Questions tagged [physics]

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

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7
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2answers
1k 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 V_\...
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2answers
616 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
450 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
64 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
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1answer
440 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 ...
5
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2answers
516 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
356 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
211 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’s ...
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1answer
163 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 ...
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4answers
3k 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 ...
2
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2answers
230 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
273 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
749 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 ...
4
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3answers
925 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
135 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 ...
6
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1answer
180 views

Is the Parker Solar Probe's semimajor axis being so close to that of Mercury's just coincidence? Does it help somehow?

Parker Solar Probe will end up in it's Sun-kissing orbit though a series of Venus flyby's, which roughly pins Parker's aphelion at Venus's semimajor axis or about 108 million km. Its final perihelion ...
3
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1answer
348 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 ...
7
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1answer
825 views

Which astronaut has experienced the largest relativistic shift in time (relative to Earth's 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 ...
4
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0answers
121 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
254 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 ...
21
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4answers
4k 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 ...
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3answers
853 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
51 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 ...
3
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3answers
531 views

At what size does a bigger solar sail stop increasing your acceleration?

Is there a point where the larger solar sail would not add more thrust? What is the most thrust a solar sail can produce? Can a solar sail be added to an ion engine and work better?
5
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1answer
695 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 ...
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8answers
12k 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 ...
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0answers
516 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
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1answer
69 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 ...
9
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2answers
703 views

How can I calculate the delta-v correctly, this way does not seem to be correct?

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/...
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0answers
78 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 "...
9
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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 the earth'...
5
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2answers
411 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?
2
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1answer
221 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
172 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
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3answers
1k 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 ...
5
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1answer
253 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 ...
8
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2answers
343 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
106 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
1k 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
1k 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 ...
6
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1answer
453 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 ...
8
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5answers
14k 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 ...
8
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2answers
2k views

Could you launch rocks from the Moon to hit Earth?

In the Robert A. Heinlein novel, The Moon is a Harsh Mistress, the plot famously revolves around sending rocks from the Moon to Earth, launched via electromagnetic rail gun and the impacts looked like ...
1
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1answer
630 views

Chamber pressure for Merlin vs Raptor

So, I've been doing some digging, and I found that the chamber pressure for the raptor engine is more than 4 times that of Merlin (~4,000 psi to ~980 psi). How would SpaceX manage to pressurize the ...
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0answers
89 views

Efficiency of 3 in line boosters of a shuttle? [closed]

What is the most efficient scenario for a total of 700 Newtons of thrust on three lined up boosters? If the air pressure for the payload booster isn't the same, can they make an efficient air ...
25
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2answers
10k views

How complex was the math and physics necessary to place Apollo 11 on the moon?

Specifically, I'm interested in how closely the models used to calculate the various burns and course corrections represented reality. Was standard Newtonian mechanics sufficient or were relativistic ...
17
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2answers
2k views

Is the Flyby Anomaly still a thing?

The Flyby Anomaly is a name given to an unexplained, unexpected difference between the best theoretical calculation of a change in several different spacecraft's velocities due to flyby (Gravity ...
7
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1answer
344 views

Negative photon pressure? What is the physics behind this expression?

The Wikipedia article on Radiation Pressure gives an equation for the pressure on a perfect reflector produced by a beam of photons with an energy flux $E_f$ (in units of power/area) as $$P=\frac{...
8
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1answer
371 views

Puzzler: What acceleration are these astronauts experiencing?

From only the video footage within the capsule, please estimate the rocket's acceleration (gee's). http://www.bbc.com/news/science-environment-39658947 Show all work and assumptions. There is a ...