# All Questions

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### Computing Flight Characteristics for Different Propellant Grain Geometries?

Consider the following image: I am interested in mathematically accounting for some of these different geometries but have had little success so far in finding how this can be done. The first thought ...
• 31
201 views

### Solar Turbines on the moon

Related to other questions about power generation on the moon. URL's will be added shortly... Given that force is experienced by objects hit by sunlight, such as a solar sail, would a turbine of some ...
62 views

### Are there occurrances of monel (nickel-copper) meteorite materials?

This question is prompted by a Space.com article on the metallic Psyche asteroid - Wendy Caldwell, a scientist at Los Alamos National Laboratory, told Space.com that some of her most promising ...
• 1,044
1 vote
36 views

### Will Ataxite be the type of nickel-iron sought for asteroid mining?

The high value metals in meteorites and asteroids - mostly Platinum Group Metals - appear associated with the nickel content (The Occurrence of Platinum in Meteorites, F. G. Hawley,1939), ie the ...
• 1,044
140 views

### What was the exhaust pressure of the Saturn V? [duplicate]

I am trying to write some code to simulate rocket launches, and I am doing a proof of concept using the Apollo 11 as a model, to fill my values. When calculating thrust I am using the equation: F=m⋅Ve+...
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164 views

### What speed could you achieve by slingshotting around earth from moon?

Imagine Apollo 13 had fuel to burn engines on the way back to earth but instead used earths gravity to accelerate and the slingshot around earth
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1 vote
75 views

### How does the Gpredict software algorithm track satellites?

I was wondering how Gpredict calculates the ground tracks, Lat, Long and elevation based on a ground station. If I understand correctly, Gpredict takes the values from a TLE (Two-Line Element) set, ...
• 43
167 views

### What could we produce with a space based industry?

The astroid belt is great place to start humanity’s journey through space. I want to know, what materials and items could be produced from asteroids. I’m mainly going to ask for useful items, such ...
• 79
105 views

### GMAT SGP TLE Propagator and maneuver

So this time I try to use GMAT(2022 ver). I am using the SPICESGP4 TLE Propagator to simulator ISS's orbit. For now it work well. However when I try to use the burn to change its orbit altitude, it ...
3k views

### Earth re-entry from orbit by a sequence of upper-atmosphere dips to reduce kinetic energy?

There are quite a few questions on this sort of theme here, and I've also read one or two other things, like non-ballistic re-entry. So this might be a duplicate, but I don't think so. To clarify: I'm ...
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41 views

### How to calculate the tank boost system for the displacement feed system?

There is a liquid rocket engine running on two components: highly concentrated hydrogen peroxide and kerosene, fuel vapor is ...
1 vote
125 views

### Interpretation of mars rover images

I’ve been obsessed with the perseverance images, specially the images from the SHERLOC-WATSON system- the UV camera tricked out with racing stripes and fuzzy dice hanging from its rear-view mirror (...
1 vote
149 views

### How do I transfer passengers from the non-rotating dock to the rotating habitat ring of my space station? [duplicate]

For a story I'm working on, my characters have just docked with a space station in Low Earth orbit. It's set in the 2080s, so we're assuming no game-changing leaps of technology, merely what's ...
140 views

### Was there a close call for Voyager 2's extended mission due to lost uplink during the Jupiter encounter?

In Uplink-Downlink (2001), Douglas Mudgway says: "[The Jupiter radiation environment] . . . resulted in loss of the uplink connection with the [Voyager 2] spacecraft on the day after encounter. ...
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190 views

### How many people would have to keep it a secret if the U.S. hadn't walked on the moon? [closed]

For another question, @user answered: "The kind of people who dismiss the hundreds of thousands who worked directly on the Apollo project, the hundreds of thousands to millions who watched the ...
• 99
192 views

### Strange swirls on the latest image from SOHO

Earlier today, I was looking at the latest image from SOHO and noticed some odd swirly lines at the bottom left of the image. They no longer appear on the site, but I saved the image before they were ...
• 73
118 views

### How could we extract xenon from asteroids and comets?

Xenon is a propellant for next which is a very good thruster. VASIMIR, which uses much more abundant hydrogen is under development and may not ready by the time we run out of resources. So, how ...
• 79
95 views

### square-cube law and TPS

Yesterday, I asked a question about the square-cube law and propellant tanks. Do larger rockets tend to have a better mass ratio due to the square cube law? I have a very similar question about TPS ...
• 133
220 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-...
• 21
4k views

### Do larger rockets tend to have a better mass ratio due to the square cube law?

Do larger rockets tend to have a better mass ratio due to the square cube law? I mean, larger tanks have a better surface-to-volume ratio, so their weight-to-volume should be improved
• 133
507 views

### Definition of "stable orbit"

I often struggle with the term "stable orbit" for objects in earths sphere of influence, since all real orbits are affected by disturbing forces. Sentences like: It is not possible to ...
• 3,288
1 vote
69 views

### How can I determine characteristic length (L*) of a rocket engine combustion chamber if there is little to no data collected on a similar engine? [closed]

I am designing a liquid bi-propellant rocket engine using Nitrous Oxide and Isopropyl Alcohol. I have all the necessary parameters for nozzle design and am at the stage of determining the combustion ...
2k views

### Delta V required to land and then ascend from the surface of every celestial body

I've been doing some research to figure out how feasible grand tour manned missions to the surface of the moons of each outer planet. This is related: Where can I find a delta v map of landing ...
221 views

### Which 6 spacecraft had the biggest effect on pushing the “Final Frontier?”

I am planning a 6-lecture course on Space Exploration for our local Elder College. It is aimed at a motivated audience with general knowledge in science. The objective is to generate interest in Space ...
• 17.6k
193 views

### Which are more efficient: oxidizer-rich or fuel rich rocket engines?

Several internet articles claim that the high Isp of the Soviet RD-180 engine (as used in the Atlas III and V launch vehicles) was (at least partially) due to the fact the RD-180 ran oxidizer-rich, ...
• 17.6k
148 views

### Which satellite is this very bright object?

For the past few years, I've been spotting this "star" periodically in the night sky. Except it's not a star because it doesn't twinkle. And I don't think it's Venus, because I've observed ...
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1 vote
106 views

### What's the reason behind SpaceX's timing of launching Starlink satellites?

I noticed a pattern in the timing of Starlink launches: In the first half of each year, Starlink launches occur rather during the day, and in the second half, they occur rather during the night (...
• 189
1 vote
69 views

### How to convert Geocentric Coordinates to ECEF using Skyfield?

I'm trying to obtain ECEF coordinates from geocentric coordinates and then plot the ground track using the subpoint function. Any advice? My objective is to create an accurate ground track. Additional ...
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2k views

### What is Earth's apparent magnitude from geosynchronous orbit?

How bright is a "full Earth" from geosynchronous altitude (22,200 mi) and would it be dangerous to look at a full Earth for too long from that distance without wearing a dimmed visor?
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2k views

### Why do Atlas III and V use Russian RD-180 engines?

The Atlas III and V first stages were powered by NPO Energomash RD-180 engines, unlike the previous Atlas II which was powered by Rocketdyne RS-56 engines. Why did Lockheed Martin switch to Russian ...
• 17.6k
101 views

### Looking for Apollo Flight Control Hardware Blueprints (such as RHC, THC and COAS)

I've been looking to build replicas of Apollo flight control hardware such as RHC, THC, ACA, TTCA and COAS, and am looking for detailed engineering drawings that show dimensions and internal ...
287 views

### Hydrogen-propelled space elevator [closed]

I'm working on a space elevator design using kerosene-burning jet engines and dirigibles supporting 1km stages of pipeline and cable stretching up to the end of the stratosphere (~50km), then using ...
1k views

### Why is the central truss segment of the ISS called S0?

Why is that segment of the ISS truss called S0, not P0, C (for center) or just 0?
118 views

### Why is the SpaceShipTwo being released from 44,300 ft, not from 50,000 ft as originally anticipated?

The VSS Unity is always released at an altitude of 44,300 ft (13.5 km) from the VMS Eve. The SpaceShipTwo was originally anticipated to be released at 50,000 ft (15.2 km) and many media still report ...
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136 views

### How I can find the angular orbital velocity of satellite in circle orbit?

I know that we have the angular orbital velocity of a satellite in circle orbit as $w_0=\frac{v}{r}$, but I want another way to find out the angular orbital velocity of a satellite in the circle orbit....
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2k views

### Which countries could launch a human into space on very short notice

I’m not sure if it's better to ask this here or on worldbuilding.se Which countries except Russia/China/US can launch their own crew into space and return them unharmed (if for some reason this really ...
• 273
199 views

### Does venus affect Earth's orbit more than Jupiter

(this question could also fit in Astronomy or Physics) Jupiter, with it's huge mass, is the obvious culprit for messing with Earth's orbit (and possibly climate). Although Jupiter is extremely massive,...
146 views

### What size of meteoroid would be needed to wipe out humanity on Earth?

This might belong on physics.SE or astronomy.SE or not on SE at all as it's not falsifiable I believe a meteoroid caused the dinosaurs to go extinct by causing a global winter. However Earth has been ...
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2k views

### How high could Ingenuity fly?

On its 59th flight, Ingenuity achieved a height of 20 meters - twice as high as its maximum height during the original 5 flights that it was designed and expected to last for. In the scheduled 61st ...
• 273
1 vote
51 views

### How to set a constant density model in STK'S Astrogator

I'm trying to verify a simplifying orbit maintenance strategy obtained from one of my numerical tools using Astrogator as a propagator. My tool uses a constant density value obtained by averaging the ...
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168 views

### Windmills in Space [closed]

What if we put a windmill like we use now in space like on moon or a space station so its attached to the surface and since we have no wind we use air tanks in the blades to rotate, everytime it slows ...
213 views

### What did I see? Multiple "satellite" flares

I came across this page this evening after witnessing around 15 what looked to be satellite flares in the same region of sky within about ten minutes. All of the objects flared multiple times with a ...
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5k views

### What assumptions were made about the sphericity of the Moon for the Apollo program?

I've just been reading about the Apollo program. Apollo 8 seems to have gone into a fairly circular lunar orbit 69 miles at perigee. Apollo 10 was pretty much similar, although they dipped down with ...
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224 views

### Where can I find the video of Apollo 16 floodlight mistaken with a UFO?

So, a few years ago (2004) NASA showed that a picture of a supposed UFO captured by the Apollo 16 astronauts through the window of the Command Module was in fact the floodlight protruding from the ...
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1 vote
78 views

### How many tonnes of cargo are stored on the International Space Station?

I think I read somewhere that SpaceX's Starship should carry 100 tonnes to the moon, and that this amount of mass was greater than the total cargo on the ISS, but I can't find a reference confirming ...
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2k views

### Why does the Psyche Spacecraft use cold gas thrusters?

In a recent article on SpaceNews they write [There exist] nitrogen cold-gas thrusters that orient the spacecraft. This seems like an odd choice for me, considering it is a multi year mission that ...
• 3,566
253 views

### What is the significance of a heat flux value of 1135 W/m^2 when jettisoning the payload fairing? [duplicate]

I have seen that many rockets jettison their payload fairing at an altitude where the aerothermal heatflux is leass than or equal to 1135 W/m^2. What is the reason behind considering this particular ...
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128 views

### Can I move Hyperion to Mars with fusion rockets?

I'm working on a SciFi story set roughly in 2100 that takes place both on the moon and Mars. One plot point hinges on terraforming Mars, the biggest stumbling block being its lack of water and ...
258 views

### How does NASA ensure nobody else communicates with probes? [duplicate]

We often hear about how various parts of Voyager have been turned off or on, or how course corrections have been made. How does NASA know that nobody else on Earth can send instructions to a probe? It ...
1 vote