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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30 views

How do you calculate gravity loss (simplified)?

Assume a rocket with constant mass and thrust. To simplify things, we can ignore aerodynamic drag, and we'll also not perform a gravity turn, hence our flight plan is as follows: -Burn radially from ...
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Why aren't globular clusters disk-shaped? [migrated]

I thought that solar systems and galaxies are disk-shaped because that is the most stable shape under gravitation. Globular clusters are very old, often times older than their host galaxies, so why ...
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1answer
348 views

Can a “gravity assist” at a black hole accelerate light faster than the speed of light? [closed]

With the help of a gravity assist from a black hole, can light travel faster than its natural light speed?? Satellites use gravity assistance. In a similar way can light traveling near black hole ...
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How much higher could g be before we couldn't launch rockets? [duplicate]

Obviously having a higher gravitational acceleration makes it harder to get rockets into orbit / escape. How much stronger could earths gravity be before we would no longer be able to do the sort of ...
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1answer
914 views

How many satellites can stay in a Lagrange point?

Lagrange points as I understand it are points in space between 2 objects where the gravitational pull between them is effectively equal. That makes station keeping at these points relatively easy. ...
2
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1answer
62 views

How microgravity in space affects body parts

There are things that naturally face downwards, like hands. How would they be affected in space microgravity? Would they rise or point downwards?
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2answers
98 views

What Gravity does the Sun affect items with at the distance of 1 AU?

At the surface of the Earth, the force of gravity is defined as 1 G. I am wondering what gravitational force the sun excerts at the distance of 1 AU (the distance Earth is at). Imagine it like this; ...
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What's the point/area of space called where there is equilibrium between 2+ different gravitational forces?

For some reason I want to call it a 'gravity well' but I know that a gravity well is just the gravitational force distribution in space due to an object with mass. But regarding my question, isn't ...
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2answers
117 views

What is the formula for Legendre Polynomials from EGM96 calculated in F447.f program?

The F447.f program is designed to calculate the geoid undulation for EGM96. I'm trying to understand how it accomplish this calculation. I stuck in ...
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0answers
62 views

Lambert problem solver needed for custom gravity in Python

I need to solve the Lambert problem, however, I have a custom gravity model. My ODE of motion is: ...
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1answer
114 views

What would a candle flame look like in low gravity?

We know what the flame of a candle looks like on Earth in 1g and what it looks like in weightlessness. But do we have an idea of what it would look like in Lunar (0.166 g) or Martian (0.38 g) gravity? ...
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114 views

At what surface gravity can't astronauts do full steps anymore?

We know that on the Moon in ~1/6 g the Apollo astronauts couldn't make full steps because they jumped with each step. At what surface gravity could you walk more like on Earth and at what gravity ...
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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.
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1answer
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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 ...
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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 ...
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2answers
158 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
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1answer
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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 ...
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1answer
108 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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1answer
98 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 ...
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1answer
126 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 ...
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1answer
109 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 ...
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3answers
223 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 ...
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3answers
407 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 ...
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1answer
56 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 ...
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2answers
350 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?
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1answer
206 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 ...
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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 ...
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1answer
230 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 ...
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1answer
78 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 ...
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1answer
184 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 ...
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1answer
150 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 ...
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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. ...
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2answers
266 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
69 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 ...
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1answer
94 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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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 ...
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2answers
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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 ...
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1answer
129 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: ...
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2answers
237 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 ...
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1answer
88 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
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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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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 ...
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1answer
134 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 ...
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1answer
299 views

JGM-3 vs EGM2008 coefficients

I've implemented the Earth harmonics calculation in JGM-3 model, using the coefficients from here ...
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1answer
289 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 ...
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1answer
143 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}=\...
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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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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 ...
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2answers
249 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 ...
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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 ...