Questions tagged [escape-velocity]

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

Filter by
Sorted by
Tagged with
8 votes
3 answers
3k views

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 ...
user avatar
  • 83
2 votes
2 answers
78 views

Is it (theoretically) correct to apply an equation that is derived from a hyperbolic trajectory, to an elliptic transfer orbit?

The equation in question is this one: $$v^2 = v_e^2 + v_{\infty}^2$$ and it is showed in this answer. The Escape velocity page on Wikipedia mentions a link (num. 4) to the book "Fundamentals of ...
user avatar
  • 7,052
3 votes
1 answer
157 views

What's the escape velocity at the near/far end of Phobos considering tidal forces?

At the Roche limit tidal forces disintegrate bodies. A rock or a human would just float away from the points nearest/farthest from Mars. The tidal forces must be higher for rigid bodies than rubble ...
user avatar
  • 401
1 vote
2 answers
151 views

How much easier is it, to explore space from a low orbit satellite, than from Earth?

Note: in this question I'm considering cost in both money and fuel terms, and looking for answers that consider both. So we know that using chemical rockets to reach the moon, or further into space, ...
user avatar
  • 1,836
14 votes
4 answers
4k views

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 ...
user avatar
  • 274
3 votes
3 answers
446 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 ...
user avatar
9 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 ...
user avatar
11 votes
7 answers
5k 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 ...
user avatar
  • 111
73 votes
5 answers
18k views

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 ...
user avatar
  • 46.3k
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,...
user avatar
3 votes
1 answer
223 views

When doing an interplanetary Hohmann transfer, are additional escape and capture burns necessary in addition to the two Hohmann Transfer burns?

When doing a Hohmann transfer, it takes a burn to change from a low orbit to the Hohmann Transfer Orbit (HTO), and a second burn to change from the HTO to a high orbit. I know how to find the delta-v ...
user avatar
0 votes
2 answers
174 views

Did a spacecraft ever use an atmosphere to accelerate away from a planet?

If a spacecraft enters flat enough into the Earth's (or another planet's) atmosphere it will "bounce off" the Earth at a higher speed. That method can be used if a spacecraft has not enough fuel to ...
user avatar
16 votes
6 answers
4k views

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 ...
user avatar
  • 421
1 vote
1 answer
200 views

Confusion with direction (vector) of minimum velocity required to reach an orbit and escape velocity

In order to achieve a stable orbit around Earth, a spacecraft has to travel at velocity not smaller than approximately 7.8 km/s. If my understanding is correct, this figure refers to component of ...
user avatar
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 ...
user avatar
  • 1,944
10 votes
1 answer
367 views

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 ...
user avatar
  • 593
1 vote
1 answer
140 views

Where can I find simple-ish math(s) about Moon launches from Earth and fuel consumption etc.?

I'm intrigued by the idea of launching from the top of a space elevator perched on the top of a Ecuadorian mountain, launching Eastwards to take advantage of Earth's spin. I'd like to just understand ...
user avatar
4 votes
1 answer
221 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,...
user avatar
13 votes
1 answer
555 views

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 ...
user avatar
  • 593
6 votes
2 answers
5k 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 ...
user avatar
  • 6,729
3 votes
1 answer
275 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 ...
user avatar
  • 1
2 votes
1 answer
396 views

Astrophysics on "The Martian"

In the movie the martian what was the purpose of the hermes crew in blasting a part of the ship? Was that explosion on the front or back of the ship? After the explosion what happened to the speed ...
user avatar
2 votes
3 answers
306 views

How fast can an orbit exist in the solar system?

How fast is too fast to stay in orbit around any particular large body in the solar system?
user avatar
  • 1
15 votes
3 answers
4k views

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 ...
user avatar
  • 1
2 votes
1 answer
257 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 ...
user avatar
45 votes
3 answers
14k views

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 ...
user avatar
  • 1,814
3 votes
3 answers
2k 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 ...
user avatar
  • 51
16 votes
8 answers
10k views

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 ...
user avatar
  • 327
2 votes
1 answer
306 views

How to achieve escape velocity from Ceres?

If I am interested in a sample return mission to Ceres using a similar propulsion technology package to Dawn, what kinds of additional propulsion would be required to land and then return? ...
user avatar
  • 273
13 votes
1 answer
2k views

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 "...
user avatar
  • 148k
11 votes
3 answers
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 ...
user avatar
  • 414
31 votes
5 answers
10k views

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 ...
user avatar
5 votes
4 answers
2k 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 ...
user avatar
4 votes
1 answer
2k 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. ...
user avatar
-5 votes
1 answer
154 views

benefits of higher rocket speed [closed]

what benefits will a rocket get if it is made to go at a speed close to light... like 3 X 10^6? if the rocket is supplied with more efficient fuel and designed to obtain lesser drag there are ...
user avatar
2 votes
0 answers
148 views

At what gravity would the rocket equation mean "cannot reach orbit from the surface"? [duplicate]

I remember reading (a long time ago in a library far, far away...) that, if Earth's gravity were that much stronger, the rocket equation (?) would mean that it were impossible to actually reach orbit ...
user avatar
  • 199
-3 votes
4 answers
2k views

How did the Roadster get high enough to take a whole-Earth picture?

According to telemetry as seen in videos of the event, the car was ejected from the Stage 2 rocket at 114km above Earth. Anything less than 160km will immediately enter a rapidly decaying orbit and ...
user avatar
  • 23
9 votes
2 answers
446 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 ...
user avatar
  • 17k
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 ...
user avatar
  • 309
6 votes
1 answer
260 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 ...
user avatar
  • 26.2k
12 votes
2 answers
1k views

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 ...
user avatar
  • 121
2 votes
2 answers
3k views

Would it be possible to go beyond Jupiter without making any slingshot?

It is said that we do not have such advanced technology in order to send a spacecraft out of the solar system. (Source: Everyone around) When a spacecraft is launched from Earth and aims to leave the ...
user avatar
  • 604
9 votes
3 answers
5k views

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 ...
user avatar
  • 604
1 vote
2 answers
489 views

What is the characteristic time to reach a hyperbolic excess velocity within a sphere of influence?

When departing a planet using a hyperbolic trajectory, one should ideally reach the sphere of influence boundary with an excess velocity needed for interplanetary transfer. Of course, the true excess ...
user avatar
  • 1,944
7 votes
1 answer
345 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 ...
user avatar
  • 1,944
3 votes
1 answer
2k 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 ...
user avatar
  • 604
2 votes
1 answer
8k views

Does escape velocity apply to rockets? [duplicate]

I know so far that escape velocity on the surface of Earth is 11.2 km/s Wikipedia says that escape velocity is the minimum speed needed for an object to escape from the gravitational influence of a ...
user avatar
  • 604
3 votes
0 answers
167 views

Isn't the escape velocity for the solar system at the Earth 42.1 km/s? Then why does the graph show 36 km/s for the same value? Is the plot wrong? [duplicate]

The graph shows that 36 km/s is the escape velocity of the solar system at the Earth. But if we do some calculations, we will get 42.1 km/s as the right answer. I have been checking all other escape ...
user avatar
  • 604
1 vote
3 answers
134 views

Payloads pulled into orbit/space [closed]

The way soldiers meet a wall in an obstacle run; they boost 1 or 2 of the team up to the top and then those up there help pull their colleagues up and over. Just wondered if there might be a way ...
user avatar
4 votes
0 answers
513 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 ...
user avatar