Questions tagged [physics]
How physics applies to a particular activity in space or to getting to space.
5
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1answer
524 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 ...
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0answers
6 views
How stable is our universe? [migrated]
I've been reading and thinking about this subject for some time but i can't seem to find a clear answer.
after reading : Aspects of the Higgs boson suggest that our universe is only “marginally ...
3
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1answer
105 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
83 views
Backwards time dilation paradox [on hold]
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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1answer
76 views
Timetravel missunderstanding(s)?… versus time dilatation during acceleration process [on hold]
Words are not the best way to communicate. To correctly describe my question I need to explain the context.
If I say "timetravel" most people I have met will think about some sci-fi movie where bunch ...
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0answers
41 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
128 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
69 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 also describe the motion of two bodies around their center of motion.
But which point ...
1
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1answer
118 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 ...
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2answers
127 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 ...
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2answers
94 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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1answer
128 views
Do slower moving particles create more thrust in space?
When using explosives a slow detonation velocity is best when it comes to moving dirt.
Does this also translate to spacecraft propulsion?
Could slowing the matter that comes out of a ...
20
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3answers
3k views
How best to maneuver inside a large room within a space station using only arm and leg motion?
Imagine the following thought experiment:
An astronaut is inside an extremely large room within a space station. Suppose that she, for whatever reason, is initially at a zero velocity with respect ...
2
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0answers
86 views
Are 2 satellites joined better than 2 apart?
Could new satellites be designed to intercept other older functioning artificial satellites or space junk already in orbit to add weight to the new satellite in order to last longer in orbit?
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0answers
44 views
Apply forces such that a satellite reaches a given point in space
I'd like to find out a strategy for solving the following simplified problem.
A small spherical craft at $t=0$ has a position and velocity vectors $\mathbf{x_0}, \mathbf{v_0}$ in a zero gravity ...
2
votes
2answers
107 views
Solid hydrogen hybrid motor engine for launch?
Would hydrogen unlike water in a solid state take less space or be more stable? How would a rocket work using a block of melting solid hydrogen instead of liquid hydrogen? Has and could any kind of ...
5
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2answers
204 views
How does the thin gold film in the glass of spacesuit helmets block thermal IR but transmit visible? What's the property?
Comments below this answer suggest that there is a thin gold coating on the glass of spacesuit helmets that blocks thermal IR (say roughly about 10 to 30 microns) but is mostly transparent to visible ...
3
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0answers
61 views
Are there any advantages to being a smaller spacecraft for reentry?
Could a ship drop its cargo or shed weight before reentry to lessen the strain on the ship during reentry? Would a ship breaking down to smaller parts before reentry have any advantages over being one ...
1
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1answer
133 views
What liquids last the longest in space?
I am trying to find something that is somewhat stable as a liquid in space. What happens to various liquid elements and compounds in a vacuum? Is there a list or table of the effects of local space ...
4
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1answer
196 views
Could a ball of water stay in orbit?
Could a water bubble (spherical occlusion of water in air or vacuum) similar to the one in the picture below remain in Earth orbit without evaporating, dispersing, or disintegrating? Assume the orbit ...
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3answers
233 views
Could a bottle rocket be up scaled to achieve orbit?
Could you construct an orbital stick stabilized rocket, by scaling up a firework?
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1answer
137 views
Would I be able to do a “slosh test” to see if a container is having liquid, in microgravity?
Suppose I had two large containers with 1 cubic meter size. The containers are identical on the outside. The containers are floating in microgravity very close to my space ship.
One was empty but ...
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0answers
23 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 ...
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0answers
88 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
283 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 ...
1
vote
1answer
91 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
219 views
Can it be calculated that near the Kármán line 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
votes
0answers
128 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 ...
4
votes
2answers
621 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
votes
2answers
422 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 ...
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2answers
473 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 ...
0
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1answer
147 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
56 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
426 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
184 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
136 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
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1answer
155 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’...
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1answer
128 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 ...
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vote
1answer
62 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
175 views
Inflatable Power Line?
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 with hydrogen/helium with different ...
1
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2answers
136 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
131 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
69 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 ...
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0answers
131 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
204 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 ...
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0answers
91 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
210 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 ...
