Questions tagged [rockets]

Questions regarding the boosters or thrusters used to propel man-made objects. For rockets firing opposite the primaries, see [retrorockets]. See wiki for other related tags.

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114 votes
4 answers
19k views

What is the purpose of having a countdown during a rocket launch?

Every rocket launch has a countdown. But what purpose does it serve?
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89 votes
6 answers
16k views

How much bigger could Earth be, before rockets wouldn't work?

hint: Apparently the Tsiolkovsky rocket equation does not actually say that you can launch a conventional rocket into orbit around an arbitrarily large and massive body. I'm looking for a number ...
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74 votes
5 answers
12k views

Difference between BlueOrigin and SpaceX rocket landings?

So, SpaceX has finally landed their booster back to the land. BlueOrigin has achieved the same thing in a recent past, but I have read so many people commenting and criticizing the comparison of ...
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60 votes
7 answers
59k views

Who coined the phrase 'Rapid Unscheduled Disassembly'?

Usually simply abbreviated as a RUD, and also sometimes expanded as Rapid Unplanned Disassembly, and being a way of understating that a rocket exploded. I saw it attributed recently to Elon Musk, ...
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56 votes
6 answers
9k views

Can a miniature Saturn V get to the moon and back?

If the Saturn V rocket along with its Apollo spacecraft was miniaturized, for example to 1/72 scale so it was five feet tall, could it still perform a moon landing like the Apollo missions and get ...
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54 votes
4 answers
13k views

Why doesn't the Falcon-9 first stage use three legs to land?

The immediate thought that would probably come into your mind would be "Because 4 legs is more stable than 3." However that is not always true. 3 legs offer the same or in some cases more stability as ...
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53 votes
7 answers
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What technological breakthroughs were required to land booster stages?

It is only recently that SpaceX developed first stages that can land again, and be reused. The (until recent) non-existent landing of re-useable rockets is presumably, partially, due to a lack of ...
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47 votes
1 answer
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What safety protocols did this Pythom Space rocket crew ignore?

The video below of Pythom Space's first rocket test has raised a few eyebrows The video prompted hundreds of replies on Twitter, including some from rather horrified rocket scientists. "We knew ...
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45 votes
3 answers
43k views

How realistic is Kerbal Space Program?

Kerbal Space Program is an independent spaceflight simulation game, which has become quickly popular due to being (kind of) precise at simulating actual spaceflights. But how precisely? How close is ...
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43 votes
2 answers
8k views

Did the Saturn V rocket have any purely aesthetic features that didn't serve an actual function?

The rocket itself is magnificent, yes, but with so many ins and outs to it, curious if the entire design was solely purpose built, or if there were features specifically for aesthetic purposes.
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42 votes
1 answer
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Do booster stages run out of fuel, or are they purposefully shut off?

When an expendable booster rocket stage nears the end of its burn, does the guidance computer shut the engine(s) off at a certain velocity/altitude for the mission, or does the stage completely ...
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41 votes
5 answers
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Why did the SpaceX Starship SN10 explode?

Much to everyone's relief. The SpaceX Starship SN10 successfully completed its flight and landed..... But, sometime later, It exploded! Why? And did it have anything to do with the fire near the ...
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41 votes
2 answers
73k views

What is the vapour/smoke that comes from a rocket before launch?

While a rocket is waiting on the platform during the final countdown, it often seems to have clouds of steam or something similar escaping from it. Is this normal, and what are these clouds?
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41 votes
1 answer
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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 ...
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39 votes
6 answers
8k views

How much has fuel efficiency increased in rockets since the Apollo missions?

I have been talking with a friend of mine and the subject turned to modern rockets versus Apollo era rockets and fuel efficiency. My friend stated that today’s rockets use half the fuel of the rockets ...
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39 votes
4 answers
10k views

What "actually" happens at T-minus-0

In most American rocket launches, the "counter" will say: 3,2,1 [awkward pause], and liftoff.... So what truly happens at T-0? Is there any standardized event that this time indicates? Is the ...
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38 votes
5 answers
8k views

How do rocket scientists do iterative development?

In software, the general process for developing anything is code, test, fix, repeat. This is easy and cheap, because running a program typically costs an incalculably small amount of money. In rocket ...
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37 votes
4 answers
12k views

Why is there a hole in solid rocket engines?

I would like to find out why there is a straight hole down the middle in all solid rocket engine motors. I thought it only makes sense in hybrid engines where pure oxygen needs to be blown down the ...
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37 votes
6 answers
8k views

Why did it take so long for methane to be used as a rocket propellant?

SpaceX have put methane on the map as a rocket fuel, but they weren't the first to consider its use. The first experiments in building a rocket engine that uses methane date back to 2007. Now methane ...
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37 votes
4 answers
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Effect of atmospheric drag on rocket launches and benefits of high altitude launch sites

What is the approximate influence of atmospheric drag on the cost of rocket launches? Is it beneficial to have launch sites located at higher altitudes? Cape Canaveral is at sea level, but I've ...
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36 votes
9 answers
13k views

Why do rocket nozzles flare?

Why do rocket nozzles open wider at the end than, let's say, get narrower? Let me explain: A jet engine works by having this amazing thing called a combustion chamber. The combustion chamber ignites ...
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36 votes
3 answers
5k views

Do rockets, launch vehicles or spacecraft contain a black-box?

Like aeroplanes, do rockets also contains some black-box kind of thing to see what went wrong at the time of failure?
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36 votes
7 answers
9k views

How much stronger does gravity have to be for space travel to be impossible? [duplicate]

I’ve heard that only a slightly stronger gravitational pull would make it impossible for rockets to launch. Is this true? I’ve heard this used as the reason why humanity is meant to be in space.
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36 votes
1 answer
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Why does this rocket have a nose cone "cozy"?

A tea cozy keeps the tea in a teapot warmer longer by insulating it. Why does the nose of the rocket shown in Apollo-era file footage used in this video (lower your volume before watching) have a ...
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33 votes
3 answers
6k views

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?
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33 votes
3 answers
5k views

Why all the 'dust' on liftoff?

To bring things back to earth (literally), why is there such a plume of what I can only imagine is dust on liftoff from launchpads on Earth? Every launch I see from Earth has a huge cloud shooting out ...
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32 votes
4 answers
8k views

Why was this Saturn rocket elevated for launch?

This is an image of a Saturn on the launch pad on July 20th 1973 It appears to be resting on an elevated platform that raises it significantly off the ground. Why was this done? It seems like a lot ...
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32 votes
1 answer
6k views

Could a Falcon 9 reach orbit with a person glued to the outside of it?

Apologies for asking a dumb question, but I'm going to ask it anyway... I was watching a music video where the singer duct-tapes her ex to the side of a rocket to exile him into space, and it made me ...
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32 votes
1 answer
3k views

Why do the Shuttle's external tanks appear to be rusted?

Wikipedia article states as STS-1 at liftoff. The External Tank was painted white for the first two Space Shuttle launches. From STS-3 on, it was left unpainted. I wonder why the ...
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31 votes
3 answers
18k views

Why are hydrogen-fluorine fuels not used for rockets more frequently?

Many rockets use hydrogen- and oxygen-based propellants as fuel. Why are hydrogen-fluorine fuels not used? It has a specific impulse of 390 seconds, higher than hydrogen-oxygen combustion (360 ...
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  • 18k
31 votes
3 answers
8k views

Why doesn't the US use European rocket engines?

US Companies have been using Russian rocket engines for their rockets for a long time, even during sanctions. But as I was going through the European rocket launches, I felt European rocket engines ...
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31 votes
2 answers
6k views

What are the chances that a spacecraft is hit by space junk?

If a rocket flies into space there is a possibility that it will encounter a piece of space garbage; even a small screw can be fatal. What are the chances that such a collision really takes place? ...
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31 votes
6 answers
21k views

Why does a rocket engine provide more thrust in a vacuum than in atmosphere?

According to NASA Each Space Shuttle Main Engine operates at a liquid oxygen/liquid hydrogen mixture ratio of 6 to 1 to produce a sea level thrust of 179,097 kilograms (375,000 pounds) and ...
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30 votes
3 answers
13k views

What is the purpose of the black-and-white patterns on some rockets?

Some rockets have black-and-white patterns painted on them. For example, the Saturn V has them at the bottom of the upper stages and the SLS block 2 is supposed to have them below the payload. In ...
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30 votes
2 answers
17k views

What is a thrust puck on Starship?

Elon Musk recently mentioned a Thrust Puck on Twitter, "We’re stripping SN2 to bare minimum to test the thrust puck to dome weld under pressure, first with water, then at cryo." He also mentioned ...
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29 votes
3 answers
5k views

Did the Challenger SRBs fail due to design for reuse?

All that I know about the Challenger tragedy was that some o-rings failed in the reusable solid rocket boosters (SRBs) due to the low temperatures that day. I'm curious if such an accident would have ...
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29 votes
1 answer
5k views

Why are spaceship capsules frustum shaped?

Why do spaceships have a frustum (portion of a cone) shape like e.g. the pressure capsule of the SpaceX Dragon on the image below?     I think there is some engineering stuff behind ...
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29 votes
4 answers
8k views

How small could an orbital rocket be?

To what extent might a booster designed to place an extremely light weight "micro" satellite with radio transmitter, say 100 grams for the sake of argument, be scaled down before factors such as ...
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28 votes
6 answers
8k views

Would rocket engine exhaust create pockets of gas in space which could hinder further space exploration?

Suppose we establish a moon base. This base would have some population, with some need for supplies, and needs for machinery in the early stages. If we establish shipping lanes in space for these ...
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28 votes
7 answers
4k views

The Martian: Does it really take a supercomputer to calculate spaceflight maneuvers?

My preemptive apologies for asking a question about a movie, and the spoilers within said question, but considering the widespread support for its scientific plausibility, I'm hoping you'll let it ...
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28 votes
4 answers
19k views

Is the SLS irrelevant if the Falcon Heavy launch is successful this year?

My take is that, like so many bad, and good, NASA ideas, the SLS will get the axe after spending billions on the NASA subcontractor(s). Regardless if the SLS comes to full life cycle, NASA will not ...
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28 votes
4 answers
3k views

What will be NASA's successor to the Saturn V rocket?

The Saturn V rockets were the "tallest, heaviest, and most powerful rocket ever brought to operational status and still holds the record for heaviest payload launched and heaviest payload capacity to ...
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28 votes
3 answers
105k views

What is meaning of T in rocket launch countdown?

In Rocket Launch countdowns I noticed That they count with respect to some parameter T as: T-10 seconds T-9 seconds . . . T-0 seconds Why not simply count as 10 9 8 . . 0 ? http://www.nasa.gov/...
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28 votes
1 answer
1k views

For a 3 booster rocket, why do they start with igniting the starboard booster, followed by the center and port?

In today's launch of the Delta IV heavy, it was stated that the starboard booster rocket would be ignited first, followed by the port and centre boosters. I would have thought this would give some ...
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27 votes
3 answers
4k views

Falcon 9 launch process - perception of launch speed

One of the things that drew attention from my local group of rocket-watchers with the Falcon 9/Crew Dragon launch is the perceived speed of the actual launch process. We have been conditioned for ...
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  • 379
27 votes
4 answers
11k views

If the ISS had an emergency, how long would it take to get a rocket to it?

If there was an urgent need to launch a rocket to the ISS, how long would it take to have a rocket ready to launch? I am trying to understand what factors take up the time to prepare for a rocket ...
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27 votes
4 answers
14k views

What's the largest single object payload ever lifted into space?

I am aware that the Saturn V is the largest rocket ever built and was capable of lifting more weight into space than anything that exists today. Modern rockets often carry several satellites up at ...
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  • 1,092
27 votes
5 answers
62k views

Is it possible to reach space using home-made rocket?

The first stage would be a high altitude balloon, which could reach 30km. Then start a rocket-candy from that high. Without cargo, is it possible to reach the edge of space (Kármán line - 100km), or ...
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  • 822
26 votes
5 answers
10k views

Why doesn't SpaceX land boosters in Africa?

Apart from the obvious answer that it'd take too long to get the booster back across the Atlantic, why doesn't SpaceX leave the main or centre booster in space a little bit longer and guide it to land ...
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  • 523
26 votes
4 answers
4k views

Why aren't payloads their own fairings?

...or if they can, why so rarely? I mean: instead of placing a satellite of nondescript shape inside a fairing which is discarded somewhere above the atmosphere, build it in such a way that its ...
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