# All Questions

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6 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 ...
10 views

### What if a pin size object travelling with a speed close to that of light, hits the surface of earth?

Of all possibilities I could imagine is that it would either get burnt or maybe pierce through the planet and get burnt up at the core. Could it be more catastrophic than this?
31 views

### Could you bounce a tennis ball off of the James Webb sunshield?

News articles keep referring to the James Webb Space Telescope's sunshield as "about the size of a tennis court", which raises the question: could it function as a tennis court? Or, more ...
427 views

### Has any piston machine been used on a space mission?

Inspired by question about engine lubrication in space. Piston engines are not used for propelling spacecraft, but there are some possible uses for especially Stirling engines and compressors: ...
45 views

Yet another kerbal question here. Background: I've built many SSTOs before, mainly small, light-payload or crew delivery ones (either boosted by a rocket or by itself). The reason why I've been shying ...
34 views

### Why time flows slower for objects moving with speed close to speed of light? [closed]

What does it mean? I assume that time was inventioned by humans and this is only an abstract idea. But why do we see the relativistic time delation? Does it mean that quantum processes flow slower ...
167 views

### Which aspects of the JWST wavefront process are the most time-consuming?

NASA is currently estimating the that the upcoming wavefront process to align the JWST's mirror segments will take around three months. This description of the WFSC process paints a picture of ...
35 views

### If I'm moving with speed of light but without any acceleration will I see any relativistic effects? [closed]

As the moving is relative there is no matter on which speed you are moving if there is no acceleration. We will fill it exactly the same as no moving (if other objects moves with the same speed). So, ...
31 views

### Could we model spacetime and light using water and waves on water? [closed]

I like to think about spacetime as about water and light and gravitational waves is a just a waves on water in that case. Can I use this analogy? Does the water waves has a limit speed like ...
33 views

### If you travel on car with the speed of light and turn on the car headlights: will it shine in gamma light instead of visible light? [closed]

If you travel on car with the speed of light and turn on the car headlights: will it shine in gamma light instead of visible light?
28 views

### On which speed the background radiation becomes dangerous for the people on space ship? [closed]

If we travel with speed close to the speed of light, the light waves becomes shorter and their energy increases (because we flight through much more light for the same time). So, even background ...
28 views

### Do photons exist from point of view of photon? [closed]

If photons travelling with speed of light it means that time is stopped for photons and there is no any distance in Universe for them. So, does it mean that photons not exist? From point of view of ...
60 views

### Why the speed of light is 300000 km/s and not any other value? [closed]

Why speed of light is 300000 km/s and not 150000 km/s or 600000 km/s. From which it depends? Why it has the value which it has?
32 views

### Could we detect the Alcubierre drive usage if some alien civilization do it? [closed]

Is it possible to detect the warp drive usage? On which maximum distance could it be done? If we detect it, can it be a natural phenomenon (for. i.e. result of some black holes fusion)?
57 views

### Is this JWST Halo orbit plot fouled up somehow?

After looking at this plot and many others I've come to the conclusion that this plot does not represent current JWST halo orbit. If the plot is supposed to be of JWST halo... it disagrees with many ...
60 views

### Parameters of the L2 insertion burn to be done tomorrow

What parameters control the impulse to be applied in the L2 insertion burn? What parameters control when/where it is to be performed? What velocity is the impulse applied to achieve? Is the vehicle ...
130 views

### Could astronauts jump from a spaceship onto a spacestation and how would it be like if yes?

I saw it happen in the videogame Alien:Isolation but not sure how realistic it was. I need help understanding some orbital mechanics for a sci-fi story that I am trying to write. The scenario I ...
66 views

### A thought experiment for relativity [closed]

So if you have astronauts and space with no reference points and one is moving none of the astronauts knows who it is. But i think i figured out a way to find out. So here is my thought experiment: ...
108 views

2k views

### Why do we use Chebyshev polynomials to predict positions of solar system bodies?

I've seen information for how to use the Chebyshev coefficients that JPL publishes, but nothing that explains why. Why isn't a simpler mathematical model used? I'm also surprised that JPL uses a ...
157 views

### Would it be possible to receive the transmissions from JWST as an amateur?

Would it be possible to receive the transmissions from JWST (James Webb Space Telescope) as an amateur, building your own antenna? Would the transmissions be encrypted? One source cites it using: S-...
51 views

### Is it (theoretically) correct to apply an equation that is derived from a hyperbolic trajectory, to an elliptic transfer orbit?

The equation in question is this one: $$v^2 = v_e^2 + v_{\infty}^2$$ and it is showed in this answer. The Escape velocity page on Wikipedia mentions a link (num. 4) to the book "Fundamentals of ...
63 views

### What is the average solar irradiation in low earth orbit?

I am trying to figure out how much power I can expect for a CubeSat in Low Earth Orbit. Is there some dataset or constant that describes the average rate of solar irradiation (per unit of area) in LEO?...
240 views

### Why making such a big deal with Max Q?

At each SpaceX launch, they always make some big deal of Max Q which most of the time comes at around 13Km and at a speed of 1700Km.h-1 But on the way back, stage 1 is at this same altitude of 13km at ...
103 views

### Halo Orbits for Dummies: Can the tilt orientation of an L2 halo orbit be modelled on Coriolis Effect?

L2 Halo orbits are often portrayed as a pair of “North” and “South” orbits. Could the difference in “tilt” around the Y axis be explained by the direction of rotation and the Coriolis Effect? https://...
2k views

### What is this South Korean rocket and why does it have separate yellow and blue exhaust plumes?

The BBC's Watching North Korea from a supersonic fighter jet (screenshot from YouTube) shows the launch of a South Korean rocket. I notice that it has both a very long, nicely expanded blue exhaust ...
136 views

### How well would a supersonic aircraft perform in the Martian atmosphere?

I started getting curious about this question during my Flight Test Engineering class. My professor was talking about a part of the International Standard Atmosphere that is a similar pressure to that ...
273 views

There is confusion in my mind over the direction of JWST’s halo orbit, depending in the source of graphics. Observing from the Earth, does JWST orbit clockwise or counterclockwise around the antisolar ...