Questions tagged [physics]

How physics applies to a particular activity in space or to getting to space.

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3
votes
1answer
87 views

How much less delta-v would it take to reach the Sun using Venus and Earth flyby's compared to direct?

@TomSpilker showed that the minimum delta-v to go from Earth orbit into the Sun is about 20.89 km/s. That's going from 200 km LEO to "perihelion at the sun's photosphere (guaranteed complete entry!)" ...
5
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2answers
505 views

What's the eccentricity of an orbit (trajectory) falling straight down towards the center?

Discussion below this answer has got me thinking. A circular orbit has eccentricity of 0, ellipses have eccentricity between but not including 0 and 1, and parabolic and hyperbolic orbits have ...
14
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2answers
3k views

Could a complex system of reaction wheels be used to propel a spacecraft?

I was think about different ways spacecraft could feasibly move around and I came across Reaction Wheels as a way they can rotate. So I was curious if a complex system of them could be used to propel ...
-1
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4answers
138 views

What kind of force is there in exact middle of earth? [closed]

Basically i have one question but this question leads to another. firstly can we dig in earth that from one side we reach other side of earth ? i mean just going through it. Now let's say we can dig ...
1
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1answer
48 views

Understanding line of sight between two satellite with oblate Earth using “scaling k-component”

I have been doing some reading on accuracy of determining line-of-sight between two satellites give a WGS84 oblate earth. The paper Rapid Determination of Satellite Visibility Periods (Alfano, Negron ...
-4
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1answer
128 views

Magnetic force-driven propulsion system for an interplanetary/interstellar spacecraft

I have come up with a conceptual idea of a magnetic force-driven space propulsion system. What I believe is very unique about this propulsion system concept is that its working principle should not ...
8
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7answers
3k views

Is it possible to get a spacecraft into earth orbit using Linear Eddy Current Braking on an orbital runway?

The "Space Runway" [I have slightly edited this to clarify some issues that have been raised] Luke Parrish mentioned an unusual and novel space launch method to me. The idea is to get a spacecraft ...
1
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1answer
208 views

Could a CubeSat be propelled by this low-tech electromagnetic propulsion system?

I have come up with a conceptual idea for a low-tech electromagnetic propulsion system for a CubeSat, and I would like to know if it would create (on a theoretical basis) a net force strong enough to ...
2
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3answers
173 views

Do spinning space stations slow down without energy input?

One thing I always wondered was if a giant spinning space station that was providing artificial gravity would slow down without any energy input. I would assume that energy is being lost to heat as ...
12
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6answers
8k views

Could a space colony 1g from the sun work?

Let me break down my thoughts and I have no science background so let me know if this could even be possible. Have the colony on an object like a big asteroid or a similar man made construct. Have ...
3
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0answers
144 views

Have there been any Foucault pendulum demonstrations in space?

A Foucault pendulum is a pendulum allowed to oscillate in 2 directions, unlike the pendulum in a clock which is restricted to 1 dimensional oscillation. On Earth, (except at the equator) the plane of ...
4
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1answer
147 views

What might be a viable avenue of propulsion research in aiming for mission delta-V north of 100 km/s?

This question was inspired by some comments of mine I left on an answer here: Is it better to develop more powerful rockets instead of seeking and developing new technologies? and thus in turn both ...
2
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3answers
142 views

Stability of rocket during flight; why does the lift force change direction when the center of pressure moves?

I am currently learning about fins and the role they play in the stability of a rocket during flight. I came across a relatively minor problem. Here is one of the resources I'm looking at: http://www....
0
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1answer
104 views

Is it better to develop more powerful rockets instead of seeking and developing new technologies? [closed]

I have question about Space Industry and Era. I'm aiming to being Rocket Scientist but I think it looks like will be so hard to reach far planets with these rocket technology that uses Newton's Laws ...
3
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1answer
107 views

Some exercise questions about Tsiolkovsky's Rocket Equation and Thrust Equation

I have found 6 of the question's answers, but I don't know they are correct. The last question about time of the burn I get negative result -0.42 seconds. Time could not be a negative value, so I ...
2
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1answer
95 views

What are Mass Rate(∆v)/∆v, Mass Rate(Isp)/Isp and time of burn(MR)/MR graphs?

I have some problems about Tsiolkovsky's Rocket Equation and some graphs. Firstly, I didn't get what I can do with Rocket Equation formulas as seen below, Also, what these three graphs try to mean? ...
0
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2answers
122 views

Average acceleration of a rocket

Given a rocket has a minimum acceleration with full tanks of say 1 g and a max acceleration with empty tanks of 3g, what's the average acceleration? Is it just 2
2
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2answers
162 views

Could electricity be generated from a Martian dust storm?

This helicopter is producing static electricity from the blades moving through the dusty air. Along with the electricity provided by wind generators could additional power be created this way from ...
5
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2answers
121 views

Flat-spin transition manoeuvre: why is the angular momentum not constant?

In an article by Rahn and Barba, in which a flat-spin transition manoeuvre is investigated, the following figure is presented: I'm trying to reproduce this figure by integrating the following coupled ...
1
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0answers
55 views

How does temperature affect a solar sail?

Is there an ideal temperature which solar sail material operates at? Does a colder reflective surface create more thrust? Related: How will JWST manage solar pressure effects to maintain attitude and ...
3
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3answers
279 views

How will JWST manage solar pressure effects to maintain attitude and station keep it's unstable orbit?

The James Webb Space Telescope presents a huge reflective cross-section to the Sun's photons, and this can generate both torque and thrust. How will JWST manage solar pressure effects to maintain ...
-4
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1answer
117 views

Can a reaction wheel decelerate to add momentum in the same direction? [closed]

Can a reaction wheel shed weight to gain speed? Could a reaction wheel at its max spin be flipped or rearranged around 180 degrees then slowed to add to its velocity?
-1
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1answer
184 views

Could this satellite wobble in orbit creating additional orbital angular momentum?

This question asks if this type of steam engine would work: Could a steam Engine outperform other electric producing devices in space? this not a sterling engine since it has far less moving parts. ...
2
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1answer
106 views

What is the point in which metal turns white hot during launch or reentry called?

This is a slow motion film of the Sprint missle. There is a point where to skin goes white hot like a light switch. What is that called? What metal gets white hot while keeping its shape?
25
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9answers
6k views

Would a grinding machine be a simple and workable propulsion system for an interplanetary spacecraft?

I am wondering if any space agency has ever considered using a grinding machine as a propulsion system for an interplanetary spacecraft. This system would not be used to lift the spacecraft off of a ...
3
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1answer
185 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 ...
3
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0answers
214 views

Could a steam Engine outperform other electric producing devices in space? [closed]

What would be the Specific Impulse of a steam-based propulsion system like this model in space? Are there any types of engine that works this way? Could 2 tanks be designed to rotate slowly in space ...
8
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2answers
2k views

What is the smallest body in which a sling shot maneuver can be performed?

This question asks about the smallest sling shot maneuver performed. What was the smallest intentional, acknowledged slingshot maneuver? I'm asking how small of an object be to perform a sling shot ...
3
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2answers
277 views

Could a fat rocket be used on Mars?

Since Mars' atmosphere is around 2% the density of Earth's then could a much wider rocket achieve orbit? Could the rocket be in the shape of a capsule or an optimal shape for reentry on Earth?
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1answer
90 views

What is the vapor pressure limit of liquid metals in space?

Would liquid metal be stable in space unlike most other liquids like water? Are there any metals that has a high vapor pressure limit? Side question: Can liquid metal be given an electromagnetic ...
2
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3answers
237 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?
3
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1answer
93 views

What is the order of magnitude forces due to Earth's magnetic field, sunlight, drag, oblateness and tidal forces compare?

What in order of magnitude does pressures vary in LEO due to diamagnetic repulsion of Earth's magnetic field, sunlight, drag, oblateness and tidal forces compare on an ideal satellite? Is there any ...
4
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3answers
383 views

Walking in a rotating spacecraft and Newton's 3rd Law of Motion

I am wondering how Newton's 3rd Law of Motion would apply in the case of a man walking the length of a rotating spacecraft. Please reference the drawing below. Say that there was a spacecraft ...
9
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1answer
182 views

Launching east from a mountain on the equator at midnight during a new moon; ranking of each contribution?

This answer is intriguing and I'm curious if it's correct, and especially which effects are most important. If you want to avoid gravity assists, the most fuel-efficient way out of the Solar System ...
1
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3answers
176 views

Delta-V to accelerate to/decelerate from .5c

I have a reasonably good understanding of delta-V (from playing KSP). However, I don't have a great understanding of how it works once you start running into the limitations of physics. I know that ...
4
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1answer
139 views

Is a kilowatt per square centimeter a typical launch engine's thermal energy flux (density)?

I saw the following image while searching for this answer in Sung Hwan Kim's thesis Germanium-Source Tunnel Field Effect Transistors for Ultra-Low Power Digital Logic It plots power density in Watts ...
1
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1answer
114 views

Heat Shielding Material for Reusable Craft

I'm a bit new to all this and have a quick question about heat shielding. My research tells me that for reusable craft (i.e. Space Shuttles) they used to use a plastic-based shields that would burn ...
1
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1answer
538 views

How to drink water on Mars?

There are craters filled with water on Mars as shown below. If fresh water is found, how would astronauts drink the water? Can the Apollo a spacesuit food/drink port be used to equalize the pressure ...
1
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1answer
111 views

Help with my tensor tension; how to derive and calculate this rigid body gravity gradient torque?

Tensors make me tense. Imagine a long thin rod in a circular orbit. The gravity gradient will produce a net torque on the rod whenever it is not oriented parallel, or perpendicular to the radius ...
3
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1answer
117 views

Help with Scott Manley's rigid body dynamics narration

I've just watched Scott Manley's video SpaceX's Water Landing Reveals Rocket "Secrets" (or, What We Learned from CRS-16) (again) and there's some rigid body dynamics in there where I'm not sure I am ...
5
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1answer
584 views

Would any manned orbital launches to date have been possible (but lower) if they were launched retrograde instead of prograde?

Manned launches have always been launched prograde to take advantage of the Earth's rotation velocity boost, and often in order to match the prograde orbit of another spacecraft for rendez-vous. I ...
3
votes
1answer
172 views

Could protons in the Sun's solar wind be used to create a photonic laser thruster for a spacecraft?

I have a conceptual idea for a photonic laser thruster for a spacecraft and I am wondering if this particular idea has already been thought of and whether or not it is capable of generating enough ...
1
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0answers
222 views

Backwards time dilation paradox [closed]

We have a pair of atomic clocks. Let's call them clock A and clock B. We switch both of them on at the same time. Clock A will stay on Earth and clock B will go with the astronauts. Astronauts with ...
1
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0answers
52 views

Could outer system probes detect lasers shone at them from earth (orbit)?

Does the Voyager spacecraft have instruments capable of detecting laser light if shone at them? New Horizons certainly does. Any other probes? Is there any laser capable of accuracy and power enough ...
2
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1answer
175 views

Why would the orbit of a satellite in GEO climb by 21 km in altitude over six months by itself?

This answer mentions several effects that tend to move geostationary satellites out of their "box" over time, but one really surprised me. According to the plot below (from there, but uncredited) the ...
0
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1answer
130 views

Which point in an orbiting body most closely follows its Keplerian trajectory?

Keplerian orbits can describe the motion of a negligible mass around a massive fixed central body, but they can also describe the motion of two bodies around their center of motion... with some ...
1
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1answer
182 views

Could a spacecraft be propelled by a 180 degree deflection of two charged particle beams?

I am wondering if the electrostatic deflection of two charged particle beams could create enough thrust, via the Lorentz Force, to propel a spacecraft. Please reference the picture below. This ...
0
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2answers
146 views

How to get experiments to space?

How would a person get an experiment done in space? What is the chain of command on something like that? I would like to drop some inflated balloons from space to reenter the atmosphere to see which ...
0
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2answers
261 views

Why are exhaust nozzles in space shaped the way they are? [duplicate]

Why are nozzles in space shaped like a cone and not like a tube ensuring all the exhaust is directed strait?
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2answers
389 views

How does the speed and volume of particles differ in producing thrust in space?

Does a slower detonation velocity push a ship more the same way explosives with a slower detonation velocity moves dirt better? At the same rate does slower particles produce more thrust from a ...