sevenperforce

Impressive. Any indication why? This is the Gen 2 Starlink group; is this a lower shell or a particularly easy inclination?

There was an incident in my family where our car was damaged while my mother was driving it, and she swears a large dog smashed into the car and then ran off. She also says a bystander told her "he does that all the time". The first time I ever had my kids in my new SUV, a bunch of deer were crossing the road so I slammed on the brakes. Came to a full stop just before I would have hit one. And then another one ran straight into the side of my car at full tilt.

I happened to work for several years for the section of the DOT that deals with steel pipeline integrity. As long as the "working" is within the tensile capabilities of the metal, there won't be any stress cracking in the metal and so it can handle a nearly unlimited number of cycles. Consider a paperclip. You can use a paperclip to clip and unclip paper an endless number of times, and the paperclip is bending each time, but it's bending across a very small range that's well within its tensile capabilities. However, you can break a paperclip quickly if you unbend it all the way and then back again several times, because that amount of bending exceeds its tensile capabilities and starts to break down the grain of the metal.

Photos show depressurization dents on the booster. Apparently common.

How certain are we of a final WDR between the static fire and the launch? On the one hand, it can't very well hurt anything, but on the other hand, I'm not sure what risk you'd be retiring by doing it, unless they think that the static fire might produce structural issues for the booster that would show up during fueling.

If not good for lick, why look like frosty? It's humid in Texas.

Having a full WDR today is really exciting.

There's no reason why it wouldn't be possible in theory, but in practice you wouldn't ever attempt that. The risk of the helicopter impacting the rover is just too high. Those blades are spinning at nearly 50 times per second and would absolutely shred the rover if there was any contact.

Yeah, but you'd be shocked by how heavy the shroud has to be. And in order for it to stretch over a significant portion of the ascent, it will have to have variable geometry.

They made it routine but it still never gets old.

Touchdown!!

Frost lines on both Superheavy tanks. No frost lines visible on Starship yet. Have they already done a full stack cryo proof? EDIT: This looks like either a partial cryo proof or an aborted full stack cryo proof, because the frost lines were larger about an hour ago: They did a partial full stack prop load on Friday.

Actively cooled heat shield? Check.

Expected cryo pressure test today; that appears to be what the extended zone is for. If that goes well, WDR next week before destack and 33-engine test.

You want to make sure you have a clear idea in your head of what "fire breathing" actually means. After all, I can breathe fire easily enough; I just put a spoonful of cornstarch in my mouth and blow it over an open flame: it makes a big gout of fire. But even if I had cornstarch-dust-producing organs, simply blowing fire out of my mouth isn't what you'd typically think of with fire breathing in the context of dragons. In media like Game of Thrones, dragons do more than just breathe fire; they spray a fluid that ignites and covers its target, like a World War II era flamethrower.

I'm guessing there's probably not going to be a destack between WDR and static fire for Starship?

Just an observation: concepts like "dragons in real life" often focus on a biological source of fuel (such as methane) but arguably the more direct biological path to a fire-breathing entity would go in the opposite direction, with the production of an extremely energetic oxidizer. Bombardier beetles can obviously produce and store hydrogen peroxide as part of an elaborate defense mechanism, although for the purposes of a large, humanoid fire-breather it would make more sense for it to be an offensive weapon like venom rather than a defensive weapon. There are already snakes which evolved to spray venom out of their fangs rather than merely injecting it. However, spraying venom is ineffective (and thus metabolically costly) unless it hits the target's eyes or other sensitive areas. Imagine if a predator with venom-spraying capabilities evolved a venom which was significantly caustic (using an oxidization reaction) and thus was able to burn away the upper layer of skin in an exothermic chemical reaction and thus deliver the venom directly into the bloodstream from a distance, even without hitting the eyes. Such a creature would be an extremely efficient predator because it could attack without closing distance, protecting it from whatever natural defenses the prey animal might have. This survival advantage would prioritize the causticity of the venom and exothermicity of the reaction, which in turn would drive the predator to evolve protections against being burned by its own venom, like heat-resistant scales. Ultimately such a creature could evolve a secondary chemical used to trigger catalytic decomposition of its venom, allowing it to self-pressurize (in the adapted fangs, which at this point have likely evolved to be used primarily for spraying and not for injecting) and fire its oxidizer-venom farther. With catalytic decomposition of a sufficiently aggressive oxidizer, it could reach the point that it was hypergolic with living tissue, igniting its target on contact.

Nuclear engines are of course terrific fun. It bears pointing out, however, that the sort of nuclear thermal engines we can currently build do not get as hot as many of the chemical engines we can build. They are more efficient not because they are more energetic than chemical engines, but because they supply their own heat and so you can use a lightweight propellant like pure liquid hydrogen without needing to bring along any heavy oxidizer.

If you want a nice look at various propellant combinations (even some pretty exotic ones), you can peep the table on this page. It has all of the data from the Joint Army-Navy-NASA-Air Force Interagency Propulsion Committee reports on propellant combos, and provides useful information like exhaust velocity, mixture ratio, chamber temperature, and propellant bulk density, both at sea level and in vacuum. If you want examples of actual propellant types used in actual rocket engines, this wikipedia page is a fantastic resource. I personally created the "Power Cycle" column for this page, actually, back in July of 2021. It has power cycle, propellant combo, specific impulse, and more.

Technically you still did get "coolest" correct. Earth has laboratories, and those laboratories include facilities which can manufacture temperatures far colder than anything in space. The coldest it gets on Pluto is -233°C, while we are able to create temperatures just a tiny fraction above -273°C. (Because Pluto and Charon are tidally locked to each other, every inch of Pluto's surface receives gradual solar insolation over the 153-day co-orbital period. Even at Pluto's extremely distant apogee, solar insolation still delivers 14,982 times more energy to Pluto than is delivered by the cosmic microwave background, which itself has a temperature of -270.3°C.)

Christmas lights! https://www.linkedin.com/posts/stoke-space_our-lights-are-hung-with-care-happy-holidays-activity-7012084589292654592-VSWK?utm_source=share&utm_medium=member_desktop

As others have said, mere ionization of atoms into plasma is nowhere near the amount of energy necessary to strip neutrons out of the nucleus. The nuclear-strong interaction holding a nucleus together, a subset of the color force, is VASTLY stronger than the electromagnetic force keeping the electrons close to the nucleus. It's not really correct to say that plasma "can revert back to the original element" once the heat dissipates, because the plasma was never anything other than the original element. I was at an adult beverage establishment last night with neon lamps. Those lamps contain atoms of neon gas. Each of these atoms contains 10 neutrons, 10 protons, and 10 electrons. The protons and neutrons are held together in a nucleus by the nuclear strong interaction (represented in red). Ordinarily, the strong positive charges of all the protons would push them apart via the electrostatic force (also known as the Coulomb force, represented here in blue), but the nuclear strong interaction is 137 times stronger than the electrostatic force, so the protons are quite happy to stay snug inside the nucleus with all the neutrons. The electrostatic force is quite good, however, at keeping the negatively-charged electrons close to the positively-charged nucleus. Here, I've depicted the neon atom's ten electrons as if they are in three concentric rings, representing the 1s orbital, the 2s orbital, and the 2p orbital, although in reality these orbitals are not rings at all. Before the neon lamp is switched on, all of the neon atoms are just bouncing around rather aimlessly in the tube: When those neon lamps are switched on, a strong electrical current runs through the gas, strong enough to rip one or two electrons free of each host atom via the Townsend process. They do not, however, rip all of the electrons free; they merely need to free enough electrons to maintain a clean plasma path for the electrical current, and then the neon lamp will glow merrily. The atoms themselves haven't moved all that much; it's the much lighter electrons that are doing all of the zipping about: This is now a plasma. Thanks to all of the free electrons, what was formerly an inert gas is now electrically conductive and will react to magnetohydrodynamic forces. Technically, this should show the inner electrons missing, not the outer electrons, because the inner electrons will actually move up to occupy the empty orbitals due to quantum excitation states. But whatever. However, you'll note that all of the atoms are still here. Just because they've lost an electron or two doesn't make them no longer atoms. Even if the plasma was so energized that literally all of the electrons were stripped away, each nucleus would remain completely intact, held together firmly by the strong nuclear interaction. None of the protons or neutrons are going to "jump" from one atom to another. You need much, much higher energies to start ripping protons and neutrons out of an atom. There is a hypothetical "plasma" called a quark-gluon plasma, where the nuclei of atoms have been compressed together so much that the protons and neutrons begin breaking apart into quarks, which "swim" freely between residual nuclei much like the electrons in an ordinary plasma. But a quark-gluon plasma would require energies far greater than even those at the center of a star. The only known quark-gluon plasma was during the Big Bang, when that was the entirety of the universe. There are some hypotheses that the centers of neutron stars contain a quark-gluon plasma kept from collapse by fermion degeneracy pressures, but we don't know for sure.

Will do. I always feel weird reporting because it feels (to me) like an assertion that someone did something wrong, rather than just a "flag for action" like it actually is.

How did I completely miss this discussion? Seems like a very promising concept. Same landing mode (kick-flip and hover) as Starship. Has the advantage of pad abort capability, which Starship lacks. Interesting split flap-cum-landing-leg design for the lifting-body re-entry control. Making it a reusable upper stage would require too much of a stretch for the lifting-body re-entry to work the way it's depicted, I think.

Not dissimilar: Also I believe this should be in the Lounge. @Gargamel or somebody?