Questions tagged [launch]

Questions regarding the takeoff or the liftoff phase of the flight of a rocket and the set of activities required for preparation of the launch vehicle leading to it.

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118 votes
6 answers
63k 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 ...
uhoh's user avatar
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115 votes
4 answers
20k 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?
Hash's user avatar
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98 votes
3 answers
141k views

What happens to the Falcon 9 second stage after payload separation?

In a Falcon 9 launch, the second stage looks like it achieves orbit along with the payload. But is that impression accurate? Does SpaceX need to do anything to deorbit the stage? I can see a few ...
Hobbes's user avatar
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71 votes
10 answers
55k views

Why is SpaceX considering Methane as fuel for their next engine, the Raptor?

Currently, SpaceX has developed the Merlin 1 family (1B (Falcon 1), 1C (Falcon 9 v1.0), 1D (Falcon 9 v1.1/F9-R/Falcon Heavy), vacuum versions and sealevel versions) which are LOX/RP1 based. (75-...
geoffc's user avatar
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67 votes
2 answers
9k views

What was Apollo 13's "Little Jolt" after MECO?

Disclaimer: This is a question about the 1995 film Apollo 13; I know Hollywood should always be taken with a moon-sized grain of salt, so the question should read as both "Is this true" and "What was ...
Diego Sánchez's user avatar
60 votes
5 answers
34k views

What are the towers around the SpaceX launch pad used for?

I noticed four(?) towers around the SpaceX launch pad during yesterday's aborted launch Image credit NBC News What are the towers used for? Tracking? Radio communications?
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59 votes
4 answers
8k views

Can gunpowder get you to the moon?

In 'From the Earth to the Moon' (1873) by Jules Verne, A huge cannon is used to send a spaceship to the moon. A lively discussion in chapter IX leads to using 400,000 pounds of fulminating cotton to ...
James Jenkins's user avatar
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 ...
Thomas's user avatar
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55 votes
4 answers
40k views

What was the fate of the main core of the first Falcon Heavy launch?

February 6th 2018 saw the first test launch of SpaceX's Falcon 9 Heavy rocket. During the main core's landing on the marine landing pad, the connection was lost. As such it is not immediately clear ...
JAD's user avatar
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54 votes
2 answers
49k views

What is the purpose of the jets of water often under rocket engines during launch?

I have watched several STS launches, and noticed that there were always huge jets of water that would begin right before the rocket engines lit. They were right under the rocket, mounted to the pad. ...
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49 votes
11 answers
41k views

Could it be possible to launch a rocket from a balloon?

There are several (commercial) organisations looking into alternative means to launch space-bound rockets. One commonly proposed method is to use a large airplane as the launch platform. This method ...
Nallath's user avatar
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47 votes
4 answers
16k views

How is a rocket stabilized during the initial, slow speed, portion of launch?

Let's say we're at T+0, just as the rocket starts to move, what keeps it upright as it clears the tower and gains speed?
nexus_2006's user avatar
45 votes
1 answer
6k views

Was the payload bay of the Space Shuttle depressurized before launch?

We know that the payload bay of the Space Shuttle Orbiter carried satellites, pieces of equipment for repairing satellites and components of the International Space Station. Was the payload bay of ...
Vishnu's user avatar
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45 votes
2 answers
82k 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?
Rory Alsop's user avatar
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43 votes
8 answers
12k views

Why is the first launch of Falcon Heavy sending a car instead of something useful?

The first launch of the new Falcon Heavy will be sending up a Tesla Roadster owned by Elon Musk as its payload instead of something more useful. Why spend all that money and effort sending up a car? ...
Cactus Kas's user avatar
43 votes
3 answers
10k views

Is a SpaceX launch completely automated?

Once the engines are ignited and liftoff occurs, are any operators/controllers on the ground making any manual changes to the flight? Or are they simply monitoring the entire event until the boosters ...
v15's user avatar
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42 votes
1 answer
7k views

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 ...
Jake Blocker's user avatar
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40 votes
3 answers
5k views

If the Apollo mandate were delivered today, would the mission vehicle(s) and profile be similar?

Among a variety of alternatives considered at the time, the Apollo configuration of 3-person CSM and 2-person LM, launched atop a single vehicle was considered the optimal choice for its day. With ...
Anthony X's user avatar
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40 votes
4 answers
11k 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 ...
Dat Ha's user avatar
  • 1,715
39 votes
5 answers
13k views

Why aren't all satellite-carrying rockets launched from airplanes?

There are several significant advantages to air launching a satellite-carrying rocket: save fuel/propellant as a horizontal take-off is more energy efficient fully mobile platform allowing the launch ...
Question Overflow's user avatar
39 votes
1 answer
9k views

Why did the Tesla Roadster spend time in the Van Allen belt?

Following the Falcon Heavy launch, the second stage + Roadster payload spent a number of hours 'drifting' through the Van Allen belt before performing the burn to put it into its current orbit. Elon ...
Baldrickk's user avatar
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39 votes
4 answers
16k views

Why didn't the Space Shuttle have a launch escape system?

Since the very beginning of space exploration, rockets had some sort of Launch Escape System (LES). From this Wikipedia article, we know that Mercury and Apollo had an escape tower, while Vostok and ...
user avatar
38 votes
10 answers
15k views

Why don't we use catapults to get to space?

Stupid question obviously. But did you ever had an idea which sounded so brilliant, but you know it is totally stupid? So, lets hear my idea: Do you know how we launch jet fighters from navy ships? ...
Pavel Janicek's user avatar
37 votes
4 answers
16k views

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 ...
Tomislav Muic's user avatar
37 votes
1 answer
6k views

Why does the Minotaur I wear a yellow jacket that "banana-peels" off as it launches?

Videos available of the recent Minotaur I launch at Wallops for NROL-111 show a yellow jacket on most of the four stage SRB-to-orbit launch vehicle. I read or heard somewhere that wires attached to ...
uhoh's user avatar
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36 votes
3 answers
4k views

Have any satellites been lost or damaged on their way to the launch site (ground/sea transport)?

On our sister site Travel Stack Exchange, someone asked about carrying a cubesat on a plane in hand luggage and is worried about damage or loss (or not being allowed on the plane). Several answers ...
gerrit's user avatar
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36 votes
3 answers
13k views

Why are rocket engines operating above 100% often considered nominal?

It was brought to the attention of the community that right before the crash of Antares the commentator noted: "Main engines at 108%" It was noted that other engines were also reported to work at ...
user avatar
35 votes
7 answers
12k views

Why didn't NASA use the shuttle to make a profit?

My understanding is the shuttle was designed as cost-effective workhorse, a space-van to ferry cargo up to the ISS, conduct zero-G experiments and put satellites into orbit. So why didn't NASA take ...
JayTarka's user avatar
  • 453
35 votes
5 answers
8k views

Has any spacecraft ever been flown manually to orbit?

Has anyone ever manually flown a spacecraft to orbit, Kerbal Space Program-style?
Vikki's user avatar
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35 votes
6 answers
10k views

Why is there a "coasting" phase in some space launches?

During the PSLV (India's Polar Satellite Launch Vehicle) C24 launch on 4 April 2014, once stage 3 (PS3) had burned out, it wasn't immediately jettisoned, but instead there was a coasting phase for ...
Rory Alsop's user avatar
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35 votes
3 answers
4k views

Why was AMOS-6 mounted on the rocket for a test fire?

I understand that the static test is a general test of pre-launch procedures, but risking a multi-million dollar payload for a test seems remarkable. Couldn't they use a mass simulator or something? ...
Abacus Lever's user avatar
33 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 ...
David says Reinstate Monica's user avatar
33 votes
3 answers
22k 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 ...
Hash's user avatar
  • 18k
33 votes
2 answers
10k views

What holds SpaceX’s rocket in place in this launch?

On a recent launch video, the gantry is at an angle and only loose tethers are attached as the rocket is prepared for launch. What is keeping it upright and in place at this point? The engines haven'...
MarsJarsGuitars-n-Chars's user avatar
33 votes
3 answers
7k views

Why is there any launch window at all for the Falcon Heavy test flight?

Why is the window only ~3 hours long, why not 2? why not 5? why not "until it launches"? I'm guessing range safety, they could only get a TFR that long?
Sam's user avatar
  • 600
33 votes
4 answers
6k views

Will the Falcon Heavy be far enough in 12 seconds to not cause damage?

Elon Musk has stated that he will consider it a success if the Falcon Heavy gets far enough away from the launch pad to not cause damage if it blows up. The Falcon Heavy underwent a 12 second static ...
PearsonArtPhoto's user avatar
  • 121k
33 votes
1 answer
29k views

What are the droplets/particles falling off rockets at launch?

In this picture from the AsiaSat 6 launch by Falcon 9 on 8th September 2014, the part of the rocket between the fairing and the engine appears to be surrounded by dust, water droplets or debris: And ...
user avatar
33 votes
1 answer
4k 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 ...
Hash's user avatar
  • 18k
32 votes
3 answers
9k views

Why do astronauts wear spacesuits during launch?

I have noticed that astronauts in every launch I've found wear a spacesuit during launch, like this example from the shuttle. I don't understand this. What kind of problem could cause loss of cabin ...
Ryan_L's user avatar
  • 1,042
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 ...
Jeremy Friesner's user avatar
31 votes
3 answers
15k views

Why does the SpaceX Falcon 9 rocket do a 180 flip for reentry?

I am very new to the rockets and this can be a very dumb question, just that I am not sure if my understanding here is right? All of the rockets engines are at bottom which help it take off and ...
KP.'s user avatar
  • 421
31 votes
5 answers
11k views

Why not travel to Mars in 2 months?

Just to clarify: I've made some research and generally know what the case is, didn't mean to make the question sound stupid. :) I know there is a thing called Hohmann transfer orbit, named after ...
Martin Asenov's user avatar
31 votes
3 answers
7k views

Do rockets leave launch pad at full thrust?

Rockets always seem to launch slower than I expect them for the thrust they can produce. Do they really launch off the pad at maximum thrust? Or do they launch at lower thrust until they clear the ...
user avatar
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 ...
Quazi Irfan's user avatar
31 votes
1 answer
5k views

What are these membranes at the aft end of the Shuttle that get torn off during lift off?

The link to the Space Shuttle launch video. At 1:30 mark, three circular disks get torn away. It happens immediately after the engine ignition begins. Here is a cropped image of the Discovery after ...
karthikeyan's user avatar
  • 4,469
31 votes
1 answer
43k views

What does 'Switch SCE to AUX' mean?

During the launch of Apollo 12 a major malfunction was caused by 2 lightning strikes. See http://www.realclearscience.com/blog/2013/02/apollo-12-struck-by-lightning.html for more info. The solution ...
OrangePeel52's user avatar
  • 2,561
31 votes
4 answers
3k views

Has Max-Q historically been a common failure point in rocket launches?

I believe that it's common knowledge that Max-Q is the point in which a rocket is undergoing the maximum dynamic stress during a launch and ascent. But, how often have rockets actually been destroyed ...
Milwrdfan's user avatar
  • 2,798
30 votes
7 answers
4k views

What technological hurdles prevent the development of a space gun?

Ever since Jules Verne wrote "From the Earth to the Moon" space guns have long been proposed as a method of launching objects into space. And for non-human, non-fragile payloads they make sense as the ...
System Down's user avatar
  • 3,009
30 votes
3 answers
5k views

Could a Falcon Heavy test flight be responsible for these observations?

We observed a bright, slow moving (in our view for several minutes) large object that eventually left large bright contrails. This was over Northern New Mexico at around 7:29 PM MST. The object was ...
MT Hensley's user avatar
30 votes
5 answers
6k views

Do any launches bypass LEO?

If sending a payload to GEO (geosynchronous orbit) or any other high orbit, you could start off launching to LEO (low Earth orbit), and then use a Hohmann transfer to raise the height of the orbit. I ...
AlanSE's user avatar
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