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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34
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3answers
14k 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 ...
77
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6answers
12k 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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6answers
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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 ...
45
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11answers
38k 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 ...
29
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1answer
58k 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 ...
52
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2answers
44k 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. ...
5
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2answers
3k views

How does one dogleg from Florida to a sun-synchronous orbit?

From NASA Spaceflight's article SpaceX Falcon 9 launches first NRO mission with NROL-76: The NROL-76 launch was not to be targeting a sun-synchronous orbit, typically used by the NRO’s optical ...
6
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1answer
1k views

Why would sub-cooled LOX tanks need to “topped-off” until the last minute or so?

Here is my understanding, let me know if I've got it right or wrong: Until recently, most cryogenic propellants were at or close to their boiling points. Each unit of heat leaking into the tank would ...
38
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5answers
12k 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 ...
22
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2answers
30k views

Launch Accelerations: Values, history

This topic: What G-forces do different launchers cause? indicates that current satellite launchers are limiting peak acceleration to about 4g. I'm pretty sure the STS (Shuttle) did the same. My ...
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5answers
22k views

Can magnets be used to launch spacecraft?

I assume there is some reason we don't use magnets to launch off Earth. Are they not strong enough? Isn't magnetic force technically stronger than gravity?? Would either of these work: A tube tunnel ...
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2answers
753 views

What regulations, agreements, or other forces can help mitigate “PrankSats”? [closed]

comment: I've used a somewhat innocuous abstraction of 'pranks in space' below, but there's no end to the trouble that could be caused and the increasing ease with which a state (nation or otherwise) ...
107
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4answers
17k 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?
12
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3answers
3k views

How long does Max-Q last?

When watching rocket launches, the commentary or status reports often mention that the vehicle is "passing through Max-Q" - how long does the "passing" take? Is the event instantaneous or is there ...
16
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1answer
973 views

Cause of apparent plume deflection on SES-10?

While watching the SES-10 flight, starting a little after T+1:30, I noticed that the direction of the first-stage exhaust plume started to diverge from the alignment of the rocket body. The ...
32
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7answers
10k 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
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1answer
26k 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 ...
7
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2answers
2k views

Which STS mission raised the normal engine throttle above 100%, and what change to the SSME made that possible?

As indirectly stated in an answer to How long does Max-Q last?, during later Space Shuttle launches the main engines were operating at above 100% of their nominal maximum thrust. Specifically from ...
57
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4answers
28k 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?
33
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2answers
7k 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'...
11
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3answers
4k views

Will the Tesla Roadster return any telemetry?

Is there any equipment fitted to the Tesla Roadster to send signals back to Earth, even for a short time after launch?
9
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6answers
2k views

What benefits can be gained from launching below ground?

ICBMs are commonly launched from below ground. How much fuel could be saved if a missile is launched below ground instead of above? If the tube was deeper with modified launch by a separate chemical ...
14
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4answers
2k views

What is a “space elevator”?

I've seen an hypothetical "Space elevator" referenced in various media the last couple of years. Is this something thats really planned in the making, or just a hypothetical scenario? How will a space ...
12
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1answer
1k views

What is it that SpaceX is editing out of their videos after posting them on YouTube?

Here are two cases where links to a specific time code in SpaceX YouTube videos stop showing the intended moment because apparently SpaceX has gone in within hours or perhaps a day and shortened the ...
10
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3answers
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On a Super-Earth 1.5x the volume and mass of Earth, would our rocket technology allow us to reach orbit? [duplicate]

To try and make parameters clear, can we say we are talking about 50% 'more Earth'? As in, Earth, but 1.5 times as big and heavy? And let us include the atmosphere. If there is 50% more of it by ...
6
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2answers
2k views

Are 'classical' gravity turns still used and recognizable as such?

If I understand correctly, the term 'gravity turn' refers to a specific way to turn from the initial near-vertical launch direction to a final tangential orbit direction in an efficient manner. It's ...
5
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0answers
212 views

Was it another Fishing Tournament?

@KimHolder's thorough answer to the question What are the consequences for a person who violates a launch exclusion zone? mentioned a fishing tournament. @PearsonArtPhoto's comment about scheduling ...
35
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10answers
14k 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? ...
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 ...
30
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5answers
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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 ...
24
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6answers
17k views

Could a Human reach escape velocity by jumping from the surface of Ceres (a dwarf planet)?

According to this answer the surface gravity of Ceres is estimated to be only $0.27 m/s^2$. With a rotation period of 9 hours. The gravity seems light enough to overcome by leg muscle alone, and if ...
19
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3answers
17k views

How much of an advantage do equator-proximal launch sites provide?

Comparing ESA's Kourou (5° off) with NASA's Cape Canaveral (28°) and JAXA's Tanegashima (30°) launch sites, how advantageous is proximity to the equator? Considering the fact that the ESA and all of ...
38
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2answers
65k 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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3answers
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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 ...
4
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1answer
609 views

For an Apollo Lunar Module Ascent Stage launch, what is the optimal profile of $\beta$ (or $\gamma$) vs time?

When Apollo astronauts departed the lunar surface in the Lunar Module's Ascent Stage, it appeared to rise vertically ($\beta$ = 0) for ~10 seconds and then begin the "tipover" (videos of Apollo 15, 16 ...
9
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1answer
918 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, ...
86
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3answers
118k 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 ...
27
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7answers
68k views

Did 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. Did the space shuttle ...
18
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4answers
5k views

What is the largest hurdle of the mission to Mars?

I was shocked when I recently found out just how long it takes to get to Mars. I've been conducting a very informal survey amongst peers of how just how long people think it takes us to travel to Mars....
33
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6answers
8k 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 ...
7
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1answer
2k views

Coefficients for linear tangent steering law

Given certain simplifying assumptions, a "linear tangent" steering law is optimal for orbital insertion of a launch vehicle: $$\tan \psi = a\cdot t + b$$ i.e. the tangent of the flight path angle ...
16
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2answers
1k views

Why would a mission to Sun-Earth L1 have an instantaneous launch window?

I was watching the webcast for Falcon 9 Flight 15 (launching DSCOVR) when they scrubbed their first launch attempt due to some issues during the terminal countdown. Before the scrub, the narrator ...
15
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4answers
24k views

How close can I get to a rocket launch and not get killed?

There was a question regarding the closest distance regular people are allowed to be near a rocket. At that distance (Baikonur I, 1.1 miles), even if a rocket explodes, there is a small chance someone ...
9
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1answer
5k views

What is the “launch energy” or C₃ measured in km² / s²

In some papers there is "launch energy" characteristic of spacecraft launched into space from Earth. Sometimes it is written as "C₃" (C3). For example, Ares V document lists "C₃" as equal or less than ...
41
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3answers
12k 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?
28
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3answers
11k 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 ...
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, ...
8
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2answers
5k views

Pros and Cons of LH2/LOX vs Other Fuels

As I stated in the answer to another question, LH2 suffers some serious drawbacks compared to other fuels. Off the top of my head, they are Extremely low density, resulting in: Lower mass-fraction ...
8
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2answers
2k views

What is the problem with aborting a Space Shuttle launch?

In the question Why didn't the Space Shuttle have a launch escape system? there was discussion in the commentary about why the Space Shuttle could not safely abort through much of its envelope. ...
20
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1answer
1k views

Ariane 4: shroud around stage?

In this image of the Ariane 4, you can see a blue shroud around the second stage. At least I think it's a shroud. It is present in many photos of Ariane 4 launches, but the drawings I've seen omit ...

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