Questions tagged [launch-sequence]

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

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1answer
69 views

At what time is the Falcon 9 loaded with fuel?

How long before launch are the fuel and oxidizer loaded into a Falcon 9 rocket? And how much time does it take to load it?
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1answer
523 views

How were the pins for Saturn V controlled release tested?

I came across the following section of the Saturn V Flight Manual (pdf): The intriguing part is that they used 12 pins to actually bolt down the Saturn V to the launch pad and the combined engine ...
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1answer
5k 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 ...
13
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1answer
2k views

What exactly is the purpose of connection links strapped between the rocket and the launch pad

I am curious on what are those multiple connection cables latched between the rocket and launch pad. What exactly is the purpose of it, I am aware that one should be for filling up the fuel. But ...
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1answer
225 views

What does “all systems are internal” mean?

When watching (once again) a large History Channel documentary series about Gemini and Apollo, in some launch scenes with the original audio, the person doing the countdown usually says "all ...
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0answers
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Why were the SpaceX ninjas (pad crew) using a stepladder to move something?

On the second launch attempt of the Dragon Crew Demo 2 (human spaceflight), sometime lower than 1:50:00 to launch, the ninjas spend about 5 minutes on a stepladder, dealing with a tube and box, which ...
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1answer
1k views

Why the long (19 hour) mission profile for SpaceX's trip to ISS?

As mentioned briefly in this question, The Russian Soyuz has been using a sub-4 hour path to ISS. Why the long ride from Canaveral? Or is the 19-hour timeframe typical of all launches prior to the "...
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1answer
160 views

Are rocket tanks being filled up until the last seconds before liftoff?

In rocket launch videos, we often observe liquid propellant rocket engines running at full thrust for several seconds before actual liftoff. We understand that liquid propellant rockets consume a ...
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2answers
5k views

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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1answer
1k views

How (and when) was the RTG in the lunar modules installed?

In this answer, it is explained that the space probes RTG's are not installed until a couple days before launch because of the heat those things generate. Now I'm curious about the Apollo RTGs. From ...
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2answers
118 views

What are these Soyuz Astronauts/Cosmonauts holding in their hands before launch? [duplicate]

What are these Soyuz Astronauts/Cosmonauts holding in their left hands before launch? I suspect it must be the pump for the active cooling system by pumping water similar to those in EVA suits, but it ...
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1answer
349 views

Why doesn't Ariane-5 lift off at T=0 seconds?

I have seen Ariane-5 lift off at T+07 seconds and not at (or close to) T=00 seconds. The following statement is from the Ariane-5 User's Manual (Page 35, Section 2.3 - Typical Mission Profile): The ...
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1answer
2k views

What does 'Rocket is in self align' mean?

I've noticed during SpaceX streams (this could happen with other LSPs but I've only noticed it with SpaceX) that shortly after the vehicle goes to internal power the controller says "Vehicle is in ...
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2answers
1k views

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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2answers
3k views

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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2answers
384 views

What event determined the transfer of control from Kennedy Space Center to Houston?

Launches at Kennedy Space Center in Florida were managed by the on-site launch control center. At some point in the mission, authority was transferred to the mission control center in Houston, Texas. ...
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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?
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2answers
590 views

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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2answers
3k views

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 ...
4
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1answer
684 views

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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1answer
355 views

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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4answers
9k 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 ...
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3answers
2k 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
7k 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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1answer
171 views

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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0answers
196 views

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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0answers
79 views

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
622 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
5k views

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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1answer
136 views

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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0answers
115 views

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
3k views

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
204 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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2answers
1k views

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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1answer
1k 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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2answers
704 views

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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3answers
951 views

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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3answers
977 views

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
236 views

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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2answers
973 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
853 views

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
2k views

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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3answers
2k views

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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1answer
1k views

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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1answer
560 views

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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3answers
245 views

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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2answers
14k 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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0answers
119 views

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". ...
4
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1answer
329 views

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 ...