for several years be able to return to Earth without consequences?

Living without gravity has consequences for the bones and muscles. To counter that astronauts have to do exercise and lifting regularly when they go to the ISS. Now are there any plans to counter ...
2
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1answer
104 views

Ballistic missile typical trajectory - along which path is it supposed to travel between Russia, China and US?

Today I was puzzled when my son was holding a school globe asking me to show with my finger a trajectory of a (nuclear) ballistic missile flying from US to China and Russia and vice versa (from Russia ...
4
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1answer
100 views

How much is the difference of gravity attraction between the highest and lowest point on Mars?

Mars has a very high mountain, wich is the Olympus Mons measuring 25 km; while Hellas Planitia is a 9 km deep crater. How much the weight of a man that on Earth is 100kg, change between the highest ...
2
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3answers
197 views

Do Curiosity's reported measurements of Mars' surface gravity (~3.717 m/s^2) include centrifugal effects?

In this answer I discuss the first results in the 47th Lunar and Planetary Science Conference (2016) conference paper First Gravity Traverse on the Martian Surface from the Curiosity Rover and a more ...
5
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3answers
379 views

Two 1000 kg gold spheres orbit their CM in near-contact, great way to measure G or limited by spaceflight issues?

The hypothetical, non-existent crowdfunding site go-launch-me is so confident, they are offering a two-for-one special. For a limited time, if your project is funded they will foot the bill for a 2nd ...
3
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1answer
54 views

Using DART to measure G

NASA plans to launch a mission called DART to kinetically impact an asteroid, primarily for the defense of Earth. One thing that I've been thinking about is the same mission could be used potentially ...
4
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2answers
313 views

How would you move in low gravity without a suit?

Assuming your in a habitable environment, how would you move on a planet or moon with significantly less gravity without the encumbering EVA suit?
8
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1answer
194 views

How to manage landing on unlandable asteroids?

If asteroid's rotation period provides greater centrifugal force than gravity, having tangential surface velocity greater than escape velocity, and/or if due to an oddly enough shape, it has no fixed ...
21
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2answers
10k views

Could colonizing Moon dangerously affect its gravity?

If we colonized Moon it would mean we are moving matter from Earth to Moon. Since Moon is much smaller than Earth could these changes somehow affect its trajectory/movement to the point we could ...
3
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1answer
188 views

Time dilation between Mars and Earth due to different mass

I am not sure I understand the Time dilation correctly but if mass has dirrect impact on time...than lets consider cosmological event - one orbit of planet Earth around Sun. This event will person on ...
5
votes
1answer
74 views

Would a person exposed to zero gravity for a long time have trouble riding a bicycle?

I just watched this video by Drew Feustel showing him having trouble walking upright after 197 days on ISS: https://mobile.twitter.com/Astro_Feustel/status/1075889929119547393 They say once you have ...
6
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1answer
177 views

Does prolonged space flight have any effect on the physical traits of the human body?

Can a variable of physical traits like height, weight, complexion be changed in outer space? Maybe by gravity or by something else that determines these traits (like the UV rays of the sun that ...
5
votes
1answer
139 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
2k 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. ...
1
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0answers
111 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 ...
2
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1answer
66 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
91 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 ...
11
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2answers
4k 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
2k 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
122 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
180 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
79 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?
0
votes
1answer
85 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?
1
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0answers
33 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
votes
1answer
132 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 ...
3
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1answer
215 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
268 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
133 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 ...
5
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0answers
42 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
219 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
votes
1answer
64 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
237 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
votes
1answer
190 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 ...
1
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0answers
72 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 ...
12
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2answers
1k 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?
0
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1answer
89 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. ...
0
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1answer
126 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.
2
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2answers
232 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 ...
1
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2answers
109 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 ...
4
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1answer
203 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
224 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
242 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 ...