25

It would be possible to design a check valve chain of high reliability of closing, but it would restrict flow and start to increase the risk of one valve sticking shut. You would probably also need pressure sensors between the valves to determine system state, so you end up with a large number of pipe to fitting joints that are potential leaks and a bunch of ...


12

Apparently the battery is only prone to explode while used. So when turning the satellite off, the risk appears to be mitigated sufficiently (I expect the battery to be discharged. A battery storing no energy can't cause an explosion, as an explosion is simply the uncontrolled and rather sudden release of said energy). This means the main risk of a GEO ...


8

Referring to moving to the designated graveyard orbit as de-orbiting is a little odd - perhaps autocorrect or a sub-editor had a go when they saw "re-orbiting" Moving to the graveyard orbit significantly mitigates the risk of damage to other operational satellites from explosion, as it is highly unlikely that neither of the apsides of resultant debris will ...


7

Hydrazine has a lot of spectral structure in the microwave regions (see paper), as does dinitrogen tetroxide (sorry, only paper I have is paper). This means that they’re pretty good at absorbing and reemitting, hence reflecting, microwave radar energy. Reflections are what the radar displays Off hand, hydrazine has such a thicket of strong lines that it’s ...


7

Many entries in this 1957-2015 Catalogue of Launch Vehicle Failures mention stage numbers. By my tally, the blame for launch failure goes to the first stage 42 times; the second, 60; the third, 36. If you restrict the reasons for failure to those that might apply to Falcon 9 (one entry is a Falcon 9, btw), or if you discriminate between explosions and less ...


6

At low temperatures, the activation energy for pure CH4 O2 oxidization is about 170kj/mole. (See figure 1 here) That’s about 1.8eV per atomic reaction. 1.8eV can be provided by 688nm red light, or any shorter wavelength. So generally, visible light can initiate reactions. I can’t quantify how many photons/cm2 it’ll take to start a runaway reaction from ...


6

I suspect Scott Manley doesn't have better access to sources than we do. All he can do is interpret what he sees using his knowledge of the field. In cases like this, it's tempting to gather any news you can, but everyone is laboring under the same lack of information. When an accident happens, there's only one source you can trust: the official accident ...


6

It was probably the launch of Apollo 16 with about 41.9 TJ. Apollo 16 carried the most fuel of the Apollo missions with a fuel mass of 1,439,894 + 160,551 + 43,727 (+ a little for LM?) = 1,644,172 pounds = 745,784 kg. They used RP-1/LOX for the first stage and LH2/LOX for the second and third stage. The N1 total mass was lower than Saturn V and it used RP-...


6

National Geographic reports that the 2014 Antares explosion carrying a Cygnus v4 for the Cygnus CRS Orb-3 mission "knocked two spectators off the bed of their pickup truck and another off her dock. The blast broke windows and imploded doors in buildings close to the launch site", which both shows that something did indeed knocked over and windows got blown ...


5

Boil-off of methane is piped to a Flare Stack and burned off so it won't be vented unburned into the atmosphere. You can see a good picture of the flarestack on the right in the image of Starhopper fueling below: (Image credit: NasaSpaceflight.com (bocachicagal)


5

Weather radar is not specifically measuring clouds or water in the atmosphere. What is measured is the amount of microwaves in the 5 GHz range reflected by anything in the atmosphere. This can be water droplets, but as well be insects, birds or any other kind of droplets, like propellant that didn't stay where is was supposed to be.


5

I'll just start with some things that came to my mind. Not planning to provide a complete list here. You can look at the craft itself prior to and shortly after launch. Was there any leakage or jets of propellant where there shouldn't be any? For example, smoke was visible during the final launch of the space shuttle Challenger. Comparing the video to a ...


5

Partial answer: Volume 2 of a March 1981 study (links below) by the DOD gives the External Tank explosive force on the pad as equivalent to 54,000 pounds of TNT. Rationale for the calculation is described in the paper. If you want to read some interesting predictions about what would have happened if one SRB came off during first stage, etc, etc, these ...


4

A firefighter on the scene reported that a number of train rail cars, and ground support tanks were burned and blew up in the process. Could be one of any of those.


4

How strong would the blast yield be? Probably not very. Rocket explosions usually consist of an initial small blast that blows the fuel in one direction and the oxidizer in the other. The fuel ignites, but since it's not mixed with the oxidizer, it burns at the interface between the fuel and the surrounding air, and doesn't generate much of a shock wave. ...


3

During the moon race, a soviet N-1 rocket exploded seconds after liftoff. This is ranked as one of the largest conventional explosions with an approximate yield of 1 kt of TNT. Upon impact of the base of the N1 with the pad, the vehicle exploded, destroying launch pad 110 east, which would take over 18 months to repair. [...] At T+23 seconds ...


3

Just to mention one facet of this multifaceted problem, any electrical field potential that exists (i.e. items that aren't on a common bias electrically) can and usually will at some point create an arc (spark) when it discharges. Coupling and de-coupling of interfaces, feedlines, etc especially would be a danger if their electrical fields are uneven. Also, ...


2

Liquid oxygen contains contains 4000 times more oxygen than normal air (by volume). A lot of materials that are almost inflameable in normal air may burn in liquid oxygen. Even pure oxygen at a pressure of 200 bar is a dangerous thing. Even stainless steel tubes did burn due to a steep pressure rise of the oxygen inside. Even an asphalt floor may be ...


2

The first stage filters out a lot of the mistakes. Pretty much the entire stack is tested to some extent during the first stage. This includes the hardware being subject to vibration and force as well as software for guidance etc. They are also subject to the most environmental factors, which are harder to predict and test than isolated hardware. They are ...


1

To augment @Mark's excellent answer let's remember Elon Musks tweet yes. This seems instant from a human perspective, but it really a fast fire, not an explosion. Dragon would have been fine. I can't find a perfect one-liner to quote, but something like An explosive charge is a measured quantity of explosive material, which may either be composed solely ...


1

The Intelsat 708 accident did a significant amount of damage to a village in China. On February 15, 1996, the Long March 3B rocket failed during launch, veering off course immediately after liftoff and crashing into a village near the launch site (probably Mayelin Village).1 An enormous explosion destroyed most of the rocket and killed an unknown number ...


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