Questions tagged [physics]
How physics applies to a particular activity in space or to getting to space.
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0answers
7 views
Converting Discharge Voltage to Temperature? Hall Effect Thruster Calculation
Trying to follow a Hall Effect Thruster design process given in this video:
Hall Effect Thruster Design Video
In 25:59, there's a calculation in which the presenter takes discharge voltage and ...
2
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0answers
61 views
Would a self-winding watch work in space without gravity?
Could a watch that winds itself with a pendulum work in space with no gravity? Could a pendulum or the self winding part be modified to work off the movements of the wrist in a microgravity ...
4
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1answer
273 views
How would gravity/acceleration be perceived by a human orbiting Earth at sea level?
I understand the impracticalities of this concept, but humor the 'what-ifs.'
Ignoring physical obstacles and the effects of atmospheric fluctuations affecting the trajectory.
Say it is possible to ...
2
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1answer
81 views
Ideal shape for a long, skinny reaction mass for LEO to cis-lunar and beyond? (a “space rail gun”)
@Ingolifs' answer got me procrastinating thinking further.
What you're asking about is a mass driver space station in low earth orbit that a payload or ship launched from earth can dock with, and ...
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2answers
139 views
Can it be calculated that within the Kármán boundary the lifting force equals the centrifugal force?
According to Wikipedia about the Kármán line:
In the final chapter of his autobiography Kármán adresses the issue of the edge of outer space:
...or 24 miles up. At this altitude and speed, ...
13
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1answer
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 "...
11
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2answers
4k 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 ...
3
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0answers
99 views
Chinese find material to make space elevator. How much will the cable weigh?
The article China has strongest fibre that can haul 160 elephants – and a space elevator? came out today in the SCMP, and I would like to find out how much the cable would weigh. But I'm not sure if ...
2
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2answers
438 views
Could a satellite in LEO “pump” or change mass distribution to gain forward momentum?
Similar to pumping your feet on a child's swing can a satellite run up and down a pole to produce a forward momentum?
Red dots is the satellite's position running up and down the pole on an ...
5
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2answers
395 views
From the General Thrust Equation towards Tsiolkovsky, how to explain dropping these terms along the way?
The NASA Glen Research Center tutorial page Rocket Thrust Equation links to the General Thrust Equation page which starts with:
Which transcribes into MathJax as:
$ \ \ \ F = \dot{m}_\mathrm e ...
-6
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2answers
413 views
Is the definition of the Kármán line from Wikipedia right? [closed]
Edit: this question is about making clear that the Wikipedia's article about the Kármán line is an interpretation, not the definition !
Why not consider the Kármán line as a curved boundary that ...
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1answer
123 views
Analytical approximations for the shapes of these plots of ISP vs nozzle diameter? (Raptor engine)
A comment on the currently unanswered question Is there an authoritative catalog for rocket launch identifiers? led me to this Github page which links to r/spacexlounge on which currently appears a ...
2
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0answers
49 views
How to make a orbital launch tube work?
Normal rockets would not work in a pressurized tube, but could a stage be made for the diagonal launch tube to save fuel and weight? Can the bottom stage be nuclear powered?
Unlike the piston launch ...
6
votes
1answer
423 views
Could I use a satellite as a vehicle for delivering airborne leaflets?
Assuming I have a satellite in a decaying orbit, could I gently release leaflets from my satellite so they were on a near-identical sub-orbital trajectory and have them touch-down safely on the ground ...
4
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2answers
174 views
What exactly means universal variable x and z?
I have been studying by myself Orbital Mechanics, and when solving the Lambert Problem, it's common to use the universal variable approach. I understand the algorithm, but I haven't found any book ...
3
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1answer
129 views
When a Saturn V reaches max Q, what fraction of the lengthwise structural load is due to drag rather than acceleration?
Ignoring all other structural loads besides the lengthwise compression of the rocket.
This is useful to know when theorizing about whether high altitude launches (e.g. from airplanes) could ...
3
votes
1answer
145 views
What causes Hyabusa-2's close-up images of Ryugu to be dark in the corners?
The NYTimes' article Hayabusa2 Prepares to Drop Rovers on Asteroid Ryugu says
Sept. 19 Rock Hoppers
Hayabusa2 is preparing to deploy two small rovers this week, each about 7 inches wide. Ryugu’...
0
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1answer
112 views
How can articulated spacecraft components increase the risk of gimbal lock?
This answer has got me baffled.
In theory, yes. In practice, no. The problem is gimbal lock...
There seems to be some risk of inducing gimbal lock if a spacecraft component of sufficient mass is ...
10
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4answers
2k views
What causes a rocket to be destroyed during launch other than leaking fuel?
There were some famous accidents where rockets launched and just went up into flames. Many had something to do with leaking fuel in some sort.
I want to focus on aerodynamic stress however, like when ...
1
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1answer
55 views
How, and How Well will Juno measure the effects of frame dragging? (GR effect due to Jupiter's mass & rotation)
This answer links to Spaceflight 101's One Week to Jupiter – NASA’s Juno Spacecraft en-route to Gas Giant after five-year Journey which says
Also, Juno will put Einstein’s General Theory of ...
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4answers
126 views
Solar Powered Inflatable launch tower?
Could the weight of a launch tower or some of a space elevator be mitigated balloons?
Similar to the children's air inflated jump houses could a tower be inflated of hydrogen/helium with different ...
1
vote
2answers
105 views
How to calculate mechanical stress on certain parts of rockets?
I'm not very proficient at aero- or fluidynamics or stress calculations, but I want to know how to calculate the stress on parts of a given rocket, given the height(or air density), orientation and ...
3
votes
3answers
101 views
What's the planetary exploration word for “impact parameter” (distance of closest approach if gravity were “turned off”)?
In particle scattering there's a term called "impact parameter", which is the minimum distance a particle would pass a second particle at rest, if the attractive or repulsive force were ignored or "...
1
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1answer
59 views
Which is stronger per Hz, radio signals from a Mars spacecraft, or Mars' blackbody radiation?
It just occurred to me that while Mars is cold from a human's perspective, from a radio engineer's perspective it's still kind-of hot.
When even the largest DSN antennas are pointed at Mars to ...
0
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0answers
95 views
What is the optimal angle for a solar-sail deorbit towards the Sun when radial thrust is included?
In this answer there's a geometrical derivation of the optimal angle of a solar sail to deorbit a spacecraft into the Sun.
The naive answer is 45° which would direct the reflected light directly ...
4
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0answers
190 views
Which astronaut has experienced the largest relativistic shift in time (relative to the surface)?
Following this answer and then this question (where I've linked to Cosmonaut Sergei Krikalev; the World's Most Prolific Time Traveller) I've noticed that currently Krikalev does not hold the precisely ...
3
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0answers
85 views
Could a laser ablation-based propulsion system really accelerate an object to 0.001 c?
Comments below this answer suggests that a laser ablation-based propulsion system, where the laser is separate from the object to be accelerated, could accelerate an object to about 1/1000 of the ...
0
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1answer
208 views
Could a reentry powered monorail and flywheel make a kinetic engine for lift?
On reentry could a flywheel spin on a magnetic bearing creating a centrifugal force to keep the ship level whilst creating a plasma air pocket from the pits in the rotating heat shield? This would ...
19
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5answers
3k views
What would be necessary in order for us to achieve a single stage to orbit, reusable rocket?
I have read articles and seen videos explaining why an SSTO (Single Stage To Orbit) rocket* is not possible. But I was wondering... What would be required to achieve this? Answers can be literally ...
0
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3answers
214 views
How does a rocket in space go faster than its own rocket engine gas velocity?
How can a rocket in space go several times faster than its own engine's gas velocity? Doesnt this break Newton's 3rd law? Gas velocity, 12,800kph, rocket speed 40,000kph?
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0answers
49 views
What particles does the space station have to worry about?
I've heard things like "even a paint chip can damage the space station" and I wanted to know to what extent that was true. I imagine the best characterization is what is the minimum momentum or ...
4
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1answer
242 views
How do rockets “blow” smoke rings? Did “smashing through Max-Q” really do this?
The Teslarati article SpaceX delivers largest commercial satellite in kick off of Falcon 9 marathon includes several beautiful photos, of the Telstar 19V launch, including the one below.
It shows ...
36
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8answers
10k views
Could a spacecraft spin so fast that it spontaneously deconstructs?
I have to admit, first and foremost, that this was inspired by Kerbal Space Program. During a launch I decided to hold the "E" key and spin my rocket to the fastest rotation speed possible. At some ...
0
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0answers
127 views
How can I calculate Mean anomaly from True longitude?
So, I have
- TLE data
- Reference frame: QMOD
- Type: Osculating
- Semimajor axis
- Eccentricity
- Asceding node
- ...
3
votes
1answer
61 views
Can we build a gravitational Radio by modulating the speed of Nuclear Reactions? [closed]
The idea is, if we can modulate the rate at which nuclear reactions take place (Fusion/Fission), can we create and modulate gravitational ripples in space time, more or less in the same was as we do ...
6
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0answers
117 views
How can I calculate the $\Delta V$
I'm learning about Astrodynamics, and I would like to ask how can I calculate the $\Delta V$ for an interplanetary mission.
I used a website for the porkchop plots (http://sdg.aero.upm.es/index.php/...
0
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0answers
45 views
Is spacecraft propulsion observable in space? [duplicate]
There are questions on this site about minimal sound in space. But I was very surprised by Russell Borogove's answer to "Why did the Saturn V stage faring appear to burn after separation?" that "...
7
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3answers
2k views
Teleporting an object into geosynchronous orbit
Assuming that a method was found to teleport objects, and at huge range, if an object was teleported from the surface to a location at the correct height (wikipedia says about 42,164 km from earth's ...
5
votes
2answers
224 views
Would space ship/station rotation for artificial gravity cause the “axis” to also rotate?
Would space ship/station rotation for artificial gravity cause the "axis" to also rotate similar to that of a helicopter with out a tail rotor?
Additionally would a second rotating section going in ...
12
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2answers
2k views
Earthing system in space?
On Earth, we have a good reason to deploy electric devices with an "Earthing system": this helps to avoid dangerous leak currents on surfaces.
Now how is this solved on a spacecraft?
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1answer
170 views
Would a rotating wheel spacecraft “flip”?
I am looking over some proposed rotating spacecraft such as the Nautilus-X and the Ares from the movie The Martian as well as much more fictional ones such as from the Jovian Chronicles and even Halo.
...
2
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1answer
123 views
Why is the cold of space a danger to satellites?
Recently, I have been learning about satellites present in space, and one of the discussions was the danger of the variance of temperatures, as space can be both incredibly hot and cold. I understand ...
5
votes
3answers
278 views
How bright is starlight in deep space?
Say I'm way out in deep space and on EVA. If I turn off all sources of illumination, can I basically still see, or am I severely impaired by darkness? Of course I can still see the stars, but will ...
4
votes
1answer
131 views
Got Milk? Why is the term “colloid” used in “Colloid or Electrospray thruster”?
From this answer to the question "Difference between colloid thrusters and electro spray thrusters" I've extracted the following:
According to the Wikipedia article Colloid thruster they are the same ...
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2answers
233 views
Would Elon Musk's roadster be able to rotate itself using its wheels as reaction control?
If so, couldn't it also rotate itself sideways somewhat by turning its front wheels? (assuming it has 4wd and electricity.)
4
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0answers
59 views
(How well) Did Juno provide any insight into the Flyby Anomaly?
I ran across an old BBC article titled Juno: The spacecraft putting sling theory to the test — Why a probe passing our planet on its way to Jupiter might end a decades-old mystery, and reveal ...
4
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2answers
963 views
Why doesn't the Tesla Roadster's windscreen crack or break in space?
The car is on the sun side of space as seen by the lens flare. This means that the car will absorb high amounts of radiation, heating the car up to well over 250 degrees Celsius . A car windscreen ...
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2answers
934 views
Did Elon Musk's Tesla Roadster actually launch to space? [closed]
I'm sorry I have to ask this question but I need evidence for a friend. My answer to her that I trust people who specialize in the field to know better than me is 'BS' to her.
So to begin...
My ...
4
votes
1answer
143 views
Is Engine thrust noticeably increased near the ground
I know next to nothing about Rocketry and Space Flight.
I assume that the majority of the force generated by a rocket's engine is simply the result of throwing gasses out of the bottom very fast, and ...
6
votes
6answers
11k views
Why doesn't Tesla's Roadster melt in space?
Tesla's Roadster is somewhere above us taking sunlight directly part of the time, then very cold on the next half of the orbit. Or when it rolls, one side gets hot, the other is cold.
Why don't the ...
