Questions tagged [launch-sequence]

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

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101
votes
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?
2
votes
2answers
366 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. ...
3
votes
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 ...
36
votes
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 ...
5
votes
2answers
579 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 ...
5
votes
3answers
1k 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?
15
votes
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, ...
15
votes
1answer
453 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 ...
16
votes
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: ...
16
votes
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 ...
10
votes
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 ...
9
votes
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 ...
8
votes
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 ...
19
votes
1answer
1k views

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-...
16
votes
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 ...
10
votes
1answer
547 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 (...
4
votes
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 ...
2
votes
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 ...
1
vote
2answers
107 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 ...