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Questions tagged [physics]

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

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2 votes
0 answers
104 views

Rocket Launch Azimuth Calculation

EDIT 2: I was told immediately when I explained this problem in other places that a closed loop guidance system would be necessary. I knew this was the case from the start and moreso, when I realized ...
18 votes
1 answer
6k views

Person falling from space

A person at rest 500 km above the Earth falls straight downwards. She has a snug magical force field around her that is totally rigid and completely protects her from outside heat. The force field ...
3 votes
1 answer
185 views

Questions about orbital ring math from Birch 1982 paper

I have been reading the original Paul Birch paper published in JBIS 1982. I have been using this copy found here. In particular I am wondering about generalizing the ideas, like for a different planet ...
13 votes
6 answers
3k views

Why does this formula say rocket efficiency depends on velocity?

Wikipedia gives the following equation for the efficiency $\eta_p$ of an engine here: $$\eta_p= \frac {2\, (\frac {v} {v_e})} {1 + ( \frac {v} {v_e} )^2 }$$ where $v$ is the rocket speed and $v_e$ ...
1 vote
0 answers
47 views

Two line element. Change epoch to epoch year and Julian day fraction [duplicate]

How to do we change this epoch 29 sep 2010 18:32:00.000 to Julian day fraction. I know that the 10272 are the last digits of the year and the day but I want to know how do we get the Julian day ...
1 vote
0 answers
52 views

What is the order of magnitude of perturbing forces in a lunar orbit in relation to the orbital altitude?

Although there are many sources that compare the magnitude of perturbing forces in an Earth orbit (see for example the answer to this question), I haven't been able to find the same information for ...
3 votes
1 answer
262 views

Orbit Determination from Position and Velocity

I'm working on a game, somewhat similar to KSP (no building rockets, just beautiful orbital acrobatics). It's in a "small" star system, radius of 6 AU, and it features celestial bodies ...
8 votes
1 answer
1k 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 ...
3 votes
3 answers
193 views

sun pointing coordinate system design

I am trying to program slew maneuver procedure for a spacecraft. My goal is to define a target coordinate system that is aligned with sun vector so that the spacecraft can slew its attitude to always ...
1 vote
0 answers
112 views

How high will this rocket be, when MECO occurs?

Find the altitude of the rocket at the time of engine cut-off. Rocket Mass = 369208 kg, Rocket Area = 391 m2, Fuel = 170697 L, Fuel density = 21 kg/l, Exhaust Speed = 1338 m/s, Exhaust Area = 164 m2
5 votes
1 answer
8k views

What is the time dilation between Mars and Earth resulting from the mass difference?

I am not sure I understand the time dilation correctly, but if mass has direct impact on time, then let's consider cosmological event - one orbit of planet Earth around the Sun. This event will person ...
3 votes
0 answers
105 views

How much lead (kg) would you need to survive for an extended period of time in Jupiter’s radiation belts?

Imagine you have a 1 by 1 by 2 meter chamber that a human needs to survive in for one year, while orbiting in Jupiter’s radiation belts. How much lead, in weight, would have to surround the chamber to ...
15 votes
1 answer
685 views

How much energy is lost by damping yaw from a SpinLaunch?

SpinLaunch hopes to launch a 200 kg satellite from a ground-based centrifuge, at 5000 mph, and more troublingly, at 450 rpm aka 7 tumbles per second. (The 3000 rpm figure mentioned in its tech sheets ...
4 votes
2 answers
1k 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 votes
1 answer
295 views

Converting Keplerian Orbital Elements into 2D State Vectors in Unity C#

I have done an extensive amount of research into this topic, but am really struggling to implement the math necessary to pull this off correctly. Just for some context: I'm trying to create a semi-...
2 votes
1 answer
470 views

What do/will "quantum gyroscopes using nitro­gen-vacancy centers in diamond" for space applications actually look like, and how do they work?

The NASA page ELaNa 41 Mission has a section labeled QubeSat - University of California, Berkeley which says: QubeSat is a technology demonstration mission. It will test and character­ize the effects ...
18 votes
7 answers
4k views

What is measured with g-forces?

When sitting at rest, a typical "g-meter" shows a value of one, however the meter is not accelerating. In orbit, it shows zero, but is under constant acceleration. The actual force of ...
14 votes
4 answers
2k views

How does Spinlaunch manage the counterweight right after launch?

Spinlaunch has successfully launched a suborbital test vehicle from a 1/3 scale demonstrator, see for instance aviationweek.com or space.com. While spinning up the arm, perfect balance is achieved ...
3 votes
1 answer
154 views

What is missing in the conversion of specific impulse from units of seconds to thrust/mass flow rate? [duplicate]

I was trying to get the Specific Impulse of the Saturn V engines, hoping for a value in N/kg/s, as I need to know the mass consumption rate per thrust value. Any and all sources give me the value in ...
5 votes
1 answer
1k views

Would a sniper bullet fired on Ceres reach orbital or even escape velocity?

What would happen if you fired a sniper bullet horizontally from the top of Ahuna Mons, the highest mountain of Ceres? Once I read somewhere that if you fired a bullet on the Moon in the correct angle,...
2 votes
1 answer
252 views

Will this homopolar motor self rotate in a vacuum?

Is it convenient to ask about the motor from the link: Roller Homopolar Motor When it is on the table, the motor rotates freely, together with the attached conductor. Will the upper motor in the ...
3 votes
2 answers
148 views

Which notes and/or books on mathematics, physics, 3D geometry preparatory to the study of orbital dynamics?

I have a master's degree in aerospace engineering and I'm preparing for job interviews for orbital mechanics/space flight dynamics engineer positions and I need material about maths, physics, 3D ...
8 votes
3 answers
3k views

Why can't buoyancy of air be used to support a mega structure as an alternative to a space elevator?

The reason for asking this question stems from recent articles about large loss of strength of carbon nano tubes with even single atom movement, tested samples showing high vulnerability to space ...
2 votes
1 answer
109 views

Closed Loop Space propulsion

While browsing for Space propulsion found this book : https://www.knygos.lt/lt/knygos/closed-loop-space-propulsion-new-faster-approach-2e4zy/ Closed Loop Space Propulsion New Faster Approach : The ...
2 votes
1 answer
247 views

Is Electromagnetic Propulsion Like Radiation Pressure propulsion?

while browsing for new propulsion methods I found the following interesting: https://en.wikipedia.org/wiki/Radiation_pressure "Radiation pressure (also known as light pressure) is the mechanical ...
3 votes
1 answer
425 views

Calculating and Drawing the orbit of a body in a 2D gravity simulation in python

I'm making a space exploration game and its in a 2d plane so no z axis, and I'm using Newton's law of universal gravity, I would really like to calculate anddraw the predicted trajectory of a body, ...
2 votes
1 answer
2k views

How did NASA calculate 22 million "rocket horsepower" for the SLS Booster?

This answer to Does NASA really report the power of rockets in horsepower? cites NASA news item Space Launch System Booster Aimed and Ready to Fire which says "What's impressive about this test is ...
-6 votes
2 answers
449 views

What's the *calculation* for the altitude near the Kármán line where the lifting force equals the centrifugal force? [duplicate]

Edit: This question is not a duplicate of the associated question and has no answers to it that were posted for that associated question. This question asks specifically for a calculation, the ...
-4 votes
2 answers
278 views

If anything, weren't the first people in orbit the first who broke the sound barrier in free fall?

Felix Baumgartner and Alan Eustace are said to have broken the sound barrier during their space jumps. But in space, there is no sound. In fact, they were still within the Earth's atmosphere so there ...
1 vote
1 answer
245 views

What will be the escape velocity for a human body?

Now imagine an average man of 70kg floating in space with no gravitational forces acting on him. Now a pebble(25 grams) spawns into existence near him. So now there's a gravitational force between ...
4 votes
2 answers
796 views

Is there less blue light available because the sky is blue? [closed]

Are the things we see that are blue .... less blue during daytime because the sky is blue (less blue light available to eluminate the ground)?
1 vote
1 answer
126 views

When a spacecraft reaches the event horizon of a black hole, what happens to its residual gravitational potential energy?

A spacecraft falling from infinity directly towards a celestial body accelerates until it impacts the surface at the surface escape velocity. For any celestial body, the escape velocity is ...
8 votes
3 answers
375 views

Do larger less dense objects heat less while entering the atmophere?

When a space craft enters the atmosphere, it gets hot and heat shielding is needed. Do objects with more surface area and less density heat up less then heavier, smaller objects? Could an object with ...
3 votes
5 answers
1k 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 ...
1 vote
2 answers
814 views

Lorentz force space propulsion

While browsing for Space propulsion, I've found the following article As shown in Figure 2, the conductor I0 gets through the coil L0, and they are fixed together and form a system. a is the main ...
0 votes
2 answers
94 views

Is it possible to avoid tearing apart from a blackhole if moving fast enough?

I have a spacecraft zooming directly into a blackhole with constant thrust. Considering the gravitational force of that blackhole and that there is no terminal velocity to slow me down. According a ...
1 vote
1 answer
326 views

For a DAWN-like solar-electric deep space mission, would using propellant particles much heavier than xenon atoms be beneficial?

For deep space missions using ion propulsion that are power-limited, this answer explains that a large mass/charge ratio ($m/q$) species is desirable. The solar-electric propulsion system used by the ...
2 votes
1 answer
610 views

How to find/extract the semi-major axis from a TLE with Skyfield?

I have a TLE: 1 33591U 09005A 21024.46740879 .00000049 00000-0 52095-4 0 9997 2 33591 99.1927 41.5349 0014084 172.6670 187.4709 14.12449679616592 And I would like ...
15 votes
3 answers
3k views

Spacesuit with no thermal insulation. Would person inside freeze or overheat?

Let us say I have a theoretical super thin spacesuit which has zero thermal insulation. As if person would be naked in space, but all other variables - pressure, oxygen, food and other life support ...
11 votes
1 answer
986 views

Star-shaped artifacts in SAR images of the "Suez Canal traffic jam seen from space"

Wikipedia's 2021 Suez Canal obstruction links to the Sentinel-1 synthetic aperture radar (SAR) image of the Traffic jam in the Gulf of Suez caused by the obstruction as seen by the Sentinel-1 ...
9 votes
4 answers
2k views

What happens if you jump on a "spin ship"?

If you're on a spin ship, or rotating wheel space station, and you jump, then you're no longer being accelerated by the rotation. What would happen? First, I'll establish some terms to make discussing ...
2 votes
1 answer
165 views

Two different Hill equations for space rendezvous

I have stumbled upon two variations of Hill’s equations across numerous scientific journals: Why are the mean motion’s positive and negative signs of these two Hill equations reversed? And are these ...
4 votes
2 answers
755 views

Satellite’s Position and Path on 2D Map [duplicate]

When the ISS orbit the Earth, its path traced on a 2D Mercator Earth Map is similar to a sinusoidal wave. I am wondering is there any way to determine the trig function of the wave, knowing the ...
-4 votes
1 answer
121 views

Will the initial velocity of an object in space get multiplied if a constant acceleration is applied? [closed]

Imagine an object travelling in space in the speed of 60 Kmph which took acceleration x if accelerated with the same x, will the object travel faster than 60 Kmph or travel in the same speed cuz of ...
3 votes
1 answer
366 views

What am I missing about rocket nozzle isentropic flow?

Playing a bit with Cpropep-Web, something looked wrong to me about how it models isentropic flow through a CD nozzle. I'm taking the RS-25 characteristics as an example. I ask for a frozen equilibrium ...
12 votes
1 answer
2k views

If Earth had a second moon, where would it be positioned? [closed]

Could Earth theoretically have another moon, beside the existing one, that would have a stable orbit? If it is possible, could Newtonian physics describe where it would be (i.e its position relative ...
1 vote
1 answer
68 views

Dependance of slosh mode on ratio of liquid height to tank height

If two liquid tanks of the same cross-section but different heights have the same liquid up to the same depth, will sloshing be the same or different in both tanks? I would assume they would be the ...
14 votes
1 answer
3k views

Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios?

Question: Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios? Are there fundamental engineering ...
3 votes
0 answers
136 views

What is this thing that goes zipping past the Electron launch?

Watching the Electron launch 07 October 2022 on https://www.rocketlabusa.com/live-stream, what do I see in the video at T + 9:12, just after they confirm secondary engine cut off? I thought it was a ...
2 votes
0 answers
133 views

Ion propulsion system [duplicate]

Good evening. Is there a formulae to calculate how much lift an ion propulsion system would create on earth, given factors like voltage, load, etcetera? Just a mathematical formulae. That is all I ask ...

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