sevenperforce

Yes, exactly, that's how I was conceptualizing it. A planetary fingerprint. I like that.

I have a good friend whose dad passed away yesterday at just under 89 years old, so I put together this graphic as a sort of tribute. Green marks where the planets were when he was born; yellow marks where the planets were yesterday. The dark grey lines show how much the planets changed positions during the lifetime, while the light grey indicates that the planet completed at least one full orbit. As you can see, he made it just slightly over one full orbit of Uranus and just over half a full orbit of Neptune.

Sobering but somehow sweet idea: a graphic showing how far the planets moved during someone's life.

Yes, they do (I think they are called natal charts), but while I’ve seen these charts depicting the arrangement of the planets relative to the zodiac, I don’t think I’ve seen a depiction of the planets themselves relative to the sun. It’s always a mishmash of planets and constellations aligning, never the physical locations of the planets. I felt like there might be an appeal to this because (a) it’s more grounded and approachable than “your conflict resolution strategy is Mars in Leo Rising with Jupiter Ascendant” and (b) it’s actually a truly unique identifier.

Someone saw an image depicting all of the planets lined up in a row on one side of the Sun, and asked me how frequently such an alignment occurs. I wasn’t quite sure so I did a little digging. Turns out that although the planets will end up clustered within a 90° arc every few thousand years, actually getting them into anything approaching a perfectly straight line would take trillions of years. This sparked a realization. If getting all the planets into a perfectly straight line (ignoring inclination) is vanishingly unlikely, then so is the repetition of any particular arbitrary alignment. That means that the alignment of the planets on any date in history is unique. Pick any date you like; the planets never arranged themselves in quite that way before and never will arrange themselves in that way ever again. If you imagine a top down view of the solar system, the planets are like the hands on a clock, with each planet making a full revolution in connection with its orbital period. Of course, this clock runs counterclockwise, but that is beside the point. With eight separate “hands“, however, it is a clock that never repeats itself. I did the math, and as long as mercury is at least 15 pixels away from the “sun”, you can uniquely depict any date in history, from the start of the universe until the universe’s end. How cool would it be if I set up a website where you could punch in your date of birth or any other date of significance and it would rotate the hands backward or forward on the clock from today’s date to show you the precise alignment of the planets on the date you chose? And then you could print it out and give it to someone as a gift or put it on a coffee mug or whatever else. Is this as cool as it sounds in my head or am I nuts?

It's done with work and so it's cosplaying Delta IV.

Correct -- concrete floats when you least expect it.

Interesting reversal of my idea.

I feel like something along these lines could work well. Big steel "dance floor" hung from the legs, so that they can still service the booster from underneath. Three giant steel triangles on hydraulics that translate inward and outward and fold up and down.

I will note that those are also nontrivial. If you put them on Superheavy, they impinge on Starship, which you may not want. If you put them on Starship, the impingement on Superheavy is less of a big deal, but that's also a lot of mass to push. Quick calculation -- at separation, Superheavy probably masses on the order of 650 tonnes, almost five times more than the S-IC first stage of the Saturn V. The eight retrorockets on the S-IC produced 394 kN for a period of just under a second. To get the same amount of pull-away acceleration on Starship, you'd need retrorockets producing a collective 1.9 MN of thrust...more than a Raptor 1 engine. If SpaceX used the same booster separation motors that Northrup Grumman uses for the SLS SRBs, they would need a cluster of 14 of them, which is pretty extreme. If the fuel and oxidizer are allowed to mix without igniting, and are then ignited, you absolutely end up with a detonation. Old strategy: use Starship to go to Mars New strategy: use Starship to make Earth into Mars

Agreed. Not waiting to put in a diverter was obviously a mistake, in hindsight. I'm guessing that they looked at the damage to the pad after the 50% static fire, did some modeling, and accepted the model's predictions about a full-up launch. The model most likely failed to account for the failure cascade discussed upthread, and so here we are. But if they were going to fire without a diverter, I completely agree with the decision to do it in an all-up test. Getting 5 million kg of propellant away from the pad as fast as possible is FAR better than firing and letting it sit there and go kablooey.

They are for both; there is no refuel on the lunar surface. True. However, the first few star ships to Mars will be one way. The upper section could incorporate blow-off panels in the heat shield to allow for those canted landing engines.

Any mention of steam or water tables is entirely off-base. While it is true that the water table in Boca Chica is quite close to the surface, that is not relevant to this discussion. At these temperatures, iron boils; whether or not water boils is entirely insignificant. The soil is probably somewhat saturated but that was not part of the failure cascade. In other news, it looks like my bad animation has already been picked up and people are running with it wildly. https://www.reddit.com/r/SpaceXMasterrace/comments/12uoqnv/starship_stage_separation_animation/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=1&utm_term=1 It does have a nice sort of beauty to it, though.

I will push back on this slightly. It's true that the stack was moving much slower than intended when it attempted the separation maneuver, but it was also MUCH lower in the atmosphere than intended. I mean, we can do the math fairly easily. At 40 km, the density of the atmosphere is 0.003996 kg/m3. At twice that altitude (but still below where the separation was planned), the density of the atmosphere is 0.00001846 kg/m3. That's a factor of 216.5 or thereabouts. You would have to be going 14.7 times faster at 80 km to experience the same amount of drag you experience at 40 km. Assuming that the separation maneuver was intended to take place at Mach 5 and 80 km but actually took place at Mach 1.5 and 40 kilometers, the drag and moments of torque on the stack were roughly 1949% of what was anticipated. That's a pretty good safety margin if you ask me. And that's before you factor in the number of rotations, the type of tumbling, and everything else going on.

You don't need fire for an explosion. FTS may have been what triggered it, but it still exploded from the fact that it was pressurized. This is why it breaks up into an incomprehensible number of pieces, not like... 3. True, but I do get the sentiment. A "Rocket exploded during launch" headline gives a very different vibe from a "Test launch terminated 24 miles over Gulf of Mexico after successful liftoff". The former gives the sense of something like Antares or Challenger or Ariane 5's maiden flight.

Wait, did SpaceX buy Spinlaunch?

An exoatmospheric Crazy Ivan should have very little structural strain -- aerospace members are usually stronger in tension than they are in compression. Here's a crude gif: Remember that this is a top-down view, not a side view.

I... Excuse me? The flip was planned? They were going to do a supersonic hammer-throw with a building-sized rocket to avoid fitting a normal separation mechanism. The HELL? This is Philip Bono levels of far-out. SpaceX, you have flabbered my gast most thoroughly, and I salute you. I've since received updated information and I've updated the graphic accordingly. It's more like this: Note that all of this is in the yaw axis. So less Pugachev's Cobra, more Crazy Ivan. Except the stack yaws 90° to port before commiting to the Ivan, and the booster then does a 270° Crazy Ivan but releases the Starship a third of the way through.

I don't think so. There's no confirmation that the booster actually fully lost hydraulic power at any point, and latches seem like the sort of thing that would get redundant loops. If I recall, one Falcon 9 was lost because of a hydraulic loss on the grid fin drivers, so they put in a backup hydraulic to make the grid fins dual redundant. The latches probably operate off the same hydraulic system as the grid fins, which makes them independent of the engine hydraulic unit.

The description from those on the inside is that the separation WAS commanded but didn't happen for some reason. The Starship is already supposed to have an abort mode for Superheavy failures. Granted, it might not have been programmed in yet, but trajectory issues alone wouldn't have been a reason not to attempt separation. That's a huge assumption. FTFY. It's not an assumption; it's just one possible theory. Do you really think this would have been the case on all latches on all sides ? Visually there was no seperation happing at all. It may have been that the set of aerodynamic forces and torques and the type of latches involved caused only one of the latches to seize, but it was in a position where it acted like a hinge and thus kept the stack connected: The gray arrow is the direction of travel, and the blue arrows are wind. At the moment of commanded separation (when Starship is pointed straight down in my graphic) the separation latches on the leeward side of the interstage are under slight compression (somewhat balanced by centrifugal force), while the latches on the windward side are under tension only. If they're under too much tension (because of higher than expected drag) then perhaps they wouldn't be able to retract, and so they would remain seized. This could explain the split-second image of Starship after Superheavy FTS but before Starship FTS, when the remains of the Superheavy interstage appear to be dangling from the aft of Starship by a single latch: If this wasn't SpaceX, I would think anyone bringing up this manoveur as being completely nuts I showed the (secondhand) source this image, and he's said it's the right idea but without a complete flip -- going back to the drawing board.

Holy crap. This does not look good. Those pilings are 150 feet deep, but still -- that's absolute devastation.

This article is almost two years old now and has obsolete information. There is no pusher stage separation mechanism. There is, however, a separation mechanism -- latches holding the booster and the starship together. When it's time to separate, those latches open. That article talks about a "small but significant" flick. Apparently it's much more than that: Just before MECO, Superheavy gimbals hard left and places the entire stack into a flat spin, and the spin continues under full gimbal for almost 270 degrees before MECO and separation are commanded simultaneously. Once separation occurs, both vehicles continue to rotate and drift apart. Starship rotates for almost another 90 degrees before igniting its engines and straightening out, while Superheavy does another 270 degrees before starting the boostback. It's a really very aggressive maneuver. My working theory is that due to thrust shortfall, the attempted separation happened lower in the atmosphere than planned, resulting in significant aerodynamic torque on the stack during the flat spin, which in turn placed too much shear force on the latches for them to open properly. Separation and MECO happen simultaneously, but MECO is not commanded until latch release is confirmed, and so in this case latch release never happened and so the booster kept pushing through the flat spin because it didn't know what else to do. The other possibility is that the latches were just fine, but because of the higher drag, the rotation rate never got high enough for the computer to command separation at all.

From the NSF forums: Really fascinating. This is honestly what I initially thought, given that the flip started at the time planned for the separation, and I was sure I could see the engines gimbaling, but I doubted myself after seeing a lot of people arguing that the HPU had gotten fragged and all the Raptors immediately stopped gimbaling. It makes sense, though. There was already a thrust imbalance from engine-outs. If all gimbal authority was instantly lost, it would have instantly spun out of control a la Challenger. Additional commentary: God, what an amazing, beautiful thing it will be when we see that.

It may have been that all of their estimates were slightly off, but they were all off in the wrong direction, and there were some exponential variables that all ended up combining to produce a Bad Day. To take your "erosion unit" numbers, let's suppose that the equation for "erosion units" is (strength units)(time units) x (plume interaction units) x (cascade variable)(time units) x (sound pressure units)(plume interaction units). If combining all these units together gives you 80 erosion units, but it turns out that the actual numbers ended up being ~18% higher than expected on average, then it gives you 600 erosion units. My best guess is that there was some sort of cascade effect. When the first engines started up, tank pressure dropped just slightly faster than expected, and so the staggered start took just slightly longer than planned, and the plume impingement was just slightly more damaging than anticipated, and plume interactions as the second set of engines started was just slightly more violent than expected, and so by the time the third bank started up the debris blowback was already greater than expected, and so on and so forth until the pad was getting absolutely rogered before the last bank of engines had even started up, and so engines were being fragged before it even lifted off. And so it lifted off slower, and then this extended proximity to a much more damaged pad fragged more engines, and so forth.

And then started re-entry while still burning for orbit...