# Questions tagged [space-travel]

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### John, in his spaceship traveling at relativistic speed, is crossing the Milky Way in 500 years. How many supernovae explosions would he experience?

John, in his spaceship traveling at a stable relativistic speed, is crossing the Milky Way in 500 years of his own time. How many supernovae explosions would he experience? From my reference frame on ...
71k views

### How many photons are received per bit transmitted from Voyager 1?

As of 2024, according to https://voyager.jpl.nasa.gov/ , Voyager 1 is around one light·day away from Earth and still in radio contact. When Voyager 1 sends messages to Earth, roughly how many photons ...
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### How to find the length of a travel between planets using the Hohmann Transfer?

I am trying to figure out how long it would take to get from one planet to another. This is for a worldbuilding project of mine. I would put my question on the Worldbuilding Stack Exchange but I ...
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### Would a photon engine work?

So as far as I know for a body to move in space it needs to accelerate using it's mass because there is nothing else to push against. And as far as I understand, basically, the photon engine is an ...
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### Why are NASA etc so good at hitting tiny targets in tiny time windows?

NASA have a tendency to arrive at targets that are so far away, within seconds of ETA, and statements like " it's like throwing an object from New York and having it hit a particular key on a ...
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### How would a spacecraft travelling near light speed say 0.9c compensate for time dilation in radio communication from spacecraft to earth?

For a spacecraft travelling at 0.9 c for 5 seconds, only 5 seconds would have passed for an observer on Aircraft, while 26.31 second would pass for a stationary observer watching from Earth. In a ...
546 views

### How do they set the clocks on spacecraft visiting several other planets?

Scientists have sent spacecraft into distant space passing nearby other planets on the voyage. How do they set the clocks to adjust for kinetic time dilation (special relativity) and gravitational ...
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### I need a ship at rest to accelerate under preferably constant acceleration/deceleration to arrive at rest at an object 55 AU away [duplicate]

I'm working on the story and I need help with the plot point. Assume that the energy needed for constant acceleration is not a problem. And there's no need to complicate this with outside forces. I ...
1 vote
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### Space mission for experimental verification of frame-dragging in the strong-gravity limit

Frame-dragging is an important general relativistic effect that has been observed in the weak-field limit by the Gravity Probe B experiment for the gravitational field of the Earth. Although the ...
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### Could you use a synchrotron particle accelerator in a descending spiral pattern to create ion thrust for space travel?

Would it be theoretically possible to use a synchrotron particle accelerator that utilizes a spiral pattern to create ion thrust for space travel? In this scenario, ions would be accelerated in a ...
141 views

### Is the kind of physics proposed for "warp drive" related to the way that space really is expanding?

As I understand, some parts of Universe really are moving faster than light -- is this expansion something we think we can create artificially? And if we can do this artificially, could it be done a ...
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### tGiven a propulsion system with constant power, how long does it take to travel a given distance in space? (non-rel. and relativistic)

Suppose a space ship of mass $m$ is travelling away from our solar system, starting with "starting speed" $v_{start} > v_{escape\ \odot}$, meaning it will escape sun and have some ...
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### For someone staying on Earth, what is the minimum possible time to send a spaceship to Alpha Centauri and have it back?

Suppose we want to send a spaceship to Alpha Centauri and calculate the minimum possible time it will take for us here on Earth to have the spaceship back. We are not interested in how fast the time ...
122 views

### How does the James Webb Space Telescope avoid stick/slip and creep problems when positioning its mirrors?

The JWST is now positioning its mirrors so they form a single image. How James Webb's Mirrors MUST Work To do this, each mirror must be positioned in 8 nanometer steps in 6 degrees of freedom. Here is ...
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1 vote
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### On which speed the relic microwave background radiation becomes dangerous for the people on space ship?

If we travel with speed close to the speed of light, the light waves becomes shorter and their energy increases (because we flight through much more light for the same time). So, even background ...
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### Why is the JWST orbit only taking 30 days?

Presumably the Ariane 5 rocket launched the James Webb Space Telescope into an elliptical orbit with its apogee at the L2 point. Such an orbit’s period is about 70 days, i.e. the journey to L2 should ...
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### Interrupted Laser propulsion and relativity

I have seen concerns that in order for a laser sail ship to work, the laser on Earth has to continue operating for centuries, which there is no gurantee of. If the laser stopped operating after 300 ...
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1 vote
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### Circling a Cosmic string in less than 360 degrees for faster space travel?

I've red that Cosmic strings would warp space such that one could circle a cosmic string in less than 360 degrees. How few degrees? If a ship were to circle a cosmic string in a spiral pattern, saving ...
• 719
1 vote
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### Would light sails be a practical means of travel in the center of Andromeda? [closed]

I've read that at Andromeda's center, stars are only 0.008 lightyears apart from each other. Is this a short enough distance for light sails to be a practical means of space travel, or is this still ...
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### What’s the offset distance for a Mars Fly-by?

Would anyone know where to look or know how to calculate the offset distance at which fly-by on Mars may be performed. It’s the variable ‘x’ in the formula 8.3-20. (Bate Mueller Astrodynamics ...
1 vote
44 views

### Derivation of time dilation formula [duplicate]

When we derive the formula of time dilation using light clocks, we always consider the projected light pulse in direction perpendicular to spaceship. What if we take the direction of light pulse in ...
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### This is a doubt regarding special theory of relativity [closed]

If a beam of light is seen from a moving spaceship in same direction as spaceship, we will observe that speed of light hasnt changed as our time has slowed down but what would happen if we see a light ...
1 vote
62 views

### Calculate point of rotation start for spacecraft with linear acceleration

I hope someone can help me with my problem. I would like to move a spaceship from A to B. I want the spaceship to accelerate to the middle of the path, then rotate 180° and then decelerate. Now the ...
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### Question about transfer of momentum in photons

Imagine a photon hits an object, then bounces off and travels in the other direction, all while retaining it’s wavelength. If the object is slightly accelerated in the direction of the incident photon’...
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### How fast could 1,767 cubic feet of fusion fuel propel a starship? [closed]

I'm designing a starship that could go to Alpha Centauri in under 15 years. My design goes at a top speed of 0.5c. Assuming the fuel is in gaseous form, could this provide enough energy to propel it? (...
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### Questions on the notion of an inertial frame of reference

Imagine an astronaut flying in an spaceship at a constant speed in completely empty space, with no acceleration whatsoever, and no outside references, just dark empty space. Q: Can the astronaut tell ...
190 views

### The pioneer anomaly [closed]

The RTG's powering the electronics had to reject hundreds of watts of black body radiation to space. The RTG’s reflected a portion of their radiation onto the backside of the main paraboidal antenna, ...
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### Energy distorting space

We know that mass distort space and time. Can energy do the same? How much heat will it take to create an observable effect? can we make a warp drive on that principle? By heating one end of a space ...
1 vote
92 views

### Does the Parker Solar Probe experience radiation pressure being so close to the sun?

Since the Parker Solar Probe does close fly-bys around the sun, does it experience any significant radiation pressure from photons emitted by the sun? Is this push, significant enough to require ...
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### Could you use a balloon to show the drag from the gas/atmosphere of something orbitting near the ISS?

If a balloon were floating next to the International Space Station (ISS), how big, light, and/or dense would it need to be such that the gas/atmosphere at that distance from the earth's surface would ...
72 views

### How would a neutral hydrogen gas interact with a relativistic spacecraft?

Inspired by a discussion from the comment thread of a gaming youtube video, I've been thinking about what kind of radiation environment a relativistic spacecraft would be exposed to as it passes ...
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### Can civilizations orbiting black holes keep time with their interstellar travellers?

Due to relativistic-velocity interstellar travel time dilation, travellers would return in the far future of any civilization launching such an effort. A chart from wikipedia indicates typical time ...
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### Wave drag in the interstellar medium

In Earth's atmosphere, an object moving at supersonic or near-supersonic speed experiences wave drag due to the formation of shock waves around the object's leading edge. At high speeds, wave drag is ...
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### Accelerating a spaceship to near speed of light

Hypothetically, suppose we have the ability to accelerate a spaceship to near speed of light (lets say 0.9c). From what I remember of relativistic kinematics, the energy required to accelerate the ...
1 vote
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### Could cosmic rays be used for power on Mars?

Most studies of radiation levels of Mars that I can easily find focus on it as a hazard for potential human visitors. As such, a figure in rads or Sieverts is provided, which lumps together all of the ...
87 views

### Can we connect several Nano Spacecraft moving at 20% speed of light? [closed]

Nano spacecrafts are one gram silicon chips that will be accelerated to 20% of the speed of light to reach Alpha Centauri in 20 years. I wonder could we connect several spacecraft after they were ...
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### What happens with trash that is left after a satellite expires?

I was reading an article that Japan is experimenting with wooden chassis for satellites so that they can keep the trash minimal. I was wondering if it was possible to design the satellites in a way ...
4k views

### "To come back to Earth...it can be five times the force of gravity" - video editor's mistake?

I've watched The Truth About Gravity With Professor Jim Al-Khalili | Gravity And Me | Spark where astronaut Chris Hadfield says at 3:55: To come back to Earth is violent Then after several seconds ...
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### If 2 spaceships left Earth for the galactic centre, travelling near the speed of light, but they left an hour apart, would they arrive an hour apart?

If a spaceship left Earth for the galactic center at 3pm one day, traveling at extremely close to the speed of light (say 99.9999999%), then a second spaceship left at 4pm, would they arrive an hour ...
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### At 50% c, I go party to IC1101 galaxy, and back home. How many times can i go before the expansion of the universe will lock me on one side? [closed]

Longer version of the question: Let's say I'm an immortal being (I could be artificial) going to "party" to IC1101, one of the biggest galaxies of the universe, 1 billion light-years away ...
1 vote
258 views

### Voyager distance

This very nice NASA page continuously updates Voyager 1 & 2 distance away. How is that distance calculated/determined?
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### Dark energy as negative matter for Alcubierre drive

Can dark energy be used for the Alcubierre drive as a substitute for negative mass? After all, to make the Alcubierre drive work, it is necessary to expand the universe behind it, and that is what ...
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### How exactly does a control moment gyroscope work?

I've searched a lot, but have not been able to find a proper explanation for the working of a control moment gyroscope. Could someone please explain it to me, preferably with vectors?
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### Could light from the Sun be used to power the Breakthrough Starshot microships?

The Breakthrough Starshot initiative aims to accelerate a swarm of 16m$^2$-area solar sails to 15% of $c$ using Earth-based lasers in the order of 100GW power in 10 minute bursts. Considering loses ...
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### Why don’t astronauts “push” spacecraft?

Perhaps it goes without saying, but according to Newton’s laws “every action has an equal and opposite reaction”. How do astronauts, especially those inside small spacecraft like the Crew Dragon, not “...
1 vote
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### How does a rocket slow down in space?

I’ve been reading about the conservation of momentum and its applications in deriving the rocket equation. I’m curious whether how can a rocket slow down in space. As far as i can comprehend, a rocket’...
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### How close would a supernova be to endanger the astronauts on the ISS?

How close would a supernova be to endanger the astronauts on the ISS? Would Betelgeuse be close enough?
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### Physics of Project Orion

I was reading the book "Project Orion" by George Dyson. For those who are unaware, Project Orion was basically a plan to launch a spaceship by flinging bombs out the rear and detonating them. The ...
From a traveler's point of view, as he is accelerating with $1g$, in under one year he would reach the speed of light. Note that from his point of view, everything looks normal so he could keep ...