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Questions tagged [launch-sequence]

Questions regarding the steps and procedures taken prior and during the launch of a space vehicle.

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Why should the roll program position the shuttle's nose to the east?

The roll program occurred during a shuttle launch for the following reasons: (...) Orienting the shuttle more parallel toward the ground with the nose to the east. ...
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Launch corridors

I was wondering where I could find a list of the launch azimuth ranges - i.e. the corridors - for the main launchpads worldwide (Baikonur, Kourou, KSC, ... as many as possible). Thank you in advance!
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What caused launch abort on SpaceX's Bangabandhu-1 launch

On Thursday, May 10th, 2018, SpaceX attempted a launch of the first Falcon 9 block V rocket carrying Bangabandhu-1 however the countdown was stopped at t-58 seconds and the launch was scrubbed for 24 ...
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3answers
924 views

How was the Centaur stage fueled in the Space Shuttle?

The Space Shuttle had the ability to launch Centaur booster stages stored inside of the Shuttle during launch. How was this stage fueled, being fueled with cryogenic fuels?
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1answer
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Fuel-optimal thrust profile for an orbital ascent on a planet with an atmosphere

This is a continuation of a previous question posted a few months ago. If we consider a SSTO vehicle launching from a planet with an atmosphere, would it be fuel optimal to have a period of lowered ...
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Databases of “scrubbed” launch attempts?

I'm curious if there is a statistically demonstrable tendency not to schedule launches on certain days, such as those that contain leap seconds (see answers below this question), year changes, or ...
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Is there an authoritative catalog for rocket launch identifiers?

For satellites there's NSSDCA/COSPAR, but I'm unable to find something similar for the launches of those objects. I'm hoping I'm not looking for something that doesn't exist as I'm assuming launch ...
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1answer
369 views

Preflighting TVC actuators on Falcon 9

It is my understanding that the Falcon 9 thrust vector control (TVC) actuators use RP-1 as hydraulic fluid and use the fuel turbopump energy to drive the hydraulic pump for the TVC. How do you do a ...
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3answers
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Were the Space Shuttle's Main Engines ever off while the Solid Rocket Boosters were firing?

I always though the Space Shuttle needed a combination of its solid rocket boosters and its main engines to remain stable while launching. The following diagram found on Wikipedia seems to agree: ...
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Why will the RP-1 loading for SpaceX's Iridium-1 mission begin at T-00:70:00 as opposed to T-01:10:00?

Why will the RP-1 loading for SpaceX's Iridium-1 mission begin at T -00:70:00 - wouldn't it usually be written as T -01:10:00? $...
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4answers
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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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What is the sequence of the main spacecraft and CubeSats separation during Falcon 9 launch?

I'm curious about timeline and the procedures related to the spacecraft separation during Falcon 9 (and perhaps other rockets if such information is available) launch. Let's assume a mission with one ...
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1answer
145 views

What does CLG INIT mean?

During India's PSLV-C35 launch on 26 September 2016, mission control's launch sequence events (stage separations, stage ignitions, etc.) included 'CLG INIT'. What does it mean?
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How can the elements involved in loading a LOX tank be involved in an explosion?

Since SpaceX has isolated the AMOS-6 Falcon 9 pad explosion to the upper stage LOX tank during fueling, it seems useful to consider in general terms what was happening at the time and what materials ...
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1answer
735 views

What is the advantage of doing a static test fire before launch?

Continuing the series of questions (part 1, part 2) inspired by the recent loss of the AMOS-6 satellite during a static test fire, here's one thing that puzzles me a bit: What kinds of problems is a ...
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1answer
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In the Saturn V launch sequence, what defined COMMIT, and what happened between COMMIT and LIFTOFF?

With the Saturn V, there were two critical moments during launch that I am curious about: The vehicle COMMITs to liftoff The vehicle LIFTS OFF LIFTOFF is fairly obvious: the booster has risen some ...
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2answers
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What is behind Dragon's Guidance, Navigation and Control bay door?

The timeline in the press kit for the upcoming CRS-9 SpaceX launch says at about 11 minutes after launch, "Dragon's solar arrays deploy", and at 2 hours 19 minutes, "Dragon's Guidance, Navigation and ...
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What's the first recorded use of a countdown associated with a rocket launch?

Counting down the seconds leading up to a rocket launch is iconic - certainly it seems that every child knows that after "5, 4, 3, 2, 1" comes "Blast off!" However, the countdown can't always have ...
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1answer
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LV Telemetry links on the launch pad

Are electronic telemetry and control links (of TT&C - telemetry, tracking and control) to the launch vehicle incorporated into the launch pad umbilical lines and handed off at launch, or is it all ...
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1answer
4k views

What is the rocket engine chilldown?

In many launch sequences I see the phrase 'engine' chilldown' coming up. What is this and why is it done?
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2answers
799 views

Are sirens (etc.) sounded before launches to warn wildlife?

This question is moderately inspired by this one, or at least the speculative answer "birds" that is ruled out on a second review of the video. Various animals have learned signals of severe ...
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1answer
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Why was Jason-3 the last launch we heard the T-13 readiness poll during a SpaceX Webcast?

On the Jason-3 mission, several times the spokeskids said that this is the last time we will hear the T-13 readiness check on a SpaceX webcast. For example, at 27:23 they say: ...this is going to ...
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1answer
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What would have happened if only one Space Shuttle SRB ignited?

The ignite command for the Solid Rocket Boosters (SRB) would not be issued unless all three Space Shuttle Main Engines (SSME) were at least 90% of thrust. The launch would have been aborted if one or ...
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1answer
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How do the launch controller headsets work?

I have listened to a number of launch countdowns, and especially as they poll for readiness, a large number of people (10-12 or more) need to respond when called on, but the sound quality is excellent....
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How good does the weather have to be for a rocket launch?

I'm watching a launch sit on hold because the sky is overcast. The announced hold reason was "thick cloud cover, anvil cloud". So they have a checklist. What is on that checklist? How do they assess ...
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What would one learn by borescoping a rocket engine after an aborted launch?

In November/December 2013, during the Falcon 9 Flight 7 (SES-8) processing flow, SpaceX managed to get the vehicle onto the pad and attempted to launch a few times without success. Either a scrub was ...
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2answers
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Is there a lower limit on time-to-orbit from launch?

Since 2013, several launches up to the ISS have taken a fast-launch. First initiated by Soyuz TMA-08M, the fast rendezvous takes the crew up in 6 hours where the previous time-to-dock was around 2 ...
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3answers
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Apollo LM ascent procedure, computer controlled or manual?

How was the Apollo LM ascent launch procedure controlled? Was it manual, semi-automatic or fully automatic? By "launch procedure" I am talking about the pitch control for the LM. I believe there is no ...
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2answers
9k views

What are the main steps in the lead-up to a rocket launch?

I know that rocket launches are extremely complex. From watching a few, I get the sense that there are some things that happen in a standard way in all rocket launches, maybe depending on propellants, ...
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1answer
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What exactly were the controller roles in the Apollo go/no-go calls?

In the Apollo era, whenever there was a significant event about to occur, the flight director (I can recall the voice of Gene Kranz) would do a sort of go/no-go "roll call". He would call off names ...
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3answers
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Are there any indicative statistics about animal loss during launches?

Are there any indications of animal loss during a launch (shuttle or rocket). I'm referring to animals in the vicinity. I'm sure that it's minimal, but does the exhaust/sound/etc. knock out a bunch ...
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What is happening in the few seconds surrounding t=0 of the Delta IV Heavy launch? [duplicate]

Watching footage of the Orion test launch on Dec 5th, one can see orange flames rise up from the base of the rocket in the few seconds before t=0 and before the engines appear to fully "fire up". ...
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1answer
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LEO insertion altitude

Does anyone know what would be the exact or approximate altitude for the stage separation and spacecraft separation of LEO insertion? Moreover, does anyone has a picture including all step of LEO ...
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Numbers for Falcon 9 booster MECO scenarios?

I hoping to look at learn more about Main Engine Cut Off (MECO) for various scenarios. 5 quantities I want are: 1) Booster mass at lift off. 2) Booster mass at MECO 3) Booster velocity at MECO (...
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What went wrong during the OG2 Mission 1 launch attempt on June 20th 2014?

Yesterday (June 20, 2014), SpaceX intended to launch a Falcon 9 to bring 6 satellites of the Orbcomm OG2 satellite constellation into orbit. However, the launch was first postponed for an hour and ...
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2answers
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Why do they say “go” and “no go”

I'm sure we're all familiar with the go/no go standard phrasing for reporting whether something is OK or not. Having a standard phrasing clearly makes comprehension easier and more reliable, ...
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On a Falcon9 launch at T-13 they poll all stations, what are all the stations they poll?

While listening to the webcast for flight 8 of Falcon 9 (Thiacom-8 mission), they did a poll of all controllers/stations at T-13:00. I could guess a number of them, but wondering what the full set ...
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2answers
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What caused SES-8's Falcon 9 launch computer to abort at T+2 seconds?

SES-8 had its launch aborted at T+2 seconds. What, exactly, caused the flight computer to decide the engines weren't ready?
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Why have a 10 minute pause at T-4 minutes?

I was watching the United Launch Alliance (ULA) Atlas 5 rocket launching NASA's MAVEN (Mars Atmosphere and Volatile EvolutioN) to Mars today, and the countdown contained a planned 10 minute pause at T-...
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4answers
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What is the purpose of having a countdown during a rocket launch?

Every rocket launch has a countdown. But what purpose does it serve?