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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2
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1answer
91 views

Why might particulate matter be shaken loose during Crew Dragon Demo-1 launch?

Here is the picture of Expedition 58 crew members enter the Dragon 2 of Crew Dragon Demo-1 for the first time. They are wearing protective gear to avoid breathing particulate matter that may have ...
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5answers
956 views

Earth Launch System with Water Propellant

Water based thrusters have been proposed (and possibly tested by now) for use in satellites and other in-space vehicles - see this NASA article. The idea is to perform electrolysis on the water to ...
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If I were to launch an rocket from the top of the troposphere, how much fuel would it save compared to launching it from sea level?

Let's say we have some kind of rockoon design where our rocket gets carried 20 kilometers up before it finally launches from its balloon/blimp platform. Would that maneuver save a significant amount ...
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1answer
142 views

Why don't silo-launched Minuteman missiles incinerate themselves at launch?

Whilst cobbling together an answer for this question, I found myself thinking about the effects of hot rocket exhaust on a rocket launching from a confined space. I assumed it would be generally ...
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2answers
119 views

launch rocket like bullet from steam/air rifle?

I've included an image depicting how exhaust energy from a rocket launch can be recouped by turning it into a large scale pressure cooker by the use of some kind of platform=sabot (thanks @...
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2answers
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Do astronauts wear G-Suits during the launch?

Nowadays, rocket launches (to the ISS) accelerate astronauts at a maximum of around 3 to 4g (source). I have seen quite a few ...
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0answers
35 views

Detailed description of space shuttle major and minor GNC loops

Warning: repetitive question ahead. Please skip if you're tired of splitting hairs on these things. Is there a detailed description of the major and minor GNC loops of the space shuttle? I've learned ...
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1answer
66 views

Noninertial effects a problem in strapdown IMUs?

Unlike stable-platform IMUs, which are fixed in space and therefore inertial, strapdown IMUs are fixed to the vehicle's body and therefore noninertial. Would noninertial effects distort the strapdown ...
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2answers
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Space shuttle state propagation---constant acceleration during cycle?

The space shuttle used a state propagation algorithm to estimate the current state vector when new data weren't yet available from the navigation system (which would come at a rate of only 0.25 or 0.5 ...
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1answer
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Was space shuttle position corrected for before orbital insertion?

The space shuttle derived its attitude and state vector primarily from its integrating accelerometers and rate gyros. Data from the accelerometers and rate gyros came in at a low rate (0.25-0.5 Hz, or ...
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1answer
52 views

Space shuttle state propagation

Space shuttle training manuals say the GNC system obtains state information from the IMU platform at a low rate (0.25-0.5Hz) and that state propagation algorithms estimate the vehicle's state vector ...
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3answers
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Why do Space X starship launches need permission from the FAA?

For Flight #7 slated for 02-Feb-2021, Wikipedia's SpaceX Starship; Testing Program says: SpaceX attempted to fly SN9 on 28 and 29 of January 2021, but failed to receive permission from the FAA. (164, ...
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1answer
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Launch azimuth from orbital inclination WRT rotating earth?

The formula for launch azimuth given latitude and target orbital inclination goes like this: $$azm = \sin^{-1} \left(\frac{\cos(inc)}{\cos(lat)}\right)$$ I assume the orbital inclination $inc$ and ...
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49 views

How long to reach final orbital inclination?

Consider a rocket launch from Kennedy, latitude 28.5 deg, to a target orbital inclination of 50.6 degrees for rendezvous with the ISS. The launch azimuth for this orbital inclination is roughly 45 deg ...
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1answer
50 views

Space shuttle Initial ADI frame Before Switch to LVLH?

The space shuttle crew switched the ADI frame to LVLH as soon as the roll maneuver was completed. They waited for that time because the LVLH frame is in mathematical gimbal lock (singularity) when ...
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Why would a launch request for a gravitational assist at Mars specify a DLA (Declination of Launch Asymptote) of 30 to 32 degrees?

The recent intriguing question Why is NASA proposing an EMEJ (MEGA) trajectory for Europa Clipper instead of EEJ? quotes "A launch service request... recently put out for Europa Clipper to do a ...
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2answers
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Why is NASA proposing an EMEJ (MEGA) trajectory for Europa Clipper instead of EEJ?

A launch service request was recently put out for Europa Clipper to do a flyby of Mars on its way to Jupiter. How is that a better trajectory than an EEJ, similar to Juno? Launch Vehicle Performance: ...
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1answer
41 views

Which reference frame for space shuttle PEG orbital insertion?

Which frame were the space shuttle's orbital insertion attitude targets specified in? The shuttle had three frame choices: LVLH, INRTL, and REF (an inertial frame whose attitude the crew could lock in ...
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28 views

Why no yaw in ADI when LVLH is selected?

The space shuttle would display the spacecraft's attitude in one of three frames: LVLH, REF, or INRTL. Launch procedures called for LVLH to be selected very early in launch. The attitude indicator ...
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1answer
155 views

LVLH frame based on inertial velocity or relative (ground) velocity?

The LVLH frame is widely used in rockets during launch. The space shuttle crew used it in its attitude readings beginning very early after launch, meaning it was very reliable as soon as the rocket ...
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0answers
58 views

What is the first time that two satellites were launched together as the same payload?

Below I've assembled some research into the question of which launch is actually the first to carry two satellites into orbit, but so far I think the results are inconclusive. So despite there being ...
4
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1answer
159 views

What is the Best position of an object in geostationary orbit relative to the launch site for rendezvous using GTO?

So let's say we have a space station or spacecraft in GEO, and I want to get another spacecraft to it from earth's surface on a direct geostationary transfer orbit, i.e. no waiting about in LEO for ...
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1answer
115 views

Missions failed before launch

The Falcon 9 - Amos-6 - mission in 3 September 2016 failed before launch - the rocket exploded during the static fire test. Some lists contain such missions but others don't - like for example ...
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1answer
184 views

Guidance vs. Navigation vs. Estimation

I'm still confused over what exactly falls under the scope of Navigation, Guidance, and Estimation systems. Say I have a bunch of IMUs and use them to determine my position and orientation and my ...
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1answer
104 views

Are westward launches more expensive than eastward launches?

Basic question for those who breathe rockets: The earth's rotation imparts to the rocket a free delta V of roughly 450 m/s if you launch straight eastward. If you launch westward instead, for a ...
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1answer
273 views

Has a rocket from a torpedo tube ever reached space?

Are submarine launches horizontal? is a general question and specifies by name two large ICBMs which are likely to need to be launched vertically. Since the large naval submarines usually come ready-...
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152 views

Why is the bottom of the SLS rocket covered with reflective silver “muffler” tape?

NASA.gov's First Artemis Rocket Stage Moved onto NASA Barge Ahead of Green Run contains a high resolution image of the rocket. The bottom end of the rocket's cylindrical shape is closed flat and ...
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43 views

How long to flip over stage 1 of Falcon 9?

Curious how fast stage 1 flips over. 180 degrees is a lot of turning. At a rate of 5 deg/s, it would take 36 seconds to flip. This seems very long for the maneuver. A more modest duration of 10 s ...
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1answer
72 views

Falcon 9 altitude and speed during reentry burn?

After MECO, stage 1 of Falcon 9 does up to three engine burns: a boostback burn followed by a reentry burn followed by a final landing burn. I'm interested here in the reentry burn. How high and how ...
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34 views

Falcon 9 Angle of attack on return flight?

Do they control for angle of attack on the return flight of stage 1 of Falcon 9? Once it reenters thick atmosphere, aerodynamic stresses would be a concern as during launch, maybe more so because you ...
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3answers
95 views

Orbital launches

In the 1950s, many US rockets were capable of reaching the lower limit of LEO altitude. Despite this, no one thought of making the launch vehicle / its payload orbit around earth, even for one ...
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1answer
64 views

Estimating time to engine cutoff?

I'd like to calculate the approximate time left to my stage-1 velocity target. A simple way to do this would be to divide my Delta V by my acceleration. Trouble is... my acceleration changes ...
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1answer
66 views

What happens with the upper stage of Deep space launches?

When a rocket is sending a spacecraft to another planet, in general, where does it separate from the upper (last) stage of the rocket? What happens to most of those upper stages? They remain in Earth ...
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27 views

Falcon 9 Stage-1 Reentry Burn: Throttle Setting, Duration?

How long does stage 1 of Falcon 9 fire its engines during its reentry burn, and what throttle setting do they use? Also, is it known how much fuel is left at MECO? Thanks if you know and can share!
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1answer
200 views

Simple alternative to Powered Explicit Guidance for orbital insertion?

Say you're playing space ops engineer and want to simulate an orbital insertion---but you're petrified by the calculations needed to get the coefficients of the linear tangent law behind Powered ...
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Falcon 9 Stage 1 Guidance After Separation?

Does anyone know how stage 1 of Falcon 9 is guided immediately after stage separation? I'm not interested at this point in getting it to a precise landing spot, nor am I interested in the landing ...
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1answer
67 views

Are Powered Explicit Guidance calculations done before or during launch?

Space shuttle orbital insertion was done using a powered explicit guidance algorithm. At the surface, the algorithm is simple, as it gives the instantaneous pitch as a linear function of time: $\phi = ...
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3answers
2k views

How much throttleback to keep acceleration under 3g?

Most rockets generally throttle back when they reach max-q to prevent structural failure. This could be the only throttleback event of the launch. But crewed rockets normally do a second throttleback ...
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80 views

Does space weather affect spacecraft launch schedules?

Does space weather affect spacecraft launches and do scientists check it before spacecraft go to space? I know there is space turbulence and it can influence a spacecraft, but can space weather?
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1answer
101 views

Do you know a rocket for launching femto and pico satellites smaller than the SS-520?

The question has already been asked here why no one has built a rocket to launch one CubeSat. Why isn't there a rocket to launch a single cubesat? If there "won't be" rockets to ...
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Falcon 9 CGT Force?

Curious how much force the Falcon 9 cold gas thrusters produce for steering? I've seen numbers in the range of 25--100 lbf, but not sure where in this range (or outside it) the Falcon 9 falls. If you ...
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0answers
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Antares yaw maneuver: how many degrees?

The Antares rocket begins launch with a very noticeable yaw maneuver that seems to rotate it more than the 1.25 degrees documented for the Saturn V. Am I being misled by perspective? Does anyone know ...
3
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1answer
41 views

Initial Yaw Maneuver: Lean into or away from tower?

Some rockets do an initial yaw maneuver to help avoid contact with the tower. I know the yaw is in the plane of the tower: the rocket either leans into or away from the tower... But which of these is ...
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3answers
6k views

Do rockets leave launch pad at full thrust?

Rockets always seem to launch slower than I expect them for the thrust they can produce. Do they really launch off the pad at maximum thrust? Or do they launch at lower thrust until they clear the ...
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60 views

Why does Falcon 9 launch with Crew Dragon solar panels facing down?

I noticed in video of the first crewed mission in August that Falcon 9 pitches down with the Dragon solar panels facing down. I'd been expecting the solar panels to be facing up, because sun. Does ...
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1answer
68 views

First satellite dispenser?

A rocket upper stage, sometimes called kick stage, is the last stage of a rocket and it is used to deploy satellites in orbit. A space tug is a spacecraft released from the upper stage and it is used ...
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5answers
3k views

Does upper atmosphere rotate with earth?

Basic question that I should know the answer to but sadly don't. The lower atmosphere must rotate with the earth because of friction---at least the very bottom of it. But what about 30 miles up? There ...
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2answers
705 views

How do they determine dynamic pressure has hit a max?

Max-Q is a key event during launch, and dynamic pressure is closely monitored so they know when a max is hit. But how exactly do they know when Q hits a max? If you track the rate at which Q is ...
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1answer
60 views

Do rockets headed to ISS get delta V benefit from Earth's rotation

A rocket on the launchpad moves Eastward with the rest of the earth as it rotates about its polar axis. This means that on launch, the rocket already has a sizable eastward velocity component: ~460 m/...
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Coordinate axes of Falcon 9 on launchpad 39A

Can someone please correct me on the orientation of the Falcon 9 rocket as it sits on launchpad 39A at Kennedy? Looking at the image below, which way should X (red), Y (green), and Z (blue) face? I ...

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