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50 views

Time relativity

Lets say that I am on a spaceship moving with the speed of 0,90c and I am looking on my friend who stayed back on earth. My friend is looking on me. From my perspective, my friend is moving 7 times ...
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1answer
42 views

Humans on earth seen from traveling space ship

If I would stand on a space ship traveling with a speed of 0,99c I would be moving 7 times slower from Earth's perspective. But if I would look back on Earth I would see everything moving 7 times ...
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2answers
78 views

Why is an Alcubierre drive shaped like it is

When I look up the Alcubierre drive I keep seeing that the drive powering the bubble is shaped like a circle - is this necessary for the creating of the "warp bubble" that travels forward? Does the ...
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1answer
74 views

How do spacecraft gain kinetic energy by passing near planets? [duplicate]

When a a spacecraft like Voyager travels close to Jupiter, it somehow gains kinetic energy. I'm not sure how this energy isn't simply lost again as it moves away from Jupiter. I'm also hoping this ...
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0answers
48 views

What's the fastest you can slingshot from one black hole to another? [closed]

Let's say you have your spaceship orbiting around a black hole. Its orbital velocity is arbitrarily close to the speed of light (or you can just set it to c*0.99 if it makes it easier.) There is ...
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2answers
77 views

Is it possible to reach outer space with this method? [duplicate]

Could we use a hot air balloon to carry a rocket and send it into orbit at a higher altitude? That is, do I need to reach a specific speed to be completely free of Earth's gravity, or can I just ...
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2answers
1k views

How does a spacecraft enter Earth's atmosphere?

If Earth whirls around the center of our galaxy at some 220 kilometers per second, how can a spacecraft, which is much slower, enter Earth's atmosphere when returning from Mars for example?
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1answer
100 views

Traveling faster than the universe is expanding?

I was thinking, if the universe is space and time expanding, lets say in 3D (like a sphere). And it is doing that in a constant or not constant speed, there is a debate about that, never mind that but ...
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2answers
82 views

What sort of propulsion technology would allow spaceships to lift off the surface of the Earth and ascend into space like we see in sci-fi movies?

In many sci-fi films, spacecraft are easily capable of lifting off the surface of a planet like a Harrier and ascending into space. It's clear that the propulsion system/jet engines aren't your ...
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0answers
42 views

How realistic is a “bolas” system for artificial gravity in space travel?

The spinning space-station is very popular in sci-fi as a means of emulating gravity in space. But it requires rather a large diameter to minimise "gravitational gradient" effects and that means such ...
2
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2answers
34 views

Does the microgravity environment in highly elliptical orbits differ from circular orbits?

I think everyone understands the microgravity environment broadcast from the ISS. But the ISS stays in a fairly circular orbit, the acceleration of gravity should be fairly uniform, the altitude and ...
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0answers
81 views

The effect of multiple Alcubierre rings

In all of the descriptions and visualizations I've ever seen of the Alcubierre drive but one, it takes the form of a single ring or toroid surrounding a spherical volume of flat space. The exception ...
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6answers
9k views

Could we send a man safely to the Moon in a rocket without knowledge of general relativity?

I'm wondering if it's possible to send a man to the Moon using equations consistent with Newtonian gravity and without the elaborate tools of Einstein gravity. Are the predictions made by Newtonian ...
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4answers
3k views

Is it possible to sail “close hauled” with a solar sailship?

I have not been able to find a clear or decisive answer about this. On Earth, a ship sails close hauled when the ship is, to some degree or another, facing into the wind. This is made possible with ...
1
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1answer
75 views

If there were intelligent life in another galaxy, would we notice? [closed]

I've read that once intelligent life successfully achieves interstellar travel, it could populate the galaxy in tens of millions of years, likely populating the most habitable planets and preventing ...
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1answer
90 views

How much energy would it require to send Earth to Proxima Centauri?

Assuming 100% efficiency of energy usage, and given the current estimates about the mass of known objects in our solar system, including Earth itself, and assuming no other objects are affected by ...
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0answers
30 views

Modeling atmospheric reentry with respect to the rotation of a planet and its atmosphere in a simulation

I am creating a hard science fiction flight simulator. I am a civil engineering student, so its a little out of my area of study. Currently I model air resistance on the velocity difference between ...
2
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2answers
53 views

How can solar sails be maneuvered?

Photons from the Sun are always radial to it and hence solar sails can only travel radially. Any techniques related to maneuvering?
2
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1answer
48 views

Does the payload of an Alcubierre drive have to be on board during the preparation phase?

I was thinking about the practical aspect of using an Alcubierre drive, assuming one existed. I'm no expert, but my understanding is that, since the destination has to be in the forward light-cone of ...
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1answer
60 views

What size astroblaster would be required to shoot a man to the moon (as alternative to rocket propulsion systems)?

Accord. to my Prof. a 92 astroblaster would be sufficient to shot a ball to the moon. I have done some research on the internet, but could not find any sufficient source. Does anyone know about ...
2
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0answers
61 views

What does it look when we travel at the speed of light? [closed]

Suppose we're in a spaceship or in a car which runs at the speed of light. We are watching the light which is coming towards eyes at the speed of the light. What would it look like when the driver ...
0
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1answer
28 views

If we are traveling to Mars in Hibernation State [closed]

If we are traveling to Mars in Hibernation State with artificial gravity. Which hibernation position of our body is the best i.e. lie flat or stand up, considering making bone loss as less as ...
3
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1answer
152 views

Why does the Cassini probe experience jerky acceleration in deep space?

I was looking at this plot of speed over time for the Cassini probe. What's going on at the right, after mid-2004? Why does it keep slowing down and speeding up again?
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1answer
722 views

Movie Interstellar - Question about Escape Velocity

The movie Interstellar shows people on a water planet where time is dilated so much that 1 hour is equal to 7 years back on Earth. Even though they lift off from Earth using a Saturn-V two stage ...
2
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1answer
2k views

Questions after watching the movie Interstellar [closed]

Awesome movie, but as a physics student, some questions do crop up When they travel to the watery planet, they say that 1 hour on this planet is 7 yrs om earth. How is this possible? Is the planet ...
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0answers
34 views

Why are centrifuge space-station designs not a reality? [duplicate]

Considering how useful it could be for the crew of a space station to have at their disposal a 1g environment (or more) at the rim to a 0g environment at the axis of rotation, why aren't modern space ...
2
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2answers
125 views

How is strong time dilation consistent with weak tidal forces?

Nolan's latest film, Interstellar, takes pains to explain to lay audience members that the passage of time slows in the presence of strong gravitational fields (as per Einstein's theory of General ...
3
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1answer
216 views

Burning fuel in space while accelerating and deaccelerating

Is it true that for acceleration in space we need not the same quantity of the fuel than during the deacceleration stage?
2
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4answers
248 views

Conservation of potential energy for a wormhole

So you managed to build a stable traversable wormhole. Somehow you managed to acquire the exotic negative-tension materials with sufficient densities to make it all work. Now you place opening A of ...
65
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4answers
7k views

Where does the extra kinetic energy come from in a gravitational slingshot?

I read in this answer in this site that the KE a free-falling ball acquires is not originated by the attracting body but that energy was actually stored in the ball when it had been lifted to the ...
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1answer
148 views

If it takes less than a year to accelerate to the speed of light at 1g why will it take the Voyager 10,000 years to reach Alpha Centauri?

Today I was doing my physics homework and there was a problem involving a space ship falling at 9.8 m/(s^2) to simulate gravity, and it asked how long would it take for the ship to reach to speed of ...
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0answers
120 views

Is it possible to build a huge spaceship like the one of of Star Trek or Prometheus?

Ok, so theoretically, is it possible to build a spaceship like the ones we see off of Star Trek or Prometheus or will physics not allow it? What are some challenge faces such an task. Also, is there ...
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3answers
122 views

spacecraft thrust through means other than liquid propellants

Is there any way of achieving effective thrust in space without using conventional fluid or gas propellants such as rocket-fuels or supercooled material? For instance: gaining thrust through solar ...
0
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1answer
60 views

Can we use water as fuel for nuclear thermal space propulsion?

As I know, the working fuel of choice is Hydrogen because of its low molecular mass. When it comes to escape velocity, the estimate vary too much, from $8$km/s to $50$km/s (gas core reactor). ...
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3answers
2k views

Is interstellar flight possible in near future in a way that would keep our civilization alive?

Is interstellar flight possible in the near future in a way that would keep our civilization alive? I mean is it practically possible to obtain technology that would enable us to travel to nearby ...
2
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4answers
158 views

How much could one slow down aging using existing spacecraft?

Imagine that I board a spacecraft and head away from the Earth at top speed until I've aged twenty years, then I turn around and come back. How much younger will I be than the unexciting folk who hung ...
0
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1answer
109 views

Does speed in space really matter?

This is about validating the science from a science fiction novel. My understanding is that speed is all relative. So while I am in a car on the freeway my speed relative to another passenger is ...
1
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1answer
81 views

How can I calculate the relationship between power and acceleration for a beam driven photon sail?

I am writing a novel, and although I have a background in physics, I am unsure of the exact equations to use. Specifically: For a photon-sail ship, how powerful would a driving laser need to be in ...
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3answers
1k views

Why does the speed of the propellant limit the speed of a space ship in open space?

Isn't speed a relative thing in space? If so, why would the speed of a propellant matter? Why can't a space ship accelerate infinitely?
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1answer
60 views

Spacecraft momentum question [closed]

Assume you're sitting in your spacecraft. The mass of you and the spacecraft is 2000 kg. You're traveling at 200km/h through the vacuum of space. You have a thruster pointing in the direction you're ...
1
vote
1answer
145 views

What would be the resulting effect of two ships passing near each other while using a Alcubierre drive

So, I don't have any formal background in physics or space. but I read about the Alcubierre drive, and now I'm curious. If two ships passed one another, what sort of interference would be generated? ...
0
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1answer
170 views

Magnetic hot air balloon [duplicate]

Normally, hot air balloons are limited to 60,000 ft (related question), the limits being the mass of the physical structure containing the air, and the heat source. If one constructed a magnetic ...
42
votes
4answers
9k views

If I'm floating in space and I turn on a flashlight, will I accelerate?

Photons have no mass but they can push things, as evidenced by laser propulsion. Can photons push the source which is emitting them? If yes, will a more intense flashlight accelerate me more? Does ...
4
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1answer
109 views

Relativistic Time dilation and travel to exoplanets

NASA recently discovered the first habitable exoplanet with the Kepler space telescope. Recently I was on this site: http://www.cthreepo.com/lab/math1/ With the Long Relativistic Journeys ...
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1answer
225 views

What happens to the acceleration of a body undergoing constant force?

Here's the problem I have, specifically relating to a rocket in deep space: A rocket burns fuel at a constant rate. Assuming its mass remains constant, what happens to its acceleration? I seem to get ...
33
votes
1answer
11k views

How long would it take me to travel to a distant star?

Suppose I wanted to travel to one of the recently discovered potentially Earth-like planets such as Kepler 186f that is 490 light years away. Assuming I had a powerful rocket and enough fuel, how long ...
1
vote
1answer
144 views

Why must spacecraft reach escape velocity to escape Earth (or any other big object)?

I think I have learned in physics that escape velocity is defined as the speed at which objects going ballistic in the opposite direction of the main gravitational force are able to finally overcome ...
3
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1answer
165 views

Mars Circular Intercept Orbit

I've been trying to simulate a spacecraft entering a circular capture orbit about Mars using Mathematica, but am having a little trouble. The simulation starts when the spacecraft enters Mars' sphere ...
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3answers
728 views

Would approaching a distant star at near the speed of light unfold its entire history in “fast-forward”?

The light we detect today in our telescopes from distant stars is really old. If we could travel fast (lets say, 90% the speed of light) towards a star a million lightyears away, all the time looking ...
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0answers
106 views

What is the cheapest way to land a grain of sand on the moon? [closed]

I have a payload that is the size and density of a grain of sand. I want to land it intact on the moon, but I am not particular about location beyond that. What is the least expensive way to get it ...