62

Those are jets of water released by the sound suppression systems installed on the pads and the mobile launcher platforms to protect orbiters and their payloads from being damaged by acoustical energy, reflected from the platform during the liftoff stage of a rocket launch. For example, this is the sound suppression system at the NASA Kennedy Space Center's ...


49

Salt does all sorts of unpleasant things to just about every building material humans use. Hot salt spray, such as you'd get from a rocket launch, is even worse: spraying something with hot saltwater is one of the techniques used for corrosion testing. Build a launch pad over the ocean, and you'll need to clean it off after each launch to try to keep the ...


47

Not even close. In fact, at 12 seconds in, you're looking at maximum damage to not just the pad itself, but the surrounding area as well. You're going to have tons of debris (most of it burning and possibly carrying even more unburnt fuel) fall from 1500-2000ft range in a giant umbrella of destruction. In 1997, a Delta II carrying the GPS IIR-1 satellite ...


42

Scott Manley of the YouTube has a great video that addresses the extra level of the tower, located at the seven minute mark of a recent posting. Verbatim transcript from the video: So pad 39A is where they launched from. An historic pad... saw the launches of Apollo, Space Shuttle, but SpaceX took control of it in 2014 and they began modifying it for ...


34

Because it is. It is a very tall structure, first stage alone is 140 feet, plus second stage, plus fairing. It is considered at the limit of how tall and thin they can make it. Wikipedia says the total height is 230 ft (70m). That is very tall, and 12 feet wide is quite thin. The only connection holding it down, is via the Octoweb clamped to the launch ...


27

The platform holding launch vehicle is called "launch pedestal" or "пусковой стол" or "стартовый стол" (in russian). Usually there are special "Hold-Down Arms" or "support arms" ("опоры пускового стола") to hold rocket. Examples: 1.. Proton is supported at bottom. There is launch pedestal model: http://www.cardmodels-r.narod.ru/html/Proton-LP1.htm In the ...


26

The American Petroleum Institute, in its standard 521, outlines limits for exposure of personnel to heat radiation from flares. As hydrocarbons and hydrogen are commonly flared, and also commonly used as rocket fuel, the data is relevant. This publication is used throughout the oil industry worldwide (and therefore is in far wider use than anything produced ...


26

The clearances were calculated to be OK up to a 95th percentile wind. I assume there was a Launch Commit Criteria (LCC) for the ground wind, but I have not been able to find an Apollo LCC document. Bottom line, as long as the winds were below what the clearances were calculated for, there was not a problem. Source Saturn V Flight Manual SA-507 A word on ...


24

Most US Launchers use a similar water suppression system for the same reasons as the Space shuttle. At some level, if you intend to launch often you do not wish your launcher to destroy the launch pad. A rocket launching usually has between 600,000 lbs thrust (Delta 4's single RS-68) to 7 million lbs thrust (Space Shuttle, or Saturn V range) and that is an ...


19

In general, umbilicals are provided from the launch pad to the vehicle for any services that need to be provided after the vehicle is installed on the launch mount, and to remove hazardous gases from the vicinity of the vehicle. Consider that vehicles can sit on the pad for long periods if problems occur during the countdown. Many different consumables may ...


17

1) Startup cost. Buying and converting a boat is much more complicated and time consuming than pouring some concrete and welding some steel. 2) Logistics. You will need at least 2 boats. One as the launcher and one as the command centre. You also need to have a reliable comms link to the rocket. You also need to house the personnel and maintain both boats. ...


17

Rockets can use different systems for attitude control (control thrusters, fins, gyroscopes, TVC, ...). Since you ask for the seconds after liftoff, the relevant system is TVC (Thrust Vector Control). TVC basically means that the engines themselves can gimbal to change the direction of the thrust. This can influence the attitude of the rocket by inducing ...


16

For shuttle it was commanded by the vehicle computers. At T-31 seconds control of most remaining countdown events was handed over to the vehicle, including SRB ignition and blowing the hold-down post nuts. Source: Countdown See What holds the Space Shuttle orbiter itself stable on the launch pad? for details of the mechanism itself


15

It typically takes a total expenditure of 9400-10000 meters per second of delta-v to reach LEO. Per the rocket equation, delta-v is proportional to the log of the propellant mass ratio, but also proportional to the exhaust velocity of the rocket engines or their specific impulse. Solid rocket boosters have relatively low specific impulse: 275 sec for ...


15

On e.g. the Saturn and Shuttle launches, vulnerable items like umbilicals are retracted into closed spaces, with a door closing over them in time to protect them. This very detailed video of a Shuttle launch shows some of those (at 9:40, for example). The audio commentary mentions (around 9:00) that the cameras on the platform and tower are inside ...


14

For Apollo, the signal came from a small computer room built inside the mobile launch platform. Giant holddown arms, whose name exactly describes their function, are positioned on the launcher surface to support and restrain the Saturn V. These arms hold the rocket during the first 8.9 seconds of ignition of its mighty engines while the computer beneath, ...


13

The Flame Trench is the big hole used to manage the flame from the rocket initially. Here's a shot of the Space Shuttle's Flame Trench: A closer look at the flame trench at LC-39A from the Space KSC blog: Note that essentially it deflects the flame so that it won't damage the rocket. All flame trenches have similar objectives. My favorite example comes ...


13

Based on this article, 39A is just concrete on top of sand. That does seem a little ridiculous though. The pumps piled up another portion of the dredged sand on the launch pad, creating a flat-topped pyramid of sand and shell 80 feet (24.4 meters) high. During the process, draglines, bulldozers and other earth-moving equipment molded the mound into the ...


13

I didn't dig too hard for sources because this is probably a very minor expansion on top of the other answers, but WHICH payloads might require vertical integration? Ones with big stinking mirrors inside like spy satellites and space telescopes. This reddit post lays out some rationale: This is mostly telescopes like Hubble. They have a very delicate ...


12

Weight distribution would be be the main reason. The Shuttle stack (or Saturn V stack) empty, weighed an immense amount. Shuttle more so, since the SRB's were full during movement. (Can't fuel a solid rocket on the pad). The SRB's weighed 1.3 million pounds each ready for flight. That is really an immense amount, over a small area. The tracks of the ...


12

To avoid damage to the pad, the rocket must have traveled down range far enough that if it exploded, the debris would not land back on the pad. The issue isn't height, it's horizontal distance. 12 seconds, as mentioned above, wouldn't get you downrange much. 30 seconds definitely would.


12

Environmental impact may be a major consideration The effect on the local water environment from that sort of blast into it could be severe and far reaching in the neighborhood around a water based launch pad. Also if there are any abort or need to dump fuel or uncombusted fuels from explosions could also have massive impacts that are immediately spread due ...


11

The closest launch to the public for an orbital launch is almost certainly the one you listed, Baikonur. I'm quite confident that for people outside, that is probably about the closest you can get as well. Quite frankly, a mile away isn't very safe to watch a launch... As for just how close can you get in a protected environment, outside of the spacecraft? ...


11

The majority of the heat of the exhaust plume can be redirected away from the actual launchpad where the rocket is sat, be it by building exhaust plume tunnels or trenches beneath the launchpad, using jets of water that also double as acoustic shock suppressors and flame deflectors, by using concrete flame deflectors, or as is the case with some launches (e....


10

The major reasons for Sea Launch's approach is to be able to launch on the equator, and not to have to worry about overflying any territory, where stages might drop. The cooling aspect is probably the least interesting part. But the main argument against it is the infrastructure costs, and salt water corrodes everything, it would seem. No matter how well ...


10

On the prelaunch press conference about LC-39A Gwynne Shotwell (SpaceX COO) said that they plan on repairing the SLC-40 pad now, hoping to finish it in summer. Youtube: NASA Holds Pre-launch Briefing at Historic Pad 39A at Kennedy Space Center Preparations for that [Falcon Heavy debut] launch will begin once repairs to SLC-40 are completed, which ...


10

The only hold-downs are the eight SRB bolts. This leads to the "Shuttle twang" when the main engines start. They're pushing to one side of the SRB hold downs, so they bend the stack just a bit. From "Space Shuttle Twang" by Tom Irvine in the Vibration Data newsletter (2010): The orbiter’s SSMEs are offset from the vehicle stack’s center of gravity. ...


10

Newton's Third Law states that if object A pushes on object B with a certain amount and direction of force then object B pushes on object A with same amount and opposite direction of force. Notice how the two bulleted clauses are nearly the same, except A and B have swapped roles, and the direction is reversed? In a rocket, object A is the rocket and ...


9

Those are remnants of the Apollo program era when the Launch Complex 39 was built. They were used to transport large removable blast deflectors to the pad when the Saturn V and Saturn 1B launch vehicles were already transported there on the crawler-transporters.    Blast deflectors at the Complex 34 launch pad. Prior to a launch, one of the ...


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