Questions tagged [escape-velocity]

The speed needed to "break free" of the gravitational attraction of a body without spending more propellant.

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146 votes
12 answers
185k 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,...
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118 votes
6 answers
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How much bigger could Earth be, before rockets wouldn't work?

hint: Apparently the Tsiolkovsky rocket equation does not actually say that you can launch a conventional rocket into orbit around an arbitrarily large and massive body. I'm looking for a number ...
uhoh's user avatar
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73 votes
5 answers
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Why is it easier to escape the solar system than get to Mercury or the Sun?

It has been mentioned several times on this site that it is "easier" (less delta-v, and hence less fuel) to reach the escape velocity of the solar system, than to reach the planet Mercury or ...
DrSheldon's user avatar
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Has any human ever had the choice to leave Earth permanently?

Far beneath the ship / The world is mourning They don't realize / He's alive No one understands But Major Tom sees / "Now the light commands This is my home / I'm coming home." Peter ...
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31 votes
5 answers
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Why not travel to Mars in 2 months?

Just to clarify: I've made some research and generally know what the case is, didn't mean to make the question sound stupid. :) I know there is a thing called Hohmann transfer orbit, named after ...
Martin Asenov's user avatar
30 votes
10 answers
14k views

How many times do you have to circle the Earth to break orbit?

My science teacher asked us this, and nobody in my class knew. We guessed it would be three, but with no evidence. (Edit: The asker has not returned to clarify if they meant leaving the Earth-Moon ...
Patrick's user avatar
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30 votes
5 answers
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How could an object barely exceeding escape velocity from the Moon eventually reach the Earth?

Since NASA is once again targetting low-cost missions to the Moon, I was thinking about low-cost methods of getting stuff from the Moon back to Earth. Although it seems reasonable to assume that ...
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29 votes
3 answers
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Why did Voyager 2's velocity drop far below escape velocity before the first gravity assist?

As per @kasperd's comment on another question. Looking at the graph below, it appears that Voyager 2 started at just over escape velocity of the solar system. Just before the Jupiter flyby, it was ...
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26 votes
7 answers
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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 ...
James Jenkins's user avatar
20 votes
1 answer
15k views

What is the escape-velocity for our galaxy?

What should be the escape velocity for our galaxy and can we calculate it? For instance, if we assume that we don't know the mass of our galaxy, you may consider it as small 'm'.
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16 votes
8 answers
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Why didn't Voyager 1 and Voyager 2 crash on into Jupiter or Uranus when they approached near to these massive planets?

I was reading about gravity assist and I read that both the Voyagers used gravitational force of these planets to speed up. But I wanted to know why weren't they completely attracted by their ...
Gamira's user avatar
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16 votes
6 answers
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Non-orbital takeoff and landing?

I know it is a naive question, but somehow I couldn't find where it is answered here earlier. There have been a number of questions and answers detailing how spacecraft need to achieve high orbital ...
Gnudiff's user avatar
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15 votes
4 answers
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What is the most fuel efficient way out of the Solar System?

I understand with current technology we can't just fly a straight line out of the solar system but which way out would need the least fuel? Currently to navigate the solar system it is a dance ...
Muze's user avatar
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14 votes
4 answers
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Why is it so hard to build crewed rockets/spacecraft able to reach escape velocity?

Why are we still not going farther than to Low Earth Orbit? Orbital velocity is about 4.8 mi/s (7.7 km/s) and escape velocity is about 7 mi/s (11.2 km/s), about 45% faster. Why is it so hard to reach ...
Greenhorn's user avatar
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13 votes
1 answer
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Largest radius sphere with Earth's surface gravity on which you could jump at escape velocity? Bigger than B612?

In the book Le Petit Prince by "French aristocrat, writer, poet, and pioneering aviator Antoine de Saint-Exupéry" the main character lives on an extremely tiny asteroid with the name B612. It is this "...
uhoh's user avatar
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13 votes
2 answers
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Is there a theoretical limit to the size of launch vehicles?

Is there a limit to the size (mass, structural issues) of boosters that can be launched either to orbital or escape velocity? I am asking about such constraints as the required thrust to weight ratio ...
DaveG's user avatar
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1 answer
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Are there any possible methods for keeping surface water on Mars?

I've been reading this wikipedia article on terraforming Mars. One of the major issues with terraforming Mars is essential molecules and elements escaping the planet. There have been several ...
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11 votes
7 answers
6k views

How fast is fuel escaping a rocket for it to reach the escape velocity 11 km/s?

I was having a discussion with a person and we were talking about whether or no the fuel had to be pushing out of a rocket at 11 km/s in order for the rocket to reach 11 km/s. I said it has to be ...
Adam's user avatar
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11 votes
6 answers
3k views

What kind of mission objective would make a parabolic escape trajectory desirable?

As far as I can tell, a trajectory with zero excess velocity would place it (essentially) in nearly the same orbit around the sun as earth (assuming it even departs far away enough for the sun’s ...
Paul's user avatar
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11 votes
3 answers
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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 ...
user27822's user avatar
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3 answers
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How could we make a fair comparison between space rockets regarding their payload mass in low Earth orbit and Earth escaping?

I was searching for comparisons between space rockets regarding their payload mass in low Earth orbit and Earth escaping. First one to see capability of the space booster (the first stages) and second ...
John Howell's user avatar
10 votes
1 answer
1k views

Are there any accurate velocity plots of all spacecraft that achieved escape velocity from the solar system? (Pioneers, Voyagers, & New Horizons)

The answer to this question provides a seemingly accurate plot of the velocity of Voyager 2 over distance along with the heliocentric escape velocity. Are there similar graphs for the other 4 ...
user177107's user avatar
10 votes
3 answers
813 views

How close was Philae to escape velocity during its first bounce?

ESA indicates that the first bounce lasted two hours and reached a height of 1 km. With the extremely weak surface gravity and low escape velocity of the body (< 1 m/s), and other publicly ...
pericynthion's user avatar
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10 votes
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what happens to particles that escape the atmosphere on planets in the solar system?

What happens to particles that escape the atmosphere of planets? (not just earth). Do they eventually form a uniform distribution of particles overtime? Do they inevitably to fall into the ...
Krupip's user avatar
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9 votes
3 answers
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How do we come up with the gravity assist (or slingshot) formula?

When you search up in google gravity assist formula, it comes up with the simplest version: Which means that: Final velocity = Initial velocity + 2 (velocity of the planet) Then if we do some more ...
Matthew's user avatar
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9 votes
2 answers
481 views

Could Starman get ejected from the Solar System?

This is not about a prediction of Starman's fate, although it might be interesting to find it so. This is about any object having similar aphelion and perihelion values to Starman (Elon Musk's Tesla ...
Anthony X's user avatar
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8 votes
3 answers
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Is escape from earth, hyperbolic in reality?

I have been reading on orbital mechanics and its strewn everywhere that beyond the escape velocity from any orbit around the earth, the trajectory is a hyperbola that approaches V_infinity and with ...
NRB's user avatar
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8 votes
3 answers
2k views

How far away will I get if I'm --just under-- escape velocity?

The escape velocity of earth is about 11.2 km/s. Let's say it was, for the sake of argument, exactly 11.2 km/s. If I go 11.199999 km/s, I'm going to fall back down to earth. But how can I determine ...
corsiKa's user avatar
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7 votes
1 answer
386 views

What factors determine how long a window of opportunity opens for an interplanetary hohmann transfer?

I know that one can determine the approximate wait time for a window of opportunity to open up for an interplanetary transfer based on the relative positions and velocities of the two planets in ...
Paul's user avatar
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6 votes
4 answers
3k views

How much Delta-V would be required to escape the Gravitational Influence of the Earth without entering orbit?

As impractical as it sounds (and it's definitely impractical) I was wondering what the Delta-V required to leave Earth's influence would look like if we launched "just straight up" into the Earths ...
Magic Octopus Urn's user avatar
6 votes
2 answers
7k views

What are the G forces leaving Earth orbit?

What were the G forces experienced by the Apollo astronauts during the translunar injection burn? Was there a lot of vibrations during the TLI burn? Is there estimates of the G forces an astronaut ...
Bob516's user avatar
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6 votes
1 answer
512 views

What is the relationship between the radius of the Hill sphere and escape velocity?

I'm currently working on a video game that will make use of a heavily simplified patched-conic model of the Solar System. I was wondering about some discrepancies between my own calculations as well ...
Vlad's user avatar
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6 votes
1 answer
277 views

What speed did the (interstellar) comet C/2017 U1 PANSTARRS have at perihelion?

C/2017 U1 PANSTARRS is a comet with an eccentricity of close to 1.2, so it is a strong candidate for having interstellar origin. It's perihelion was at 0.25 AU. What speed did it have relative to the ...
LocalFluff's user avatar
5 votes
2 answers
3k views

Apollo 11 mission report shows velocity well below escape velocity thousands of km on the way to the Moon

This is from the Apollo 11 mission report. It says the vehicle was going at 7.6 km/s when the CSM separated from the third stage. It was not in orbit at this point, it was thousands of KM from earth. ...
user26129's user avatar
5 votes
3 answers
1k views

Is non-evacuated tube maglev launch possible? [duplicate]

I heard about evacuated tube transportation technology and it's application to launch cargo or even shuttles to space. Example of such project would be StarTram. The fact that acceleration phase to ...
Marek's user avatar
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5 votes
1 answer
1k views

Would a sniper bullet fired on Ceres reach orbital or even escape velocity?

What would happen if you fired a sniper bullet horizontally from the top of Ahuna Mons, the highest mountain of Ceres? Once I read somewhere that if you fired a bullet on the Moon in the correct angle,...
LoveForChrist's user avatar
5 votes
1 answer
1k views

Is space travel possible from a large planet? [duplicate]

I was playing with a rocket design simulator, and I noticed that if I set Earth's gravity to be much higher than it is today, it became impossible to design a rocket that could reach escape velocity. ...
Beaker's user avatar
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4 votes
2 answers
2k views

Why can't deep-space missions escape orbit by skipping off the atmosphere?

If skipping off the atmosphere during re-entry runs a real risk of of the spacecraft "escaping" from orbit, why don't deep-space missions use this method instead of using power to reach escape ...
Aaron J Spetner's user avatar
4 votes
2 answers
2k views

How much thrust to launch a regulation size FIFA soccerball into orbit

How much thrust is necessary to launch a regulation size FIFA soccer ball into orbit around the Earth? Let us assume a size 5 which weighs between 420g and 450g. Remember, we will need thrust to ...
Maximin's user avatar
  • 59
4 votes
3 answers
863 views

Is it possible to launch picosatellite into orbit from railgun on high-altitude plane?

Is there some combination of a plane that flies high enough, with a railgun small enough to fit into the fuselage, and a satellite small and durable enough, to make this feasible?
Benito Ciaro's user avatar
4 votes
1 answer
319 views

Belt of matter at ~14 AU?

In this terrific answer user Hobbes presents a graph of escape velocity as a function of distance from the Sun: I notice that at about 14 AU the graph goes from decreasing exponentially to ...
dotancohen's user avatar
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4 votes
1 answer
299 views

Sulphur Hexafluoride atmosphere for Ceres?

So, I have read that the escape velocity of Ceres is 514 m/s, and orbital velocity(for a low orbit) is 360 m/s... Now, the RMS(Root Mean Square) velocity of Sulphur Hexafluoride at 72 $^o$F (23 $^o$C,...
mzs.112000's user avatar
4 votes
1 answer
473 views

Laniakea Delta-V and Escape Velocity

We live in the Laniakea supercluster. Galaxies including the Milky Way are being pulled toward the "Great Attractor" in its center. Two questions (note that the answer to one can be used to derive ...
geometrian's user avatar
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4 votes
0 answers
519 views

Why is an escape velocity needed? [duplicate]

This is probably a stupid question, so I apologise in advance, but why is it that you need to achieve a certain speed to leave the planet? I understand that an orbit needs a speed so that when you ...
Alex Mann's user avatar
3 votes
3 answers
3k views

Apollo Missions - Travel time to moon [duplicate]

I must be missing something - escape velocity is about 25,000mph. The distance to the moon about 240,000 miles. That computes to about a 9 hour flight. Why did it take 3 days for Apollo missions to ...
Marvin's user avatar
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3 votes
1 answer
601 views

What is the escape velocity of Saturn at Enceladus distance?

To what velocity would a spacecraft have to accelerate to launch from the surface of Enceladus into orbit around it? And from the orbital distance of Enceladus, what would be the escape velocity from ...
Eric Nielsen's user avatar
3 votes
3 answers
543 views

Bucket loop between Earth and Moon?

Please don't bite my head off. If this is so stupid that it deserves to be squashed, I'm quite happy to delete the question. I mainly would like to know whether anyone's ever suggested this (I ...
mike rodent's user avatar
3 votes
1 answer
377 views

Has any human had the capability of leaving the Solar System?

Inspired by Has any human ever had the choice to leave Earth permanently? and the answers and comments there, has any human had the capability of leaving the Solar System? I'm thinking of Apollo ...
Andrew Henle's user avatar
3 votes
1 answer
327 views

Could escape velocity be achieved in the atmosphere?

When rockets launch for orbit they travel up and the air thins respectively to the speed increasing. How fast can a rocket for travel at sea level before it would fail or the elevation would have to ...
Muze's user avatar
  • 1
3 votes
1 answer
3k views

Roughly, how fast do rockets travel?

I know that different rockets are built with different a range of different sizes or purposes, but there must be some kind of range of typical speeds for those things when leaving the Earth. So how ...
Matthew's user avatar
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