Questions tagged [design]

Questions about how space vehicles and related hardware are designed. See also [structural-design] and [engine-design].

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9
votes
2answers
971 views

If not constrained by underpasses, etc., would Falcon 9 have been less of a flying noodle?

This excellent answer to the question Why is Falcon 9's shape so tall and skinny? mentions California, Florida, Texas and Alabama, within and between-which there must be at least a few limiting ...
26
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3answers
2k views

Why are RTGs different colors?

This is an image of the radioisotope thermoelectric generator (RTG) for Cassini: This one was for one left on the Moon: And this one is for the Multi-Mission RTG, used by Curiosity on Mars: One is ...
8
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2answers
926 views

What are these very large, square panels on Inmarsat 5?

Question: What are these very large square panels on Inmarsat 5's? They seem to each have an extremely reflective mirror-like flat/smooth tiled-appearing side, and a nearly black side with a lot of ...
18
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4answers
3k views

Does the ISS have zenith-facing windows?

I was looking at the NASA image of the day today, and it made me wonder about the windows on the ISS. I often see pictures of Earth taken from the ISS, but I was wondering if they had any windows that ...
9
votes
1answer
911 views

Just how much can tall skinny rockets bend? (roughly, safely)

Below is a GIF I prepared and used in an earlier question, and the answer seems quite reasonable. With a height to diameter ratio of about 70 m to 3.7 m (nearly 20:1) a weight-conscious design, ...
8
votes
1answer
435 views

What is the function of this array of what looks like mirrors on TESS?

The Mashable.com article TESS is about to become your new favorite NASA mission shows a beautiful photo of the TESS spacecraft in a state that looks like it is nearly ready to launch. There is a ...
3
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1answer
586 views

Why are some reaction wheels sealed with low pressure gas, others with vacuum?

This answer and this answer address the question Do reaction wheels generally run in vacuum, or are they pressurized? Sealed or vented? and they both mention that sometimes momentum wheels are sealed ...
24
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4answers
6k views

Is the Pi really fit for outer space?

Recently, there has been growing interest in using Raspberry Pis in CubeSats. NASA is even in on the trend. But, considering that outer space is pretty harsh on electronics (i.e. radiation and cosmic ...
20
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3answers
6k views

Could 3D printing be used to achieve perfect grain geometry of solid and hybrid rocket motors?

Solid cores, either for solid-fueled of hybrid rocket motors, use various propellant grain geometries to achieve thrust curve needed. For example, some of these could look like:    &...
8
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1answer
5k views

The types of motors used on the Martian rovers?

I have a question regarding the types of motors that were used on the Martian rovers, specifically the Mars Exploration Rovers and Curiosity. I am wondering about the main 6 motors that turn the ...
38
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1answer
4k views

Why do the Russians use these fence-like interstage fairings?

When we look at various Russian rockets we often see a metal structure looking like a kind of garden fence separating some stages. To my knowledge, only the R7 family (Vostok, Voshkod, Soyuz) and N1 ...
19
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3answers
4k views

Why is Falcon 9's shape so tall and skinny?

Compared to most rockets I know of, Space X's Falcon 9 seems unusually tall and skinny. The v1.1 version is nearly 70m tall, yet only 3.6m thick. For comparison, Atlas V is 58m tall and 3.8m thick, ...
19
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2answers
2k views

What would the challenges be in developing a Falcon Heavy with three or four strap-on boosters?

Falcon Heavy has a standard Falcon 9 Full Thrust (FT) rocket core with two strap-on boosters derived from the Falcon 9 FT first stage. What about a heavier Falcon Heavy with four strap-on boosters (or ...
6
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1answer
742 views

Ballpark comparison of a hypothetical Falcon 'Quad' Heavy with cross feeds

This engineering question got me wondering. If cross feed technology were sufficiently developed, and stresses could be managed (these are big if's, and there are more I'm sure), how would these ...
24
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10answers
8k views

Can you really use Arduino for a small spacecraft?

A group of Russian geeks intends to shoot a small vehicle to the moon, which is supposed to photograph the places of the Apollo landings. This will be the ultimate proof that people actually visited ...
12
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3answers
810 views

Strategies for combating ESD and ground plane potential shifts on spacecraft charging?

What are some common design guidelines/practices to combat the electrical effects of spacecraft charging(e.g. ESD, ground plane shift). Is it to focus on more resilient parts, and reduce resistance/...
12
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2answers
2k views

Why was the Shuttle's LOX tank on top of the LH2 tank, since that makes it more top-heavy?

The external tank for the shuttle contained tanks of liquid Oxygen and Hydrogen for the main engines to use. These two have similar (though not equal) volumes, but the Oxygen is heavier in an obvious ...
36
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8answers
6k views

Wheels vs. tracks for rovers

On Earth, there are plenty of examples of vehicles that roam difficult terrain having tracks instead of wheels, while all (at least those I am aware of) extraterrestrial rovers have wheels. Is there ...
15
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1answer
1k views

How are self-destructs implemented in rocketry?

Many rocket systems are equipped with self-destructs to prevent an out-of-control vehicle from wandering too far from its intended path and becoming a hazard. Presumably, the objective is to kill the ...
6
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1answer
147 views

Mass ratio of solar-electric versus radioisotope thermo-electric power for propulsion; beyond how many AU do RTGs win?

Solar-electric propulsion has been used several times now in deep space missions. This question explores the scalability in comparison to Radioisotope thermoelectric generation or other nuclear-based ...
3
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1answer
588 views

Where is the center of mass of the ISS relative to it's internal coordinates?

I'd like to find a fairly precise location of the center of mass of the ISS. I understand it moves for several reasons, including shifting of loads, flexing, and thermal expansion, but to say 1 meter ...
31
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7answers
15k views

Why are Rocket engines at the base of the rocket?

I don't know much about Rockets, but all that I have seen, from the Saturn V to SpaceX's Falcon 9 have the engine at the bottom. Doesn't this make the Rocket really unstable, like balancing a pencil ...
16
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6answers
4k views

What are the criteria to put the oxygen tank above or below the fuel tank for a given stage of a rocket?

Inside a rocket, tanks are put one above the other. This make sense as it may be a good compromise between tanks shape and the aerodynamicity of the whole rocket. In some rocket stage, the oxygen tank ...
54
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4answers
6k views

Why wasn't an RTG used on the Juno spacecraft?

When I first heard about the Juno spacecraft, I was surprised that it would be using solar panels to generate power throughout the mission. Why wasn't a radioisotope thermoelectric generator (RTG) ...
19
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1answer
7k views

What materials are the windows on the US Segment of the ISS made out of?

Presumably the various windows on the different modules of the ISS are consistent on the different segments of the ISS. What are the windows on the US Segment made out of? Do they have special ...
12
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2answers
1k views

Origin of term “Block I”, “Block II”, etc

In NASA spacecraft development, subsequent versions of a design are referred to as "Block 1", "Block 2", etc. What is the origin of this naming convention? Why not just call them "Version 1", "...
11
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1answer
634 views

Why are planetary probe RTGs tilted at a jaunty angle?

This image from here: Does the Dragonfly project (quadcopters on Titan) envision attached RTG's or would they be static and revisited for charging? and this image show that the RTGs on these two ...
13
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1answer
873 views

Why does the YF-75D nozzle have such a strong spiral pattern?

Why does the YF-75D nozzle material have such a strong spiral pattern? Is it a result/biproduct of a manufacturing process only, or does it have some specific function? edit: The last, cropped ...
10
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1answer
390 views

Advantages of a Solid Fueled Upper Stage

I was recently looking at the specs of the Antares launch vehicle and I was surprised to find out that they were using a solid fueled motor as their upper stage. I've always learned that in the upper ...
8
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3answers
748 views

Did von Braun have “a thing” for fins? Why did Saturn I block 2 get fins because it's a “von Braun” rocket?

At about 05:55 in Scott Manley's new video NASA Might Be Giving Away A Saturn I Rocket - Here's Why I Love This Vintage Booster he says: So the Saturn; the first ...
7
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1answer
457 views

How quickly might a Titan rover or drone get covered in oil and dirt? Will it need windshield-wipers?

These questions and their answers address some potential aspects of a rover on Saturn's moon Titan. Titan rover survival challenges What are the technical challenges in building a Titan rover that ...
7
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1answer
432 views

Why does PSLV use four stages to get to LEO, and why do they alternate solid, liquid, solid, liquid?

Is there a simple way to explain why ISRO's PSLV launch vehicle uses four stages to get to LEO, and why they alternate as follows: ...
7
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0answers
288 views

Were solar concentrators on HS-702 just a stop-gap measure until triple-junction PV cells were available?

According to Gunter's Space Page discussion of early versions of the Hughes HS-702 Bus: The first version of the 702 used solar arrays with concentrators. These concentrators tended to early fogging, ...
4
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2answers
131 views

Have there been any square 4U (2x2) cubesats?

How much did each MarCO 6U cubesat weigh? suggests that the density of a MarCO 6U cubesat might be as low as 0.75 g/cm^3 whereas I think they are usually about twice that. That led me to speculate ...
30
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7answers
8k views

Why weren't Saturn V and the Soviet N-1 Moon rockets made larger in order to simplify Lunar missions?

During the Apollo missions the Lunar lander was separated, turned around and docked during flight. And the command module was left in Lunar orbit during the surface mission. The Soviets planned to ...
29
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4answers
7k views

Why does the Falcon 9 have 9 engines?

What are the reasons for using 9 engines in the first stage of the Falcon 9? Why not 8 or 10? Looking at the Raptor engine, they seem to be looking at 9 engines again. Is there some specific advantage ...
26
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1answer
5k views

Falcon 9 design: Why is the cargo fairing so much wider than the lower parts?

Why does the cargo fairing have a much larger diameter than the lower part of the rocket? Of course a larger diameter lets thicker payloads fit. But then the first, inter, and second stage could have ...
32
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4answers
5k views

When did the concept of “stages” enter rocketry?

The staged rocket design is common now, but at some point in the history of rocket design it must have been revolutionary. When was the staged design introduced? Was it quickly accepted or did it ...
9
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5answers
10k views

What is the optimum shape for a spacecraft?

I understand that these days a spacecraft design is very much centred on what can be lifted into space by current rockets, hence the modular, cylindrical shape of the ISS. So, with current ...
7
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5answers
1k views

What sort of analysis was performed before “modern” computing and the invention of finite element analysis and computational fluid dynamics?

I am not sure if this question is appropriate for this SE - Ideally this should be posted in Engineering SE but as far as I'm aware it does not exist! (I can only assume that the scope of engineering ...
12
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2answers
2k views

Why is there so much variation in the number of engines on launchers?

There is much variation in the number of engines used in the liftoff stage of various launchers. Saturn V had 5 Space shuttles had 5 (3 main + 2 SRB) Falcon 9 has 9 Soyuz has 20 N1 had 30 Delta Heavy ...
8
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2answers
736 views

Does new technology make it advantageous to have walking rovers?

Watching Boston Dynamics progress with their walking robots makes it seem like maybe a version adapted to function off-world could compete with wheeled rovers now: ...
7
votes
2answers
2k views

Why Use Helium?

I apologize in advance if this question has already been asked and answered elsewhere, but why do RP-1/LOX rocket systems use helium for propellant tank pressurization? I understand the fact that O2 ...
25
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6answers
9k views

Why aren't rockets built with truss structures inside their fuel & oxidizer tanks to increase structural strength?

I've been wondering how a rocket fuselage can support all the weight of the upper stages when it is only made of a cylinder of very thin sheet metal. (Especially considering acceleration, vibration ...
22
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2answers
7k views

Why were Space Shuttle astronauts able to walk off the orbiter?

I am watching loads of ISS related videos and there is one detail I recently noticed; At the time, when Space Shuttles were still in operation and visiting ISS, when astronauts returned home, they ...
8
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2answers
1k views

What are the common space application adhesives used in Earth orbiting satellites?

For quite some time, I am reading about space adhesives. Selecting the right adhesive for space applications is extremely important, mainly due to the high vacuum (around 10-8 Torr), and the variation ...
6
votes
0answers
146 views

Are black and white stripes any better than uniform gray for thermal control?

Q: What color is a spaceship? Several answers and comments on Why were Europe's first few satellites so stylish? Why the pronounced alternating white and black stripes? contain phrases like "...
4
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0answers
247 views

What were Hubble's jerk and jounce limits? Did JWST have the same?

From Wikipedia: In physics, jerk is the rate of change of acceleration; that is, the derivative of acceleration with respect to time, and as such the second derivative of velocity, or the third ...
4
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1answer
222 views

Balancing Perseverance Mars Rover; couldn't they just “move stuff around a little” rather than add 6+ kg of dead weight?

The NASA News item NASA's Perseverance Mars Rover Gets Balanced says: Just as an auto mechanic places small weights on a car tire's rim to bring it into balance, the Perseverance team analyzed the ...
3
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4answers
932 views

Just how pointy does a rocket's nosecone need to be?

There are some beautiful images of the Qu8k rocket launch on this web page and I show a few below. There's a video (below) and the PDF Qu8k Final By Derek Deville, November 27, 2011 The stainless ...