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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3
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1answer
192 views

How much fuel could a rocket save by launching from an airship/blimp?

What could the Kozlov’s Aerosmena project blimp add to fuel saving if space rockets were launched from it? Where would you place the rocket and airship on this chart?
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2answers
266 views

First interplanetary launch from California! How far from Earth will InSight be when it separates from the Centaur 2nd stage?

The Phys.org article Bound for Mars—countdown to first interplanetary launch from California says: In the early morning hours of May 5, millions of Californians will have an opportunity to witness a ...
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1answer
73 views

What are the longest current rocket payload fairings, capable of carrying long space station sections?

Space News' China launches Tianhe space station core module into orbit China successfully launched a 22-metric-ton module April 28, beginning an intense period of missions for constructing the nation’...
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3answers
8k views

Why do astronauts wear spacesuits during launch?

I have noticed that astronauts in every launch I've found wear a spacesuit during launch, like this example from the shuttle. I don't understand this. What kind of problem could cause loss of cabin ...
2
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1answer
164 views

What does 'a nudge' mean in the context of rocketry?

The following paragraph is from a wired.com article: When I visited this past fall, SpinLaunch employees were still unpacking from the move. As we walked among giant sheets of steel, Yaney explained ...
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1answer
103 views

Why are some Starlink launches announced as instantaneous and some not?

I have not been able to find information online to chart out the SpaceX Starlink launches to see which have announced instantaneous launch windows and others are not announced as such, leading to my ...
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2answers
2k views

How might SpinLaunch actually spin something fast enough to launch it into orbit?

update: TechCrunch's SpinLaunch spins up a $35M round to continue building its space catapult is worth a read and contains this cool rendering. Click for full size Ars Technica's Edition 1.34 of the ...
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0answers
84 views

Has California implemented its “rocket tax” yet?

Here are some questions from 2017: California's rocket tax "by the mile", how would that work exactly? What expenses and risks might the state of California incur that might partially ...
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1answer
61 views

What is the semicircular puff coming from the Falcon 9 first stage in this picture?

When I was watching the Crew 2 launch this morning, I noticed that while the first stage was coasting up and back down, it kept giving off arc-shaped "puffs". I did not see any corresponding ...
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141 views

How fast could a stone be thrown using a sling while standing on the moon?

Similar to this question except not about using a machine: What payloads and launch speeds could a sling launcher get using modern materials on the Moon? How fast could a stone be thrown using a sling ...
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1answer
2k views

How far around the world does a rocket travel before it enters orbit?

If a rocket launches from Florida, how far around the world does it travel before it reaches orbit? Is it in space before it completes crossing the Atlantic? Does it vary for different powered ...
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0answers
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How much would it cost to launch a 0.5U Satellite?

I have seen the figures for 1U, 3U and 12U Satellites such as those provided here, but I have been unable to find pricing for the launch of a single 0.5U or 0.25U satellite. I have seen many academic ...
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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
60 views

Attitude control with cold gas thrusters

Consider the cold gas thrusters on a Falcon 9. There are two thruster pods on stage 1 and two on stage 2. Each pod has four orifices to fire along the x, y, and z axes of the scacecraft. By varying ...
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244 views

SN11 was launched in fog. Why not wait for better conditions?

The fog certainly frustrated the external observers, but it doesn't seem ideal from SpaceX perspective either. All the external observers were very distant from the launch/landing site and would be ...
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1answer
109 views

News of eXCITe with QIKcom-2 and SeeMe, have they been launched, or is there currently one scheduled?

Comments under the question What ever happened to SHERPA? about NovaWurks, Inc. led me to search for the DARPA eXCITe microsatellite. Spaceflight 101's page includes: Th(e) objectives of the ...
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1answer
76 views

Terminal velocity on reentry?

I've seen many references to "terminal velocity" on reentry, e.g., prior to a Falcon 9 landing burn. And I'm confused by this. Because terminal velocity comes from drag which depends closely ...
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1answer
130 views

Powered Explicit Guidance: Should rocket be pitching down at orbital insertion?

I simulated an orbital insertion using Powered Explicit Guidance as used in the space shuttle. The PEG algorithm works great. I hit all my targets: altitude, velocity, orbital inclination, longitude ...
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2answers
8k views

How many rockets have been launched into space? (roughly, of course)

First I was going to ask how many rocket bodies lay at the bottom of the ocean, but I simplified further. Remember, this includes sounding rockets; anything passing the Kármán line. I'm looking for ...
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Falcon 9 flipover duration

This launch video shows a very gradual stage-1 flipover. The flipover starts right after MECO, before the 3:00 mark, and it continues slowly until just after the 6:00 mark. Or that's the impression I ...
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1answer
85 views

State vector update on reentry

The integration errors from IMU state measurements would seem very problematic when you're coming in for a landing, where error tolerances would probably be as small as they could get. This must mean ...
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6answers
13k views

How much bigger could Earth be, before rockets wouldn't work?

hint: Apparently the Tsiolkovsky rocket equation does not actually say that you can launch a conventional rocket into orbit around an arbitrarily large and massive body. I'm looking for a number ...
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2answers
435 views

Ullage control with single engine stage?

How does a single-engine upper stage, like that of Falcon 9, do ullage control before starting the engine? Does it fire its cold gas thrusters? Does it fire the engine at minimum throttle for a second ...
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1answer
30 views

Ullage control on stage shutdown?

Is ullage control a thing only engine startup? Would a rocket like the Saturn V or Falcon 9 leave an engine running for a second or two longer just for ullage control?
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28 views

3g Throttling: Does Falcon 9 kill engines if acceleration over 3G?

I'm simulating a launch and I often hit minimum throttle before I hit MECO (triggered at 15% fuel mass---my reserve for stage-1 reentry). Acceleration then begins to rise to maybe 3.3 g by the time ...
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4answers
6k views

Which has been the most gregarious rocket, launched from the most sites?

Which orbital launch vehicle has been "getting around" the most? Which rocket has put things in orbit from the largest number of different launch sites? For the purposes of this question, allow for ...
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3answers
1k views

How much of a rocket's energy is used to achieve altitude vs horizontal velocity?

Given how it is significantly easier to achieve suborbital spaceflight, I was wondering about how a rocket spends its energy budget. If you magically could launch a rocket from 0 km/s but from an ...
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109 views

What about recycling the helium used for sub-cooling the LOX in the tank of a rocket before launch?

Helium is a rare and expensive noble gas. When it is loaded into a rocket to be used after launch, it is not possible to recycle it. But the helium used for sub-cooling the LOX before launch (see ...
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Falcon 9: Landing leg helium pressure?

So it seems the Falcon 9 landing legs are powered by a helium precharge. Does anyone know the pressure of that precharge? If no numbers for Falcon 9, is there at least a reasonable range of what the ...
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4answers
13k views

How is a rocket stabilized during the initial, slow speed, portion of launch?

Let's say we're at T+0, just as the rocket starts to move, what keeps it upright as it clears the tower and gains speed?
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0answers
38 views

How much of NASA's annual budget goes to launch

I've been trying to figure out how much of NASA's budget goes to launch costs. I would also be interested in the same question for the global space market. What I've tried I started with a simple ...
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2answers
1k views

Barriers to launching a cubesat

Cubesats and femto-sats are a nice place for universities and small enterprises to set their sights on. There are a number of sources of hardware and software (some even available at reasonably low ...
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2answers
822 views

What secondary payloads, if any, are launching on the inaugural flight of Falcon Heavy?

Overshadowed by a silly, yet awesome primary payload — 'a cool colored cool electric sports car playing a cool track' on to a heliocentric orbit, are there other satellites/secondary payload Falcon ...
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1answer
515 views

How do the secondary payload abilities of different launchers compare?

ULA with their Atlas V seems to be the leading launch service provider for secondary payloads. This FISO presentation is convincing anyway. And good for them since miniaturization of satellites ...
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1answer
293 views

When have secondary payloads damaged the primary payload of a launcher?

Primary payload customers have traditionally been cautious when allowing secondary payloads on the same launcher. For example, a secondary payload is not trusted to have its own chemical propulsion ...
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1answer
30 views

Falcon 9: How many engines on first burn in two-burn reentry?

Consider a Falcon 9 two-burn reentry maneuver. My understanding is that the second, final, burn is always single-engine. And I think the first burn can be either single-engine or three-engine. But I'm ...
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0answers
51 views

Falcon 9 Flipover Direction?

Consider a Falcon 9 at MECO. The rocket's close to 30 deg relative to the local horizon, down from the 90 deg it had at launch. Stage 1 separates and flips more or less 180 degrees for the return ...
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3answers
138 views

How do cubesat owners first find out their cubesat's initial trajectory? How do they point antennas at it before official TLEs start to appear?

When cubesats are first deployed it can sometimes take several days before they start appearing in official TLE distributions, and even then if many were deployed it may take a lot more work to decide ...
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2answers
109 views

Falcon 9 Max Q on reentry?

Max Q for a Falcon 9 is on the order of 30-40 kPa during launch. What would the number be on descent? Do they allow for greater dynamic pressures in that portion of the flight? Or is the rocket still ...
2
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1answer
126 views

Hover Slam Landing: How is it Done?

I want to simulate a hover slam landing. Is there an overview of the maneuver anywhere? I'm especially interested in the control algorithm used to bring the rocket stage to a halt at just the right ...
3
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1answer
128 views

Find the jump condition of the mass costate of a Launch Vehicle ascent problem solved via an indirect method (Pontryagin Minimum Principle)

I'm trying to solve a trajectory optimization problem for a class of problems like the old Altas-Centaur SLV3 Centaur launch vehicles. Those are a stage and a half design where the 2 LR-87 engines ...
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2answers
3k views

At what height does it become international territory / outer space, instead of state-controlled air territory?

According to International Law, to what altitude does the jurisdiction of a state extend? Is there a definite limit mandated either through treaties or court judgements? After reaching that limit, ...
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1answer
150 views

Is it possible to launch a rocket with steam by using a fission reactor?

The idea is to use a fission reactor to turn water into steam pumping it outside the reaction chamber through heat pipes.
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1answer
68 views

Space shuttle PEG ascent burns

I'm reading a public document on the powered explicit guidance algorithm used in the space shuttle. The document suggests that PEG ascent maneuvers always involved at least three phases: Constant ...
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6answers
550 views

Has any rocket been launched into orbit from a plain flat surface?

Related: Why will Superheavy/Starship have a landing pad so close to the launch pad? Most launch vehicles are launched from somewhat complex launchpads with towers, erectors, flame trenches or ...
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8answers
4k views

Is it possible to get a spacecraft into earth orbit using Linear Eddy Current Braking on an orbital runway?

The "Space Runway" [I have slightly edited this to clarify some issues that have been raised] Luke Parrish mentioned an unusual and novel space launch method to me. The idea is to get a spacecraft ...
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1answer
1k views

Rocket launch: closed vs. open loop?

I've seen many comments that pitchover and gravity turn are "open loop" and that powered explicit guidance (PEG) leading up to orbital insertion are "closed loop." And this has me ...
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1answer
92 views

SpaceX launch simulation software?

Say you're a SpaceX launch engineer. You have a mission design meeting where you'll talk about different mission scenarios. The meeting is in a few hours. Would you run a quick simulation in KSP to ...
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0answers
32 views

How to calculate launch window?

Say I want to launch a rocket in the next 5 days for rendezvous with the ISS. I need to figure out when the orbital plane of the ISS will intersect my launch site---e.g., Kennedy. The orbital plane is ...
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0answers
36 views

Reasonable argument of periapsis?

My intuition for orbital parameters is still poor, so I'm wondering if someone can tell if my argument of periapsis seems reasonable. I'm simulating a launch from Kennedy (28.1 deg latitude, -80.6 deg ...

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