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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144
votes
12answers
168k views

Couldn't I escape Earth's gravity traveling only 1 mph (0.45 m/s)?

It is said that in order for an object or a projectile to leave Earth's gravitational pull, it must reach Earth's escape velocity, meaning reach a speed of 7 miles per second (~11 km per second). Well,...
8
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1answer
136 views

Sensitivity of Space Telescopes and Instruments

I have been doing a bit of light reading on space telescopes and have been amazed by the reported sensitivity of some of the instruments. In particular, the Laser Interferometer Space Antenna (LISA) ...
5
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3answers
506 views

Lunar sub-orbital trajectories

How do you determine (what is the formula?) the delta-V for a sub-orbital 'hop' from one location on the Moon to another? Is it different from a typical orbital calculation?
33
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3answers
4k views

What causes microgravity (i.e. non-zero gravity) in orbit?

NASA and others seem careful to talk about microgravity instead of zero gravity. Why is for example the ISS not in zero gravity? Is it because of movements onboard? Because of variations in center of ...
8
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3answers
810 views

Gravity Assist - Orbiting Satellites & Speed Increases

So, a gravity assist in very simple terms is when an object uses a planet's gravity and rotating momentum to increase the objects speed. If this is true, why doesn't the ISS get further and further ...
8
votes
1answer
698 views

Is there a profile of atmospheric pressure and gravity of Uranus?

One of the intriguing facts about Uranus is that somewhere within the gravity is about 0.9g. Now, if one wants to daydream about living on Uranus in slightly chilly balloons, it would be interesting ...
5
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1answer
404 views

Could increased atmospheric pressure act as a countermeasure for effects of microgravity?

Are there any possibilities to counter the negative effects of low or micro gravity by increasing the atmospheric pressure?
12
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2answers
433 views

What work is being done to develop and test artificial gravity?

There are many ways to produce artificial gravitational effects, such as a rotating spacecraft, linear acceleration, or harnessing magnetism. Possibly there are other ways to produce gravity that have ...
5
votes
1answer
359 views

Are Delta-V requirements for leaving the surface of a planet proportional to gravity?

I am trying to gain some intuition about Delta-V requirements. My understanding is if the Delta-V budget was doubled, the difficulty of the mission is more than double because of the exponential ...
3
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2answers
1k views

Where is the gravity generated on a spaceship in super fast space travel?

After reading the question: Is artificial gravity feasible in manned long-term space exploration?, I am having a hard time imagining what experiencing the "continuous acceleration" method of gravity ...
6
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1answer
937 views

How do I calculate lowest possible mission delta V from Escape velocities?

The gravitational potential of an object around the sun, relative to some point far far away (from the sun), should be smaller zero and proportional to $V_{escape}^2$. Hence the speed one needs should ...
25
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6answers
17k views

Could a Human reach escape velocity by jumping from the surface of Ceres (a dwarf planet)?

According to this answer the surface gravity of Ceres is estimated to be only $0.27 m/s^2$. With a rotation period of 9 hours. The gravity seems light enough to overcome by leg muscle alone, and if ...
9
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2answers
3k views

Why do malfunctioning satellites come back to Earth?

In school, I learned that if a satellite moves at a speed $\sqrt{gR}$ (the square root of the product of the acceleration due to gravity and radius of the Earth), then it will remain in Earth's orbit. ...
22
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1answer
3k views

How did the Apollo astronauts train for the 1/6G lunar landing?

It goes without saying that training/conditioning one's reflexes for a situation is highly relevant to some professions. Pilots train in a computer simulator. During the Apollo missions computers ...
10
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2answers
753 views

Is it possible to perform the Galileo's Leaning Tower of Pisa experiment on the Moon?

Since the Moon has no atmosphere, is it possible to perform the Galileo's Leaning Tower of Pisa experiment on its surface? Has any astronaut performed anything similar?
8
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1answer
109 views

To what celestial bodies are GRAIL-like missions planned?

GRAIL recently constructed a complete gravity map of Luna's irregular gravity field. Are similar GRAIL missions on the anvil to any other Celestial bodies as yet? As a corollary (probably opinion-...
14
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1answer
4k views

How does the gravity of a massive non-spherical object act on things around it?

Firstly, not sure if this question ought to be in the physics SE site. Please let me know if it should. Secondly, I don't know a whole lot about physics (I'm just inquisitive). So please try to keep ...
6
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1answer
64 views

Will any near future lunar missions use GRAIL data?

Lunar missions are known to be the subject to the exceptionally disuniform gravity. GRAIL generated a very high resolution gravity map of Luna. Will any missions to Luna in the near future (say, ...
10
votes
1answer
595 views

Besides Luna, what celestial bodies exhibit lumpy gravity?

http://www.space.com/21364-moon-gravity-mascons-mystery.html writes to say ...These geologic structures, called mascons (short for mass concentrations), are so dense they alter the moon's ...
0
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2answers
118 views

Is there a table of the gravitational pull of a spacecraft? [duplicate]

I would like to put a spin on What is the maximum mass of a satellite that can be placed in GEO? Gravity is a function of the mass of both (all) bodies, and their relative separation. Wikipedia lists ...
13
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2answers
2k views

Alcubierre “warp” drive and gravitation/orbital considerations

There are a few questions regarding the Alcubierre drive here, so I'll pose this one and see what I get. Currently, our space exploration vehicles, both manned and unmanned, are at the mercy of ...
5
votes
1answer
1k views

Does a gravity assist increase the g force on the ship?

In my mind, I picture a gravity assist sling shot boost like a ball on the end of string being swung until the centrifugal force grows strong and then is released. Where gravity is the string, the ...
10
votes
1answer
593 views

Back to Earth's gravity, what astronauts do?

After a long period in space and once back to earth, what do astronauts to get again used to the Earth's gravity?
5
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1answer
596 views

Does living in space affect humans' strength?

I am an enthusiast of space exploration. Is it possible that strength of a human can be increased or decreased by keeping them in microgravity? From this link. Astronauts can become as weak as 80-...
5
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3answers
1k views

Could a black hole be used as portable gravity device? [closed]

I don't use the term artificial gravity because, the gravity from a black hole is real. If you have harnessed and are able to control a black hole would you be able to use it as portable gravity ...
6
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5answers
8k views

How to simulate Earth's gravity in future colonies on other planets?

What would be a viable means to simulate and maintain Earth's gravitational acceleration in a future colony built on another planet? I am mainly focusing on terrestrial planets, where a colony could ...
14
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4answers
1k views

How do spacecraft measure onboard gravity?

How do spacecraft measure onboard (micro)gravity at any given point in time (especially when subject to the gravitational fields of multiple bodies)? I'm guessing that rudimentary accelerometers won't ...
19
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2answers
2k views

How deep is the force well of L4 and L5 Lagrangian Points of Earth-Sun set?

The Lagrangian Points are points in space, where the combination of gravitational pull of a set of two bodies and the centripetal force of orbiting one of them add up to zero. The special property of $...

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