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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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4answers
15k 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?
67
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10answers
41k 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-...
57
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4answers
7k 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 ...
56
votes
3answers
49k 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 ...
55
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5answers
6k views

How much bigger could Earth be, before rockets would'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. Question: "How much bigger ...
54
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4answers
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 ...
53
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6answers
8k 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 ...
53
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4answers
20k 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?
44
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3answers
9k 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 ...
42
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2answers
35k 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. ...
41
votes
11answers
35k 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 ...
40
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8answers
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? ...
39
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3answers
8k 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?
38
votes
1answer
6k 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 ...
38
votes
1answer
8k 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 ...
36
votes
5answers
11k 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 ...
36
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3answers
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? ...
35
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4answers
8k 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 ...
35
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3answers
10k 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 ...
35
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2answers
45k 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?
34
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3answers
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?
34
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3answers
4k 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 ...
34
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10answers
12k 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? ...
34
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4answers
10k 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 ...
33
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5answers
6k views

Has any spacecraft ever been flown manually to orbit?

Has anyone ever manually flown a spacecraft to orbit, Kerbal Space Program-style?
32
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3answers
5k 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 ...
31
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3answers
13k 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 ...
31
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6answers
6k 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 ...
31
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2answers
5k 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'...
31
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3answers
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 ...
30
votes
3answers
13k 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 ...
30
votes
4answers
7k 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 ...
30
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3answers
13k 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 ...
29
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5answers
9k 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 ...
29
votes
5answers
16k 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 ...
28
votes
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 ...
28
votes
4answers
4k 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 ...
28
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1answer
4k 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 ...
28
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1answer
2k 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 ...
28
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2answers
3k views

SpaceX CRS-5 Launch: What is the footage that appears to contain bubbles?

I'm currently watching the live stream of the CRS-5 launch. They've been cycling through several different camera angles including one which looks a lot like bubbles in water, or perhaps blobs of ...
28
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1answer
56k views

What is the current cost-per-pound to send something into LEO?

As a student of economics and finance I would love to learn more about the cost structures of sending a payload into orbit. More specifically - What is the cost-per-pound to send something into LEO ...
27
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3answers
9k 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 ...
27
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6answers
3k 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 ...
27
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1answer
3k views

Was Amos 6 insured for pre-launch operations?

The Falcon 9 rocket, complete with the Amos 6 payload, just blew up (Or RUDed) on the launch pad. I believe the standard language for most launch insurances is that it is only covered after "...
26
votes
4answers
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 ...
26
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7answers
61k views

Does the space shuttle fly straight “up” when leaving Earth?

I was watching space shuttle launch recently, and at 2:53 you can see the space shuttle from an angle, even though it's high above the earth and you should see only the bottom. Does the space shuttle ...
25
votes
3answers
7k 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 ...
25
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3answers
5k views

How can the reusable Falcon 9 succeed when the reusable Space Shuttle failed?

Space Shuttle was designed to be partially reusable but was later shut down because it turned out to be very expensive to run compared to disposable spacecraft. Now Falcon 9 is suddenly reusable to a ...
25
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1answer
5k views

Does anyone who works at SpaceX know the paths of classified payloads?

As SpaceX has launched both NROL-76 and OTV-5, does anyone at SpaceX know the trajectory of the vehicle, or is the falcon upper stage under the direct control of the Air Force?
25
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1answer
18k 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 ...